Hello everyone. I hope someone can shed light on an issue I am having with my vehicle. I had made this post on Trailvoy and did get some feedback, but no solution. So, in an effort to find a resolution, I will cut and past my dillemma I had posted on Trailvoy.
***Post #1***
Vehicle:
2003 Envoy XL SLE
4.2L I-6
Mileage: 92,000
Hi everyone -
I am desperately looking for help on the rather serious REP issue.
Yesterday, for example, REP manifested itself no fewer than 45 times while my girlfriend was driving it. Today, I took the vehicle for my usual 34 mile commute and I got it once.
Symptoms: In the 10-20 seconds leading up to the truck going into REP mode, throttle response is sluggish and or "notchy" (meaning the truck accelerates not smoothly or linearly, but in a 'stepped' mode). Then, there is a moderate shudder lasting, at most, 2 seconds, then - boom into REP mode. Both Check Engine and REP lights come one.
Turning the truck off/on gets it out of REP mode. Check engine light stays on.
Environment: South Florida winter, little rain, low moisture. I was thinking we were looking at some sort of moisture issue with the wiring or harness, but in this rather dry enviroment I am not seeing it. Also, during rainshowers - the REP neither increases or descreases.
I've been dealing with this issue for a year now, if not more.
What Has Been Done:
I have replaced the Throttle Body Assembly (Delco). This did not alleviate the TEP issue.
I took the truck to the GMC dealer. They have no idea what was going on but noticed that fuse-box was out of a Trailblazer and not an Envoy. They said this could be a cause, but not 100% certain. That repair\labor cost me $1200 and did not resolve anything.
What I do have, but have not installed yet, is an accelerator, throttle-by-wire assembly. I got that after reading in some spots that this could be a culprit.
Codes:
After having the check engine light on for a while, I hook up the code reader to it and it comes back with these codes:
P0171
P0172
P0340
P1221
P1516
P1481
I cleared the check engine light and codes then took her out for a ride to try to induce another REP. Upon starting the motor, I get the following code:
P0340
HOWEVER, this code does not trigger the Check Engine or REP light.
About 15 minutes into my ride, the usual shudder and REP event occurs. This time the reader tells me:
Code 1: 1221
Code 2: 0340
Code 3: 1221
Odd that 1221 showed up twice.
Anyway, engine-codes.com tells me that GMC 1221 has to do with TPS 1-2 correlation. As mentioned before, this is a genuine Delco aftermarket throttle body\TAC.
I still have the old throttle body.
I will also note that the engine idles rather roughly. I thought it was an engine mount issue, but a mechanic friend of mine took a quick look at it and said it was OK there.
So, I am wits end here. I cannot discern a pattern and I need this vehicle to be working properly.
***Post #2***
Today, two things occurred.
1. When starting the vehicle cold, the vehicle holds on to 1st gear too long under moderate acceleration. When it does grab 2nd, it does so rather roughly. This goes away once the vehicle is up to operating temperature.
2. After my 35 mile commute, upon hitting the light at the end of the exit ramp I take, the vehicle shuddered violently, engine almost went off, and message center said "OIL PRESSURE LOW" then "STOP ENGINE" for a few seconds each. NO REP light appeared. Check engine light was already on. Engine stabilized itself a few seconds after that, but at a highly elevated IDLE speed (almost 1000 RPM).
I have seen this before where the vehicle sit at this high idle. Sometimes restarting the vehicle helps being the idle back down, sometimes it does not.
Also - not sure if I've mentioned this in the OP, but the truck does idle roughly all the time. The idle is relatively stable (until the motor starts hiccuping just before the dreaded REP appear) , but it is rough - and, of course, more pronounced when the vehicle is cold.
Lastly, I should note - the engine has no trouble starting at all.
***Post #3***
So, I went ahead and switched out the accelerator assembly, which you may or may not know is throttle-by-wire on this truck. It was a royal pain in the ass to switch out, but I got it done.
Of course, I disconnected the battery before starting.
So, after switching the unit out, I started her up. I noticed a couple of things.
