Do I need a FMU?

[2plus4plus0eq6]

Ok guys so I have a s14 sr20det in my 89. I am boosting right around 10-12 psi at the moment. a little while ago I was at like 15 psi but noticed some spiking so I reduced it. Anyways.. my car is really the only boosted car I have driven recently so I can't compare it with anything else.

at Idle, my AFR sits at around 12-15. Once my boost starts climbing, my AFR increases to about 17-18. Is this normal?

From my understanding, more boost = more fuel which should be determined from MAF sensor and ecu right?

I am positive I don't have any boost leaks. My vacuum is at like -25 and it passed a boost leak test no problem.

I have a FMU I got off a friend a long time ago. I don't know much about these things, but I am thinking I stick it in if I need more fuel coming out of my injectors when boost is increased? I don't know what ratio I will need if I even need one. I'll have to check to see which one I got off him.

Any thoughts?
Thanks

[e1_griego]

17 is very lean.

If the car doesn't run fine with all stock components you have other problems: dying fuel pump, maybe, or something like that.

Don't band-aid the problem by adding parts that work around the original issue.

[2plus4plus0eq6]

17 is very lean.

If the car doesn't run fine with all stock components you have other problems: dying fuel pump, maybe, or something like that.

Don't band-aid the problem by adding parts that work around the original issue.

I know what your're saying. I don't want to band aid anything, but I don't want to throw money around buy replacing things that don't need to be fixed either and still having the problem. I have a walbro fuel pump. Its only a few years old.

Anyways. I found an exact picture of the FMU my buddy sold me when I really didn't know shit about cars.

http://www.ebay.com/itm/BLOX-BXFU-00400-4-BL-FMU-Type-A-4-1-ratio-Blue-/290761032998

It has no writing on it. Its blue. Fittings look exactly the same as this one. I dont know what ratio it is. Can someone with some experience help me please. First of all:

1. Do I need a FMU if I am increasing boost? Is this why I am leaning out?
2. What ratio FMU should I be using? I am assuming that by not running an FMU my ratio is 1:1 right and I would only need to increase the fuel pressure a little so maybe a 4:1 FMU?
3. Is there a way to check the ratio of the current FMU I have? (EDIT: I believe I can check the size of the disk inside the FMU)
4. Are there issues that could occur from under sizing/over sizing the FMU for my engine?

[e1_griego]

No, you don't need an fmu, and on an SR should never ever need one.

[2plus4plus0eq6]

No, you don't need an fmu, and on an SR should never ever need one.

Is this because it comes boosted from factory? Now I am concerned why my AFR increases as boost increases

[Mitsubayati]

I was expecting to open this thread up and see that someone had bumped a thread from 2002.

The SR from the factory is boosted, there should be no need for an FMU. Those are just the poor man's FPR and in this case, the ecu is tuned for this engine with boost.

[2plus4plus0eq6]

I was expecting to open this thread up and see that someone had bumped a thread from 2002.

The SR from the factory is boosted, there should be no need for an FMU. Those are just the poor man's FPR and in this case, the ecu is tuned for this engine with boost.

After doing more and more research, I am starting to see that. I do have a FPR that I can put on (not a rising rate one - not sure if this type is better) that could help the leaning out problem. I think ultimately I need nistune when I get more cash.

[KAT-PWR]

Check the easy shit first.
Fuel filter!!!!

You don't need nistune you need to fix your shit.

[2plus4plus0eq6]

Check the easy shit first.
Fuel filter!!!!

You don't need nistune you need to fix your shit.

Should be fine. Its got like less than 10k on the fuel filter - running a 300zx filter

[zombiewolf513]

What is your fuel pressure gauge reading?

[2plus4plus0eq6]

What is your fuel pressure gauge reading?

I don't know. My stuff isn't installed yet. Someone at a shop that I use sometimes told me that it was dumb to install a FPR and that only newbs need them. they were also the one who said turbo surge is fine that that I was wasting my money putting on a BOV to be like fast and the furious lol..

Its hard to know what components are necessary when I get random answers all the time.

[zombiewolf513]

It depends on the need. Your car NEEDS a FPR, but the stock one will probably suffice unless youre really boosting up. What you need is a gauge to make sure that your fuel pressure is good. If you have no air leaks, your timing is good and your TPS is set correctly, I'd be looking at the fuel system, sparkplugs or exhaust system for leaks before the AFR sensor.

