While I'm stopped such as at a redlight with my foot on brake, after around 20-30 seconds I get this feeling as if someone just bumped me lightly in the rear end or a feeling as if my car wanted to accelerate by itself. It lasts only for a quick second and may or may not happen again after every 30 seconds or so depending on how long I'm at the stopped position.

My trans is auto and I have an Injen SRI. I disconnected the battery for 15 mins to reset everything, but still have the problem.

 

Somethings that you could do:
Shift the car into nutural when you stop and watch the rpm guage (does it consistantly jump up when youyr stopped) If so then that is why.

If that doesnt work I Get a Trainny Fluid Flush just to be sure, but it sounds more of a engine idle problem to me. Is your AC on when this happens?

 

It's the open air intake. If you watch A/F numbers on our car with an open air intake, the range is all over as the MAS sux and cant deal well with the open element. Eventually the ECU finds a RPM that is suitable and settles down, hence why the bumping stops.

 

^ wow good answer. way better then my suggestion. Thanks (even though it wasnt my post)

 

Interesting. Besides the occasional bumping, is there anything I should worry about? Is there a higher performance MAS available for such applications on a Lancer?

 

hey did ur car stopp doing that now? cuz i just got my 04 lancer es 3 weeks ago and it starting doing exactly the same as you said...felt like it wanted to accelerate by itself while stopped at a signal light. im gonna call the dealer tomorrow cuz im scared and i dont know anything about cars....

 

not yet, but you could switch to a MAP sensor and a standalone system, if you wanted, not worth it to me on a lancer tho

 

tward i had that issue! turns out 2002 lancers some were defective. the car wanted to drive while in park with autos. I took the phantom to the dealer cuz my RPMs were 2000 in park. they told me about this problem. They bltch slapped my ECU and it now doesn't do that only jumps to 2000 in the morning then after warming up settles to around 800.