High Idle. Trouble code list inside. Im stumped
02-23-2014, 08:45 PM
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High Idle. Trouble code list inside. Im stumped Had this in the PCM Diagnostic section, but didnt get any hits. Need some help here guys.
Ok bear with me guys this may be long winded as I let you know my symptoms and what I have done as far as trouble shooting so far.
Ok, so I have a 98 Firebird Formula with a 99 LS1 engine. 98 PCM and harness.
Mods: Long tube headers, Rear O2 sims, K&N filter, Magnaflow Cat back.
When I purchased the car the previous owner deleted the AIR/EGR without tuning them out so I reinstalled both.
-Brand new IAC valve installed
-Brand new TPS installed.
No vacuum leaks, pcv system is brand new, intake manifold gaskets are new, throttle body gasket is new.
Symptoms:
Cold starts are crap. The engine will start, idle and chug at about 400 rpm and eventually die. Restart and give it some gas for a few seconds and it will run at around 550-600 rpm....
Here is the kicker though, as the car warms up the idle speed increases. Fully warm it idles at 1100. <<<this drives me crazy and is my main issue.
Here are my trouble codes:
P0133: Bank 1 sensor 1 slow response
P0153: Bank 2 sensor 1 slow response
P0102: MAF sensor circuit low frequency
P1133: Bank 1 sensor 1 Insufficient switching
P1153: Bank 2 sensor 1 Insufficient switching
Ok the last two codes are probably a result of the longtubes. Would any of the other codes cause a high idle situation?
Please help me out guys. Thanks.
Ok bear with me guys this may be long winded as I let you know my symptoms and what I have done as far as trouble shooting so far.
Ok, so I have a 98 Firebird Formula with a 99 LS1 engine. 98 PCM and harness.
Mods: Long tube headers, Rear O2 sims, K&N filter, Magnaflow Cat back.
When I purchased the car the previous owner deleted the AIR/EGR without tuning them out so I reinstalled both.
-Brand new IAC valve installed
-Brand new TPS installed.
No vacuum leaks, pcv system is brand new, intake manifold gaskets are new, throttle body gasket is new.
Symptoms:
Cold starts are crap. The engine will start, idle and chug at about 400 rpm and eventually die. Restart and give it some gas for a few seconds and it will run at around 550-600 rpm....
Here is the kicker though, as the car warms up the idle speed increases. Fully warm it idles at 1100. <<<this drives me crazy and is my main issue.
Here are my trouble codes:
P0133: Bank 1 sensor 1 slow response
P0153: Bank 2 sensor 1 slow response
P0102: MAF sensor circuit low frequency
P1133: Bank 1 sensor 1 Insufficient switching
P1153: Bank 2 sensor 1 Insufficient switching
Ok the last two codes are probably a result of the longtubes. Would any of the other codes cause a high idle situation?
Please help me out guys. Thanks.
02-23-2014, 09:00 PM
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Also, to add, the IAC valve that was installed when I purchased the car didnt have a pintle in it at all! It didnt have an O ring either....the car still idled at 1100 even with that. So the IAC was the first thing I replaced, but it still idles exactly the same.
This is very frustrating...you would think with the IAC valve with no pintle that it would have idled at 3000rpm or something....
This is very frustrating...you would think with the IAC valve with no pintle that it would have idled at 3000rpm or something....
02-23-2014, 09:38 PM
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Anywho, just found out something. I took the throttle body off and took the IAC valve off again to reinspect and it looks like someone shoved some JB weld into the port that the pintle goes into and drilled a small hole in the JB weld to get some airflow, i guess. Who does that?!.
Also, should the IAC valve pintle have any movement when the key is just switched to ON? My new IAC valve doesnt do anything...
Last edited by MadFirehawk86; 02-23-2014 at 09:45 PM.
02-23-2014, 09:53 PM
#5
Sounds like you may need a new/used TB. While we do not sell them, we can sure help you with the tuning portion.
We have HPT at a great price AND offer the ability to help you with your tune.