If you arent boosting the stock turbo over 10psi, the pressure surge isnt going to do much. Its surge during WOT thatll kill everything. Ive gone a long time without a BOV and pushed it hard, better boost response like a stock recirc valve. A trick I found is that if you start getting some surge on a throttle off situation, clutch in and bloop the throttle a baby bit. I use a tial BOV now for the 15-22psi boosting, don't buy cheap ebay shit.

[2plus4plus0eq6]

It depends on the need. Your car NEEDS a FPR, but the stock one will probably suffice unless youre really boosting up. What you need is a gauge to make sure that your fuel pressure is good. If you have no air leaks, your timing is good and your TPS is set correctly, I'd be looking at the fuel system, sparkplugs or exhaust system for leaks before the AFR sensor.

If you arent boosting the stock turbo over 10psi, the pressure surge isnt going to do much. Its surge during WOT thatll kill everything. Ive gone a long time without a BOV and pushed it hard, better boost response like a stock recirc valve. A trick I found is that if you start getting some surge on a throttle off situation, clutch in and bloop the throttle a baby bit. I use a tial BOV now for the 15-22psi boosting, don't buy cheap ebay shit.

Ok well let me give you an idea of my setup

s14 Zenki Sr20det w/ t28 stock turbo
megan racing exhaust manifold w/ fiber wrapping
custom 3" downpipe (with flex pipe) to 3" straight exhaust
Innovate AFR gauge and o2 sensor
FMIC
HKS SSQV BOV on cold side before throttle body
Generic ceramic ball w/ spring boost controller
spark plugs bkr7e gapped at 28
base timing has been increased since my lightweight flywheel and driveshaft was causing stalling.
TPS has been set back to stock setting
I actually don't know what my timing is set at, but I was getting backfire and shitty power. I messed with it and its running way better now. Still leaned out on the gauge just the same way as it does now
My boost is set at 10-12psi right now, but I was at like 15-16 before
Running 94 octane

[KAT-PWR]

I'd be looking fuel related still. Filter get trashed pretty quick if there is shit in the tank. A buddy's filter basket in the filter itself was flopping around causing sporadic AFRs. Flushed the tank replaced the filter good to go.

[2plus4plus0eq6]

I'd be looking fuel related still. Filter get trashed pretty quick if there is shit in the tank. A buddy's filter basket in the filter itself was flopping around causing sporadic AFRs. Flushed the tank replaced the filter good to go.
Fair enough. Wouldn't hurt. Cheap to do

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[2plus4plus0eq6]

I just had a weird thought..... I believe my stock injectors are 370cc. I would guess with my setup I am sitting around 250-275whp with 12-14psi.

Could this be the problem? I heard that 370cc is good for 250whp.

I think this could be the problem. I should throw my FPR on and crank that bitch up to 4 bar. That should fix the problem lol. If the injectors break, then I'll buy some 740cc

EDIT: Anther possible reason is the stock SR Maf. I heard the engine leans out once the maf starts to max out. This true?

[omgosh]

Test the wideband o2 sensor to make sure its still good. When they go bad they read lean.

Id keep it around 12-14psi...you dont have enough injector for much more.

[2plus4plus0eq6]

Test the wideband o2 sensor to make sure its still good. When they go bad they read lean.

Id keep it around 12-14psi...you dont have enough injector for much more.

How do I check it? I am pretty sure its fine. Its pretty much brand new. Its not like its reading lean all the time. It seems to be performing like it should

[Croustibat]

Check the easy shit first.
Fuel filter!!!!

You don't need nistune you need to fix your shit.

That, exactly.


You have a fuel delivery problem, and it comes from a dead fuel pump, insufficient wiring thickness for the pump, blocked fuel sock, blocked fuel filter or defective FPR.

Of course everything "should be fine", that is the concept of a failure. Everything should be, but at least 1 component has failed, so check the easy and cheap things first...

So first, check voltage at the pump, engine running.
then check pump & sock condition, also make sur it is a genuine walbro.
then check fuel filter
then check fuel pressure

my money is at 60% on a counterfeit or dying pump drawing too much amps throught the way too thin pump harness, 20% on a clogged sock and 20% on a clogged fuel filter.


Generic ceramic ball w/ spring boost controller

Bin that crap and get a real boost controler.


base timing has been increased since my lightweight flywheel and driveshaft was causing stalling.

Set your base timing correctly, the problem is not caused by a light flywheel or driveshaft but by your crappy fuel delivery and most likely a dead neutral switch and/or a dead temperature sender. I have a 12lbs flywheel... and a dead neutral switch so i got that dip.

