Irregular Engine Speed When Cold
#1
01-05-2013, 12:20 AM
Join Date: Mar 2012
Location: Hellertown, Pennsylvania
Posts: 550
Irregular Engine Speed When Cold
Hey guys, I have a somewhat odd problem that I can't quite figure out. I have a 2003 A6, 2.7t with about 127,000 miles on it.
When cold and in drive, the engine speed is very irregular. For instance, when pulling out of my driveway and onto my street, I notice the engine feels like it's all over the place. The tachometer confirms this as well. The speed will fluctuate by about 150 to 200 RPMs. This issue goes away after about five to ten minutes of driving the car. This problem is not present when the car is cold and in park or in neutral.
I took it to the dealer for some BS work that I didn't want to bother with and I brought this concern up to them. They noted that since my SAP was disconnected at the time (I decided it would be a good idea to break the wiring harness. It's functioning correctly now, though) that the car would operate in this manner because the cat wasn't heated up and the o2s were able to get a proper reading. Once the cat warms up, the problem would go away. Well I hooked up the SAP and the problem is still there.
Here is a list of some information that I think may be helpful / important to figuring this problem out:
I'm currently not getting any codes when scanning using vagcomm. Could an o2 sensor be on its way out?
When cold and in drive, the engine speed is very irregular. For instance, when pulling out of my driveway and onto my street, I notice the engine feels like it's all over the place. The tachometer confirms this as well. The speed will fluctuate by about 150 to 200 RPMs. This issue goes away after about five to ten minutes of driving the car. This problem is not present when the car is cold and in park or in neutral.
I took it to the dealer for some BS work that I didn't want to bother with and I brought this concern up to them. They noted that since my SAP was disconnected at the time (I decided it would be a good idea to break the wiring harness. It's functioning correctly now, though) that the car would operate in this manner because the cat wasn't heated up and the o2s were able to get a proper reading. Once the cat warms up, the problem would go away. Well I hooked up the SAP and the problem is still there.
Here is a list of some information that I think may be helpful / important to figuring this problem out:
- I changed out my SAP about a year ago. The original one finally died after making the usual whining noises before it finally gave out.
- There was a bad EGT sensor on bank 1 (passenger side). I have since replaced this and haven't gotten a fault code about it in a long while.
- The original ECT sensor was recently replaced. I put an aftermarket green sensor in and the dealership spotted this right away. They actually gave me an OEM one free of charge. (I bet your dealership won't do that for you!)
- Recently cleaned the MAF in hopes of cleaning gunk and other debris off of it.
- Timing belt was just changed about a year ago by myself. Everything went according to plan
I'm currently not getting any codes when scanning using vagcomm. Could an o2 sensor be on its way out?
Last edited by Nebuchadnezzar; 01-05-2013 at 12:23 AM.
#2
01-05-2013, 11:43 AM
Hey guys, I have a somewhat odd problem that I can't quite figure out. I have a 2003 A6, 2.7t with about 127,000 miles on it.
When cold and in drive, the engine speed is very irregular. For instance, when pulling out of my driveway and onto my street, I notice the engine feels like it's all over the place. The tachometer confirms this as well. The speed will fluctuate by about 150 to 200 RPMs. This issue goes away after about five to ten minutes of driving the car. This problem is not present when the car is cold and in park or in neutral.
I took it to the dealer for some BS work that I didn't want to bother with and I brought this concern up to them. They noted that since my SAP was disconnected at the time (I decided it would be a good idea to break the wiring harness. It's functioning correctly now, though) that the car would operate in this manner because the cat wasn't heated up and the o2s were able to get a proper reading. Once the cat warms up, the problem would go away. Well I hooked up the SAP and the problem is still there.
Here is a list of some information that I think may be helpful / important to figuring this problem out:
I'm currently not getting any codes when scanning using vagcomm. Could an o2 sensor be on its way out?
When cold and in drive, the engine speed is very irregular. For instance, when pulling out of my driveway and onto my street, I notice the engine feels like it's all over the place. The tachometer confirms this as well. The speed will fluctuate by about 150 to 200 RPMs. This issue goes away after about five to ten minutes of driving the car. This problem is not present when the car is cold and in park or in neutral.
I took it to the dealer for some BS work that I didn't want to bother with and I brought this concern up to them. They noted that since my SAP was disconnected at the time (I decided it would be a good idea to break the wiring harness. It's functioning correctly now, though) that the car would operate in this manner because the cat wasn't heated up and the o2s were able to get a proper reading. Once the cat warms up, the problem would go away. Well I hooked up the SAP and the problem is still there.
Here is a list of some information that I think may be helpful / important to figuring this problem out:
- I changed out my SAP about a year ago. The original one finally died after making the usual whining noises before it finally gave out.
- There was a bad EGT sensor on bank 1 (passenger side). I have since replaced this and haven't gotten a fault code about it in a long while.
- The original ECT sensor was recently replaced. I put an aftermarket green sensor in and the dealership spotted this right away. They actually gave me an OEM one free of charge. (I bet your dealership won't do that for you!)
- Recently cleaned the MAF in hopes of cleaning gunk and other debris off of it.
- Timing belt was just changed about a year ago by myself. Everything went according to plan
I'm currently not getting any codes when scanning using vagcomm. Could an o2 sensor be on its way out?
1st what do, in the morning, know this are oil build engine with high pressur. start the car and let it run for at least 3 mns.Then When ever i drive it, gear changes easily and can accelerate and deccelarate. The weather could be a factor because I did not have this little issue in the summer.
This is what I know so far
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