This is a strange thing that happens to me every so often, seemingly so at random. It's impossible to reproduce and sometimes doesn't happen for weeks or months at a time.

First of all, sometimes I experience jolts in acceleration. It's most noticable when accelerating hard but has done it when just moving slowly through the first few gears as well. It's as if the engine totally dies for a split second (it doesn't actually cut out or anything) and then almost instantly kicks back in with a shit load of power jolting the car forward and then continuing as normal. That's the best way I can describe it.

The other thing that was happening the other day when my car was misbehaving (did about 3 or 4 jolts in one day) is that sometimes I will put my foot down and it won't rev for a second or two. Kinda like the engine isn't even switched on but then the gas does kick in and it goes.

The NEXT thing it does is the rpm dips approaching junctions when decelerating rapidly and sometimes it stalls, or sometimes picks back up to 800rpm. All of the obove behaviours are more noticable once the car has warmed up a bit and never when cold. Most of the time the car runs spot on and you can't fault it but every so often it has a really shitty day where it will jolt and stall and not rev properly (had one a few days ago like this!).

Now I look after my car and service it well. I have replaced a few items recently all with genuine parts either from pug or Bosch or whereever. Check my profile before you tell me I need new spark plugs or lambda or a stepper or whatever because I will just scream at you.

Now I did manage to find one thread on this jolt problem which pointed to the fuel pump. I've also checked my earths and they are all nice and secure (will be fitting an earthing kit hopefully this evening anyway).

So I'm really looking for the hardcore mechanics and experts to offer their advice as I've done most of the obvious things (check my profile before posting or I will keeeeeeeeel you!) On my profile you will see all the new bits. I've done a couple of full services very recently. The car has occasionally acted up both before and after every service and part change to date so it's nothing new I've put on or done to it.

Thanks in advance.

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Black GTi-6 (Phase2.7 and-a-bit R/97)

I've had my plugs out a few times recently and I've tried interfering with the wires to the coil packs and nothing has come up. 99% of the time the engine runs sweet and there is no way to try and diagnose the fault as it only happens momentarily and not very often. It could be this but I have no way of diagnosing them properly.

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Black GTi-6 (Phase2.7 and-a-bit R/97)

pm roland rat.. he had this problemo

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Team Ducati 748
2003 Subaru Impreza STi

gingec, I've cleaned my induction up loads recently, just before I threw in the towel and bought a new stepper. It is noticeably better with the new stepper but I think the rev dropping problem now is something else rather than the engine starving of air because of a tired stepper.

Interesting idea about the oil. My throttle body usually has half a teaspoon of oil laying around in the bottom but I know that's normal. I might have to get the multimeter out on the sensors. Incidently, my old and tired stepper still has the correct resistance across the relevant pins so testing them using the autodata stuff won't always show they are dodgy.

I was debating on getting a new MAP, AIT and TPS. I'll probably end up changing everything and still have occasional problems like that other guy on here. Can't remember who it was that has changed and checked even more than me and still gets trouble with stalling etc.

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Black GTi-6 (Phase2.7 and-a-bit R/97)

I had the same problem and a new stepper motor & new MAP sensor sorted it for me

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Just Drive It