The ECU in these cars will pull a lot of timing (a lot, like 25°) when the car is not up to temp, until a load threshold / rpm threshold is crossed. Maybe the temp sensor is gone too.

Upping boost the worst possible way (MBC) and increasing timing is the best way to destroy your pistons ring land, so i suggest you stop right now your experiments and let someone who knows about cars do his job.
It WILL cost you money, but that will be way less than getting an engine rebuild.


So sort your fueling problem (or pay someone to do it), then bring your car to a tuner. DONT buy a nistune, you already did enough damage to that engine already. Get your ECU socketed, leave the tuning job to a tuner, if he uses nistune he will plug his board in your ECU or just use his own, and then burn the data on a chip. No need to buy one. Blank chips are worth a couple of $ and an eprom burner may be around 10$ on ebay, if he says you need one he's trying to rip you off. Unless you want the extra e85 sensor to get real flexfuel control and launch control; then you need a nistune board.

I feel sorry for you, but somewhat your friend is right saying you may be too dumb to install an FPR. It is a good thing you didn't because most will mess your tune anyway, and you don't need one.
Don't worry, you will improve in due time, but it will cost way less if you start by reading than trying to do things. My 0.02 though, that is your money going in a money pit, not mine :p

[KAT-PWR]

You should direct wire your fuel pump with a relay powering straight off the battery anyway.
I was going to mention the fake walbro thing. So many people be like "got this new walbro dawg, $30 brand new on ebay bro got a deal."
No, you just got a knock off fuel pump.

[2plus4plus0eq6]

That, exactly.


You have a fuel delivery problem, and it comes from a dead fuel pump, insufficient wiring thickness for the pump, blocked fuel sock, blocked fuel filter or defective FPR.

Of course everything "should be fine", that is the concept of a failure. Everything should be, but at least 1 component has failed, so check the easy and cheap things first...

So first, check voltage at the pump, engine running.
then check pump & sock condition, also make sur it is a genuine walbro.
then check fuel filter
then check fuel pressure

my money is at 60% on a counterfeit or dying pump drawing too much amps throught the way too thin pump harness, 20% on a clogged sock and 20% on a clogged fuel filter.


Bin that crap and get a real boost controler.


Set your base timing correctly, the problem is not caused by a light flywheel or driveshaft but by your crappy fuel delivery and most likely a dead neutral switch and/or a dead temperature sender. I have a 12lbs flywheel... and a dead neutral switch so i got that dip.

The ECU in these cars will pull a lot of timing (a lot, like 25°) when the car is not up to temp, until a load threshold / rpm threshold is crossed. Maybe the temp sensor is gone too.

Upping boost the worst possible way (MBC) and increasing timing is the best way to destroy your pistons ring land, so i suggest you stop right now your experiments and let someone who knows about cars do his job.
It WILL cost you money, but that will be way less than getting an engine rebuild.


So sort your fueling problem (or pay someone to do it), then bring your car to a tuner. DONT buy a nistune, you already did enough damage to that engine already. Get your ECU socketed, leave the tuning job to a tuner, if he uses nistune he will plug his board in your ECU or just use his own, and then burn the data on a chip. No need to buy one. Blank chips are worth a couple of $ and an eprom burner may be around 10$ on ebay, if he says you need one he's trying to rip you off. Unless you want the extra e85 sensor to get real flexfuel control and launch control; then you need a nistune board.

I feel sorry for you, but somewhat your friend is right saying you may be too dumb to install an FPR. It is a good thing you didn't because most will mess your tune anyway, and you don't need one.
Don't worry, you will improve in due time, but it will cost way less if you start by reading than trying to do things. My 0.02 though, that is your money going in a money pit, not mine :p



Thanks? I guess? I can see you're trying to be honest, but instead come across more of a dick than being helpful. You are right with some stuff, but seemed to have twisted some words around to make yourself feel better.

First of all. My walbro is genuine. I ordered it straight from them. Could it be dying? maybe. Last time I opened the tank, i hand cleaned it out and the pump sock was clean which was not that long ago. Do I need a better boost controller? Yes I do. I know that, but I'm not getting one until the spring. My temp sensor could be off. Its working, but might be off a bit - I should replace it. Do I need nistune? Well I have an 89 and don't have a consult port unless I splice one in so I can't pull any engine codes. Its a guessing game. Thats one of the main reasons why I wanted nistune so I could see if there were any issues.

My friend didn't say I was too dumb to put a FPR on. It was a local shop that said it was a dumb idea to put an aftermarket FPR on. I don't know the reason you try and twist words to put people down.

