odd happenings

[jaekormtb]

Got some strange behavior from my 1999 C4 recently that I thought I might share. 

About two months ago I finally changed the fuel filter, and that's when things started. To change the fuel filter, I also had to pull the airbox. The filter there is relatively new, so I just banged the light dust out of it and put it back in. Also, the air-straightener in front of the MAF had popped out, so I got that back where it belonged. On my test drive, It felt like the car had a bit more pep. Super! After a couple of days of commuting I decided to open her up on a back road. In 2nd as the car passed 4K she really took off, so much so that the ABS and PSM warning lights both came on. I knew that I was feeling some wheel spin, but sure didn't expect that. After shutting the car off, the lights did not reappear. However, on any WOT acceleration, there would be a big surge from 4-5K and it would   trigger the ABS and PSM lights. ??? And then the check engine lights started. They'd come on when the car was up to temps and idling around parking lots, etc. It was the typical MAF codes, so I pulled it out and gave it a good spraying with MAF cleaner. The car is now back to it's normal behavior - no giant surge at 4K,  :(, no wheel spin, no ABS/PSM lights, no CELs. and maybe a bit better mpg. 

I'm guessing the MAF was reading less air than the engine was getting, so fuel delivery was down creating a lean condition that gave me a bit of a boost.

Any other thoughts??

 

[judgejon]

Please don't start laughing at my reply.  I understand exactly what you're saying re the MAF.

But what kind of a back road were you on?  Fairly straight-line?  Lots of twists and curves?

On a fast acceleration around a twisty curve you can get the ABS/PSM lights to come on if your tires are mismatched.

The car will throw the ABS/PSM codes if you run different brands of tires on the car, even if the fronts or rears are paired.

If that happens other codes may also be thrown.  Just asking...

A better answer is that you fixed it the problem by simply cleaning the MAF.  Get the car back out onto the same back road and run again.

Good luck.

Edited May 23, 2016 by judgejon

[rockhouse66]

Sounds bizarre!  On a related note, is there supposed to be a flash on the dash when the PSM activates?  I have never seen it on my 2004 C2 and I have managed to get myself in some situations where I expected it!