SR20DET running lean

[Nikzilla]

So I just finished up a bunch of work on the car, mostly maintenance and stuff, put it back together, set the timing, idle stop screw, TPS, IACV, got it to run smooth. I also put in a Fuel Pressure Gauge, a boost gauge, and a wideband.

The SR is stock apart from a FMIC and a 3 inch elbow-back.

Went for a test drive to Autozone and back. It felt a bit sluggish under boost, the car jerked forward (kinda like when you drop the clutch too fast) and the exhaust sounded like it was flapping (dunno how else to explain that sound). Checked my AFR's and fuel pressure. Fuel pressure is 35-37 psi at idle, 42-43 psi under boost. AFR is at 13.4-14 at WOT under boost at 3-5k RPM. I didn't wanna rev it past that.

Now, I'm thinking my fuel pressure is low. I should probably get a Walbro 255 and an FPR, but why was it running smoothly before? Or did I just not notice it?

[ultimateirving]

wallys are recommended for SR swaps and would definitely be a good idea to upgrade. And correct my if im wrong, but it should increase fuel pressure by 1 psi for each psi of boost. So if at 7 psi, it raises to 43-44ish psi, you should be ok.
If you took a bunch of stuff apart i would run a boost leak test make sure nothing is leaking where it shouldnt be.
And the ecu check for codes too

[Nikzilla]

wallys are recommended for SR swaps and would definitely be a good idea to upgrade. And correct my if im wrong, but it should increase fuel pressure by 1 psi for each psi of boost. So if at 7 psi, it raises to 43-44ish psi, you should be ok.
If you took a bunch of stuff apart i would run a boost leak test make sure nothing is leaking where it shouldnt be.
And the ecu check for codes too

From what I understand, it's supposed to idle at 43.5 psi, and with 7 psi of boost, it should be at 50.5. Mine is idling at 35-37 and boosting at 42-43.

I fixed all my vacuum leaks with the cigar test. It idles smooth.

This is gunna probably sound dumb, but I don't think my car has a consult port. How do I check for codes? It's pre OBD.

[ultimateirving]

From what I understand, it's supposed to idle at 43.5 psi, and with 7 psi of boost, it should be at 50.5. Mine is idling at 35-37 and boosting at 42-43.

I fixed all my vacuum leaks with the cigar test. It idles smooth.

This is gunna probably sound dumb, but I don't think my car has a consult port. How do I check for codes? It's pre OBD.

The fuel pressure should be at about 43psi with the vacuum line unplugged. and i think your right about being closer to 50 psi.. I forgot that the vacuum pulls the pressure down to 35ish...

I think any boosted car should at least have a walbro but thats just me.
Also the codes can be checked if your ecu has a led in it, you need to search check ecu code sr20det and there are plenty of tutorials

[Mikester]

Just to be clear, a Walbro IS a higher output pump; and definitely flows beter... but it has zilch to do with fuel pressure and everything to do with volume. An adjustable FPR just puts an additional potential point of failure into the system and really serves no purpose on a stock SR... OEM FPR will perform nicely up to 400+ hp. Just my opinion- I'm a huge fan of the KISS concept.

Definitely add a Walbro to the 'get this' list; but I think you have a vac/boost leak somewhere... or a fuel leak.

[Nikzilla]

Just to be clear, a Walbro IS a higher output pump; and definitely flows beter... but it has zilch to do with fuel pressure and everything to do with volume. An adjustable FPR just puts an additional potential point of failure into the system and really serves no purpose on a stock SR... OEM FPR will perform nicely up to 400+ hp. Just my opinion- I'm a huge fan of the KISS concept.

Definitely add a Walbro to the 'get this' list; but I think you have a vac/boost leak somewhere... or a fuel leak.


Aight, I'll do a pressurized boost leak test. I did a visual inspection around the new fuel pressure sensor, no leaks detected. Is there some special way to hunt down fuel leaks? Note: It did not reek of fuel.