The problem with buying used is, you always get someone else's problems also. The long tubes are what is causing your codes so far. The fuel trims are likely very off in the wrong direction. The only way to fix that is with a tune. Period.
I would also check the size of the hole in the TB blade itself. It should be VERY small. If it is opened up, that can cause issues as well. Esp a high idle at any time. The other issue seems to be related to your JB weld modified TB.
Hope that helps!
We have HPT at a great price AND offer the ability to help you with your tune.
The problem with buying used is, you always get someone else's problems also. The long tubes are what is causing your codes so far. The fuel trims are likely very off in the wrong direction. The only way to fix that is with a tune. Period.
I would also check the size of the hole in the TB blade itself. It should be VERY small. If it is opened up, that can cause issues as well. Esp a high idle at any time. The other issue seems to be related to your JB weld modified TB.
Hope that helps!
02-23-2014, 10:18 PM
#7
The maf sensor frequency could either be a blown fuse (which would cause quite a few issues) the maf being bad or turned around backwards, or there not being a maf at all. A good visual inspection of the engine bay and all the fuses in all the different fuse panels inside and outside the car can help you determine if something simple is causing more issues.
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02-23-2014, 10:27 PM
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Ok thanks for the responses so far everyone! Its much appreciated! I will purchase some new O2s this week.
I managed to get the JB out of the throttle body, but now it is idling at 2000rpm. New IAC, new tps is installed....idle relearn maybe?
I managed to get the JB out of the throttle body, but now it is idling at 2000rpm. New IAC, new tps is installed....idle relearn maybe?
02-23-2014, 10:33 PM
#9
The O2 sensors will do no good if you dont get a tune. You will just foul another set. We do recommend the Denso oxygen sensors. We have them for a VERY good price. Denso makes some of the higher quality oxygen sensors.
As far as the high idle problem, the throttle cam screw may be adjusted improperly. You need to know your TPS voltage at idle and with the car shut off. Without that you are really flying blind. HPT can tell you all of that, graph the wave forms of your oxygen sensors to tell you the health of them, and give you more information as to what else may be wrong. It really is the best way to find out all you will ever need to know as well as help anyone else that you may ask for assistance.
As far as the high idle problem, the throttle cam screw may be adjusted improperly. You need to know your TPS voltage at idle and with the car shut off. Without that you are really flying blind. HPT can tell you all of that, graph the wave forms of your oxygen sensors to tell you the health of them, and give you more information as to what else may be wrong. It really is the best way to find out all you will ever need to know as well as help anyone else that you may ask for assistance.
02-23-2014, 10:56 PM
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The O2 sensors will do no good if you dont get a tune. You will just foul another set. We do recommend the Denso oxygen sensors. We have them for a VERY good price. Denso makes some of the higher quality oxygen sensors.
As far as the high idle problem, the throttle cam screw may be adjusted improperly. You need to know your TPS voltage at idle and with the car shut off. Without that you are really flying blind. HPT can tell you all of that, graph the wave forms of your oxygen sensors to tell you the health of them, and give you more information as to what else may be wrong. It really is the best way to find out all you will ever need to know as well as help anyone else that you may ask for assistance.
As far as the high idle problem, the throttle cam screw may be adjusted improperly. You need to know your TPS voltage at idle and with the car shut off. Without that you are really flying blind. HPT can tell you all of that, graph the wave forms of your oxygen sensors to tell you the health of them, and give you more information as to what else may be wrong. It really is the best way to find out all you will ever need to know as well as help anyone else that you may ask for assistance.
If the throttle stop screw isnt adjusted right will it cause the IAC valve to not operate?
02-23-2014, 11:39 PM
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The JB weld thing has me intrigued though, seems to me it had this idle issue and someone was trying to chase it down and couldnt figure it out so they just JB welded the IAC pintle hole shut....kinda scares me actually. Like i said the IAC and TPS are brand new and the IAC isnt moving at all. I wonder if something is wrong with the PCM????
