Scooby125

I just brought a version 2 Sti RA in form Japan and took it for a couple of short spins the last few days for the first time.
It drives perfect but after giving the engine a bit of a warm up of handy driving I decided to give it a bit of a blast in 2nd and 3rd gear and at about 4000rpm its like it just lost power for a few seconds and came back good again. This happend two days in a row. I took it for a spin yesterday but didnt boot it too much and it seemed fine but as I said I didnt go too high in the revs just to be on the safe side.
I think I am getting a bit paronoid now with all these stories of big end failure etc.
I know a Subaru mechanic and he says that its because it hasnt been drivien in months between getting over here and being idle at the auctions etc but what do ye think. I dont want to cause any damage to the car and hope I havent done up to now.

Thanks...

jjones

is it a (A) misfire - slight judder
or (B) fuel cut - headbutt windscreen?


(A) could be coil packs (weak item on that phase engine most likely) or plugs
(B) caused by overboost - what mods do you have?

Scooby125

Thanks,
Id probably be leaning more towards A but having said that I wouldnt call it a judder as in it seems like the power just dropped alot and then picked back up again.
The car is totally standard apart from rear exhaust. Well I hope there arent any hidden mods I dont know about anyway..

jjones

might be teaching grandmother to suck eggs - but are you running a minimum of optimax/super unleaded?

the fact it is standard points more towards the coil packs. there is one for each plug. they are a bit tricky to get to and are held in with a single screw. moving the washer bottle out of the way and the top half of the airbox will make access a lot easier. when removed if there is no obvious damage (the plastic bit which is closest to the plug) check for cracks. some say a wind or 5 of insulation tape around the end helps out. replacements are not cheap - think they are around £60 each, but you only need to replace the faulty one(s).

Scooby125

good opening line....

well I have put in SUL plus NF but I put this in about 2 weeks ago but only got to give it a spin a few days ago so it was sitting in the tank for about 2 weeks un used.

Thanks for the info on the coil packs and I suppose if it was that, it would probably be the lesser of two evils.

When I said earlier of what the Subaru guy said, he said this after he had it for a day and giving it a service. Would there be any truth in what he said about it happening because of the car being idle for so long. He didnt say anything about coil packs or anything although from what you say makes more sense.
I also rekon they gave it a decent drive because they used a good bit of petrol. I hope they didnt trash it if its a case that there is damage being done when its cutting at 4-4.5k revs.

When I drove it yesterday, it was after putting in fresh sul and booster and it was fine but I didnt give it a hard drive so it could still be there on hard boost.

Ill check out the coil packs and see anyway as a starter.

Would a diagnostic check of the car pick up any possible causes?

Thanks again.

Bewick

I bought a MY94 WRX last week and I'm having the exact same problem. At first I thought it could have been 'cos its been sitting there doing nothing for a while and the engine just needs a good run in back to normal, with my engine its doing it a bit higher up the rev range, maybe about 6k or a tiny bit higher, and tends to be only in 3rd gear by what I can remember. I was going to have a check of the coil pack as thats what my local Subaru specialist said too, but the more I drive it the less it seems to do it (I hope!!)

Dan

Fantom

The problem is likely to be the spark plugs. Make sure they are gapped to 0.7mm rather than 1.1mm. I also had this problem and it was very frustrating!
Hard to get to the spark plugs but worth a check. Coil packs on both of my 10 year old Imprezas have been fine so fingers crossed its not them as they are more expensive than plugs! Also clean your boost solenoid. Search the forums for threads on how to do this.

Hope you get it sorted

Steve

Bewick

Cheers for the help and advice, as this is my first Impreza I haven't much knowledge about the engine so all help is very much appreciated. I will Have a look at the plugs and look into cleaning the boost solenoid. I had a brief look at where the plugs are and I can tell this is going to be a laugh getting those out!!!

Dan

Scooby125

Thanks for all the help, so its start with the cheapest cause and work my way up. If its any of the causes listed above at least its not fatal to the engine (I think).

If the car is overboosting and if what I am experiencing is a fuel cut which I dont think it is, when the car hits this fuel cut, is this a safe mode hense no damage being done to the engine. Am I correct in saying this.

