Lean idle when warm, checked basics

[di-devol]

Well, the car runs fantastic, good afr's after first start. Good afr's in boost, good afr's cruise.

This seems to be an intermittent problem.

So here we go:
On a cold start car runs rich(normal) 20 vac. Once warm occasionally, vac goes to 12-15 and runs so lean that the wideband maxes out full lean. Car "lopes" like a V-8.
Car occasionally run lean on VERY light throttle/Tip-in as well.
The thing that is getting me is would the car even run this lean? Idle is stable at 850rpms. Doesn't die, even running a un-reticulated BOV(runs rich when opened of course).

No vac leaks
No boost leaks(checked @30psi)
No exhaust leaks
02 sensor good
Maf is good
Injectors are brand new(and good)
CTS good
TPS good
Timing @15
Fuel pressure stock with nismo fpr


JWT tune
Sard 850's
GT2871r
Z32 maf
9:1 cp
Tomei 256 PonCams

Help if you can, the only thing that COULD be it I think is my MAF placement.
Could be a little too close:

[Turbo Nismo]

If the car is only lean in iddle I guess it won't be a problem at all, unless if it leans out when boosting. My car is lean in iddle as well and in cruising also to safe up some gas, but when boosting it's perfect.

[di-devol]

I figured lean on no-load isn't the end of the world, and I don't mind the sound at all aha, but it just bugs me that shit aint right.

[di-devol]

Got it. Runs prefect at 14.5-15.1afrs at idle now.

Maf was to close to the turbo. LOL.

[di-devol]

Ok, Car has been waaaaaaaaaaaaaay better since moving the maf away from the turbo. Now it's doing it, BUT it's now intermittent. I'm going to try a different maf and see if that helps, maybe this one is on it's way out? Car drives perfect in boost, good in cruise, intermittent lean at tip-in.


Here is a video of it running good, then running lean, shows vac dropping when it runs lean.

WATCH YOUR EARS

http://s906.photobucket.com/albums/a...ent=MOV019.mp4

Any thoughts?

[KiLLeR2001]

Judging by your temperature gauge needle, you are running a bit too hot. When my car reaches normal operating temp the needle is in between the 2nd and 3rd marker. I've noticed that when it starts creeping up past the 3rd marker the car starts running worse. I don't have an AFR gauge so I can't give you any numbers but in the video your needle is in between the 3rd and 4th marker, too hot IMO.

edit:

Here's my gauge waiting in line at Chik-fil-a... Idle is a little high I think my foot was resting on the throttle when I snapped this picture. Usually it idles around 850rpms.

[di-devol]

^hmm, I never pay attention to that needle. I have a aftermarket gauge, shows about 160 in that video. Oil temp is about 160 as well, it's cold in the mornings here and with the oil cooler car runs on the cooler side.

[KiLLeR2001]

Originally Posted by di-devol

^hmm, I never pay attention to that needle. I have a aftermarket gauge, shows about 160 in that video. Oil temp is about 160 as well, it's cold in the mornings here and with the oil cooler car runs on the cooler side.

Ah I see, then you are fine. I'm guessing it could be the MAF then. Usually if its O2 or CTS related you'll run richer. Maybe over time the MAF being too close to the turbo damaged it beyond repair. I would try a known working one next.

[di-devol]

Thanks alot man, I hit the dyno at 4:30 today and I'm a little nervous aha. It's good in boost so I should be ok.

[di-devol]

Ok, well the dyno didn't go well at all. Started leaning out hard in higher rpms. I need to back up a bit to make sense of everything for those with the same problems.

First start the engine ran lean, all the time. I thought the stock fpr was bad and installed a nismo fpr.

That didn't change anything.

I found out the maf was too close to the turbo, moved it.

That changed the lean idle to a Intermittent issue.

On the dyno, car ran super lean the whole time, lean in boost, lean idle, tip-in/light throttle sucked. Gave up and went home.

I have a problem letting things go, so I start thinking again.

Put the stock fpr in.

No more lean idle.

Went for a drive, no lean issues at all, then the car dies and won't start. T start to trace wires and find the maf signal wire at the ecu had 1 thread connecting it. I find the ecu connector loose as well.

Drive home happy, get home and find a massive exhaust leak where the DP meets the cat. That explains the dyno's afr's reading leaner than my innovate WB.

Plugs before on the Right, plugs after the Dyno on the Left:


The exhaust leak was making it seem leaner that it was, it was lean, just not THAT lean.