1. The truck still idles rough, however the hesitation that I was feeling when pressing on the accelerator from a standing start is, for the most part, gone. She does not accelerate any quicker or anything like that.
2. As mentioned, the idle roughness is unchanged. The roughness is significant enough that it rattles the grill a bit - and that be heard from inside the truck. Idle seems to be ok at 700 RPM or so.
3. The "whoooooooooa" sound of the fan clutch seems to be a bit more pronounced and seems to linger a bit until 40 MPH. Before I switched out the accelerator, the fan clutch sound stopped when the tranny shifted from first to second.
4. I took her out for a 30 minute spin. About 10 minutes into it, to my disappointment the REP manifested itself. I did the usual: pulled over to the side of the road, turned the car off, waited 10 seconds, then turned her back on. Check Engine light stayed lit, but REP went away - and I was able to drive the truck normally.
5. About 10 minutes later, I stopped off at CVS to get something. When I came back out, the Check Engine light was gone - which is unusual because it usually lingers for about 4-5 times the ignition is turned on to start - and only then if no new codes appear, it will go away. But like I said, the next time I started the truck, the SES was off.
There was no other drama for the rest of the trip.
What I do notice is still some irregular throttle response at around 20 to 30 MPH. The truck bogs down, not accelerating as you would expect her to.
***Post #4***
Quick update....
So after replacing the gas pedal assembly and going through my regular commute, I have to report that the issue has not been resolved.
I am still getting the usual SES/REP condition with no rhyme or reason.
I am about to set this vehicle on fire and drive it straight into a canal. VERY frustrating.
So I am not even sure where to go from here. I am thinking about sending off a letter or a phone call to GM regional - or even Detroit - to see if I get any sort of traction. In the meantime, I am going to look into getting rid of the Envoy.
$1500 in repairs and parts and I am no closer to resolving the issue.
-----
Sorry for the long post. These are the 4 posts I made over at Trailvoy, so there is quite a bit of information here.
I am currently at wits end and I dont know what the next step it. If there are any additional steps or any thoughts as to what is going on, please let me know.
Thanks,
George
***Post #1***
Vehicle:
2003 Envoy XL SLE
4.2L I-6
Mileage: 92,000
Hi everyone -
I am desperately looking for help on the rather serious REP issue.
Yesterday, for example, REP manifested itself no fewer than 45 times while my girlfriend was driving it. Today, I took the vehicle for my usual 34 mile commute and I got it once.
Symptoms: In the 10-20 seconds leading up to the truck going into REP mode, throttle response is sluggish and or "notchy" (meaning the truck accelerates not smoothly or linearly, but in a 'stepped' mode). Then, there is a moderate shudder lasting, at most, 2 seconds, then - boom into REP mode. Both Check Engine and REP lights come one.
Turning the truck off/on gets it out of REP mode. Check engine light stays on.
Environment: South Florida winter, little rain, low moisture. I was thinking we were looking at some sort of moisture issue with the wiring or harness, but in this rather dry enviroment I am not seeing it. Also, during rainshowers - the REP neither increases or descreases.
I've been dealing with this issue for a year now, if not more.
What Has Been Done:
I have replaced the Throttle Body Assembly (Delco). This did not alleviate the TEP issue.
I took the truck to the GMC dealer. They have no idea what was going on but noticed that fuse-box was out of a Trailblazer and not an Envoy. They said this could be a cause, but not 100% certain. That repair\labor cost me $1200 and did not resolve anything.
What I do have, but have not installed yet, is an accelerator, throttle-by-wire assembly. I got that after reading in some spots that this could be a culprit.
Codes:
After having the check engine light on for a while, I hook up the code reader to it and it comes back with these codes:
P0171
P0172
P0340
P1221
P1516
P1481
I cleared the check engine light and codes then took her out for a ride to try to induce another REP. Upon starting the motor, I get the following code:
P0340
HOWEVER, this code does not trigger the Check Engine or REP light.
