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Engine keeps cutting out
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Old 19 Jun 2013, 09:12 AM   #1 (permalink)
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Engine keeps cutting out

Hi all, I'm new to here and I know very little about my scooby so please be kind!

I've got a 1994 Impreza WRX 2 litre and the engine keeps cutting out on me during gear changes, it doesn't seem to matter whether you are gearing up or down / what speed you are doing etc. There's no coughing or spluttering, the rev counter just drops and the engine dies immediately after a gear change (but not every gear change). This only seems to happen after about 10/15 minutes of starting the engine. I originally thought it was a key / immobiliser / ignition barrel issue as this only started when I started using the spare key, went back to using the old key and it was fine for a day before it started doing it again, which now makes me think it isn't a key issue. The last time I drove it it cut out on me 5 times in a 2 mile distance. Now I'm starting to wonder if it's the maf or fuel pump or something else.....

In the meantime I thought as it had been stood on the drive for a while that there might be crap in the fuel tank that had been dragged through and causing problems so I poured half a can of redex into the fuel tank and now it seems I've made it worse. Most of the time it's running ok (other than the above issue) and other times it's struggling (chugging and generally sounding a bit rough) but it doesn't last long and yesterday I noticed that you'd be driving down the road and you'd start to lose acceleration (felt like id braked but hadn't) and then it would jerk and come back all of a sudden. This only started after the redex but I don't know whether it is related to the other problem.

I had a similar issue many years ago which turned out to be the fuel pump but I've never owned a turbo before and don't wanna just go spending money on parts I don't need. Last night we cleaned the maf sensor and air filter, not tried it since as we haven't put the filter back on the car yet. The only other thing that concerns me is there is some dodgy looking wiring beneath the back seat above the fuel tank, there's a tiny black box and some wires look as though they're bypassing something. The black box thingy (sorry for the appalling technical terminology) looks like it might have been very warm at some point in the past. It doesn't look like a professional job which makes me wonder if the previous owner has bodged something, any ideas please? Thanks
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Old 19 Jun 2013, 10:42 AM   #2 (permalink)
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Re: Engine keeps cutting out

clean the IACV out, it will be full of crud.
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Old 24 Jun 2013, 02:07 PM   #3 (permalink)
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Re: Engine keeps cutting out

Hi, got the IACV cleaned out and it's been fine for a few days, none of the cutting out at gear changes so I think that problem is cured thanks but it's really badly struggling with the second issue, it starts as soon as it's warm, jerking and coughing and spluttering but to the point where it becomes undrivable. Since my original post it's also had an oil and filter change and fuel filter change, any ideas on that issue? Thanks
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Old 24 Jun 2013, 07:06 PM   #4 (permalink)
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Re: Engine keeps cutting out

have you had the coil packs and ht leads checked as the leads maybe arcing?

As for redex it made mine worse until I used up 2 tanks of fuel but you will need to get the revs quite high for the redex to work, you will know when its going through as the exhaust fumes smell different.
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Old 24 Jun 2013, 08:10 PM   #5 (permalink)
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Re: Engine keeps cutting out

could be maf related or the 02 sensor playing up..
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Old 25 Jun 2013, 08:25 AM   #6 (permalink)
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Re: Engine keeps cutting out

Thank you for you replies guys, I really appreciate the help.

I don't think it's the ht leads or coil pack as I would expect it to be misfiring a lot and the needle to be bouncing around a lot at idle. Once you start it up the needle sits around 900 then drops to about 750 - 800 and sits steady until it's warm then it might run for a few minutes or even 20 minutes but eventually it just splutters and dies. When it does this and I'm driving I just put my foot flat to the floor and eventually it comes back to life, unfortunately the problem is much worse when driving it as it's doing it almost constantly. It never does it when the engine is cold. It could well be the redex as this issue only started the day after I put it in. I've used up half of the tank with redex in it and I filled up again with esso premium stuff in the hope that it would water it down a bit more but the problem is worse than ever.

Could be the o2 sensor, I had an o2 sensor die on my vectra and I just disconnected it and the car ran fine but had a constant light on the dash, please correct me if I'm wrong but I assume I can do the same on the impreza to test this? Is there anyway to test the maf without buying a new one and changing it? I heard somewhere that you could test it by trying to run it without it connected but I'm convinced that it can't be true!

My big fear is if it's a fuel starvation problem I've heard that I can damage the turbo if I carry on driving it with the problem, is that true?

Thanks
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Old 25 Jun 2013, 11:38 AM   #7 (permalink)
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Re: Engine keeps cutting out

your wrong, the HT leads break down when hot, the plugs can be blown out on boost and fine on idle,
the unplug the maf isnt a true way to tell on an Impreza,
so your either gonna have to get it on a rolling road,so they can check the fueling to rule out the maf/02 or pop it to a specialist, its so much easy to fix a car in front of you that you can drive and hear then guess on the tinternet.
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Old 25 Jun 2013, 12:22 PM   #8 (permalink)
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Re: Engine keeps cutting out

Thanks, that's good to know. We've got a mate who's just bought one of these but a year younger and it's got no running problems so might be worth borrowing his and swapping bits until we find the problem. Yeah I know it's easier for a garage to detect the problem but it's getting it there when it's driving so badly!!!! can anyone recommend anywhere to take it in the Lincolnshire area?
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Old 26 Jun 2013, 08:00 AM   #9 (permalink)
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Re: Engine keeps cutting out

these guys
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Last edited by Technical_Bob; 26 Jun 2013 at 09:29 AM.
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