I'm not the kind of guy who necessarily like to pay people to do shit. If I feel like its way out of my capabilities or I don't have the time, then yes I will. Depending on certain things, I don't have a problem risking it and blowing shit up. Its give me a reason to fix it and install aftermarket parts.

[KAT-PWR]

You can't pull codes.....
....or you havent looked at how to pull codes?
http://www.ka24development.com/ecu_codes.html

When you blow shit up, most of the time it doesn't blow up nicely, and its not a simple "upgrade it"
You don't "blow" a blow off valve and just replace it with a new better one. You blow pistons and you spin bearings and you buy a new motor. Or spend thousands to rebuild

[2plus4plus0eq6]

You can't pull codes.....
....or you havent looked at how to pull codes?
http://www.ka24development.com/ecu_codes.html

I can't pull codes

[KAT-PWR]

http://i166.photobucket.com/albums/u116/waxball88/30D022D1-47F4-4BA5-B520-71AA350FBCFA_zpsmmykydus.png
Thats crazy i've pulled codes on my KA's ecu plenty of times without consult using the little LED on the back of the ECU
http://i166.photobucket.com/albums/u116/waxball88/413D69BE-2AC5-41EE-96E8-E27650402377_zpsamzqnurb.png

[2plus4plus0eq6]

http://i166.photobucket.com/albums/u116/waxball88/30D022D1-47F4-4BA5-B520-71AA350FBCFA_zpsmmykydus.png
Thats crazy i've pulled codes on my KA's ecu plenty of times without consult using the little LED on the back of the ECU

Thanks for the help. I've tried that as well. It wasn't working for me. I've heard lots of times that some sr ecu leds don't work

[KAT-PWR]

did you have the ignition in the on position

[2plus4plus0eq6]

did you have the ignition in the on position

hah yes....

[jr_ss]

S14 SRs don't have the LED function. You need a port or scan tool, pre OBD2.

Remove your manual boost controller. You've already maxed out your injectors at 10psi anyway.

[Croustibat]

Thanks? I guess? I can see you're trying to be honest, but instead come across more of a dick than being helpful. You are right with some stuff, but seemed to have twisted some words around to make yourself feel better.

First of all. My walbro is genuine. I ordered it straight from them. Could it be dying? maybe. Last time I opened the tank, i hand cleaned it out and the pump sock was clean which was not that long ago. Do I need a better boost controller? Yes I do. I know that, but I'm not getting one until the spring. My temp sensor could be off. Its working, but might be off a bit - I should replace it. Do I need nistune? Well I have an 89 and don't have a consult port unless I splice one in so I can't pull any engine codes. Its a guessing game. Thats one of the main reasons why I wanted nistune so I could see if there were any issues.

My friend didn't say I was too dumb to put a FPR on. It was a local shop that said it was a dumb idea to put an aftermarket FPR on. I don't know the reason you try and twist words to put people down.

I'm not the kind of guy who necessarily like to pay people to do shit. If I feel like its way out of my capabilities or I don't have the time, then yes I will. Depending on certain things, I don't have a problem risking it and blowing shit up. Its give me a reason to fix it and install aftermarket parts.

Yup, sorry about the dumb part, i misread "it was dumb" for "i was dumb".

You don't like to pay, just like everyone actually. I don't either, but i know there are some jobs I either can't do or won't do, because consequences of a failure are too much to deal with.

Some jobs on a car have nearly no consequence when someone fails to do them correctly. Some, on the other hand, means "badly destroyed engine", and these are the ones we are talking about.
SR ringlands are well known for not liking knock at all, and adding boost while advancing ignition and running lean is the exact receipe for that. Adding an MBC that by definition spikes is not helping either. It could actually blow anytime. You say you don't mind, but believe me, you will say otherwise when you'll need a new engine.

My car is now running and handling very well, i am basically polishing it (engineering wise ... paint job would really be needed). I am running a nistune now and making my own maps. I used romEdit a long time ago ... just telling you what a nistune can and cant do. Yes, it helps with reading codes and finding faulting sensors too, but it wont help your leaning problem unless it is sensor related ( MAF, temp sensor, O², CAS ...) But if you only need a nistune for this, it is quite an expensive buy.

My money is still on the fuel pump dying or being choked by insufficient wiring thickness or/and clogged sock / fuel filter :p

[2plus4plus0eq6]

S14 SRs don't have the LED function. You need a port or scan tool, pre OBD2.

Remove your manual boost controller. You've already maxed out your injectors at 10psi anyway.

If s14 SR's don't have the led function then why does mine have a dial and led on it?