About 15 minutes into my ride, the usual shudder and REP event occurs. This time the reader tells me:
Code 1: 1221
Code 2: 0340
Code 3: 1221
Odd that 1221 showed up twice.
Anyway, engine-codes.com tells me that GMC 1221 has to do with TPS 1-2 correlation. As mentioned before, this is a genuine Delco aftermarket throttle body\TAC.
I still have the old throttle body.
I will also note that the engine idles rather roughly. I thought it was an engine mount issue, but a mechanic friend of mine took a quick look at it and said it was OK there.
So, I am wits end here. I cannot discern a pattern and I need this vehicle to be working properly.
***Post #2***
Today, two things occurred.
1. When starting the vehicle cold, the vehicle holds on to 1st gear too long under moderate acceleration. When it does grab 2nd, it does so rather roughly. This goes away once the vehicle is up to operating temperature.
2. After my 35 mile commute, upon hitting the light at the end of the exit ramp I take, the vehicle shuddered violently, engine almost went off, and message center said "OIL PRESSURE LOW" then "STOP ENGINE" for a few seconds each. NO REP light appeared. Check engine light was already on. Engine stabilized itself a few seconds after that, but at a highly elevated IDLE speed (almost 1000 RPM).
I have seen this before where the vehicle sit at this high idle. Sometimes restarting the vehicle helps being the idle back down, sometimes it does not.
Also - not sure if I've mentioned this in the OP, but the truck does idle roughly all the time. The idle is relatively stable (until the motor starts hiccuping just before the dreaded REP appear) , but it is rough - and, of course, more pronounced when the vehicle is cold.
Lastly, I should note - the engine has no trouble starting at all.
***Post #3***
So, I went ahead and switched out the accelerator assembly, which you may or may not know is throttle-by-wire on this truck. It was a royal pain in the ass to switch out, but I got it done.
Of course, I disconnected the battery before starting.
So, after switching the unit out, I started her up. I noticed a couple of things.
1. The truck still idles rough, however the hesitation that I was feeling when pressing on the accelerator from a standing start is, for the most part, gone. She does not accelerate any quicker or anything like that.
2. As mentioned, the idle roughness is unchanged. The roughness is significant enough that it rattles the grill a bit - and that be heard from inside the truck. Idle seems to be ok at 700 RPM or so.
3. The "whoooooooooa" sound of the fan clutch seems to be a bit more pronounced and seems to linger a bit until 40 MPH. Before I switched out the accelerator, the fan clutch sound stopped when the tranny shifted from first to second.
4. I took her out for a 30 minute spin. About 10 minutes into it, to my disappointment the REP manifested itself. I did the usual: pulled over to the side of the road, turned the car off, waited 10 seconds, then turned her back on. Check Engine light stayed lit, but REP went away - and I was able to drive the truck normally.
5. About 10 minutes later, I stopped off at CVS to get something. When I came back out, the Check Engine light was gone - which is unusual because it usually lingers for about 4-5 times the ignition is turned on to start - and only then if no new codes appear, it will go away. But like I said, the next time I started the truck, the SES was off.
There was no other drama for the rest of the trip.
What I do notice is still some irregular throttle response at around 20 to 30 MPH. The truck bogs down, not accelerating as you would expect her to.
***Post #4***
Quick update....
So after replacing the gas pedal assembly and going through my regular commute, I have to report that the issue has not been resolved.
I am still getting the usual SES/REP condition with no rhyme or reason.
I am about to set this vehicle on fire and drive it straight into a canal. VERY frustrating.
So I am not even sure where to go from here. I am thinking about sending off a letter or a phone call to GM regional - or even Detroit - to see if I get any sort of traction. In the meantime, I am going to look into getting rid of the Envoy.
$1500 in repairs and parts and I am no closer to resolving the issue.
-----
Sorry for the long post. These are the 4 posts I made over at Trailvoy, so there is quite a bit of information here.
I am currently at wits end and I dont know what the next step it. If there are any additional steps or any thoughts as to what is going on, please let me know.
Thanks,
George
