Hi people

First of all I'm talkin about my hawkeye sti running 350 bhp/torque.
Over the last few week it feels like its runnin a little lumpy. It's fine when speeding up/boosting. It's also fine when slowing down. It's only seems to do it when keeping a constant speed. (Foot on throttle and keeping it at the same spot). It also does it if at a stand still and rev it and hold it and a constant rev. It's drops and rises. It won't stay at a certain rev if you get what I mean. Could this be spark plugs or maybe over fueling and need a tweek on the map


Cheers
James

 

Possibly the idle control valve thingy

 

My Dad has an MX5 and he put a turbo on it, bought a standalone ECU and needs to map it a bit better as it hunts a bit at idle. Could be this. Or as Daddyscoob says, idle control valve. Good luck

 

Use the search function, there are a few threads about this.

 

The car does seen to idle ok. Does this mean the idle control valve is ok or could it still be it. Think ill clean up the maf first n Cheak that. And then maybe plugs. R the plugs sumthing I can do ( how easy they are to access) and see if that helps
Cheers
James

 

I had a similar problem with my bug sti, have you left the car standing for any length of time ? As that had cause problems with the idle control valve. If it is the idle valve there is an easy fix, which may worth trying, let me know if you want me to find the guide which I've got in an old total impreza I have.
Jon

 

When was the car last serviced? How old are the existing plugs in the car and how long have they been in the car?

 

The car been recently serviced. Not sure on the plugs. May try the icv and maf then the plugs

 

how much is an ICV ?

 

About £300 for a new one mate

 

There is no idle control valve if its a drive by wire car. (UK STi). If JDM then this post is not relevant.

Its possible that what you are feeling is the closed loop fuel control adding and subtracting injector duty to maintain the afr at stoich, thats a very possible cause.

Its possible that the ecu is pulling ignition which makes the car drive in a this way I call that "phantom knock syndrome" and its down to block resonance exciting the knock sensor out put at certain rpm points when there is no det there at all in reality.

Its possible you have a cracked piston which will make the car drive oddly under certain cruise conditions.

If you can get someone to log the car while this is going on then you will be able to see wether either of the first two possibilities is a reality.

cheers

bob