Yup, sorry about the dumb part, i misread "it was dumb" for "i was dumb".

You don't like to pay, just like everyone actually. I don't either, but i know there are some jobs I either can't do or won't do, because consequences of a failure are too much to deal with.

Some jobs on a car have nearly no consequence when someone fails to do them correctly. Some, on the other hand, means "badly destroyed engine", and these are the ones we are talking about.
SR ringlands are well known for not liking knock at all, and adding boost while advancing ignition and running lean is the exact receipe for that. Adding an MBC that by definition spikes is not helping either. It could actually blow anytime. You say you don't mind, but believe me, you will say otherwise when you'll need a new engine.

My car is now running and handling very well, i am basically polishing it (engineering wise ... paint job would really be needed). I am running a nistune now and making my own maps. I used romEdit a long time ago ... just telling you what a nistune can and cant do. Yes, it helps with reading codes and finding faulting sensors too, but it wont help your leaning problem unless it is sensor related ( MAF, temp sensor, O², CAS ...) But if you only need a nistune for this, it is quite an expensive buy.

My money is still on the fuel pump dying or being choked by insufficient wiring thickness or/and clogged sock / fuel filter :p

I know what you're saying. I probably exaggerated when I said that. I guess I really don't want shit to blow up lol. I just drove my car and I wasn't boosting at all, but I did notice my AFR going high. This makes me think that the injectors and Maf are not at fault. Should I adjust the timing for now to be safe while I sort out this fuel problem?

Months ago I was backfiring like crazy and had shitty power so I checked over my engine. Noticed my TPS was totally off so I set it back to stock. I fiddled with the camshaft sensor as well to make my idle better. When I took it for a drive, I noticed things were way better. My AFR is increases when my RPMs increase now just as it did then, but only in the last week it seems to have gotten worse.

I think I will grab a new temp sensor and fuel filter and test my fuel pump and see if that changes anything. I still think putting a FPR on and setting it to stock would be good to at least monitor the pressure. What do you think?

[zombiewolf513]

You can jump wires directly on the ecu to send it into diagnostic mode

[2plus4plus0eq6]

You can jump wires directly on the ecu to send it into diagnostic mode
Sounds risky. Could fry it if you don't know what you're doing. But I am curious. How?

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[zombiewolf513]

Not really risky, look at the pinout for your ecu for 12v and the chk pin, and jump

[2plus4plus0eq6]

Not really risky, look at the pinout for your ecu for 12v and the chk pin, and jump
Hm interesting. Thanks for the tip. And this should get my led flashing?

Click Image here (https://www.dropbox.com/s/eyyp4rbxy1gxk1x/ECUS14ZSR20DET_zenki.jpg?dl=0)

Pin 31 or 32?

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[jr_ss]

If s14 SR's don't have the led function then why does mine have a dial and led on it?

That's interesting. What ECU do you have? My ECU didn't have an led or switch/dial. Perhaps it was just my ECU and I manifested that information in my head.

Either way, you do have some steps to take.

[2plus4plus0eq6]

That's interesting. What ECU do you have? My ECU didn't have an led or switch/dial. Perhaps it was just my ECU and I manifested that information in my head.

Either way, you do have some steps to take.
It's a Zenki. Says wc on it I think. I tried the steps before but wouldn't hurt to try again.. all I remember was it being a pain in the ass getting the ecu back into place. I actually paid a shop to do it. I gave up LOL

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[Croustibat]

I know what you're saying. I probably exaggerated when I said that. I guess I really don't want shit to blow up lol. I just drove my car and I wasn't boosting at all, but I did notice my AFR going high. This makes me think that the injectors and Maf are not at fault. Should I adjust the timing for now to be safe while I sort out this fuel problem?


It could be your injectors dying too, but from the symptoms you are describing, i don't think they are the problem.

You should adjust the timing to where it should be. You WILL lose power but it will save your engine. It should be set at 15°, unless it came at 10° ... some of these engines were set at 10. I don't know a way to know which is which without reading the maps in the ECU. Should be ok with 15 though.


Months ago I was backfiring like crazy and had shitty power so I checked over my engine. Noticed my TPS was totally off so I set it back to stock. I fiddled with the camshaft sensor as well to make my idle better. When I took it for a drive, I noticed things were way better. My AFR is increases when my RPMs increase now just as it did then, but only in the last week it seems to have gotten worse.

