Rough Idle
Thread Starter
|
Junior Member
Joined: Jan 2010
Posts: 8
From: Vancouver B.C.
Rough Idle
Hi Guys,
I hope this is OK for my first thread? I have been checking out a lot of websites and found yours. It looks great and I won't do the grab and run thing
Well here goes. My car is a 2008 CTS RWD with a 3.6 litre non-direct injection. I bought the car used from a GM dealer and the car has been accidented and repaired. I found the car on the internet and it came from Vancouver Island and I have been taking it to my local dealer here in the lower mainland to try and find the problem with the idle. After about 3 weeks of going back and forth they can't find the problem and are trying to blame the accident for the problem. Saying that they think the frame is bent. And until that is inspected and corrected if there is a problem with the frame they won't "start throwing parts at it". For the life of me I can't see how a bent frame has any bearing on an engine when the car is not even moving. Mind you I am concerned that the frame may be bent and I have contacted the original dealer and made him aware of what is going on. So he is looking into get the car back over to the island to check it out.
I should say to start the description of the bad idle that the car has it's moments, when the idle is perfect and smooth and without any issues at all. This doesn't happen often actually. It only happened once that I actually tried to make it happen and it wouldn't do it again. Until I got back onto the highway and drove 5 miles and came to a stop and it was there once again. But it ran that time for about 45 minutes without incident. I started and drove the car to the highway and did about 15 miles and went around that area stopping and starting and tried fast starts and mild starts and fast stops and fast turning and anything I could think of. It ran so well I thought I had cleared the fault whatever it was. I was so happy. I then got back on the highway and when I came off the highway and came to a stop the idle went back to being rough and terrible. When it ran well the idle was at 700 rpm and when it idles poorly it idles at just over 500 rpm. The weather was better last week just a little warmer and it ran better. This week is slightly cooler and it's back to where it was. That being, a harmonic type vibration that could make your dentures vibrate. It's as though something doesn't release when coming to a stop. A pressure build up that doesn't return to normal at a stop. Mind you it happens even if you don't drive the car. If it warms up and hasn't been driven the roughness still comes into play. After saying all that, if I hold the brake and apply a little gas to bring it up to 700 rpm, it is better, and almost like it is when it is at 700 rpm doing it itself. Man I hope that made sense. It doesn't sound like it's missing it is an even roughness. Of course it is rougher with the A/C on. Which I have on most of the time. It just pronounces the vibration more with the A/C on.
So now onto what I have checked out on the car. I knew it was accidented and wanted to see underneath to check it out. A friend of mine has a lift so we got it up and checked it out. Everything looks brand new under there except for some mud which is mostly in the front and going back to just about mid car underneath. We didn't see anything unusual. We did notice that the hood and the front fenders had been removed and saw that the drivers side lower control arm has been adjusted outward in the front of the control arm which supports the dealers observation that the frame may be bent. But we couldn't see anything really out of wack. I did notice after cleaning out the mud that there were items that were not tightened properly and it's possible that if a shock or lower control arm was replace that they didn't align it properly after installation. That will be confirmed when we get the frame inspected. There wasn't a lot of mud in actuality it may be that who ever drove the car may have been on a dirt road and following someone since there was mud in the radiator fans too. I took out the fan assembly and cleaned it all up. It's that I am **** about things like that. Put it this way when I am finished the car will be better than when it came off the assembly line. I also detail the underside of my cars.
I also removed the air bridge and inspected the MAF and throttle body. I cleaned up the throttle body and found a slight score mark where there may have been a piece of grit. Also there is a square piece underneath the airbridge that looks like it contacted a pulley in the accident. It has a crescent shape burned into it. But not through the plastic. With the throttle body I felt the shaft that the butterfly is on is a little sloppy in it's housing. But I don't have a new one to compare it to. While in the engine bay I opened every connector and inspected for cleanliness and water intrusion. I didn't find any sign of anything. I cleaned the outside of all connectors thoroughly before opening them. There was only one connector I was unable to open and that one was for an oxygen sensor on the passenger's side. I was just not in a good position to get to it. There was a tab inserted to prevent opening of the connector and I didn't want to disturb it at that time. When talking to the dealer they said that they found the steering rack was not torqued down supporting my thoughts on bad installation of parts. I have also removed the air plenum to check things out and inspect the coils and plugs. Since the dealer doesn't want to do anything until they see a code on their scanner. Also a low idle for me is something like a vacuum leak or a bad spark plug. Anyway everything went well but there were two coils that were kind of brown looking. One more than the other. Which could mean internal arcing but then I could be all wet with that observation. They all metered out roughly the same as the other ones. I didn't have the stats on the metering so I was just able to compare them to each other. I put everything back together and the problem persists.