[Kingtal0n]

Just to be clear, a Walbro IS a higher output pump; and definitely flows beter... but it has zilch to do with fuel pressure and everything to do with volume. An adjustable FPR just puts an additional potential point of failure into the system and really serves no purpose on a stock SR... OEM FPR will perform nicely up to 400+ hp. Just my opinion- I'm a huge fan of the KISS concept.

Definitely add a Walbro to the 'get this' list; but I think you have a vac/boost leak somewhere... or a fuel leak.

Finally someone with common sense I can retire

in reference to your engine, check for leaks between the maf and the compressor. And if it's a redtop, I suggest trying several different SOHC maf sensor hot-wires (and cleaning yours) because they all perform differently. I've done back to back testing.

[Nikzilla]

Finally someone with common sense I can retire

in reference to your engine, check for leaks between the maf and the compressor. And if it's a redtop, I suggest trying several different SOHC maf sensor hot-wires (and cleaning yours) because they all perform differently. I've done back to back testing.

But wouldn't the fact that it's failing to pressurize to 50 psi under boost be a sign that the fuel pump can't keep up?

Also, it's an S13 blacktop

[Kingtal0n]

But wouldn't the fact that it's failing to pressurize to 50 psi under boost be a sign that the fuel pump can't keep up?

Also, it's an S13 blacktop

Of course. I was only adding to the discussion. I never disagreed with anything. Someone already said the obvious: 43.5 + (X) psi of boost is where your pressure usually sits. You seem to have gotten that idea quite well, why repeat?

As a side note, since you made me post about fuel pressure. If you DO happen to install a completely unnecessary regulator, you may as well take some load off your fuel pump and lower the pressure a bit. If you have enough injector, drop the psi a few (3-7psi) and your pump will live longer, and the fuel will stay colder.

[Nikzilla]

Of course. I was only adding to the discussion. I never disagreed with anything. Someone already said the obvious: 43.5 + (X) psi of boost is where your pressure usually sits. You seem to have gotten that idea quite well, why repeat?

As a side note, since you made me post about fuel pressure. If you DO happen to install a completely unnecessary regulator, you may as well take some load off your fuel pump and lower the pressure a bit. If you have enough injector, drop the psi a few (3-7psi) and your pump will live longer, and the fuel will stay colder.

The aftermarket FPR may be unnecessary, but won't it kill fuel efficiency?

But the butt of my question is. Is the fuel pump likely to be the main cause of my lean condition? Should I make time to drive to FRsport to pick up a Walbro before the weekend, or should I not worry about it and instead hunt for more vacuum leaks?

[Kingtal0n]

The aftermarket FPR may be unnecessary, but won't it kill fuel efficiency?

But the butt of my question is. Is the fuel pump likely to be the main cause of my lean condition? Should I make time to drive to FRsport to pick up a Walbro before the weekend, or should I not worry about it and instead hunt for more vacuum leaks?

What do you mean by fuel efficiency? your car has a regulator. If you install another one, then theres two of them. They do not work differently. One may have larger ports and a more reliable, newer design, or it could be a worse design with cheap parts. Either way, they do the same thing.

You should have a walbro in the tank, yes. Everyone with an sr20 on a budget needs at the very least, that. If you are about to tell me that you have an sr20 with a stock pump in the tank... Just do not tell me that.

[Nikzilla]

What do you mean by fuel efficiency? your car has a regulator. If you install another one, then theres two of them. They do not work differently. One may have larger ports and a more reliable, newer design, or it could be a worse design with cheap parts. Either way, they do the same thing.

You should have a walbro in the tank, yes. Everyone with an sr20 on a budget needs at the very least, that. If you are about to tell me that you have an sr20 with a stock pump in the tank... Just do not tell me that.

I was under the impression that the stock FPR with the walbro will run at like 70 psi, hence making the car run stupid rich, wasting gas. I thought the point of an aftermarket FPR was to relieve that extra pressure.

And yeah I do have a stock pump. I bought the car like that lol. I'll get it swapped this weekend then.

[Mikester]

1. The aftermarket FPR may be unnecessary, but won't it kill fuel efficiency?

2. Is the fuel pump likely to be the main cause of my lean condition?

3. Should I make time to drive to FRsport to pick up a Walbro before the weekend, or should I not worry about it and instead hunt for more vacuum leaks?

