I give up....
Thread Starter
Instructor
Joined: Aug 2011
Posts: 127
Likes: 0
From: Milton Florida
I give up....
ok. so here is my problem. my '03 isnt idling correctly whenever i put it in neutral, it's rpm falls to around 425-500 rpm for a second or 2 and then procedes to bounce back and forth between 450ish-950ish rpm. it only does this after i've been driving, if i just fire it up and let it idle, it runs just fine. it's throwing codes p0171 and p0174. i cleaned the maf already.i was thinking fuel filter, but mine was made in march of '03 so i believe everything is in tank??? anyway, anyone have any ideas???
thanks ahead of time
thanks ahead of time
Team Owner
Joined: May 2003
Posts: 23,480
Likes: 9
From: East Meadow NY
St. Jude Donor '12
Any mods?
You may have a vacuum/air leak some place. Check all of the connections from the air filter to the throttle body. Make sure they are snug. Check all of the hoses of the PCV system and make sure they are attached and not worn/rotted out.
You may have a vacuum/air leak some place. Check all of the connections from the air filter to the throttle body. Make sure they are snug. Check all of the hoses of the PCV system and make sure they are attached and not worn/rotted out.
Thread Starter
Instructor
Joined: Aug 2011
Posts: 127
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From: Milton Florida
Tech Contributor
Joined: Jan 2004
Posts: 20,030
Likes: 289
From: Wylie TX --> Less is More, except under the hood !
Vacuum leak is possible... (like said above)
Has your car been tuned by a local tuner lately ? Sometimes tuners forget to add some fuel to the "neutral/idle" fuel table.
I just added a Fast intake and I need my tuner to add ~3% or so more fuel to my neutral/idle table so that it does not stumble when I push in the clutch. Mine does the same as yours sometimes after a long drive and I just push in the clutch. I have already had it dyno tuned, and a drive along tune too. Most of the tuning bugs are worked out so far.
I don't have any air leaks anywhere he told me.
Toque
Has your car been tuned by a local tuner lately ? Sometimes tuners forget to add some fuel to the "neutral/idle" fuel table.
I just added a Fast intake and I need my tuner to add ~3% or so more fuel to my neutral/idle table so that it does not stumble when I push in the clutch. Mine does the same as yours sometimes after a long drive and I just push in the clutch. I have already had it dyno tuned, and a drive along tune too. Most of the tuning bugs are worked out so far.
I don't have any air leaks anywhere he told me.
Toque
Advanced
Joined: Jul 2009
Posts: 56
Likes: 0
From: Kentucky
Have you tried checking your idle air control motor/ valve? You can usually unplug them and see if it continues to run the same. If it does, then more than likely your idle air motor is bad. Sometimes you can clean them and it will straighten up, if it doesn't you should be able to pick up a new one at the auto parts store. Unfortunately they usually cost around a $100 dollars on average.
Hope This Helps- David
Hope This Helps- David
Drifting
Joined: Jan 2010
Posts: 1,447
Likes: 1
From: Katy TX
Have you tried checking your idle air control motor/ valve? You can usually unplug them and see if it continues to run the same. If it does, then more than likely your idle air motor is bad. Sometimes you can clean them and it will straighten up, if it doesn't you should be able to pick up a new one at the auto parts store. Unfortunately they usually cost around a $100 dollars on average.
Hope This Helps- David
Hope This Helps- David
Advanced
Joined: Jul 2009
Posts: 56
Likes: 0
From: Kentucky
Well I was speaking in general, it was a quick suggestion usually they are located on the throttle body. I have never looked at mine to see if they came on the c5s. I am now looking to see if the came on these cars, I may have spoke too soon.
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Tech Contributor
Joined: Aug 2008
Posts: 2,902
Likes: 21
From: Oak Hill Virginia
Another vote for vacuum leak. If I were to take a wild guess I'd tell you to take a very close look at the PCV hose coming off of the passenger side of the throttle body. Pull your passenger side fuel rail cover and follow that hose as far as you can to check for dry-rot. Mine was literally broken in half from rotting and I missed it the first time I looked for a leak...
Thread Starter
Instructor
Joined: Aug 2011
Posts: 127
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From: Milton Florida
I'm pretty sure I know what everyone is talking about but....
If anyone would be so kind or already has a picture of the engine bay could put some arrows to the vacuum lines that I need to check to make sure I don't miss something... :-) I've never done anything on an ls engine so I'm not super familiar with exactly what all this stuff is and don't wanna bugger nothing up. O and i have around 125k miles, I bought it @ 118 and there aren't any real good maintenance reports from the previous owner so.... Yup thanks
If anyone would be so kind or already has a picture of the engine bay could put some arrows to the vacuum lines that I need to check to make sure I don't miss something... :-) I've never done anything on an ls engine so I'm not super familiar with exactly what all this stuff is and don't wanna bugger nothing up. O and i have around 125k miles, I bought it @ 118 and there aren't any real good maintenance reports from the previous owner so.... Yup thanks
Burning Brakes
Joined: Feb 2008
Posts: 949
Likes: 1
From: Tampa fl
St. Jude Donor '14
I have been having idle issues on my 04 after I did modifications. I have the Borla straight pipes, but I also did a blackwing intake. My idle has a hiccup in it not necessarily a variation like yours but I would try an idle relearn proceedure first. Its free! I would go over the vac lines thouroughly, and check your plugs and wires. Do a google image search for LS1 vacuum diagram and you will find a few good pictures.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
LS engines DO NOT have Idle Air Motors. The electronicly controlled throttle body commands the throttle blade open to the correct position to hold the idle at the correct RPM. The PCM LEARNS the correct throttle Blade position to maintain the correct idle. Each time ypou start the engine, the PCM commands it to the last correct position that had a proper idle For your idle to vary like that, You may have one or more of the following conditions:
1- The TB is not able to operate the Throttle Blade smoothly
2- The throttle body/blade is very dirty
3- You have a vacuum leak at one of the vacuum lines
4- You have an air leak causing unmetered air into the engine between the TB abd MAF
5- MAF is dirty
6- MAF is defective
7- MAP sensor is defective
8- Manifold is not properly torqued down to the heads.