I wish I could have the dealer replace the throttle body, the MAF sensor, and the two coils and possible the oxygen sensor that had mud on it to see if that takes care of the problem. But they would just look at me. But the car is an Optimal Vehicle with more than a year and a half of factory warranty left on the vehicle. That is why I felt confident when buying the vehicle that the problem would be corrected.
So there it is!! I hope I have given you enough info. If you have any questions I will be more than willing to provide you with more info if I can.
Thanks for your time it is much appreciated.
I hope this is OK for my first thread? I have been checking out a lot of websites and found yours. It looks great and I won't do the grab and run thing
Well here goes. My car is a 2008 CTS RWD with a 3.6 litre non-direct injection. I bought the car used from a GM dealer and the car has been accidented and repaired. I found the car on the internet and it came from Vancouver Island and I have been taking it to my local dealer here in the lower mainland to try and find the problem with the idle. After about 3 weeks of going back and forth they can't find the problem and are trying to blame the accident for the problem. Saying that they think the frame is bent. And until that is inspected and corrected if there is a problem with the frame they won't "start throwing parts at it". For the life of me I can't see how a bent frame has any bearing on an engine when the car is not even moving. Mind you I am concerned that the frame may be bent and I have contacted the original dealer and made him aware of what is going on. So he is looking into get the car back over to the island to check it out.
I should say to start the description of the bad idle that the car has it's moments, when the idle is perfect and smooth and without any issues at all. This doesn't happen often actually. It only happened once that I actually tried to make it happen and it wouldn't do it again. Until I got back onto the highway and drove 5 miles and came to a stop and it was there once again. But it ran that time for about 45 minutes without incident. I started and drove the car to the highway and did about 15 miles and went around that area stopping and starting and tried fast starts and mild starts and fast stops and fast turning and anything I could think of. It ran so well I thought I had cleared the fault whatever it was. I was so happy. I then got back on the highway and when I came off the highway and came to a stop the idle went back to being rough and terrible. When it ran well the idle was at 700 rpm and when it idles poorly it idles at just over 500 rpm. The weather was better last week just a little warmer and it ran better. This week is slightly cooler and it's back to where it was. That being, a harmonic type vibration that could make your dentures vibrate. It's as though something doesn't release when coming to a stop. A pressure build up that doesn't return to normal at a stop. Mind you it happens even if you don't drive the car. If it warms up and hasn't been driven the roughness still comes into play. After saying all that, if I hold the brake and apply a little gas to bring it up to 700 rpm, it is better, and almost like it is when it is at 700 rpm doing it itself. Man I hope that made sense. It doesn't sound like it's missing it is an even roughness. Of course it is rougher with the A/C on. Which I have on most of the time. It just pronounces the vibration more with the A/C on.
So now onto what I have checked out on the car. I knew it was accidented and wanted to see underneath to check it out. A friend of mine has a lift so we got it up and checked it out. Everything looks brand new under there except for some mud which is mostly in the front and going back to just about mid car underneath. We didn't see anything unusual. We did notice that the hood and the front fenders had been removed and saw that the drivers side lower control arm has been adjusted outward in the front of the control arm which supports the dealers observation that the frame may be bent. But we couldn't see anything really out of wack. I did notice after cleaning out the mud that there were items that were not tightened properly and it's possible that if a shock or lower control arm was replace that they didn't align it properly after installation. That will be confirmed when we get the frame inspected. There wasn't a lot of mud in actuality it may be that who ever drove the car may have been on a dirt road and following someone since there was mud in the radiator fans too. I took out the fan assembly and cleaned it all up. It's that I am **** about things like that. Put it this way when I am finished the car will be better than when it came off the assembly line. I also detail the underside of my cars.