TPS is a pain to set. I did mine not so long ago, when i was tired of the engine "jumping" from no power to POWEEEEEER at the slightest throttle input. I think it needs to be set so the ECU reads around 0.40V (or was is 0.48? ) at idle. If you did set it "by hand" with no tools, then it is messed up. The TPS is not really used when engine is hot, except to cut fuel injection when releasing the pedal and jumping to max fueling when going full throttle. It should not have influence on any other pedal position.

What camshaft sensor are you talking about ? The CAS ? This is what you need to move so it stay at 15° at idle. Changing timing will change performance and AFRs.

TBH it looks like your problem has been there for a long time, but you managed to hide it mostly until now; meaning it got worse.


I think I will grab a new temp sensor and fuel filter and test my fuel pump and see if that changes anything. I still think putting a FPR on and setting it to stock would be good to at least monitor the pressure. What do you think?

Start by checking fuel pump voltage, while engine running, it is free. You should have alternator voltage there, around 14V. If it is lower, you need thicker cables. This is a known problem, there are upgrade kits that use the standard power wire to trigger a relay with a thicker wiring. Very easy to install (i went the hard way, new thicker cable all the way, it was a pain).

as for the temp sensor, first get your ECU to give you its codes, it will tell you if the temp sensor is dead (it won't tell if it gives an offset response though).

You could check your sensor manually with an ohmmeter, nissan gives its values at various temp in the FSM. There are a lot of "adaptable sensors", but i have seen most of them not having the characteristics of the nissan sensor.

I suspect your O² sensor might be faulty too (or the wrong one).

Also, check your gearbox neutral switch.

Don't change your FPR. You need a standard 1:1 FPR, the OEM one is fine, and changing it usually alters the fuel delivery, so you'd need a remap. Finally, most of them have a really crappy membrane. Basically, if the FPR itself, without the gauge, cost less than 80$, it is crap and will leak internally or tear its membrane in a couple of months.

You can monitoring fuel pressure by Ting after the fuel filter and putting fuel hose and gauge there. Then use your windscreen wiper to hold it, in a way your passenger can read it while you drive. If you dont see 45psi + boost on it, then something is clogged, or the pump is defective (and/or the wiring is insufficient, but at this point i assume you already checked that).

[spools420a]

17:1 afr @ 11 psi I highly doubt its running that lean I;m willing to bet your using a autozone blinky light afr guage and not a wideband o2.

[Kingtal0n]

17:1 afr @ 11 psi I highly doubt its running that lean I;m willing to bet your using a autozone blinky light afr guage and not a wideband o2.

It certainly can be running that lean. I've made 420rwhp at 18:1 air fuel ratio in the past. Toasted the rings of course. But do understand- air fuel ratio is like a thermostat. If you turn it up (numerically) things get HOT. And that will ruin engine parts in a hurry.

[2plus4plus0eq6]

It could be your injectors dying too, but from the symptoms you are describing, i don't think they are the problem.

You should adjust the timing to where it should be. You WILL lose power but it will save your engine. It should be set at 15°, unless it came at 10° ... some of these engines were set at 10. I don't know a way to know which is which without reading the maps in the ECU. Should be ok with 15 though.


TPS is a pain to set. I did mine not so long ago, when i was tired of the engine "jumping" from no power to POWEEEEEER at the slightest throttle input. I think it needs to be set so the ECU reads around 0.40V (or was is 0.48? ) at idle. If you did set it "by hand" with no tools, then it is messed up. The TPS is not really used when engine is hot, except to cut fuel injection when releasing the pedal and jumping to max fueling when going full throttle. It should not have influence on any other pedal position.

What camshaft sensor are you talking about ? The CAS ? This is what you need to move so it stay at 15° at idle. Changing timing will change performance and AFRs.

TBH it looks like your problem has been there for a long time, but you managed to hide it mostly until now; meaning it got worse.



Start by checking fuel pump voltage, while engine running, it is free. You should have alternator voltage there, around 14V. If it is lower, you need thicker cables. This is a known problem, there are upgrade kits that use the standard power wire to trigger a relay with a thicker wiring. Very easy to install (i went the hard way, new thicker cable all the way, it was a pain).

as for the temp sensor, first get your ECU to give you its codes, it will tell you if the temp sensor is dead (it won't tell if it gives an offset response though).

You could check your sensor manually with an ohmmeter, nissan gives its values at various temp in the FSM. There are a lot of "adaptable sensors", but i have seen most of them not having the characteristics of the nissan sensor.

I suspect your O² sensor might be faulty too (or the wrong one).

Also, check your gearbox neutral switch.

