wierd occurence: CEL but no codes present
01-21-2009, 06:54 PM
#1
kevin@rotaryresurrection
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wierd occurence: CEL but no codes present
Here's something wierd that happened to me.
My car has ran flawlessly since I put the engine swap in back in the summer. Earlier this week, I was accelerating hard in 3rd and at about 7000rpm the car hit a wall and the CEL started flashing. I let off and cruised for a while, it seemed fine, and accelerated fine. I got home and tried to pull the code with my OBD2 scanner and it said there were none. I chalked it up to 'whatever" and went on my way. Car drive fine for several more days. This may or may not have been related to the below occurence.
Then today I started it up and let it warm up, and noticed I had a solid CEL when I got in and was ready to leave. So I tried to pull the code and the scanner again said I had no codes.
I went to pull out and found that I had no throttle response. The car would rev slowly in neutral and barely in gear. It seemed to be applying a maximum of about 25% throttle and I could not accelerate past 2600rpm in gear.
I turned around and came back home. Turned the car off and on several times, same symptoms. Tried to pull codes...could not. CEL remained solid.
I tried resetting NVRAM and KAM per MM's post in the sticky thread, to no avail. CEL remained constant, however I could now rev the car freely and it drove normally again.
To verify my code scanner was communicating properly, I went under the hood and unplugged the AFM, Baro sensor, and throttlebody/TPS. Then tried to start the car in this condition, to force codes into the PCM. Then I scanned again and got several codes...all of which related to those 3 components only.
I cleared those codes, and then the CEL disappeared and has not returned.
Any of you PCM/computer gurus wanna tell me WTF that was all about?
My car has ran flawlessly since I put the engine swap in back in the summer. Earlier this week, I was accelerating hard in 3rd and at about 7000rpm the car hit a wall and the CEL started flashing. I let off and cruised for a while, it seemed fine, and accelerated fine. I got home and tried to pull the code with my OBD2 scanner and it said there were none. I chalked it up to 'whatever" and went on my way. Car drive fine for several more days. This may or may not have been related to the below occurence.
Then today I started it up and let it warm up, and noticed I had a solid CEL when I got in and was ready to leave. So I tried to pull the code and the scanner again said I had no codes.
I went to pull out and found that I had no throttle response. The car would rev slowly in neutral and barely in gear. It seemed to be applying a maximum of about 25% throttle and I could not accelerate past 2600rpm in gear.
I turned around and came back home. Turned the car off and on several times, same symptoms. Tried to pull codes...could not. CEL remained solid.
I tried resetting NVRAM and KAM per MM's post in the sticky thread, to no avail. CEL remained constant, however I could now rev the car freely and it drove normally again.
To verify my code scanner was communicating properly, I went under the hood and unplugged the AFM, Baro sensor, and throttlebody/TPS. Then tried to start the car in this condition, to force codes into the PCM. Then I scanned again and got several codes...all of which related to those 3 components only.
I cleared those codes, and then the CEL disappeared and has not returned.
Any of you PCM/computer gurus wanna tell me WTF that was all about?
01-21-2009, 07:02 PM
#2
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You got way more experience than me(I know this), but I have to ask. Is your OBD2 fully CAN compatible?
You know that 7k flashing was a misfire.
Today you got limp mode...so while it was warming up, it didn't like something. How long was it idling before you hopped in?
I'm guessing once you did the resets it could rev correctly and run...........so did the PCM just get a glitch?????? All it takes is one dropped bit and I guess it could send the computer and therefore the car into limp. Wish you knew which reset actually helped..........might narrow it a bit??????
How cold was it there this morning?
What exactly is your code scanner?
Well, I can't help much but I'm going to be watching this thread as I'm helping someone with their car and while not exactly the same...............some of what you said is comparable to what we saw when trying to debug her car.
After deflooding it(it's an auto) we got no real throttle response at all except we had to hold it at 5/6ths or more to the floor to keep it at 750-800rpm. It would go no higher and there was no CEL. We know that she was missing the air intake hose on the intake, but not sure it would cause the car to do what we saw............unless the MAF was getting really wacky, but you'd think we'd get a cell. We were using a Scanguage II.
I also saw a thread just within the last two days that could SOMEWHAT relate to what you saw(in a way)...I'll see if I can dig that up.
You know that 7k flashing was a misfire.
Today you got limp mode...so while it was warming up, it didn't like something. How long was it idling before you hopped in?
I'm guessing once you did the resets it could rev correctly and run...........so did the PCM just get a glitch?????? All it takes is one dropped bit and I guess it could send the computer and therefore the car into limp. Wish you knew which reset actually helped..........might narrow it a bit??????
How cold was it there this morning?
