When my car is hot it runs perfect (after say 15mins or driving)

but before that it runs really bad, i know they run better hot and shouldnt be nailed when cold...

But when its hot it boosts to 12 PSI with no problem and never splutters etc!


When cold it boost to 12 psi then splutters / back fires and goes to 8psi (safe mode i think) then boost back up and does the same again

Sometimes backfires at 8-9ish boost... After a while it all goes and runs perfect!

Ive changed the MAF sensor and no difference

Its a 1993 WRX, with DECAT, HKS induction, Dumpvalve


WHAT COULD THIS BE?? TO ONLY HAPPEN WHEN COLD???


ANY HELP GUYS???

 

i was thinking maybe coil packs? but wouldnt these still break down etc under high revs when hot?

 

I've the same problem (v. occasionally) with my 1995 WRX Import, with DeCat & Dumpvalve.

 

first thing i'd change is coolant sensor.

 

I have exact same problem om MY95 import, de-cat and STI Panel Filter, seems worse when car has not been driven for a few days. So far changed
MAF
Lamba
Coolant Temp sensor
Ideas greatly welcomed

 

well the only thing we all have in common is the DECAT, but mine was doing it long after i fitted that! Although the decat will make it back fire more!

So anyone got any solutions ?

 

there are many possibilities. the most common ones benno has done. one cause which can sometimes get missed is leaky valve stem seals. the longer it is parked up the worse it'll be when first started up from cold.
check your exhaust on first(cold) start-up for any hint of blueish smoke and particularly at about 3500revs after pulling away from standstill(have a friend follow you if your not sure.

 

Might be completely wrong here but when cold more fuel is added, runs richer, to help bring things upto temp. Is it something that has recently started or always done it?

Either way you REALLY dont want to be flooring it until the oil has reached operating temperature (80+ deg) unless you fancy a rebuild sooner rather than later.

 

recently started so i dunno :-S

Is it hard to fit an OIL TEMP guage?

 

My problem seemed to start a couple of months after I fitted my decat downpipe. Has been getting steadily worse.
Once up to operating temp and you give it a bit of boost it hesitates then boost kicks in and it is fine after that.
I have been checking oil level and it hasn't moved, haven't seen any blue smoke whilst cold either but have not had someone follow me.
Benno

 

i noticed with mine that the revs are all over the place aswell when cold!!!!!

They drop down and i can hear like a reley clicking or sominthing!

Please help me

 

May be difficult to tell when going along but if it is from the inner wing near the drivers side strut then it could be the boost solenoid

 

it sounds like its inside, dash or somin... it clicks and the revs flicker up and down :S

I have scoobies :-( ok only when there not running right.... Its just as well there so awsum the other times to make up 4 it! :-)