Lean Idle After Pulling Efi

[Fubar231]

So last night after some hard pulls the CEL came on, code 12, 34, and 52 *FUUCK* anyways, went home, pulled the EFI to reset stuff, went back out for some hard pulls and everything was all good. I think the 52 was from when i brake boosted and built too much boost at a low RPM. Anyways, my Idle is like 16.5-16.7 on my wideband, but when driving, getting on it, whatever, its fine. 14.7 while cruising, 10-11's @ wot... Just dont understand why the idle is so lean. Vac at idle is 18-19 so that seems right too, egts are fine water temps fine oil psi is fine... Just lean idle and i dont get it!!!

Mods are...
Apexi intake, cooleze intake pipe, 57 trim ct-26, ic pipes and spearco replica, walboro 255 , lex afm, 550s, turbo back exhaust, mhg, tons of gauges. I think thats all that really matters.

Anyways, any ideas why the lean idle?

Thanks,
Shane

 

[super.secret.supra.club]

my vac at idle is 24. i think ou might have a va leak. maybe a small vac house

 

[Fubar231]

Im pretty sure i dont have any vac leaks, i just put a new head on the car less than a month ago, im pretty sure your vac is just due to elevation or something. Mines been 18-19 since i bought the car 3 years ago. I also pulled the EFI again and its still 16.5-17 at idle, but fine everyother time... Any ideas???

Oh, and ill probably boost leak test it tomorrow or within a day or so just to rule that out, but i replaced all the vac lines when i did the headgasket.

 

[enjoi.this]

After doing hard pulls like that its possible you popped off vac lines. 15psi seems to be where they like to come off.

 

[shaeff]

So last night after some hard pulls the CEL came on, code 12, 34, and 52 *FUUCK* anyways, went home, pulled the EFI to reset stuff, went back out for some hard pulls and everything was all good. I think the 52 was from when i brake boosted and built too much boost at a low RPM. Anyways, my Idle is like 16.5-16.7 on my wideband, but when driving, getting on it, whatever, its fine. 14.7 while cruising, 10-11's @ wot... Just dont understand why the idle is so lean. Vac at idle is 18-19 so that seems right too, egts are fine water temps fine oil psi is fine... Just lean idle and i dont get it!!!

Mods are...
Apexi intake, cooleze intake pipe, 57 trim ct-26, ic pipes and spearco replica, walboro 255 , lex afm, 550s, turbo back exhaust, mhg, tons of gauges. I think thats all that really matters.

Anyways, any ideas why the lean idle?

Thanks,
Shane

Shane,

1) ALWAYS put zip ties on the ends of your vacuum hoses. The tiny ones work best, are readily available, and will prevent any vacuum hoses from popping off under boost.

2) Your code 52 has absolutely NOTHING to do with boosting/RPM/engine load or even detonation/pre-ignition.

3) 34 is usually due to a boost leak. What mods do you have?

Pull the EFI fuse and go for a drive. See what comes back, then fix those specific problems.

 

[Fubar231]

Shane,

1) ALWAYS put zip ties on the ends of your vacuum hoses. The tiny ones work best, are readily available, and will prevent any vacuum hoses from popping off under boost.

2) Your code 52 has absolutely NOTHING to do with boosting/RPM/engine load or even detonation/pre-ignition.

3) 34 is usually due to a boost leak. What mods do you have?

Pull the EFI fuse and go for a drive. See what comes back, then fix those specific problems.

1) Zip ties, got it. Got them on some lines... Not all of them though.

2) Cleared away after pulling EFI, hard runs and didn't come back. I believe it was from boosting 15lbs @ 2k rpm in 3rd gear (Brake Boosting)... Not doing it that low in RPM range anymore.
At least thats exactly what i was doing when the CEL came on for it. Was on the freeway and didnt want to go down to 2nd, so brake boosted in 3rd (Auto) and when it built full boost the light came on, so after that i just limped it home.

3) 34 was stored from previously from a ic coupler coming off and re-tightening it.

Im going to boost - leak test the system tomorrow and see if i find anything, because the more i drive it the more it seems like it is a little vac leak, cause the idle is real funky too... We'll well see. Ill report back with more findings tomorrow.

Oh yeah, but after pulling EFI i didnt get any codes again. Ive pulled it 2-3 times today and test-driven it a few times and no codes came back.

 

[shaeff]

1) Zip ties, got it. Got them on some lines... Not all of them though.