1. No. Aftermarket FPR does the very same thing as stock... It just gives a broader effective range of pressure regulation so you can set it up for specialty tunes and boost levels you will likely not see for quite some time.

2. No. My money is either on a vac/boost leak or shitty power or ground. Most times in my experience (not a mechanic, just a guy who's had an SR for 8+yrs), the fuel pump will eoither work, or not work. HOWEVER, I've seen a lot of stock, 20yr old 240's with tons of 'shit' swirling around the tank; and the filter sock had fallen off a decade or so ago... any debris in the pump plumbing or lines could cause this as fuel demand increases. Also, although a higher volume fuel pump IS a good thing to have, the stock 240SX fuel pump will handle the SR's [stock] fuel demand all day long. If you don't want to pay for a Walbro, a 300ZX fuel pump is a nice alternative.

3. MORE vacuum leaks??? LMAO!

Just because it idles smooth, does not mean you don't have a leak somewhere. This is one of the problems with forced induction- any leaks may only be detectable under [boost] pressure... Boost pressure falls, so will fuel pressure. Check every single line, fitting etc in the system... make sure they are tight and pliable.

- Have you verified a good, tight fuel system from the tank to the motor? A slightly loose or hairline-cracked fuel line will be fine at idle, but as pressure/demand go up; fuel will start to leak out... meaning less fuel pressure at the rail.

- Have you verified a good charging voltage (should be 14.2 - 14.6VDC) at the battery? If it reads more like 15 - 15.6VDC, I'd recommend you check your charging circuit- this will absolutley affect your fuel pump's output under load (found this out the hard way on the dyno recently). There is a connector near the main fuse box that should be connected with an SR swap.... Sometimes, it gets overlooked.

I was under the impression that the stock FPR with the walbro will run at like 70 psi, hence making the car run stupid rich, wasting gas. I thought the point of an aftermarket FPR was to relieve that extra pressure.

And yeah I do have a stock pump. I bought the car like that lol. I'll get it swapped this weekend then.

No. See note #1 above.

Okay... A Walbro does not add pressure- it only adds capability in the way of flow rate & volume. The regulator controls the pressure; and it doesn't matter what kind of pump is in there... The fuel pump output (volume/flow rate) is based on the regulated pressure... Higher pressure = less flow. At stock boost levels, a stock pump can handle the steiffeling of flow... However, once system pressure requirement goes up (like boosting 15-20+psi), THIS is where the higher volumetric output of the Walbro comes into effect, keeping you from turning your pistons into 86mm cockrings. Even though the thought process is 'less flow to the rail is bad,' it's the PRESSURE it's under and volume being sent via the pump that keeps the rail full, not the other way around. It's pretty cool, actually.

On that note, if your alternator charging voltage is up, that means that there is unnecessary load (resistance) somewhere in the electrical system. Larger load on the electrical system means there is less available current for the fuel pump to use. Remember- as boost goes up, it requires more juice (current) to push fuel out of the tank under higher pressure. End result = lower-than-normal fuel pressure under load.

[Nikzilla]

Mikester thank you very much for your amazing detailed reply!

I just bought the Walbro and a Tomei FPR, might as well, they're good modifications.

I just started the car up to look at my fuel pressure, and I noticed something. it idles at about 35-37, when I rev it to 2-3k, it goes up to 42-43, but if I hold it, after 2 seconds it falls back down to 35-37. Is that normal?

The reason I said "more vacuum leaks" is because I already replaced 2 different cracked hoses lol.

I'll follow your advice and check for boost leaks by pressurizing the intake system to 7 psi. I'll also check the charging voltage.

Thanks!

[Kingtal0n]

At stock boost levels, a stock pump can handle the steiffeling of flow..

Not always. I've swapped quite a few cars in the last 10 years and 90% of them would not boost 7psi with the stock in tank fuel pump.

My money is on the pump

[Nikzilla]

Not always. I've swapped quite a few cars in the last 10 years and 90% of them would not boost 7psi with the stock in tank fuel pump.

