Sr20 Redtop problems

[nismo90]

Whats up everyone! Well i have been a Zilvia member for a while, have mainly been searching and buying.. Especially as of lately considering i have a S14 with a redtop now. :) To start out here is my setup:

Sr20 Redtop in 95 S14
T28/BB Turbo
Stock 370cc injectors
Godspeed Intercooler (Probably to big for what i am running.. ha)
3" downpipe and Exhaust
Stock ECU
MAF out of a 89 soc ka24 (have been told are the same as a sr20)
Stock boost solenoid
Walbro 255 pump



What is happening is when i build more than 2lbs of boost it just starts sputtering.. if i ease into the throttle and stay at 2lbs its happy.. cannot punch it though..

I have checked for boost leaks and have all of them squared away except for my bov flange.. (very small leak around the weld) dont know if its bad enought that the ecu cant compensate for it?? Planning on fixing it asap. Also when we had everything apart we tested the injectors, found that a couple were sticking slightly.. figured they may free up once ran some. One last note is that it does have problems starting up cold, have to help it out some with the gas pedal.


Not to sure what could be causing this, wondering if i need a Tune considering the slight upgrades, i plan on going with nistune.. but thought i would throw all of this out there for some much needed help.. Thanks for any insight!

[nismo90]

Any Ideas out there??

[cotbu]

No tune is going to help you now, and don't let anyone tell you different.
You'll run the risk of detonating. If you were to get the car running right, with the leaking injectors and boost leak. You'd have to lean the tune out, just to get it idling properly then in boost well... bad news.

check ecu codes!
Repair the leaking injectors and minimize the boost/vacuum leak, make sure the mafs is function properly and 02 sensor, adjust tps and set/verify timing 15deg. Get the engine idling steady. then if you have a wideband and boost gauge do a full throttle pull. if it feels funny don't push it. Take note of boost and afr. then check codes

[jvega]

did you rewire the maf wires? I thought you have to rewire the maf wires when you use the z32 or the sohc maf.

[towlie]

Fix the boost leak and report back in

[nismo90]

did you rewire the maf wires? I thought you have to rewire the maf wires when you use the z32 or the sohc maf.

I did have to cut off the the old plug and wire in the one for the sohc maf.. forgot the exact wire colors and what not.. I know its a 3 wire plug.. if wired wrong would the car even run?? the ecu is not throwing any codes..

[nismo90]

No tune is going to help you now, and don't let anyone tell you different.
You'll run the risk of detonating. If you were to get the car running right, with the leaking injectors and boost leak. You'd have to lean the tune out, just to get it idling properly then in boost well... bad news.

check ecu codes!
Repair the leaking injectors and minimize the boost/vacuum leak, make sure the mafs is function properly and 02 sensor, adjust tps and set/verify timing 15deg. Get the engine idling steady. then if you have a wideband and boost gauge do a full throttle pull. if it feels funny don't push it. Take note of boost and afr. then check codes

Did you mean to say a tune is a must with my setup.. I know its always a good idea especially with a Turbo setup, just wanting to make sure since its close to stock.. ha

I am not getting any ecu codes.. To make sure i am checking correct, i turn the screw on ecu to the counter clockwise position then turning the key on?? Thats how i have been doing it.

Have replaced the O2 sensor, and still wondering about the wiring for the MAF.. I had to replace the plug to use the SOHC maf, need to verify what the 3 wire's are on the harness vs plug.. Its running so figured it may be correct.. ha No wideband yet, have a narrow band i thought about hooking up till i get a wideband.. but def am being cautious so i dont screw up my motor.

[jvega]

I did have to cut off the the old plug and wire in the one for the sohc maf.. forgot the exact wire colors and what not.. I know its a 3 wire plug.. if wired wrong would the car even run?? the ecu is not throwing any codes..

it would run, just like crap.
Once my maf clip fell off while is was driving and it just kept sputtering, low rpm's, couldnt go over 2k rpm, but i still drove it for a few min like that untill i got home and saw.

