Help me with an issue!!
06-12-2010, 09:21 PM
#1
Burning Brakes
Thread Starter
Help me with an issue!!
First off I have a 1988 928 S4 with an automatic transmission. I drive it daily to school and it has performed flawlessly for 3 months. Today however I go out and start it up reverse out of the drive and put it back in drive.
As I get on the gas a little the car starts bucking, I was applying even pressure on the gas and it would accelerate and slow and then accelerate and slow back and forth.
I stopped the car and watched the idle. It idles fine right where it is supposed to, but when I press the accelerator in park and hold it in one spot it revs and comes back down and then revs and come back down again. The fluctuations are from 1000 rpm to about 3000.
I thought for sure it was a vacuum leak, but I have run a vacuum check on the motor with a gauge and they all appear to be fine.
The funniest part is when I let it idle and warm up real good the problem goes away for the most part with only slight interruptions and less frequent when accelerating or revving.
I have inspected the MAF and all wires appear to be in good order, now my question is where do I go from here. I have listed all the symptoms I could think of. If there is anything I am forgetting to check or someone knows a solution please help me out!
TIA
Catfood
As I get on the gas a little the car starts bucking, I was applying even pressure on the gas and it would accelerate and slow and then accelerate and slow back and forth.
I stopped the car and watched the idle. It idles fine right where it is supposed to, but when I press the accelerator in park and hold it in one spot it revs and comes back down and then revs and come back down again. The fluctuations are from 1000 rpm to about 3000.
I thought for sure it was a vacuum leak, but I have run a vacuum check on the motor with a gauge and they all appear to be fine.
The funniest part is when I let it idle and warm up real good the problem goes away for the most part with only slight interruptions and less frequent when accelerating or revving.
I have inspected the MAF and all wires appear to be in good order, now my question is where do I go from here. I have listed all the symptoms I could think of. If there is anything I am forgetting to check or someone knows a solution please help me out!
TIA
Catfood
06-12-2010, 10:52 PM
#4
Team Owner
from your post it could be the temp2 sensor as it seems to run better when it warms up
06-13-2010, 12:16 AM
#6
Rennlist Member
With the MAF unplugged it should run, but crappy-- the LH goes into a "limp home" mode.
It's already running crappy, so if the problem is a dead MAF then it will run equally crappy whether the MAF is plugged in, or not.
So if there is no change then the MAF is likely dead, if it runs worse with the MAF unplugged then maybe the MAF is ok and the problem lies elsewhere.
And as Andrew said, lots of good troubleshooting info available-- methodical testing is usually rewarded.
Good hunting!
It's already running crappy, so if the problem is a dead MAF then it will run equally crappy whether the MAF is plugged in, or not.
So if there is no change then the MAF is likely dead, if it runs worse with the MAF unplugged then maybe the MAF is ok and the problem lies elsewhere.
And as Andrew said, lots of good troubleshooting info available-- methodical testing is usually rewarded.
Good hunting!