My money is on the pump

Well, we shall find out on saturday when I put the sucker in!

[ultimateirving]

Well, we shall find out on saturday when I put the sucker in!

Nik, see about getting a new fuel pump cover o-ring too. They often aren't reusable because they swell and are damn near impossible to put back in.

[Nikzilla]

Nik, see about getting a new fuel pump cover o-ring too. They often aren't reusable because they swell and are damn near impossible to put back in.

Shit. Every fucking time I drive down to FRsport, when I come back I always have a "SHIEEEEEEET I FORGOT ABOUT THAT!" moment.

[Nikzilla]

Yay! Local dealer has em in stock! Today is a good day.

[pablito_s13]

i have a trick for that o ring

1. Just do a cut on it

2. match the size to the gas tank hole

3. Cut the extra peace that overlaps off

4. Tape it back together with electrical tape.

Worked for me. i got tired of buying that "O" ring every time i remove my fuel pump

[Mikester]

^^Don't get me wrong... First time I did a Walbro swap, I did exactly ^^that^^ (minus electrical tape)... But I wonder... How many times does one realistically remove their fuel pump?
:D

[Nikzilla]

^^Don't get me wrong... First time I did a Walbro swap, I did exactly ^^that^^ (minus electrical tape)... But I wonder... How many times does one realistically remove their fuel pump?
:D

Haha exactly what I was wondering!

[Nikzilla]

Ok, so I swapped the fuel pump.

People who said that FPR's aren't necessary were 100% correct. The fuel pressure is 100% to spec without the FPR.

So I took it for a test drive, awesome! The AFR seems dead on. I decide to go to Firestone to get an alignment. So I'm turning onto the main road, hit boost in 1st gear, hear a loud PSSSSSSSSFT, the car stumbles and dies. The hotpipe just flew off the intake turbo elbow. I call my mom to bring me a damn 8mm socket and put it back in lol.

So I decide to go for a drive. Under WOT, the FPR starts at about 14 at 3k and goes down to 11.7 by 5k. I'm pretty sure that's dead on.

BUT,

I notice something REALLY weird on the highway. If I drive with the throttle juuuust barely in, (pretty much exactly how much throttle you would need to maintain 60mph) the AFR's shoot up to 20 in about 2 seconds and the car starts to stumble. But if I push the gas just a BIT more, you feel like a kick as the AFR's come back down to normal and the engine returns to normal. This made it very annoying to drive, as I had to go from 0% throttle to 50% throttle every couple of seconds to maintain speed. And after about 30 minutes of driving my hotpipe flew off again lol. Good thing I had the wrench with me.

So, since I did a full idle stop screw, TPS, IACV and timing adjustment to get the thing to run, I thought maybe I didn't tighten the TPS well enough, and it slipped, causing the TPS to read as idle under part throttle, and hence the ECU is using idle fuel map tables.

When I got home, I stuck probes down the TPS connector and it read 0.5V dead on.

So WTF is going on?

[TheRealSy90]

You aren't using the idle screw on the throttle body to adjust idle right? The tb should close fully.


Sent from my iPhone using Tapatalk

[TheRealSy90]

And do you have a wideband or are you just looking at fuel pressure while your driving?


Sent from my iPhone using Tapatalk

[Nikzilla]

Have a wideband.

I used this thread to setup my idle:

Idle Problems ? this worked for me SR20DET - Hardtuned.net (http://www.nissansilvia.com/forums/index.php?showtopic=281371)

So basically I closed the IACV, disconnected TPS, adjusted stop screw until it idled at 750rpm, then adjusted TPS until it read 0.5V with the throttle closed, then adjusted IACV until it idled at 825rpm (although it's more like 750 right now, I gotta adjust it again (the car prolly wasn't all the way warm)).

[Kingtal0n]

Ok, so I swapped the fuel pump.

People who said that FPR's aren't necessary were 100% correct. The fuel pressure is 100% to spec without the FPR.