Don't change your FPR. You need a standard 1:1 FPR, the OEM one is fine, and changing it usually alters the fuel delivery, so you'd need a remap. Finally, most of them have a really crappy membrane. Basically, if the FPR itself, without the gauge, cost less than 80$, it is crap and will leak internally or tear its membrane in a couple of months.

You can monitoring fuel pressure by Ting after the fuel filter and putting fuel hose and gauge there. Then use your windscreen wiper to hold it, in a way your passenger can read it while you drive. If you dont see 45psi + boost on it, then something is clogged, or the pump is defective (and/or the wiring is insufficient, but at this point i assume you already checked that).

I will double check my timing. That should definitely be done. I'll get back to you guys when I can. My TPS is set correctly. I followed the FSM and used a multimeter. The FPR I have is a megan racing one I got a while ago. Its not a rising rate one so I am sure its 1:1. I will double check other stuff before considering that right now anyways.

You know.. all in all.. I have to say my car runs really good. No backfiring, lots of power. Consistent power through each gear. I was going for a cruise last night. nothing is knocking - maybe due to my 94 octane. My idle was between 10.7-11.2 AFR. I started to punch it a bit. I hit like 17-18 AFR then as I started to climb in boost hard, it dropped back down to 15 while boost was increasing. Its a strange thing thats going on. If it helps, I will try and take a video of the AFR while driving and see if you guys notice anything weird.

17:1 afr @ 11 psi I highly doubt its running that lean I;m willing to bet your using a autozone blinky light afr guage and not a wideband o2.

I got an innovate AFR wideband o2 wideband gauge and sensor. Its considered one of the best in the market. Sometimes I do think my AFR is not accurate. Makes me believe I could possible have an exhaust leak that messing up my reading. Something that I will have to check.

[Croustibat]

overfueling without boost and underfueling on boost means you have no pressure change depending on intake pressure, either the boost reference is disconnected or the FPR is broken. If that megan FPR is installed, i have no doubt it is the culprit.

17:1 on boost means you are probably hitting 1000°C EGT, Your engine and turbo will quickly disagree with that.

[2plus4plus0eq6]

overfueling without boost and underfueling on boost means you have no pressure change depending on intake pressure, either the boost reference is disconnected or the FPR is broken. If that megan FPR is installed, i have no doubt it is the culprit.

17:1 on boost means you are probably hitting 1000°C EGT, Your engine and turbo will quickly disagree with that.

I still have the stock FPR on the motor. Would partial throttle mess up readings? The AFR seems lower on WOT than partial throttle. Have I been looking at the numbers wrong this whole time?

[cotbu]

Have I been looking at the numbers wrong this whole time?
If this is anyway true, you fail epically!
1: you have a gauge that was useless to you!
2: The interwebs!

Its like having a watch with a bunch of diamonds. If you can't tell what time it is? Then its a bracelet!

[2plus4plus0eq6]

If this is anyway true, you fail epically!
1: you have a gauge that was useless to you!
2: The interwebs!

Its like having a watch with a bunch of diamonds. If you can't tell what time it is? Then its a bracelet!

hah hey man. I wouldn't be on here asking for help if I knew what I was doing. Its a learning process

[Croustibat]

gauge showing 14.7 = stoeich, less than that =rich, more than that = lean, no matter what fuel you use (because sensor reads lambda and multiplies it by 14.7, and lambda will always equal 1 when stoeich, won't change depending on the fuel). This IS in the manual of your AFR gauge. It helps to read manuals, esp. when you have no idea what it is supposed to mean...

Anyway, check your boost reference... that is the air tube going from intake manifold to FPR. Yours is probably blocked or disconnected... or your FPR really died. But oem ones are quite solid.

[2plus4plus0eq6]

gauge showing 14.7 = stoeich, less than that =rich, more than that = lean, no matter what fuel you use (because sensor reads lambda and multiplies it by 14.7, and lambda will always equal 1 when stoeich, won't change depending on the fuel). This IS in the manual of your AFR gauge. It helps to read manuals, esp. when you have no idea what it is supposed to mean...

Anyway, check your boost reference... that is the air tube going from intake manifold to FPR. Yours is probably blocked or disconnected... or your FPR really died. But oem ones are quite solid.

Thanks for all the help. Its appreciated. I understand the numbers, but sometimes have a hard time knowing when to expect stoich, rich, lean through the rpms on accel, on deccel, etc. stupid thing seems to jump around. I'll have to look at some youtube videos to see how a AFR gauge is supposed to react.