What exactly is your code scanner?
Well, I can't help much but I'm going to be watching this thread as I'm helping someone with their car and while not exactly the same...............some of what you said is comparable to what we saw when trying to debug her car.
After deflooding it(it's an auto) we got no real throttle response at all except we had to hold it at 5/6ths or more to the floor to keep it at 750-800rpm. It would go no higher and there was no CEL. We know that she was missing the air intake hose on the intake, but not sure it would cause the car to do what we saw............unless the MAF was getting really wacky, but you'd think we'd get a cell. We were using a Scanguage II.
I also saw a thread just within the last two days that could SOMEWHAT relate to what you saw(in a way)...I'll see if I can dig that up.
Last edited by Mazurfer; 01-21-2009 at 07:15 PM.
01-21-2009, 07:14 PM
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kevin@rotaryresurrection
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You know that 7k flashing was a misfire.
Today you got limp mode...so while it was warming, it didn't like something. How long was it idling before you hopped in?
Well, I can't help but I'm going to be watching this thread as I'm helping someone with their car and while not exactly the same...............some of what you said is comparable to what we saw when trying to debug her car.
After deflooding it(it's an auto) we got no real throttle response at all except we had to hold it at 5/6ths or more to the floor to keep it at 750-800rpm. It would go no higher and there was no CEL. We know that she was missing the air intake hose on the intake, but not sure it would cause the car to do what we saw............unless the MAF was getting really wacky, but you'd think we'd get a cell.
After deflooding it(it's an auto) we got no real throttle response at all except we had to hold it at 5/6ths or more to the floor to keep it at 750-800rpm. It would go no higher and there was no CEL. We know that she was missing the air intake hose on the intake, but not sure it would cause the car to do what we saw............unless the MAF was getting really wacky, but you'd think we'd get a cell.
The car will run poorly or not at all without the proper AFM measurement (which you are not getting without the duct between afm and tb).
Last edited by RotaryResurrection; 01-21-2009 at 07:21 PM.
01-21-2009, 07:19 PM
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If I remember...........That other thread I saw.....someone had let it warm-up for quite awhile and got in and had a CEL and no throttle response, I think. Hopefully I can find it, but you my friend have a strange one there. 
01-21-2009, 07:54 PM
#9
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I'd be tempted to try another reader, but what the hell do I know 
I know you checked it by producing others, but that's all I got. And..,,,,,,,,that's really the least of your worries right? You got a CEL and the car didn't behave for some period of time.
I know you checked it by producing others, but that's all I got. And..,,,,,,,,that's really the least of your worries right? You got a CEL and the car didn't behave for some period of time.
01-21-2009, 08:00 PM
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kevin@rotaryresurrection
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To add to all this, the other day I got in the car and it was really cold out. I drove 3 or 4 miles up the road on the 4 lane in 6th gear, and stopped at a red light waiting for my left turn signal to go into the store. As I rolled to the red light, the car would not come out of 6th gear. I tried and tried but it was locked in gear. So I had to BURN the f'ing clutch to get it moving enough to get into the parking lot. And then it promptly came out of gear and worked normally again. I dont know if the trans was just cold or something...it's never done that before.
Now my car smells of burned clutch disc.
At least I can change it in a 2 hour period, but still, f'ing thing sucks.
01-22-2009, 02:59 AM
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kevin@rotaryresurrection
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Fuel level was damn near a full tank in both wierd instances.
Coils and plugs...possible also.
None of this explains why there was a limp mode and a CEL with no code present, and why the NVRAM/KAM reset would not clear the CEL.
01-22-2009, 11:16 AM
#15
Administrator
you let it idle too long. there were new idle time limits set as part of the 3305g recall
maybe a TPS problem as well?
CALIBRATION CHANGE INFORMATION
The revised PCM calibrations will change throttle control in order to prevent thermal damage due to exhaust
overheating while the vehicle is stopped, and engine RPM is high for an extended period of time. There are two
PCM logic modes that have been modified to prevent extended high engine RPM while the vehicle is stopped.
ELECTRONIC THROTTLE FAILSAFE MODE
If the PCM detects a problem with the electronic throttle control system, the PCM failsafe mode will fix the
engine RPM to 2700. This is to allow limited driving even when throttle control does not exist.
- FAILSAFE MODE PRIOR TO PCM PROGRAMMING
PCM fixes engine RPM at 2700 until ignition is switched off. The PCM will remain in failsafe mode until
the malfunction has been repaired.
- FAILSAFE MODE AFTER PCM PROGRAMMING
When the PCM is in failsafe mode, the PCM will default to 2700 RPM to allow the vehicle to be driven if
there is an electronic throttle error. However, the PCM will cut the failsafe mode and RPM will default to
1100 when the following conditions have been met for more than 5 minutes:
• Engine temperature more than 140°F.