So I took it for a test drive, awesome! The AFR seems dead on. I decide to go to Firestone to get an alignment. So I'm turning onto the main road, hit boost in 1st gear, hear a loud PSSSSSSSSFT, the car stumbles and dies. The hotpipe just flew off the intake turbo elbow. I call my mom to bring me a damn 8mm socket and put it back in lol.

So I decide to go for a drive. Under WOT, the FPR starts at about 14 at 3k and goes down to 11.7 by 5k. I'm pretty sure that's dead on.

BUT,

I notice something REALLY weird on the highway. If I drive with the throttle juuuust barely in, (pretty much exactly how much throttle you would need to maintain 60mph) the AFR's shoot up to 20 in about 2 seconds and the car starts to stumble. But if I push the gas just a BIT more, you feel like a kick as the AFR's come back down to normal and the engine returns to normal. This made it very annoying to drive, as I had to go from 0% throttle to 50% throttle every couple of seconds to maintain speed. And after about 30 minutes of driving my hotpipe flew off again lol. Good thing I had the wrench with me.

So, since I did a full idle stop screw, TPS, IACV and timing adjustment to get the thing to run, I thought maybe I didn't tighten the TPS well enough, and it slipped, causing the TPS to read as idle under part throttle, and hence the ECU is using idle fuel map tables.

When I got home, I stuck probes down the TPS connector and it read 0.5V dead on.

So WTF is going on?

1. never adjust the throttle body open/close
2. the tps is rarely a problem, just leave it "centered" and forget about it
3. Check for boost leaks, fill the plumbing with compressed air (15~ PSI). If you had done that your hot pipe would have come off during the boost leak check instead of the on the road.
4. your oxygen sensor sounds like it is bad. Try unplugging your O2 sensor (NARROWBAND) to see if that fixes the problem of leaning out on the highway.

[TheRealSy90]

Yeah you never use the throttle body to adjust idle, it's supposed to close all the way that's what the iacv is for.


Sent from my iPhone using Tapatalk

[Nikzilla]

Yeah well my friend accidentally touched it in his ignorance when I asked him to adjust idle while I watched the revs lol, so I had to follow the procedure to reset the whole system.

The O2 sensor sounds like a good point, but I thought it trims the fuel through the whole powerband, no? Why would it only happen at 10% throttle? I'll give it a shot right now, if that doesn't work, I'm gunna have to build a bloody boost leak tester.

[Nikzilla]

Ok so I unplugged the O2 sensor. The symptoms are pretty much the same, except now instead of leaning out continuously, it just holds at 16.5. Add a bit more throttle and it settles down at the 14-15 it's supposed to be. Oh. and also, if you give it half throttle in high gear at low rpm (like 2-3k) it jerks a bit.

I'll try to build a boost leak tester today.

[Kingtal0n]

Ok so I unplugged the O2 sensor. The symptoms are pretty much the same, except now instead of leaning out continuously, it just holds at 16.5. Add a bit more throttle and it settles down at the 14-15 it's supposed to be. Oh. and also, if you give it half throttle in high gear at low rpm (like 2-3k) it jerks a bit.

I'll try to build a boost leak tester today.

it might be a bad tps. Just unplug the tps and try again to eliminate it as a suspect. The car will get it's info from the maf sensor. If there is no boost leak (test that first!), and the problem does not go away when you unplug the tps + O2, then you are left with only [maf sensor, ecu, wiring, or a leak between the turbo and maf] for the most part.
When you do your boost leak check, try to include the plumbing between the maf and turbo.

[Nikzilla]

it might be a bad tps. Just unplug the tps and try again to eliminate it as a suspect. The car will get it's info from the maf sensor. If there is no boost leak (test that first!), and the problem does not go away when you unplug the tps + O2, then you are left with only [maf sensor, ecu, wiring, or a leak between the turbo and maf] for the most part.
When you do your boost leak check, try to include the plumbing between the maf and turbo.

I was thinking it might be the TPS too. I was gunna check it's voltages through out the range.

Do you mean just take it for a drive with MAF only as the ECU's input?

[Kingtal0n]

I was thinking it might be the TPS too. I was gunna check it's voltages through out the range.