2) Cleared away after pulling EFI, hard runs and didn't come back. I believe it was from boosting 15lbs @ 2k rpm in 3rd gear (Brake Boosting)... Not doing it that low in RPM range anymore.
At least thats exactly what i was doing when the CEL came on for it. Was on the freeway and didnt want to go down to 2nd, so brake boosted in 3rd (Auto) and when it built full boost the light came on, so after that i just limped it home.

3) 34 was stored from previously from a ic coupler coming off and re-tightening it.

Im going to boost - leak test the system tomorrow and see if i find anything, because the more i drive it the more it seems like it is a little vac leak, cause the idle is real funky too... We'll well see. Ill report back with more findings tomorrow.

Oh yeah, but after pulling EFI i didnt get any codes again. Ive pulled it 2-3 times today and test-driven it a few times and no codes came back.

1) Good.

2) Code 52 has nothing to do with knock/detonation/boost/ or any of that. Code 52 is an electrical problem that's limited only to the knock sensor circuit. There is nothing that can cause it other than the following:

* Knock sensor circuit (wiring)
* Knock sensor
* ECU

Boosting at 1krpm in fifth gear wouldn't even cause it if you tried doing that uphill with no EGR. LOL.

It's always a good idea to give everything a once-over, clear codes, and see what comes back unless you know for sure that you're starting with no codes to begin with. If you got 52 once, I can about guarantee it'll be back unless you ran the car with one or both knock sensors unplugged.

 

[Fubar231]

So, i havnt pressure tested the system yet, but i went down there and my cooleze intake pipe (accordian hose) was pretty much falling off the turbo inlet. I tried to get it back on there but the silicone coupler i used before is jsut giving me the biggest pain in the ass and does not want to go over the intake pipe and turbo at the same time. Might save up and get a 3" coupler thats not 2 inchs long total. Anyways, if my intake pipe was leaking air past the afm before the turbo, could that cause the lean idle?

I did look over the engine and couldn't find any vac lines just laying around. Checked under the intake manifold, behind it, around the turbo, behind the block, above it and in front of it and didn't see any hanging vac lines. My first guess would it would have been the one that connects to the bottom of the intake manifold but... i dont believe it is.

Anyways, could the lean idle be caused by a leak post afm pre turbo?

Thanks again everyone

EDIT: Shaeff, i thought code 52 was knock. I thought it popped up when the knock sensors hit a certain hz or frequency due to knocking... If im wrong can i please be enlightened?

 

[shaeff]

So, i havnt pressure tested the system yet, but i went down there and my cooleze intake pipe (accordian hose) was pretty much falling off the turbo inlet. I tried to get it back on there but the silicone coupler i used before is jsut giving me the biggest pain in the ass and does not want to go over the intake pipe and turbo at the same time. Might save up and get a 3" coupler thats not 2 inchs long total. Anyways, if my intake pipe was leaking air past the afm before the turbo, could that cause the lean idle?

I did look over the engine and couldn't find any vac lines just laying around. Checked under the intake manifold, behind it, around the turbo, behind the block, above it and in front of it and didn't see any hanging vac lines. My first guess would it would have been the one that connects to the bottom of the intake manifold but... i dont believe it is.

Anyways, could the lean idle be caused by a leak post afm pre turbo?

Thanks again everyone

Unmetered air can cause a lean condition.


Check out www.siliconeintakes.com for couplers. Great people to deal with, high quality products, fantastic communication, and quick shipping. I get all my silicone stuff through them. (and t-bolt clamps, v-bands, etc...)

EDIT: Shaeff, i thought code 52 was knock. I thought it popped up when the knock sensors hit a certain hz or frequency due to knocking... If im wrong can i please be enlightened?

Not at all. You won't get any codes at all if you get knock (regardless of whether it's spark knock or rodknock). Code 52 is just letting you know that you have a malfunction in the knock circuit, with the only possible problem areas as follows:

* Knock sensor circuit (wiring)
* Knock sensor
* ECU

It's not due to anything other than the ECU not receiving the signal(s) from the sensors, or a bum ECU (which is very uncommon)

 

[Fubar231]

Thanks Shaeff, actually just got back in from fixing it. Went to jegs and grabbed a 3" coupler for 10$ and now its all good to go. It was infact unmetered air entering the system after the AFM, because the silicone coupler that was on the turbo and intake pipe was messed up and leaking air. Thanks again.

Thanks for all the help guys.

 

[shaeff]

Glad you got it all taken care of.

 

[Supracentral]

Also, since it was mentioned in this thread - here's the scoop on vacuum gauge readings:

http://www.supramania.com/forums/showthread.php?21167-Boost-leak&p=249145&viewfull=1#post249145