The FPR tube.. thats a good idea. the thing could have a hole in it or something. I will check it out. I am flying out tomorrow morning for a little vacation for the week but once I get back I will take a look at stuff and reply back so its not just another thread left without answers or solutions for future people looking at this.

Thanks to everyone for all of the tips and suggestions. I think I need to check over a bunch of stuff. process of elimination to try and narrow down the problem.

[TheRealSy90]

First, stop adjusting and messing with your timing to "make it idle better". Set the timing where it's supposed to be and leave it alone!

Second, you don't need an adjustable or aftermarket fpr, at all. Your setup is far from requiring an adjustable regulator and the stock one will work just fine. Honestly the stock one works fine even over 400hp.

The reason your car stalls out is not the light flywheel or whatever, its because your bov is vented to the atmosphere and not recirculated, and your ecu is not tuned to compensate for that. The light flywheel just makes the issue even worse, but a stock setup will do the exact same thing when you don't recirculate the bov. So you need to recirculate it to the intake pipe, after the mafs, or get the ecu tuned for the vented bov.

Too much stuff you're trying to do is just bandaids for incorrect maintenance and engine setup.

10-12 psi should run perfectly fine on your setup. Any more than that you'll need it retuned to be safe. If you insist on running 15psi i'd recommend a tuned ecu.

[Croustibat]

AFR should be around 14.7 - 15 at idle, and between 10 (although that is very very rich, i don't recommend it) and 12 @ WOT. I usually map mine between 14 and 16 on cruise, depending on speed and EGTs, but i am running e85, i am quite sure you don't want to go above 15 with regular gas.

Lean AFR at idle or low load is not really dangerous. It produces heat and pollution, but thats it. It will also go lean on pedal release because the ECU cuts fuel delivery, then enable it again when reaching an rpm threshold (i raised that to get rid of the "near stalling when coming to a halt). So don't worry about that.

Dangerous AFRs are when your foot is on the pedal.

Anything leaner than that is asking for trouble. Even with good AFR values, it does not mean you are out of trouble. Timing is equally important, if not more.

Basically there are not a lot of different working fuel & timing settings when mapping an engine. There are however an infinite number of wrong settings that can or will blow the engine.

[2plus4plus0eq6]

AFR should be around 14.7 - 15 at idle, and between 10 (although that is very very rich, i don't recommend it) and 12 @ WOT. I usually map mine between 14 and 16 on cruise, depending on speed and EGTs, but i am running e85, i am quite sure you don't want to go above 15 with regular gas.

Lean AFR at idle or low load is not really dangerous. It produces heat and pollution, but thats it. It will also go lean on pedal release because the ECU cuts fuel delivery, then enable it again when reaching an rpm threshold (i raised that to get rid of the "near stalling when coming to a halt). So don't worry about that.

Dangerous AFRs are when your foot is on the pedal.

Anything leaner than that is asking for trouble. Even with good AFR values, it does not mean you are out of trouble. Timing is equally important, if not more.

Basically there are not a lot of different working fuel & timing settings when mapping an engine. There are however an infinite number of wrong settings that can or will blow the engine.

You raised your base idle? Can you please explain in detail. That's what I did cause I was stalling

First, stop adjusting and messing with your timing to "make it idle better". Set the timing where it's supposed to be and leave it alone!

Second, you don't need an adjustable or aftermarket fpr, at all. Your setup is far from requiring an adjustable regulator and the stock one will work just fine. Honestly the stock one works fine even over 400hp.

The reason your car stalls out is not the light flywheel or whatever, its because your bov is vented to the atmosphere and not recirculated, and your ecu is not tuned to compensate for that. The light flywheel just makes the issue even worse, but a stock setup will do the exact same thing when you don't recirculate the bov. So you need to recirculate it to the intake pipe, after the mafs, or get the ecu tuned for the vented bov.

Too much stuff you're trying to do is just bandaids for incorrect maintenance and engine setup.

10-12 psi should run perfectly fine on your setup. Any more than that you'll need it retuned to be safe. If you insist on running 15psi i'd recommend a tuned ecu.

Well.. it's recirculated

[Croustibat]

You raised your base idle? Can you please explain in detail. That's what I did cause I was stalling


It really is easy, i plug my computer on the nistune and set base idle value to 1000 :p

Seriously though, the dip is caused by various problems. Once the car is sorted (ie timing set, fueling ok) it should mostly disappear. If not, a remap will sort it out.

Usually though, that dip is caused by being too lean, having a boost leak and / or timing too retarded. That dip is a symptom, don't try to fix consequences, fix problems.