[nismo90]

it would run, just like crap.
Once my maf clip fell off while is was driving and it just kept sputtering, low rpm's, couldnt go over 2k rpm, but i still drove it for a few min like that untill i got home and saw.

mine runs fine, once it starts.. not wanting to start up easy when cold.. Once started it idles just fine and runs great till i hit over 3 pounds..ha

[cotbu]

Did you mean to say a tune is a must with my setup.. I know its always a good idea especially with a Turbo setup, just wanting to make sure since its close to stock.. ha

I am not getting any ecu codes.. To make sure i am checking correct, i turn the screw on ecu to the counter clockwise position then turning the key on?? Thats how i have been doing it.

Have replaced the O2 sensor, and still wondering about the wiring for the MAF.. I had to replace the plug to use the SOHC maf, need to verify what the 3 wire's are on the harness vs plug.. Its running so figured it may be correct.. ha No wideband yet, have a narrow band i thought about hooking up till i get a wideband.. but def am being cautious so i dont screw up my motor.

I meant, a tune wouldn't help you right now with your problem. You need a mechanic or fix the problems first. Most tuners are not mechanics and will proceed to tune even though there's a mechanical problem.

Your mafs wiring issue questions can be answered by an fsm, mafs diagram or an sr20det swap wiring guide. As a Zilvia Freak I gauge the original post on a scale. If the issue is a 2 or lower, I try to let the OP find the info him/herself. I rated you problem as a 1.

Match the sr wires to the ABC pins of the SOHC MAFS
SOHC
A Black / White +12V (Power)
B Black MAF Ground
C White MAF Signal

Leaking injectors often cause hard start issues. Have you fixed the leaky injector issue?

[nismo90]

Going to throw something else out there.. i did set my base timing before i found one of the two wires going to my knock sensor cut.. have not checked since i fixed that.. could not having the knock senosor working correct when setting base timing be a issue??

[cotbu]

if you were actually in the knock map then yes could be an issue. if it were just a circuit code i'd say it's debatable. After you make the repairs go back and do a basic tune up, includes setting the timing.

1 more time, you have to fix as much as you can then move on to getting it running correctly. Even if you have jerry rig something (not recommended) at least you'll know where to start. My tps bolt and cas ear is still jerry rigged after 4years.
I type jerry rigged XD!

[nismo90]

if you were actually in the knock map then yes could be an issue. if it were just a circuit code i'd say it's debatable. After you make the repairs go back and do a basic tune up, includes setting the timing.

1 more time, you have to fix as much as you can then move on to getting it running correctly. Even if you have jerry rig something (not recommended) at least you'll know where to start. My tps bolt and cas ear is still jerry rigged after 4years.
I type jerry rigged XD!

Agreed! I am plan on taking care of all the small issues this weekend, then will let everyone know the verdict!

Thanks again for all the help!

[nismo90]

Ok just to update.. Today i was able to try some parts off a friends car (all working on his) MASS, Ignitor, and ECU... Still same result, sputtering when hitting over 2lbs of boost. I did recheck the Base timing, and tested the injectors. Pulled fuel rail off and turned key on and off a few times (to prime system) and found no leaking injectors.. I also had a spare plug which i hooked to one injector at a time, i hooking 12 Volts to them, all seemed to be clicking just fine.

Now i am wondering if a fuel pressure regulator would cause something like this to happen?? Or a Coolant temp sensor considering it is really hard to start when cold.. Thanks for any more advice!

[SLiDe_WaYz]

What are your spark plugs gapped at that could be a issue as well.

[nismo90]

Yup, gapped them to .30 This is crazy! Also, i have been researching how to check for codes on the ecu, is turning the diagnostics screw fully clockwise "running mode" and Counter clockwise "diagnostics mode" ??

[SLiDe_WaYz]

Yes it is, and stock boost you should be gapped at .028

Count the flashes for the codes, also check the sr20 FAQ section on here it's stickied, and lists all the codes/what they are.

[nismo90]

Yes it is, and stock boost you should be gapped at .028

Count the flashes for the codes, also check the sr20 FAQ section on here it's stickied, and lists all the codes/what they are.

Ecu is not throwing any codes.. I may try getting new plugs, even though the current plugs are only a month old.. Also checked the CAS to make sure it was not off a tooth..

[Toi]

Did you check to see if the intake manifold is leaking through any of the gaskets? Have you got a pressure tester to verify you have no boost leaks?

[ultimateirving]

Stock maf cannot compensate for any boost leaks. get those fixed or it will forever sputter and break up when u enter boost.

