Matt Beau

I have a new (to me ) 5 door '99 with about 100k km on the clock. As far as I can tell, it is all stock, and for the most part, I am quite happy with it.

However, I've noticed that under light acceleration (say from 2000 RPM), you can feel it accelerate in a cyclic manner. That is to say it accelerates a bit, slows down a bit, accelerates a bit, etc. It's not something most people would notice, but once pointed out, my passengers can feel it.

On a somewhat related note, while cruising on the autoroute, I find that it's a bit difficult to maintain a certain speed. I'm not sure if it's related to the above surging though. It seems that I'm either slowing down, or accelerating. The response is very non-linear.

Are either of these behaviours normal, or is there perhaps a small problem? They're more like minor annoyances, but annoyances nonetheless.

FWIW it pulls hard to redline.

RON

Matt, the my99's dod suffer with this as a rule, however, it may be worth getting the MAF checked, or at least do an error check, if the MAF's faulty, you don't want to be redlining it til it's sorted!!!

Matt P

It might be a case of "they all do that sir...", or at least they do during warm up while the lambda sensor is open circuit. So it might just be worth getting your lambda sensor checked out. The lambda sensor is ignored on WOT so getting your MAF checked at the same time wouldn't do any harm

The_Judge

Lambda sounds likely, if you're not experiencing the problems foot to floor above 3000rpm (ish). However, if you are, then it could be MAF or wastegate solenoid (amongst other things). Click here for advice on checking those...

Matt Beau

I did have it stumble one time when I went to accelerate hard and the engine was around 3-3.5k RPM. Only happened once though...

I was thinking a "lazy" O2 sensor might be causing what I'm feeling. It does happen warm or cold as far as I can tell.