CivicD

Hi Guys,

I have an MY93 WRX Import. Been in the country since 1998. Got receipts for cam belts and servicing etc but am starting to experience some minor problems as listed below:

When I got the car the Uppipe was buggered, not blowing too bad but blowing none the less. I have now fitted an STI decatted up pipe. I run the car on Shell Optimax and have not been useing any Octane boosters.

Engine Questions & Problems

I fitted a Apexi induction kit a week or so ago and this seems to be where the problems started for me. I was getting fuel cut quite often which I think is over boost (I don't have a very accurate boost gauge at the moment) but it was boosting to approx. 1.5 bar. I took it easy with this in mind and sorted the boosting problem with a MBC. After reading around on here I relised that induction kits are not really the way to go on Scoobies because of heat soak etc so decided to remove the induction kit and put the original airbox back on with a new Subaru Filter. This seemed to be a little better but after removing the MBC and refitting the Boost control solenoid pipes and now have over boost again or fuel cut. The car seems to stutter a little as well, regardless of throttle position, also when I do get a fuel cut symptoms it is followed by the mother of all backfires. This happens mainly in 1st, 2nd and 3rd.

I have completly decatted the car, there was no cat on the uppipe when I got it nor is there one now, downpipe has been decatted as well. I have a Bailey's VTA DV and a straight through 2.5" Stainless exhaust system with only the back box (4.5" Slash-Cut SS).
MAF related perhaps !!! - <<EDIT to Say - Just done the MAF test by unplugging it and the engine cut straight away so my thinking is now the Lamda/O2 sensors - Does this make sence ??

Brakes etc

Just a quick one here, does my car (MY93 WRX) come with vented rear disc's as standard. I did'nt think they did but mine deffo has them. Has someone fitted them or is this a Jap Import Thing ??

Tyre Presure

What pressure should my tyres be set to. Currently have GoodYear Eagle F1's in 16" on Speedline 5 spoke Alloys and they were at 36 PSI on the front and 30 PSI on the rear, when I got the car !! what would be the ideal setting for these ?

Sorry for listing the questions etc like this but I am currently connecting to the net through my mobile phone via GPRS and think it would be easier to to keep questions in one post.

Any help with any of the above would be greatfully recieved.

Regards & Thanks

Chris

The_Judge

That could be your first problem. Unless you can get a ScoobyECU, or replace the entire ECU with a mappable one, you should really be using a good quality octane booster at every fill-up. I'm guessing you don't have a Knocklink... That could be your second problem.

Are you saying it only started overboosting after fitting the induction kit? What was it boosting to before the problems started?

What boost level did you decide to set it to? You could also have probably sorted the overboost problem by giving the wastegate solenoid a damn good cleaning, adjusting the pre-tension of the wastegate rod, and increasing the bore of the restrictor...

Not sure where you picked that up from! Induction kits can create problems with MAF sensors, through oil contamination, and moreso vibration. There aren't any heat soak related problems that I know of...

That would point at the wastegate solenoid/actuator/restrictor as mentioned above.

Could be MAF related. Possibly because of damage caused by induction kit...?

Your VTA dump valve probably contributes towards that!

You'd normally only get fuel cut in higher gears, say 3rd/4th/5th, as 1st/2nd can't build the same level of boost pressure. But if your boost gauge is anywhere near correct, 1.5bar in the higher gears would probably build enough boost pressure in the lower gears to hit fuel cut.

That's probably the main culprit for your overboost. And the wastegate solenoid/actuator/restrictor are contributing factors.

That test may/may not be an accurate method of testing MAF health. Have you tried the other tests? Click here for more info.

I doubt if it's lambda sensor related, as you've already said throttle position makes no difference. If it was lambda related, you'd notice it only at idle/part throttle/cruise.

Pass (sorry!).

Don't think there's a right or wrong really. What works on one person's car might feel too hard/soft on another. I think the recommended pressures are 33psi front and 30psi rear, so seems a good starting point really.

Makes sense! However, you'd better not be sitting in some pub beer garden with your laptop, whilst I'm sat here at work...!