My car has developed a misfire. In the morning it will run on 3 cyl for a while. Sometimes it will clear within a few miles, other times it doesn't clear for ages. I took it into the garage yesterday and the changed the plugs but it's still doing it. I'm taking it back again tomorrow when it will hopfully still be doing it (as they can only diagnose it when it's actually misfiring).

Any ideas what the problem might be?

 

Depending on the cars age, it may have coilpacks in need of replacement. What model and year is it?

 

Plug leads? I had one break down intermittently, and it produced an intermittent misfire at about 4000rpm.
Alcazar

 

It's a UK MY95 with 175,000 miles

There are going to look at the leades tomorrow and replace it FOC if this is the fault.

How much is a new coil pack....

 

one thing- I hope its the coil packs NOT a timing issue.. probably isnt the wisest move to continue driving around with 3 cyl..

each to their own tho..

 

The misfire happens at all revs. V lumpy on idle. No power

Will I be causing any problems to the engine by running with a misfire? When it clears itself it runs fine (with a few hesitant moments).

 

I can't comment on a Subaru, but your symptoms sound very much like a plug lead faulty. The age (8years) sounds about right as well.

 

Thanks. I hope that's all it is. I took a look under the bonnet to see if they were loose, but I couldn't find them lol...

 

IIRC, the MY95 ran individual coilpacks over each plug. There are no HT leads in this system. The coilpacks do degrade over time, and are generally ~50 quid each. If you don't have any service history telling you if any have been replaced in the past, then I suspect you may be better off replacing the whole set, as once one goes due to old age, the others are likely to follow.

 

Agree with Moray..

The coil packs on my 96 went in the same way.. cold mornings and the occasional miss in first at WOT..

I bought one new one and thought I'd swap it around until I found the faulty one.. it ran so much better with the one changed but still ran on three and missfired that I then bought the other 3.

I am surprized they have lasted to 175k.. I had to change mine at about 108k I think.. now 135k and no reoccurance etc..

They are not difficult to swap and are £50 each as said..

JGM

 

Problem has been fixed now. It wasn't the plugs, leads or coil packs... I'm too embarissed to say what it was

 

Go on, tell us -it's Friday!!
ww

 

Oh well... for the good of the community....


A couple of months ago I fitted a ScoobyECU. Everything was running fine afterwards . A few weeks later I went over to my brothers to fit a switch so I could change between standard and Scooby ECU. I *thought* we had plugged everything back correctly. Car ran great. No problems at all... until last week, when I started to get the odd hesitant moment. I tried flicking the ECU switch to see if that would cure it, but in the end it just start to misfire. I though it was either the plugs or leads on their way out. The poor chap at the garage spent 3 hours back tracking the problem until he came to the ECU, where he found that the top connected was not connected properly and was a little loose. Even after fully connecting it it still misfired, so he came over to tell me what he had found and asked if I had anywork done on it recently. I told them about the chip, but said that it had been working fine for the last couple of months. He explained about the loose connector and said that something on the ECU may have been fried, at which point I started to see £££ notes flying out of my bank account....

Anyway, I went into the workshop with him and I explained about the switch. We switched it back to the ScoobyECU (had been running on standard since the hesitation started), and the engine started to run fine again. Switched back to standard and still ran fine

Needles to say, I was both relived and a bit red faced about it all. I guess I should have checked the connectors myself, but I thought they were fine as it had been running fine for a couple of months like that.

They were very good about the labour charge as the chap there "looks after me" . Will buy the machanic a drink next time I'm there...

 

Well glad it is sorted now then mate.



JGM