[johnny180]

coilpacks had same problem

[nismo90]

Stock maf cannot compensate for any boost leaks. get those fixed or it will forever sputter and break up when u enter boost.

Did another leak test and found my bov flange is leaking.. And the o-ring which seals the valve. Will fix this and see what happens.. Hopefully this was it! Thanks again for all the tips, knowing it can get old helping one person so long.. ha

[nismo90]

Ok, another update.. Still having issues with the sr.. Really hard to start "when cold" once warmed up it will start decent. It does backfire some when shifting and driving it normal, seems sluggish down low and has a small mis.

It will only boost 5lbs or so before it sputters bad, i can get into it easy and it will pull ok, but cannot go wot.
Have done the following:

No boost leak
Tested injectors (leak test, ohm test)
Verified good spark (and replaced plugs)
Replaced coolant temp sensor
Tested Mass (and tried a friends from a running car)
Hooked up another ECU. (for correct model Sr)
Tried another ignitor
Tested IACV

I did find the Knock sensor is not reading correct (ohms) so it could very well be bad.. Also i have not tested my CAS.. Would one of these two cause all of this?? I know a bad knock sensor will retard the timing and possibly put it in Limp mode (or whatever it is called).. Sorry for this mess.. just need to get it resolved!

[nissansrdub]

it never hurts to double check all connectors, corrosion could be in one of the plugs. double check the brown plug under the dash right behind the passenger vent. ??? worth a shot, plus it wont cost you anything. good luck

[nismo90]

it never hurts to double check all connectors, corrosion could be in one of the plugs. double check the brown plug under the dash right behind the passenger vent. ??? worth a shot, plus it wont cost you anything. good luck

Yeah iv thought it could be wiring.. I did the wiring myself for the swap.. i am not questioning my job just the shape the harness was in when i got it.. seemed someone else went through it before i did.. I'm considering getting a new harness from wiringspecialties..

Anyone else have experience with knock sensor's?? Have been wondering if it would cause it to run bad down low and put the ecu in Limp mode etc??

[Taylor008]

Knock sensor should only have one wire going to it if it's the same as KA. It's a shielded wire.

It would absolutely make it run bad/misfire as your ECU is compensating for the bad resistance of the KS. Definitely get it replaced or solder in a resistor to diagnose your problem as the sensor is in a tricky place. (Once again, if it's the same as KA...)

When my knock sensor was bad it would lack serious power and bog under 4k rpm and then pull pretty smooth past that, although not the same as a correct powerband.

edit: just remembered you said no ECU codes... You sure you're checking right? You should be getting a code 55 if everything checks out. 34 is knock sensor iirc.

[SLiDe_WaYz]

Ok, another update.. Still having issues with the sr.. Really hard to start "when cold" once warmed up it will start decent. It does backfire some when shifting and driving it normal, seems sluggish down low and has a small mis.

It will only boost 5lbs or so before it sputters bad, i can get into it easy and it will pull ok, but cannot go wot.
Have done the following:

No boost leak
Tested injectors (leak test, ohm test)
Verified good spark (and replaced plugs)
Replaced coolant temp sensor
Tested Mass (and tried a friends from a running car)
Hooked up another ECU. (for correct model Sr)
Tried another ignitor
Tested IACV

I did find the Knock sensor is not reading correct (ohms) so it could very well be bad.. Also i have not tested my CAS.. Would one of these two cause all of this?? I know a bad knock sensor will retard the timing and possibly put it in Limp mode (or whatever it is called).. Sorry for this mess.. just need to get it resolved!

CAS could defiantly cause your problem I had the same issue. Swap your CAS with a buddy to test that theory before you spend 300 plus on a new one and it not fix the problem.

I had the same problem on my first swap the CAS was bad and the maf was also bad. But, knock sensor would also make you car bog and stall

[Luvs2slide]

Check your coil packs.

[nismo90]

Check your coil packs.

Well the verdict is in.. have a bad coil pack.. Borrowed some from a friend and she is happy now! :) Pulls Great!! cant believe it.. ha Yeah im a little excited since this is my first Nissan project/swap.. use to working on honda's.. ha

Now need to determine what coil pack is bad! Where is the cheapest place to buy coil packs??

BTW: Thanks for all the advice!