Do you mean just take it for a drive with MAF only as the ECU's input?

yes unplug the tps, and/or O2. try them in sequence, first one, then the other. Or both at once if you want, but issues are more difficult to diagnose when you start making more than one change at a time.

[Nikzilla]

Tried it. Same exact thing. Maybe it's supposed to run at 16.5 in 4th gear at 2200 RPM steady?

[Nikzilla]

Once I put the TPS and O2 back in thou, it became worse. It would lean out continuously until my gauge would max out and the car would start dying in a course of 2 seconds.

[Kingtal0n]

Once I put the TPS and O2 back in thou, it became worse. It would lean out continuously until my gauge would max out and the car would start dying in a course of 2 seconds.

did you test for boost leaks first? Fill the plumbing to 15psi.

Try Resetting the ECU as well. Leave the O2 sensor UNPLUGGED, unplug the battery, Cycle the ignition. Wait a few minutes. Then re-connect the battery. LEAVE the O2 Disconnected and take it for a drive.

It sounds like a bad O2 sensor, or wrong O2 plug / wiring, combined with a poor signal from the maf. What ECU does the car have? #62? Could also be an air leak, but we are going to eliminate that as a possibility because you are going to do a boost leak check FIRST.

[Nikzilla]

did you test for boost leaks first? Fill the plumbing to 15psi.

Try Resetting the ECU as well. Leave the O2 sensor UNPLUGGED, unplug the battery, Cycle the ignition. Wait a few minutes. Then re-connect the battery. LEAVE the O2 Disconnected and take it for a drive.

It sounds like a bad O2 sensor, or wrong O2 plug / wiring, combined with a poor signal from the maf. What ECU does the car have? #62? Could also be an air leak, but we are going to eliminate that as a possibility because you are going to do a boost leak check FIRST.

I already did the ECU reset. After I first went for a drive with the O2 unplugged, when it was at 16.5, I stopped for lunch and unplugged the battery.

It's a stock ECU.

And yeah, I'll start building that bloody boost leak tester now.

[Kingtal0n]

I already did the ECU reset. After I first went for a drive with the O2 unplugged, when it was at 16.5, I stopped for lunch and unplugged the battery.

It's a stock ECU.

And yeah, I'll start building that bloody boost leak tester now.

If you get a chance, grab a SOHC maf sensor hotwire. Usually I just goto the local junkyard (U-Pull-it) and grab a few at a time. Get it with the plug because the plug is different slightly. All you need is a Philips head screwdriver, and something to cut the wires with. Dont take the whole maf- just the hotwire portion that bolts into the maf with 2 screws.

Also, when you get a chance, pull out the maf hotwire from your own maf, and clean it. I just use brakeclean but you are not supposed to- they sell special maf cleaner for it.

[Nikzilla]

If you get a chance, grab a SOHC maf sensor hotwire. Usually I just goto the local junkyard (U-Pull-it) and grab a few at a time. Get it with the plug because the plug is different slightly. All you need is a Philips head screwdriver, and something to cut the wires with. Dont take the whole maf- just the hotwire portion that bolts into the maf with 2 screws.

Also, when you get a chance, pull out the maf hotwire from your own maf, and clean it. I just use brakeclean but you are not supposed to- they sell special maf cleaner for it.

I'll do that too, thanks!

[Nikzilla]

Ok so.

I got myself a can of tomato sauce. That shit fit perfectly in my intake.

Got 2 tire valves, hoses, hose clamps, and a tire pressure gauge. Drilled 2 holes in the tomato can, put the valves through them, sealed them with quick steel epoxy. Took the stem out of one valve, hose on that valve running to the pressure gauge, which has it's spring mechanism taken out. Everything is hose clamped. Took out the MAF/pod filter combo and put the tomato can in there and clamped it.

I couldn't find my old bike pump so I just used the tire inflator that comes on my battery jumper. I let that sucker run for 10 minutes straight, the pressure gauge didn't even budge. I couldn't feel any air coming out of anywhere, it all seemed air tight. I even took out the tomato can, put it to my mouth and tried to blow. It's air tight. I pulled the vacuum hose of the wastegate, and I could just barely feel the air coming out. I had to lick my finger just to feel it.