• Transmission in neutral or park.
• Vehicle speed is less than 2 MPH.
FREE REV MODE
When the engine RPM is held at high levels and the vehicle is stopped, the PCM will reduce the engine RPM to
prevent thermal damage.
- FREE REV MODE PRIOR TO PCM PROGRAMMING
RPM is limited to 2500 to prevent overheating when the conditions below are met for more than 5 seconds.
• Shift lever is in N position and/or the clutch pedal is stepped on (AT vehicle: the shift lever is in P or N
position)
- Temperature of coolant is 221°F or more.
- Engine RPM is 5,000 or more.
• When the engine RPM is 1100 or less, and/or the temperature of coolant becomes 212°F or less, PCM
returns to the normal control mode.
- FREE REV MODE AFTER PCM PROGRAMMING
The PCM will reduce RPM to 900 if the throttle is held above certain RPM levels (free-reving) for predetermined
time periods under the following conditions:
• Engine temperature more than 140°F.
• Transmission in neutral or park.
• Vehicle speed is less than 3 MPH.
Engine RPM Time
+8500 + 10 Seconds
3000-8500 + 2 Minutes
1300-3000 + 5 Minutes
EXAMPLE:
• Engine running at operating temp, trans in "N" & stopped. Hold RPM at 4000, after 2 minutes have
elapsed at this RPM, the engine will return to idle regardless of throttle input. Throttle will return
after accelerator pedal is fully released, or ignition is shut off
The revised PCM calibrations will change throttle control in order to prevent thermal damage due to exhaust
overheating while the vehicle is stopped, and engine RPM is high for an extended period of time. There are two
PCM logic modes that have been modified to prevent extended high engine RPM while the vehicle is stopped.
ELECTRONIC THROTTLE FAILSAFE MODE
If the PCM detects a problem with the electronic throttle control system, the PCM failsafe mode will fix the
engine RPM to 2700. This is to allow limited driving even when throttle control does not exist.
- FAILSAFE MODE PRIOR TO PCM PROGRAMMING
PCM fixes engine RPM at 2700 until ignition is switched off. The PCM will remain in failsafe mode until
the malfunction has been repaired.
- FAILSAFE MODE AFTER PCM PROGRAMMING
When the PCM is in failsafe mode, the PCM will default to 2700 RPM to allow the vehicle to be driven if
there is an electronic throttle error. However, the PCM will cut the failsafe mode and RPM will default to
1100 when the following conditions have been met for more than 5 minutes:
• Engine temperature more than 140°F.
• Transmission in neutral or park.
• Vehicle speed is less than 2 MPH.
FREE REV MODE
When the engine RPM is held at high levels and the vehicle is stopped, the PCM will reduce the engine RPM to
prevent thermal damage.
- FREE REV MODE PRIOR TO PCM PROGRAMMING
RPM is limited to 2500 to prevent overheating when the conditions below are met for more than 5 seconds.
• Shift lever is in N position and/or the clutch pedal is stepped on (AT vehicle: the shift lever is in P or N
position)
- Temperature of coolant is 221°F or more.
- Engine RPM is 5,000 or more.
• When the engine RPM is 1100 or less, and/or the temperature of coolant becomes 212°F or less, PCM
returns to the normal control mode.
- FREE REV MODE AFTER PCM PROGRAMMING
The PCM will reduce RPM to 900 if the throttle is held above certain RPM levels (free-reving) for predetermined
time periods under the following conditions:
• Engine temperature more than 140°F.
• Transmission in neutral or park.
• Vehicle speed is less than 3 MPH.
Engine RPM Time
+8500 + 10 Seconds
3000-8500 + 2 Minutes
1300-3000 + 5 Minutes
EXAMPLE:
• Engine running at operating temp, trans in "N" & stopped. Hold RPM at 4000, after 2 minutes have
elapsed at this RPM, the engine will return to idle regardless of throttle input. Throttle will return
after accelerator pedal is fully released, or ignition is shut off
maybe a TPS problem as well?
01-22-2009, 12:15 PM
#16
kevin@rotaryresurrection
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I have let it idle FAR longer than that before, especially with the remote start installed. The idle was not artificially high...it was doing it's normal warmup routine and was down around 1000rpm, nearly fully warmed up.
Also this PCM has not been flashed recently. I do not know which flash it has, but it's been at least a year or more since it could have been flashed.
Also this PCM has not been flashed recently. I do not know which flash it has, but it's been at least a year or more since it could have been flashed.