Going back to the dyno to verify it's all good.

New video of idle:
MOV020.mp4 video by di-devol - Photobucket

[Walperstyle]

No offence to other guy regarding the temperature, but no two cars are the same. Don't worry about temperature unless its in the 3/4 or higher range. If you have a water cooled turbo/location of where you live/type of thermostat are just a few things that play into temperatures.

Sounds like you found the main problem though.

[di-devol]

^Nope, running lean again. There is something I'm missing, something I overlooked. I will find it.

[KiLLeR2001]

What is your fuel pressure at 850rpms idle with the vacuum unplugged?

[di-devol]

Stock at 3bar with the stock fpr, I set it to 3bar when I had the Nismo fpr installed. Now I'm thinking there is nothing wrong with the Nismo one though, it ran better at first. I'm moving something, something is changing after the fact to make it run lean.

[KiLLeR2001]

When you plug in the vacuum then what does it read?

[di-devol]

37-38psi with either fpr.

[KiLLeR2001]

What fuel pump? After driving your car, if you remove the gas cap do you get a surge of air out the tank? Any weird sounds coming from the fuel pump?

Exhaust manifold to turbo manifold, what method are you using to make sure the nuts don't shake loose causing an exhaust leak?

[di-devol]

Walbro 255, removing the gascap, there usually is a pshhh sound yes, Fuel pump sounds normal, Manifold to turbo, s15 gasket, studs, nuts tack wleded, with locking tabs ahaha(I had problems previously with that).

I did have an exhaust leak where the DP meets the Cat when I was on the dyno.
When we upped the fuel pressure to 85psi, when building boost it showed rich about 10afr, then as started to climb to about 15afr at 5500rpms. I know an exhaust leak would show lean, but I wouldn't think it would get worse exponentially(ish) like that(especially starting off rich).

[KiLLeR2001]

The fact that you're telling me it starts to act up after the car warms up leads me to believe this may have something to do with your fuel ventilation system. Do you have the vent blocked off? If not, your fuel check valve may have gone bad. If too much pressure builds up in the tank it can affect your pump. There shouldn't be a swoosh of air after removing your gas cap. My friend had an issue with this because he blocked off his gas tank vent. Killed one of his pumps like this. He got a new pump and unblocked his vent and he hasn't had a problem since.

[di-devol]

I don't know what's going on anymore lol, I need to start over step by step.

[rcdad123]

put a fuel pressure gauge on it and go for a drive. watch the fuel pressure gauge while driving. if the fuel pressure goes lower than 3 bars where you set it under load/boost, the fuel pump might be going bad.

[di-devol]

On the dyno, we upped the pressure to 85psi, at WOT, the pressure did go down to 65psi.. I don't know if a walbro could hold 85psi anyway lol. BUT, 65-psi it should still not cause it to run lean.

[di-devol]

Getting the logs from teh dyno runs I did, maybe it will shine some light on what's going on.

[di-devol]

Ok, wtf is going on? I replaced the wideband sensor with a new bosch replacement, old one that came out was covered in black soot. Calibrated it in open air with a reading of 22.1afr.

Idle is still lean, I have intermittent lean light throttle. RICH AS HELL in boost now, 9:1-10.5:1.

Oh, lord, sounds like a boost leak now.

[KiLLeR2001]

Sounds like a boost leak. I would start double checking everything. How's the intake manifold gaskets (upper and lower)?

[di-devol]

Originally Posted by KiLLeR2001

Sounds like a boost leak. I would start double checking everything. How's the intake manifold gaskets (upper and lower)?

I'll check them.
I'll boost leak test when I get off work, I appreciate the help from everyone!

[di-devol]

Nope, no boost leaks. When it does idle correctly vacuum is at 19-20. Light throttle seems good right now, boost is good as well. I just dunno.

[di-devol]

Only lean at idle intermittently, light throttle seems to hesitate rarely. Boost seems very good, starts of rich at 9.5 then hits 10.8 and holds there.

When it does idle lean, it idles at 22.1 for about 10 secs then richens up to 14-15 for about 15 secs, then goes back to lean.

Why the hell is it intermittent?

[KiLLeR2001]

I'm starting to think something with the tune at this point.

[di-devol]

Originally Posted by KiLLeR2001

I'm starting to think something with the tune at this point.

If it was the tune, it wouldn't run great half the time. If it was running lean from the tune, it would never run great, there are times when it bloody perfect. Something is up.

I have to find it.