Also to this could this possible drop in power for the few seconds have anything to do with det?
Thanks..

Big Daz

Had the same problem (or similar ) for a few months end of last year, I eventually found out it was the lambda sensor - New one and tada, problem solved
Daz

Scooby125

Big Daz,

Was it trial and error that you found the cause or can a diagnostic check the reason?

Big Daz

Select Monitor didn't come up with anything
It was my AFR that helped me decide the problem, sometimes its appeared too rich and occasionally showed too lean (especially during missfires), I checked MAF & it was Ok, Idle swich was also Ok(Quick clean to confirm this) so that narrowed it down to Lambda - Its an easy replacement and worth a go, nothing to lose, another bonus is - I now get 50 miles extra from a tank of fuel
Daz

Scooby125

Thanks mate, what year is your car?

Scooby125

Just to add, the Subaru mechanic described it as a missfire, are we still talking about coil packs/plugs/lamba sensors???

Big Daz

Mines a MY95 UK with mods
Yep still think its Lambda. Its regarded as a consumable item. rumour has it, its best to be changed every 30K miles - mines had done 68K so it was due to be replaced.
Daz

Scooby125

Am I correct in saying that the lamba sensor is not on the downpipe like the MY00 turbo. Did you get one form a main dealer?

Baggers

Sounds like a MAF failure. If it was fuel / ignition related the car shouldn't cut back in and take off at higher revs. I had a similar prob, same symptoms - MAF.

As a quick test, warm the car the unplug the MAF at idle. If the engine dies, the MAF is likely OK (but cannot be guaranteed) if the engine baulks then picks up, it's likely on it's way out. If there's no change, it's stuffed.

Suggest you change the MAF as a matter of caution anyway.

Baggers

The lambda has is closed loop at WOT, the ECU ignores it. If this is happening only hard on boost it will probably not be the O2 sensor.

Scooby125

Thanks mate,

The possible list seems to be getting longer lol. I replaced the maf in a MY00 before but I just had to buy the sensor which was about £80. Is it different for the version 2 model sti (1996)

jjones

yes it is a lot more expensive for a 1996 model. it comes with a housing and will cost ~£230 from a dealer. the mafs were a weak point of the 99/00 models. fairly uncommon for earlier mafs to fail - although it does happen.

Baggers

Try swapping it for another part (anybody else local???), see if it cures the prob b4 buying a new one.

Scooby125

Yep good idea mate before being out of that pocket just incase its not the cause...

pan93wrx

hi , i have the same prob on my 94 wrx/sti , only now and again when been used for a while. changing the sparkplugs to ngk pfr7b's the weekend to see if this helps.

2.5RS King

Had the same problem from a JDM STI ver2. Did you check your boost levels??

Mine was boosting to 1.17 bar at those revs and it was the ECU cutting the fuel. The ECU on mine has been tuned so it runs at to just under that at WOT but sometimes peaks at the fuel cut level when really pushing it.

I am also getting a lean light but I think that is plugs and a cold air intake.

Remember - its a 8 year old car. Chances are its been tuned a bit...

Bewick

So how much is this 'lambda sensor' and where abouts will it be located as I'm new to an Impreza engine and haven't got a clue?!?

Dan

Baggers

do a search on 'bosch lambda', you'll find some links and a part number

Scooby125

2.5RS, if my ecu was tuned a bit, how would I know. I am pretty sure that the car is totally standard.

2.5RS King

Ridiculous pwr??? The ver2 is only suppose to be running ~260 bhp and like most stock ECUs it comes in a little slow yet abruptly (lag). Straight from Japan they also should have a speed limiter at ~120 (?) mph - can you break that?

The pwr in mine floods in and pulls all the way to redline. The low end torque also will be greatly improved. Other than butt dyno feelings hook up a boost gauge and see what you are putting out - stock boost tops at around 0.96 bar

Scooby125

Thanks for the info, I will check them things out...

Scooby125

Hiya,

I did this test and when i pulled out the maf sensor plug, the car just cut out so all seems to be ok here.

Thanks.