My brothers 03 STI has been running perfectly for a very long time now. He has Defi gauges all reading good figures/temps etc.

He has just had to jump start his car due to flat battery and since then the cold start idle has stopped working and the oil temp gauge is reading 110-130 after mere mins of start up.

I'm thinking the jump start caused a power spike and fried a part of the ECU that reads oil temp/engine temp... thinking the oil temp is high and therefore no need for the cold start to kick in?


I had this exact same problem with my classic STI, the cold start ceased to function and the oil temp was always sky high from driving off boost it just shot up to over 120.

I have jumped my car a couple times but see this as a common denominator for both our cars...

Is it just a co-incidence that my brothers car is behaving exactly as mine did after jump starting?

Further info: jump leads were non surge variety and battery terminals were used correct way round (but negative lead to battery not chassie - I also cant tell you in which order leads were attached or removed)

 

Did you turn all your lights heaters on etc I was told this when jumping cars it's best to turn everything on to prevent spikes etc I dunno how true this is but I've always done this and never had a problem it does sound to me that maybe summit has fried is there any local auto electricians near you that could take a look ???

 

The standard ecu doesnt read oil temp at all. That will be after market guage and sender.
The cold idle issue and oil temp reading are probably two seperate issues. Worth checking the engine earths though. Coolant temp sensor would be first thing to check

 

The ECU in my brothers car is an ECUTek and mine has a Simtek. Both have Defi gauges.

No electrics were on when the car (either car) was jump started. We were ignorant to the power spike issue so didn't take any preventative measures.

Coolant temp sensor and gauge both reading normal figures which have not changed b4 or safter the jump starting.

Its just the cold start and oil temp all of a sudden.

I've got a guy near me that does ECU management, but would he have the necessary software to access an ECUTek cpu? I thought all after market ECU's were specialist... I know with my Simtek, no place was able to access it as they didn't have the software... only Scooby mappers and the like have the ability.

 

I've read other posts on other Scooby sites that say as the ECU is directly connected to the battery, jumping causes spikes (also dependant on the order you connect and disconnect the leads) which sends the spike directly to the ECU and fries parts of it...

Other ppl say always use non-surge leads... but all these things are preventative. I need to know how to cure the problem or if others have had this trouble??

 

Hi there

You can access EcuTek ECU without the problem,only what you can't is map the car without the EcuTek SW,yes off course you can overwrite EcuTek ECU with right tools

And as above jump start shouldn't cause those problems,if jump cables has been used in correct way

Jura

 

So its worth having a local boy look at it then and see if the ECU is throwing up any error codes.

Thanks for all comments guys