Hey some quick info on my car: 98 wrx, fmic, sti gearbox, hd clutch, unichip, bov and some exterior mods.

About two months ago my car randomly started stuttering/shaking, dropping revs, stalling etc. Since my car had done 110,000km and I read people with similar issues i put it down to being an AFM problem. I went and got the AFM cleaned at a workshop. The car seemed fine after that.

Two weeks later, it started happening again. I called another workshop and explained the situation. They said they would replace the AFM and do a general service on the car aswell because it was due. Unlucky for me, the AFM for a late 98 wrx model was over $700 instead of the usual $200 (as quoted by subaru according to my VIN number icon_sad.gif). So i took it into the workshop and replaced the AFM and got my service done. What they noticed was that the previous owner had rewired the window spray nozzle to spray directly into the engine as alternative cooling (??) and this had caused some corrosion. They cleaned out the engine, so now my engine bay was clean, serviced, and the faulty AFM had been replaced. They checked the o2 sensor aswell but said it was fine. The car was running like a dream after that.

Fast forward to now, approximately one month after the second workshop. The car is slowly creeping back into its old habits again, a couple nights ago I noticed the car was hitting flat spots at around the 3k mark just cruising down straight roads, eg. shifting from second to third i noticed that me pressing on the accelerator was kind of doing nothing, so i pressed a bit harder to get over the flat spot and it was fine into the high revs. The weather has been unusually hot lately so I figured maybe something to do with the heat. Last night was a nice cool night however and I took the car out for a bit of a drive. Halfway down my street the car hit the flat spot again, except this time when i accelerated more it started stuttering and when i pulled over the revs were flutuating and it almost stalled. I turned the car off for a few mins, started it again and it was fine, I drove it home and now im here.

Sorry for the long post but please does anyone have any suggestions or similar experiences that they managed to solve?? I'm now thinking it could be a fuel issue?

I dont generally know much about cars....mechanically speaking, but from a few things Ive read, I might have said something to do with fuel? Blockage or faulty fuel pump?



sounds like the previous owner was a moron.
Really, what do they expect is going to happen, Ive heard of spraying onto intercooler, even radiator to assist in cooling, but not this.
Im assuimg that was meant to say onto instead of into ??

[QUOTE=fizzle85az] Halfway down my street the car hit the flat spot again, except this time when i accelerated more it started stuttering and when i pulled over the revs were flutuating and it almost stalled. I turned the car off for a few mins, started it again and it was fine, I drove it home and now im here.
QUOTE]

I used to have a very similar problem when I had a unichip. I was sometimes minding my own business driving down the road and the check engine light would come on. If I tried accelerating it was alright as long as I didn't make significant boost. When it went over 13-15 psi then it would start stuttering. I pull over, turn the car off, turn it back on again and it would be fine. I spoke to the mechanic (at a certified dealer) and he said something about how if the car over boosted then it would drop cylinders or something like that to save the motor. And it would also happen to make the car stutter and carry on.

Needless to say I got rid of the Unichip and haven't had a problem of that kind since.

Are you running an after market air filter?? try giving your AFM a spray with Contact cleaner, only takes a minute & may cure it. I make it a habit of spraying mine every couple of months & it's cured the probs I had earlier.

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Beaten up old 98 Gen 2 Liberty, 13.0, stock V3 STI running gear.
07 Transit motor home
69 VF & 70 VG Valiants needing full restoration
Yamaha Zooma 50cc rocket hopefully going with the Transit.

Yes i meant ONTO sorry lol. Yeah ive been reading a few threads and unichip seems to be a pretty common problem, but to change ecu's is gonna be very expensive.......

pimpreza: ive had the afm cleaned and completely replaced in the last month and a bit, there is no chance it is the afm. and if it is, i hate subaru.

[QUOTE=fizzle85az]Yes i meant ONTO sorry lol. Yeah ive been reading a few threads and unichip seems to be a pretty common problem, but to change ecu's is gonna be very expensive.......

You where half way through $700 for afm and the service'S , i think is the uni chip and the AFM .
http://www.perth-wrx.com/vb/sale/10813-dms40s-vf37-twinscroll-autronic-r-comps.html

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[SIGPIC][/SIGPIC]11.617 120mph

if you've got an aftermarket oiled air filter, it'll continue to fuck out AFM's...
thats what pimpreza was getting at..

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Balls.

I think you need to get your car on a dyno with somebody who tunes UniChips and see what is actually going on. Go see Tim Slako at West Oz Racing, he tuned my UniChip and did a very good job of it!

I freely admit that the Unichip is not the best computer (which is why I'm going to a VERSO), but with your modification level it should be fine. I mean if you read some posts on RexNext you will see guys over east running more mods than yourself with a UniChip and they are pulling good numbers, without any of the problems you are experiencing.

Get it on a dyno dude...

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...He said Smooth Bee the skins is fat
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I dress warm so that I won't catch pneumonia
My rhymes are stronger than ammonia
I'm a diamond, you're a cubic zirconia

i had similar weirdness that most associate with the afm, and similarly changing the afm seemed to fix the problem for a short time

however in the end i needed a new throttle body and stepper motor. which was cheaper i got them s/h off the forums after a 'wanted' post, not sure why people had these laying around but they did!

couldn't you have got your throttle body taken off and cleaned? when they put it back together they reset all the throttle steps and whatnot anyway? only costs $100