01-22-2009, 12:58 PM
#17
Kevin ill soon have some used coils for you to try and swap and see if thats a problem, but i guess you only have a random problem not a constant one. I have had problems with friends' cars that have pretty much all been coils and acted the same. Limp mode with 2 bad coils. Hard misfire acting with one bad coil.
01-22-2009, 01:22 PM
#18
I would entertain the possibility of a weak fuel pump, since this is approx a 123k mile pump at this point in time. One would think that such a condition would happen once the pump had run long enough to get "hot", and the condition would not show up at idle or during light driving, only during heavy throttle.
Fuel level was damn near a full tank in both wierd instances.
Coils and plugs...possible also.
None of this explains why there was a limp mode and a CEL with no code present, and why the NVRAM/KAM reset would not clear the CEL.
Fuel level was damn near a full tank in both wierd instances.
Coils and plugs...possible also.
None of this explains why there was a limp mode and a CEL with no code present, and why the NVRAM/KAM reset would not clear the CEL.
beers
01-22-2009, 02:17 PM
#19
kevin@rotaryresurrection
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Kevin ill soon have some used coils for you to try and swap and see if thats a problem, but i guess you only have a random problem not a constant one. I have had problems with friends' cars that have pretty much all been coils and acted the same. Limp mode with 2 bad coils. Hard misfire acting with one bad coil.
Coils and fuel pumps usually start to act up after they have been running for 15-30 minuntes or more and have gotten nice and hot in my observation (on other cars), just like what swoope describes.
01-22-2009, 02:21 PM
#20
fuel could very well be the case as maybe an injector? fuel system cleaner? i know that motor had like 70k on it when you picked it out of that car from me.
I would think fuel injector is something that could fail but not leave a real CEL, the motor just knows its not running right, but not why.
I would think fuel injector is something that could fail but not leave a real CEL, the motor just knows its not running right, but not why.
01-22-2009, 02:37 PM
#22
kevin@rotaryresurrection
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the injectors are from a different engine, lower mileage, and as stated above, were sent out for cleaning and balancing by an injector shop before installation. Fuel was at 7/8 tank and is shell 93.
Guys, let me clarify here. I am less asking about the possible mechanical issues that could contribute to limp mode etc; I am more asking the computer tech guys here why the computer set a MIL indicator but refused to spit any codes out or clear the MIL light via 2 seperate methods that should have done so.
Guys, let me clarify here. I am less asking about the possible mechanical issues that could contribute to limp mode etc; I am more asking the computer tech guys here why the computer set a MIL indicator but refused to spit any codes out or clear the MIL light via 2 seperate methods that should have done so.
01-22-2009, 03:05 PM
#23
Usually, that means the PCM either has a communication issue with one of the other modules (immobilizer, cluster, etc) or is experiencing a backup power failure, a ROM failure or some other internal hardware failure.
That is all depending on the efficacy of your CAN scanner.
That is all depending on the efficacy of your CAN scanner.
01-22-2009, 05:22 PM
#24
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^..............this is why I started down the path and asked you if you possibly had another scanner to try.....and again, it should be on that is CAN compatible.
01-22-2009, 08:45 PM
#25
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Ive had the same problem in the last week including today.
First time Started the car cold 19 degrees outside. Let it sit and came back 10 mins later to a solid check engine light and my engine temps still pretty cold. Realized it was in limp mode once i tried moving it and it felt like 10 hp. Procedded to to do the ecu reset. Car ran fine but just lik RR sold check engine but no codes on the obd scanner. I let the battery sit disconnected for a few mins and check engine went away.
Today, Started the car in 25 degrees weather and same thing pretty cold engine temp, solid check light, and 10 hp feel. Reset it and went on with my day.
Its pissing me off as the coils,plugs, etc were changed less than 10k ago.
Now what i believe is the culprit is the the Air pump EGR setup. Ive heard my air pump whine a few times in the cold and now i think its coming back to haunt me.
I guess the failed air pump is causing the limp mode.
????
First time Started the car cold 19 degrees outside. Let it sit and came back 10 mins later to a solid check engine light and my engine temps still pretty cold. Realized it was in limp mode once i tried moving it and it felt like 10 hp. Procedded to to do the ecu reset. Car ran fine but just lik RR sold check engine but no codes on the obd scanner. I let the battery sit disconnected for a few mins and check engine went away.
Today, Started the car in 25 degrees weather and same thing pretty cold engine temp, solid check light, and 10 hp feel. Reset it and went on with my day.
Its pissing me off as the coils,plugs, etc were changed less than 10k ago.
Now what i believe is the culprit is the the Air pump EGR setup. Ive heard my air pump whine a few times in the cold and now i think its coming back to haunt me.
I guess the failed air pump is causing the limp mode.
????