The most common cause is #1, #3 & #4. You already stated that you cleaned the MAF. How did you clean it??
DTCs codes p0171 and p0174 are LEAN bank 1 & 2! VACUUM LEAK!!!!!!
Spray some carb cleaner around the manifold where it meets the heads and a round the vacuum lines and if the idle surges when you spray a specific area, that is the area where the vacuum leak is.
BE CAREFUL.. That stuff is very flamable!!!!!!!!!!!!
BC
1- The TB is not able to operate the Throttle Blade smoothly
2- The throttle body/blade is very dirty
3- You have a vacuum leak at one of the vacuum lines
4- You have an air leak causing unmetered air into the engine between the TB abd MAF
5- MAF is dirty
6- MAF is defective
7- MAP sensor is defective
8- Manifold is not properly torqued down to the heads.
The most common cause is #1, #3 & #4. You already stated that you cleaned the MAF. How did you clean it??
DTCs codes p0171 and p0174 are LEAN bank 1 & 2! VACUUM LEAK!!!!!!
Spray some carb cleaner around the manifold where it meets the heads and a round the vacuum lines and if the idle surges when you spray a specific area, that is the area where the vacuum leak is.
BE CAREFUL.. That stuff is very flamable!!!!!!!!!!!!
BC
Thread Starter
Instructor
Joined: Aug 2011
Posts: 127
Likes: 0
From: Milton Florida
LS engines DO NOT have Idle Air Motors. The electronicly controlled throttle body commands the throttle blade open to the correct position to hold the idle at the correct RPM. The PCM LEARNS the correct throttle Blade position to maintain the correct idle. Each time ypou start the engine, the PCM commands it to the last correct position that had a proper idle For your idle to vary like that, You may have one or more of the following conditions:
1- The TB is not able to operate the Throttle Blade smoothly
2- The throttle body/blade is very dirty
3- You have a vacuum leak at one of the vacuum lines
4- You have an air leak causing unmetered air into the engine between the TB abd MAF
5- MAF is dirty
6- MAF is defective
7- MAP sensor is defective
8- Manifold is not properly torqued down to the heads.
The most common cause is #1, #3 & #4. You already stated that you cleaned the MAF. How did you clean it??
DTCs codes p0171 and p0174 are LEAN bank 1 & 2! VACUUM LEAK!!!!!!
Spray some carb cleaner around the manifold where it meets the heads and a round the vacuum lines and if the idle surges when you spray a specific area, that is the area where the vacuum leak is.
BE CAREFUL.. That stuff is very flamable!!!!!!!!!!!!
BC
1- The TB is not able to operate the Throttle Blade smoothly
2- The throttle body/blade is very dirty
3- You have a vacuum leak at one of the vacuum lines
4- You have an air leak causing unmetered air into the engine between the TB abd MAF
5- MAF is dirty
6- MAF is defective
7- MAP sensor is defective
8- Manifold is not properly torqued down to the heads.
The most common cause is #1, #3 & #4. You already stated that you cleaned the MAF. How did you clean it??
DTCs codes p0171 and p0174 are LEAN bank 1 & 2! VACUUM LEAK!!!!!!
Spray some carb cleaner around the manifold where it meets the heads and a round the vacuum lines and if the idle surges when you spray a specific area, that is the area where the vacuum leak is.
BE CAREFUL.. That stuff is very flamable!!!!!!!!!!!!
BC
i pulled the maf and grabbed some maf cleaner from autozone and sprayed the heck out of it. it made the engine codes go away for about 4 days worth of driving, but then they came back.
im also throwing codes:b0361 and b0441. is this at all related??
how can i check if the throttle blade isnt going smoothly??
Last edited by cwis9992; Feb 1, 2012 at 02:20 PM.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
POP OFF the air bridge, turn on the ignition (engine OFF) and depress and release the throttle. It should go from the IDLE position to fully open to idle position smoothly.
Turn the ignition OFF and you should be able to move it to fully open and it should flop to the near idle position on its own (It WILL NOT fully shut on its own but you cna force it to the fully shut position.)
Clean it while you have the air bridge tube off the front!
Bill
Turn the ignition OFF and you should be able to move it to fully open and it should flop to the near idle position on its own (It WILL NOT fully shut on its own but you cna force it to the fully shut position.)
Clean it while you have the air bridge tube off the front!
Bill
Thread Starter
Instructor
Joined: Aug 2011
Posts: 127
Likes: 0
From: Milton Florida
POP OFF the air bridge, turn on the ignition (engine OFF) and depress and release the throttle. It should go from the IDLE position to fully open to idle position smoothly.
Turn the ignition OFF and you should be able to move it to fully open and it should flop to the near idle position on its own (It WILL NOT fully shut on its own but you cna force it to the fully shut position.)
Clean it while you have the air bridge tube off the front!
Bill
Turn the ignition OFF and you should be able to move it to fully open and it should flop to the near idle position on its own (It WILL NOT fully shut on its own but you cna force it to the fully shut position.)
Clean it while you have the air bridge tube off the front!
Bill
Do I need to use brake cleaner or what??