I also removed the air bridge and inspected the MAF and throttle body. I cleaned up the throttle body and found a slight score mark where there may have been a piece of grit. Also there is a square piece underneath the airbridge that looks like it contacted a pulley in the accident. It has a crescent shape burned into it. But not through the plastic. With the throttle body I felt the shaft that the butterfly is on is a little sloppy in it's housing. But I don't have a new one to compare it to. While in the engine bay I opened every connector and inspected for cleanliness and water intrusion. I didn't find any sign of anything. I cleaned the outside of all connectors thoroughly before opening them. There was only one connector I was unable to open and that one was for an oxygen sensor on the passenger's side. I was just not in a good position to get to it. There was a tab inserted to prevent opening of the connector and I didn't want to disturb it at that time. When talking to the dealer they said that they found the steering rack was not torqued down supporting my thoughts on bad installation of parts. I have also removed the air plenum to check things out and inspect the coils and plugs. Since the dealer doesn't want to do anything until they see a code on their scanner. Also a low idle for me is something like a vacuum leak or a bad spark plug. Anyway everything went well but there were two coils that were kind of brown looking. One more than the other. Which could mean internal arcing but then I could be all wet with that observation. They all metered out roughly the same as the other ones. I didn't have the stats on the metering so I was just able to compare them to each other. I put everything back together and the problem persists.
I wish I could have the dealer replace the throttle body, the MAF sensor, and the two coils and possible the oxygen sensor that had mud on it to see if that takes care of the problem. But they would just look at me. But the car is an Optimal Vehicle with more than a year and a half of factory warranty left on the vehicle. That is why I felt confident when buying the vehicle that the problem would be corrected.
So there it is!! I hope I have given you enough info. If you have any questions I will be more than willing to provide you with more info if I can.
Thanks for your time it is much appreciated.
Last edited by Vanman; Jan 29, 2010 at 11:44 AM.
Tech Certified Members
Joined: Jun 2007
Posts: 2,701
Hi Guys,
I hope this is OK for my first thread? I have been checking out a lot of websites and found yours. It looks great and I won't do the grab and run thing
Well here goes. My car is a 2008 CTS RWD with a 3.6 litre non-direct injection. I bought the car used from a GM dealer and the car has been accidented and repaired. I found the car on the internet and it came from Vancouver Island and I have been taking it to my local dealer here in the lower mainland to try and find the problem with the idle. After about 3 weeks of going back and forth they can't find the problem and are trying to blame the accident for the problem. Saying that they think the frame is bent. And until that is inspected and corrected if there is a problem with the frame they won't "start throwing parts at it". For the life of me I can't see how a bent frame has any bearing on an engine when the car is not even moving. Mine you I am concerned that the frame may be bent and have contacted the original dealer and made him aware of what is going on. So he is looking into get the car back over to the island to check it out.
I should say to start the description of the bad idle that the car has it's moments when the idle is perfect and smooth and without any issues at all. This doesn't happen often actually it only happened once when I actually tried to make it happen and it wouldn't do it again. Until I got back onto the highway and drove 5 miles and came to a stop and it was there once again. But it ran that time for about 45 minutes without incident. I started and drove the car to the highway and did about 15 miles and went around that area stopping and starting and tried fast starts and mild starts and fast stops and fast turning and anything I could think of. It ran so well I thought I had cleared the fault whatever it was. I was so happy. I then got back on the highway and when I came off the highway and came to a stop the idle went back to being rough and terrible. When it ran well the idle was at 700 rpm and when it idles poorly it idles at just over 500 rpm. The weather was better last week just a little warmer and it ran better. This week is slightly cooler and it's back to where it was.
