Hi.
I’m new today so sorry if I posted this in the wrong area. Haven’t really got the hang of it all yet.


Ive just had an Apexi Power FC and controller fitted to my 1995 impreza WRX by a tuning company. They also fitted an up rated Walbro fuel pump
and denso spark plugs.
Now since having these fitted when the car is cold or its really cold weather or wet the car will stall when I come to a stop. Then while driving it jerks runs really rough and there is a popping noise coming from the exhaust. If I put my foot down a little it gets through it and once the car has warmed up its fine. It will not always do this though. Some days its fine. The garage who fitted it have had It back several times put a few different maps on and sods law its never done it while they have it and they cant find the fault.
It never used to do it on the standard ECU.

Any help with this would be really appreciated.
Thanks.

Chris

 

PM sent

 

First point of all would be the fuel correction settings on the power FC however I am sure this would have been checked or changed at some point in light of your problem, with that said the base settings are near spot on for standard cars.

The jerking and popping would suggest the car runs lean on the cold start. As it’s not consistent other than that of the power FC you may find the starting temp brings the problem on more so on colder days or vice versa.

 

The fueling on the car is fine as the guys who mapped it have checked several times.
Today i cleaned the idle air control valve and maf. Going to leave the car over night and see what its like from cold in the morning.
When i was cleaning the idle air control valve i blew down the pipes and twisted the valve. I noticed that in the position where its ment to stop the air or water it leaked air out a little. Does anyone no if its ment to seal up competley if so i gues i need a new one. While i was there i took the intercooler of and cleaned up the earth wire under it as it was rusty and dirty.
On my comander for the PFC i checked the sensors and the one for the MAF was only running at 1.2v where as all the other sensors were around 4V. Could this mean it on its way out.

chris

 

MAF reading chould be about 1050mV from memory.
A reading of over 1300mV was a bad sign.
This needs checking as its a couple of years now since I used a powerFC.
who did the work? pm me if you dont want the aggro of posting it

 

well it stoped it stalling but the popping noise and rough running is still there when cold

 

well it stoped it stalling but the popping noise and rough running is still there when cold

 

not on a 95 etc.. 99 maybe

 

oops, my bad

what voltages should be seen Simon?

 

I have have a v.1 WRX, and my Commander reads anywhere between 1.08 and 1.1V, when at idle on a warmed through engine, which Si says is spot on .

So would the OP's quoted 1.2V (at idle though?) mean an 'out of scale' failing MAF?

 

depends on idle speed, induction etc.. better to compare engine off voltage.

Simon

 

Of course - just to illustrate that, my Commander showed 1.3V his morning after starting, because of cold engine i.e. requiring more fuel - so more air - hence the slightly higher reading... Presumably? lol