After driving my max hard (WOT runs) a week ago i came to a stop (in drive) and the max started vibrating a little. rpms would go down from 600~ to like 500 and bounce back up to 600 after a slight vibration at 500. it would do it every 5 seconds. In neutral (i think it idles higher in neutral) it wouldnt do it and in park it wouldnt do it either.
a week went by without a reoccurence until i drove the max hard again yesterday.

today i went to the track and it just progressively got worse. it does the same thing, just harder and more often. in neutral it will do it.

i ran a couple times with it like this and my times were terrible. there is this loss in power where the car is usually very strong, in the midrange it just feels choked. but when it gets to top end around 5k rpm you feel a kick like its back to normal power.

anyone know what this could be? throttle position sensor? anything fuel related?
seems like if the engine isnt too hot, and im not bringing it to very high rpm i could avoid the problem, so its not like a constant problem, however i want to fix it immediately.
thanks for the help and sorry if this question is asked frequently.

also, the car never stalls just fyi.

 

My car does the same thing, but after I drive the car heard with WOT acceleration, it actually idles smoother, and higher~around 650 where I want it, instead of 500 which is rough. Possibly becuase the car has over 50 thousand city miles on it. (originally from staten island)

 

most of my driving is city driving, but usually short trips on weekdays, only on the weekend do i really open it up and drive for long periods of time.
i dont get the problem when i dont drive it hard.
i thought it was just an idle problem until i saw my HORRID track times and felt the loss in power on the track AND on the street. i was embarassed.

 

I have a friend going through the same thing. New coils and ks. The power is back but the idle is still ****ty. Once in a while it'll even stall.

Tomorrow I'll be testing the MAF, TPS and maybe cleaning the IAS.

Check her thread out Here

 

test your charging system.
test MAF
Clean IACV

 

Hmm... I didn't think of the charging system. It serp belt probably is pretty beat by now.

 

you dont think it'd be the tps? i see one for sale in the fs section im about to get.

i'll clean the iacv next chance i get.
how do you test the maf? and the charging system?

 

http://phatg20.net/modules.php?name=...ownload&cid=73

 

uh,what????

 

yea i have the same exact problem

 

I have similar issues. I cleaned the TB, IACV, ran seafoam and cleaned MAF connector. Thinking about TPS. How do you "test the MAF" I had the car running the other day and unplugged the connector and the car shut down, that mean anything special? purchasing a used MAF on friday anyway.

 

The link I posted above will help with testing the different sensors and what not.

Disconnecting the MAF will always cause the car to shut down. The MAF helps to meter the amount of air flowing into the engine, thus telling the computer how much gas it needs.

 

Ok, good. I was hoping that was normal... My problem is fluctuating idle which used to stall out occasionally until I cleaned my IACV and opend the screw all the way. My bigger problem is when driving the car acts like it's got either bad gas or like Cylinder misfire, but I'm not pulling ANY codes. It happens at mosly light acceleration or coasting at any RPM and any gear. Maybe I should just start my own thread instead of jacking this one, but it seems the problems are similar...

edit: The car smells like she is running real rich lately. And I'm pretty sure it's not bad fuel as I've switched between numerous stations and ran seafoam and drygas while doing so.

 

i dont mind. i dont think my problem is a misfire or anything like that. i think its intake/throttle related.
what im gonna do is put on a new TPS and see if it stops .either way i'll also clean the IACV cause i've never done that.
hope to have it done within this week.

 

I'm begining to think it's my TPS, but not real sure. Let us know how yours goes. I had a stalling issue that was fixed by cleaning the IACV and adjusting the screw. I've always been under the impression that a misfire would pop a MIL or at least a ghost code but haven't gotten anything so far.

 

as soon as i can buy this one...i'll do it.