So now onto what I have checked out on the car. I knew it was accidented and wanted to see underneath to check it out. A friend of mine has a lift so we got it up and checked it out. Everything looks brand new under there except for some mud which is mostly in the front and going back to just about mid car underneath. We didn't see anything unusual. We did notice that the hood and the front fenders had been removed and saw that the drivers side lower control arm has been adjusted outward in the front of the control arm which supports the dealers observation that the frame may be bent. But we couldn't see anything really out of wack. I did notice after cleaning out the mud that there were items that were not tightened properly and it's possible that if a shock or lower control arm was replace that they didn't align it properly after installation. That will be confirmed when we get the frame inspected. There wasn't a lot of mud in actuality it may be that who ever drove the car may have been on a dirt road and following someone since there was mud in the radiator fans too. I took out the fan assembly and cleaned it all up. It's that I am **** about things like that. Put it this way when I am finished the car will be better than when it came off the assembly line. I also detail the underside of my cars.
I also removed the air bridge and inspected the MAF and throttle body. I cleaned up the throttle body and found a slight score mark where there may have been a piece of grit. Also there is a square piece underneath the airbridge that looks like it contacted a pulley in the accident. It has a crescent shape burned into it. But not through the plastic. With the throttle body I felt the shaft that the butterfly is on is a little sloppy in it's housing. But I don't have a new one to compare it to. While in the engine bay I opened every connector and inspected for cleanliness and water intrusion. I didn't find any sign of anything. I cleaned the outside of all connectors thoroughly before opening them. There was only one connector I was unable to open and that one was for an oxygen sensor on the passenger's side. I was just not in a good position to get to it. There was a tab inserted to prevent opening of the connector and I didn't want to disturb it at that time. When talking to the dealer they said that they found the steering rack was not torqued down supporting my thoughts on bad installation of parts. I have also removed the air plenum to check things out and inspect the coils and plugs. Since the dealer doesn't want to do anything until they see a code on their scanner. Also a low idle for me is something like a vacuum leak or a bad spark plug. Anyway everything went well but there were two coils that were kind of brown looking. One more than the other. Which could mean internal arcing but then I could be all wet with that observation. They all metered out roughly the same as the other ones. I didn't have the stats on the metering so I was just able to compare them to each other. I put everything back together and the problem persists.
I wish I could have the dealer replace the throttle body, the MAF sensor, and the two coils and possible the oxygen sensor that had mud on it to see if that takes care of the problem. But they would just look at me. But the car is an Optimal Vehicle with more than a year and a half of factory warranty left on the vehicle. That is why I felt confident when buying the vehicle that the problem would be corrected.
So there it is!! I hope I have given you enough info. If you have any questions I will be more than willing to provide you with more info if I can.
Thanks for your time it is much appreciated.
I hope this is OK for my first thread? I have been checking out a lot of websites and found yours. It looks great and I won't do the grab and run thing
Well here goes. My car is a 2008 CTS RWD with a 3.6 litre non-direct injection. I bought the car used from a GM dealer and the car has been accidented and repaired. I found the car on the internet and it came from Vancouver Island and I have been taking it to my local dealer here in the lower mainland to try and find the problem with the idle. After about 3 weeks of going back and forth they can't find the problem and are trying to blame the accident for the problem. Saying that they think the frame is bent. And until that is inspected and corrected if there is a problem with the frame they won't "start throwing parts at it". For the life of me I can't see how a bent frame has any bearing on an engine when the car is not even moving. Mine you I am concerned that the frame may be bent and have contacted the original dealer and made him aware of what is going on. So he is looking into get the car back over to the island to check it out.
I should say to start the description of the bad idle that the car has it's moments when the idle is perfect and smooth and without any issues at all. This doesn't happen often actually it only happened once when I actually tried to make it happen and it wouldn't do it again. Until I got back onto the highway and drove 5 miles and came to a stop and it was there once again. But it ran that time for about 45 minutes without incident. I started and drove the car to the highway and did about 15 miles and went around that area stopping and starting and tried fast starts and mild starts and fast stops and fast turning and anything I could think of. It ran so well I thought I had cleared the fault whatever it was. I was so happy. I then got back on the highway and when I came off the highway and came to a stop the idle went back to being rough and terrible. When it ran well the idle was at 700 rpm and when it idles poorly it idles at just over 500 rpm. The weather was better last week just a little warmer and it ran better. This week is slightly cooler and it's back to where it was.