02-23-2014, 11:46 PM
#13
They use that alot to get better "airflow" out of the TB. If it were ported, that is possibly the reason, but another reason as to why it is still acting odd. The real only option may be to get a new/better tb. We have the BBK ready to go and it does make more power and look nicer than stock as well as fit all the factory sensors and it is 100% correct. No need to worry about anything. We can even help walk you through install to make sure everything is correct if needed.
I would not blame the PCM until you have checked out all the other things first and gotten a tune at least to find out. But you cannot get a tune until you figure out everything that is wrong. Most of it seems to be related though. If the tune were messed with before, they can very possibly max the IAC out also, which isnt good. You/we can tell all of that with HPT.
We know the IAC is an expensive piece in itself also. Make sure you check all the fuses with your owners manual to make sure you have no blown ones, that all the proper sizes are in their places, AND that every fuse it shows you need you have in the panel. I have seen fuses removed before for any number of reasons and not replaced.
I would not blame the PCM until you have checked out all the other things first and gotten a tune at least to find out. But you cannot get a tune until you figure out everything that is wrong. Most of it seems to be related though. If the tune were messed with before, they can very possibly max the IAC out also, which isnt good. You/we can tell all of that with HPT.
We know the IAC is an expensive piece in itself also. Make sure you check all the fuses with your owners manual to make sure you have no blown ones, that all the proper sizes are in their places, AND that every fuse it shows you need you have in the panel. I have seen fuses removed before for any number of reasons and not replaced.
02-24-2014, 12:35 AM
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It is a very good possibility that the tune was messed with. The previous owner had HPT and I saw the interface in the back seat when I was looking at the car...shouldve been a red flag, but the car was cheap so I proceeded forward.
I really cannot afford any down time with this car, it is my daily so a mail order tune is not feasible. I also just changed duty stations so I cannot afford to drop 400-500 bucks on an HPT set up at this time, but it is my next large investment when I have some extra cash.
I really cannot afford any down time with this car, it is my daily so a mail order tune is not feasible. I also just changed duty stations so I cannot afford to drop 400-500 bucks on an HPT set up at this time, but it is my next large investment when I have some extra cash.
02-24-2014, 12:44 AM
#15
What we offer is not a mail order tune. You can still keep it a daily driver. We remote tune your setup VIA HPT, which we sell, and within minutes we can tell you if the tune has been messed with and we can get you set up with a new tune and any other possible places to look to get your car a reliable DD in no time.
It would sure keep you from taking it to a costly repair shop and them going off in left field. $75+ an hour adds up if they get caught chasing their tail.
Even if you know someone with HPT we can help you through them also. Flexible options.
It would sure keep you from taking it to a costly repair shop and them going off in left field. $75+ an hour adds up if they get caught chasing their tail.
Even if you know someone with HPT we can help you through them also. Flexible options.
02-24-2014, 11:36 PM
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Nope PCV system is brand new with no vacuum leaks.
What I need is someone that has actually tuned the idle on an LS1 to chime in on what would cause an IAC valve to not operate at all. The IAC is brand new and the TPS is brand new. I start the car up and it idles at 2000rpm steady, no hunting, no bogging, just a steady 2000rpm.
My wife's 01 Z28 IAC... I can hear it move when I shut her car off and the idle is spot on, but my car nothing...because it doesnt even attempt to regulate my idle.
Im at my wits end on this...and YES i realize I need a tuner and I am trying to locate one.
What I need is someone that has actually tuned the idle on an LS1 to chime in on what would cause an IAC valve to not operate at all. The IAC is brand new and the TPS is brand new. I start the car up and it idles at 2000rpm steady, no hunting, no bogging, just a steady 2000rpm.
My wife's 01 Z28 IAC... I can hear it move when I shut her car off and the idle is spot on, but my car nothing...because it doesnt even attempt to regulate my idle.
Im at my wits end on this...and YES i realize I need a tuner and I am trying to locate one.
02-24-2014, 11:45 PM
#20
First off is to check and see if you are getting the same readings as you are getting on your wife's car. Since you have another Fbody it makes it alot easier to compare. Sometimes bad terminals can cause you to get stuck in left field. Make sure all the terminals look good in the first place. They can vibrate open and cause little to no connection and therefore communication.