Does the tire inflator just suck? Do I need to use a bike pump?

I'm also gunna hook up a paint can with a burning rag in it between the tomato sauce and the bike pump to get smoke in the system.

I also took the opportunity to clean the MAF with MAF cleaner spray. It didn't look dirty at all thou.

[Mikester]

Ya know what I think? I wonder if you verified the condish of your plugs after all that running lean. A 'stumble' at certain levels but good all in/all out good be as simple as shitty plugs.

[DashS13]

my sr started doing the stumbling and hesitation after i installed the s14 sr turbo inlint. Maf is stock, and its mounted directly on to the inlit itself. This hesitation is around 2500-3000 rpms, and it stops after i open up the throttle body a little more. checked the plugs out and all were good, but it just dies and i can smell unburned gas without even getting out of the car

[Nikzilla]

Ya know what I think? I wonder if you verified the condish of your plugs after all that running lean. A 'stumble' at certain levels but good all in/all out good be as simple as shitty plugs.

I actually did check them and regap them right before I went for my first drive when I got the car running. They looked just fine. I gapped em to 0.032in. I'll check em again today. The lean could have indeed killed em.

my sr started doing the stumbling and hesitation after i installed the s14 sr turbo inlint. Maf is stock, and its mounted directly on to the inlit itself. This hesitation is around 2500-3000 rpms, and it stops after i open up the throttle body a little more. checked the plugs out and all were good, but it just dies and i can smell unburned gas without even getting out of the car

That sounds strangely similar to my problem. Can you describe what was the cause in a bit more detail please?

[Mikester]

Couldn't hurt to swap them out. Try gapping to .030.

[DashS13]

unfortunately i have yet to find the cause. i have been ignoring the diag screw on the ecu due to not having a precision screw driver handy, mine honsetly feels like more boost leak related. my car recently started dieing after high revs and the bov lets off, gonna check the recirculation on that also if diag screw takes me no where, also started doing this when the temp out side was average of -15 in the morning...dont know if thats a huge issue or not

[Kingtal0n]

Ok so.

I got myself a can of tomato sauce. That shit fit perfectly in my intake.

Got 2 tire valves, hoses, hose clamps, and a tire pressure gauge. Drilled 2 holes in the tomato can, put the valves through them, sealed them with quick steel epoxy. Took the stem out of one valve, hose on that valve running to the pressure gauge, which has it's spring mechanism taken out. Everything is hose clamped. Took out the MAF/pod filter combo and put the tomato can in there and clamped it.

I couldn't find my old bike pump so I just used the tire inflator that comes on my battery jumper. I let that sucker run for 10 minutes straight, the pressure gauge didn't even budge. I couldn't feel any air coming out of anywhere, it all seemed air tight. I even took out the tomato can, put it to my mouth and tried to blow. It's air tight. I pulled the vacuum hose of the wastegate, and I could just barely feel the air coming out. I had to lick my finger just to feel it.

Does the tire inflator just suck? Do I need to use a bike pump?

I'm also gunna hook up a paint can with a burning rag in it between the tomato sauce and the bike pump to get smoke in the system.

I also took the opportunity to clean the MAF with MAF cleaner spray. It didn't look dirty at all thou.

1. we usually just use a small piece of pvc with a single hole for the tire valve
http://i10.photobucket.com/albums/a109/dave926/2011-01-08153208.jpg


2. You need to use an air compressor and verify that the plumbing builds 15psi of pressure, and holds it there.

3. Points of interest when doing your check:
a. the hose that runs from the turbo inlet to the valvecover can be blocked with a large black marker, use a hose clamp
b. put the PCV in place of the maf. use the maf clamp to seal it up. No need to use sealant or anything liquid anywhere when doing this.
c. use a tire valve so you can do this anywhere you would normally fill your tire.
d. If the engine is stopped in such a way that both an intake and exhaust valve is open simultaneously, the air will leak right out into the exhaust (because it will flow through the IACV). If at first you see no pressure building, listen in the exhaust for airflow, then bump the engine slightly to move the valves closed.
e. alternatively to d., you can remove the hose from the IACV and block that as well. But this is not recommended because that hose is usually very difficult to remove without taking off the cold pipe.