So now onto what I have checked out on the car. I knew it was accidented and wanted to see underneath to check it out. A friend of mine has a lift so we got it up and checked it out. Everything looks brand new under there except for some mud which is mostly in the front and going back to just about mid car underneath. We didn't see anything unusual. We did notice that the hood and the front fenders had been removed and saw that the drivers side lower control arm has been adjusted outward in the front of the control arm which supports the dealers observation that the frame may be bent. But we couldn't see anything really out of wack. I did notice after cleaning out the mud that there were items that were not tightened properly and it's possible that if a shock or lower control arm was replace that they didn't align it properly after installation. That will be confirmed when we get the frame inspected. There wasn't a lot of mud in actuality it may be that who ever drove the car may have been on a dirt road and following someone since there was mud in the radiator fans too. I took out the fan assembly and cleaned it all up. It's that I am **** about things like that. Put it this way when I am finished the car will be better than when it came off the assembly line. I also detail the underside of my cars.
I also removed the air bridge and inspected the MAF and throttle body. I cleaned up the throttle body and found a slight score mark where there may have been a piece of grit. Also there is a square piece underneath the airbridge that looks like it contacted a pulley in the accident. It has a crescent shape burned into it. But not through the plastic. With the throttle body I felt the shaft that the butterfly is on is a little sloppy in it's housing. But I don't have a new one to compare it to. While in the engine bay I opened every connector and inspected for cleanliness and water intrusion. I didn't find any sign of anything. I cleaned the outside of all connectors thoroughly before opening them. There was only one connector I was unable to open and that one was for an oxygen sensor on the passenger's side. I was just not in a good position to get to it. There was a tab inserted to prevent opening of the connector and I didn't want to disturb it at that time. When talking to the dealer they said that they found the steering rack was not torqued down supporting my thoughts on bad installation of parts. I have also removed the air plenum to check things out and inspect the coils and plugs. Since the dealer doesn't want to do anything until they see a code on their scanner. Also a low idle for me is something like a vacuum leak or a bad spark plug. Anyway everything went well but there were two coils that were kind of brown looking. One more than the other. Which could mean internal arcing but then I could be all wet with that observation. They all metered out roughly the same as the other ones. I didn't have the stats on the metering so I was just able to compare them to each other. I put everything back together and the problem persists.
I wish I could have the dealer replace the throttle body, the MAF sensor, and the two coils and possible the oxygen sensor that had mud on it to see if that takes care of the problem. But they would just look at me. But the car is an Optimal Vehicle with more than a year and a half of factory warranty left on the vehicle. That is why I felt confident when buying the vehicle that the problem would be corrected.
So there it is!! I hope I have given you enough info. If you have any questions I will be more than willing to provide you with more info if I can.
Thanks for your time it is much appreciated.
dang ! you have provided lots of good info but there is one more that is needed. Codes!
i agree with your assessment of the frame but it also sounds that the repair job was not completed and needs to be done before driving the car again. safety issues come to mind. your dealer is probably afraid to touch the car and inherit the liability of the bad job done on the accident. i cant blame them.
also, by your description, it sounds like an electrical issue .. read our e-ghosts thread in the FAQ. specially the topics of dielectric grease.
the most likely issue is a bad wire or connector.
.
Last edited by stomper; Jan 29, 2010 at 11:32 AM.
Thread Starter
|
Junior Member
Joined: Jan 2010
Posts: 8
From: Vancouver B.C.
Thanks for the reply! And to answer your question about codes. No there are no codes. The dealer says that the idle will not throw a code till it drops 100 rpm or increases 200 rpm from specification. Which is between 600 and 700 rpm. So the car is within those parameters. Is there a way of bringing up the codes on the DIC display? I didn't read anything in the owners manual but I think earlier models you could do this and I haven't tried pushing buttons yet to see if I can bring anything up. But the dealer says that all the computers are up to date with firmware and all are reporting correctly. So it's on to something like a bad ground or bad connection. I just wish I knew what device or component can cause a drop in rpm and cause this vibration that I am experiencing. Today I tried disconnecting that suspect coil at idle and it caused a drop in rpm so that is working OK. I was thinking of using a hair dryer and putting it in front of the air intake to see if warmer air would change anything. Sort of simulating a hotter ambient air temp. Incase the intake air temp sensor which I think is a part of the MAF sensor assembly is not working properly. Since the car ran perfectly the other day, but it was a very warm day compared to other days since I have owned the car. Any other ideas that I could try, to try and simulate and isolate the problem would be appreciated. Thanks!!
Last edited by Vanman; Jan 29, 2010 at 04:45 PM.
Tech Certified Members
Joined: Jun 2007
Posts: 2,701
rough idle is not the same as erratic idle.
smells out the tail pipe?
if no smells, it could be just erratic idle .. TPS, throttle intake, throttle cable/pedal/linkage sticking, cruise control linkage sticking, a valve seat not seating, etc ...
codes .. your info center can provide .. go to our fAQ and see how.
.
smells out the tail pipe?
if no smells, it could be just erratic idle .. TPS, throttle intake, throttle cable/pedal/linkage sticking, cruise control linkage sticking, a valve seat not seating, etc ...
codes .. your info center can provide .. go to our fAQ and see how.
.
Thread Starter
|
Junior Member
Joined: Jan 2010
Posts: 8
From: Vancouver B.C.
Well thanks for the reply. But I have scoured the site for info and really haven't come up with anything that relates to my year 2008 CTS. If anyone else has info regarding obtaining codes from a 2008 DIC that would be great. And any other ideas also. Even if it's just to say Hi! I'll get to the bottom of this sooner or later and everyones help would be great.
I'll get to the bottom of this sooner or later and everyones help would be great.
Tech Certified Members
Joined: Jun 2007
Posts: 2,701
Well thanks for the reply. But I have scoured the site for info and really haven't come up with anything that relates to my year 2008 CTS. If anyone else has info regarding obtaining codes from a 2008 DIC that would be great. And any other ideas also. Even if it's just to say Hi! I'll get to the bottom of this sooner or later and everyones help would be great.
I'll get to the bottom of this sooner or later and everyones help would be great. 
Junior Member
Joined: Dec 2006
Posts: 9
From: new york
Rough idel
Vanman this sounds just like the E.G.R. problem I had with my sts. I did not get a code for three weeks. Then I bought a code reader, It showed me the problem. Then I replaced the E.G.R. and NEVER had a rough idle since
Thread Starter
|
Junior Member
Joined: Jan 2010
Posts: 8
From: Vancouver B.C.
Thread Starter
|
Junior Member
Joined: Jan 2010
Posts: 8
From: Vancouver B.C.
Well it took a little longer than expected but the car is fixed. And so as I stated I won't leave everyone guessing as to what the cause was.
As explained earlier the car had been in an accident. The dealer was correct in his assumption that the accident was to fault for the rough idle. The car did go to a frame shop to inspect the frame and came back with a clean bill of health. From there the dealership found that the engine mounts had pulled away and were causing the direct transmission of any engine vibration to the frame.
So there it is. Engine mounts replaced and cradle re-aligned and a wheel alignment and the car purrs like a kitten. And probably less vibration than a new car since great care was taken to get it right. So I am so pleased you wouldn't believe. I no longer have to shift into neutral at a stop to diminish the aggravating noise and vibration.
So if anyone else is not satisfied with their idle they may question the alignment of all parts in question. Tight tolerances are involved in todays cars unlike in years past. Have a great day I am going to have a wonderful day.
As explained earlier the car had been in an accident. The dealer was correct in his assumption that the accident was to fault for the rough idle. The car did go to a frame shop to inspect the frame and came back with a clean bill of health. From there the dealership found that the engine mounts had pulled away and were causing the direct transmission of any engine vibration to the frame.
So there it is. Engine mounts replaced and cradle re-aligned and a wheel alignment and the car purrs like a kitten. And probably less vibration than a new car since great care was taken to get it right. So I am so pleased you wouldn't believe. I no longer have to shift into neutral at a stop to diminish the aggravating noise and vibration.
So if anyone else is not satisfied with their idle they may question the alignment of all parts in question. Tight tolerances are involved in todays cars unlike in years past. Have a great day I am going to have a wonderful day.
Thread
Thread Starter
Forum
Replies
Last Post