And I may have forgotten something. I've been driving an N/A vehicle for a few months so my turbo instincts are corrupt. XD

[Nikzilla]

Ok, I found a massive fucking hole in my intake right behind the MAF.

Wtf is this hole?

http://i.imgur.com/eG91rIU.jpg?1

I'm gunna seal it up for now.

P.S. Ditched the tomato sauce, tried again with chicken noodle. Confirming Chicken Noodle is best for finding boost leaks.

[Nikzilla]

Ok well I did a super professional job of sealing it.

http://i.imgur.com/Xqa7qEP.jpg

Brb gunna pressurize the intake again.

[Nikzilla]

I still couldn't get pressure into the system, so instead I hooked up my chicken noodle soup to a paint can and burned an oily rag in there to create smoke, and then pumped it into the intake. No smoke came out, but I still couldn't pressurize it (I think my schrader valve seals are letting loose under pressure), however, when I pulled a vacuum line off, a significant amount of air pressure came out, which means that the system does indeed hold pressure!

[Kingtal0n]

I still couldn't get pressure into the system, so instead I hooked up my chicken noodle soup to a paint can and burned an oily rag in there to create smoke, and then pumped it into the intake. No smoke came out, but I still couldn't pressurize it (I think my schrader valve seals are letting loose under pressure), however, when I pulled a vacuum line off, a significant amount of air pressure came out, which means that the system does indeed hold pressure!

no, dont cop out. you need to hold 15psi in there. Something starts leaking at 2psi you cant even hold 1psi of pressure thats not a good sign. Some leaks wont even show up till 5psi;

[Nikzilla]

Ok, so I took her for a test drive.

She's dead on! It seems like that hole was the only issue remaining.

60mph cruise, 15.5 afr, high RPM pull, dead on 11.0 afr.

Awesome!

Thank you guys for helping me pin this sucker down!

[Nikzilla]

no, dont cop out. you need to hold 15psi in there. Something starts leaking at 2psi you cant even hold 1psi of pressure thats not a good sign. Some leaks wont even show up till 5psi;

What's leaking isn't the car but my boost leak tester. I couldn't find any PVC endcaps that could fit, so I had to use food cans. I tried my best to seal them as good as I could, but under pressure they still break loose.

If I want to test it to 15psi, I would need to find 2.5inch PVC endcaps somewhere.

[Mikester]

Definitely add a Walbro to the 'get this' list; but I think you have a vac/boost leak somewhere...

Glad you found that hole... Sucking in un-metered air is never a good thing.

[Nikzilla]

Ok, looks like I'm not quite done yet!

Patching up the hole did help. Before, my AFR at WOT at 5k+ RPM was 12-12.4. Now it's 11.0.

However, I was still disturbed by the 16.5 5th gear 100kph cruise, as I read that it should be about 147, and sometimes it would stumble hard (jerk the car a lot) under half-throttle at about 2500 RPM up until it would boost. So I decided to plug my O2 back in, because I thought that it would trim the fuel map and smooth out the car.

After driving it for 2 hours with the O2 plugged in, it gradually leaned out the car, making it worse, and the problem came back where it would lean out to 20+ under very light throttle. It became very hard to drive as I had to pulse the throttle on an off to use the fuel enrichment to richen the mixture. So I unplugged the O2, and cycled the ECU (disconnected battery for 30min). It became drivable again, albeit still at 16.5 on the highway.

Now, I'm 70% certain that I destroyed the O2 sensor while making the car run right. My other 20% is set on another vacuum leak. 10% uncertainty.

What do you guys think?

I ordered a consult cable, and it should be arriving this week. I don't wanna potentially replace a perfectly good O2 sensor, so I'm going to wait and abstain from driving the car until I can see what's up in DataScan.