Fiesta 1.3 misfire

My daughter's 94 Fiesta has a bad misfire .

Symptoms are: Lack of power Sounds as though it is not firing on all cylinders Blackened plugs

What I've done so far: Checked tappets (OHV engine) Changed plugs Changed air filter Changed fuel filter Checked fuel pump output Checked diaphragm in pressure control valve Checked resistance of HT leads Checked sparks Checked for split hoses. Checked compressions.

It is one of those that looks as though it has a carburettor but in fact has an injector in it.

Is there any way of checking the injection/management system without special gear?

Can anyone suggest anything else because I'm out of ideas?

Thanks

Dave

Reply to
DJ
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"DJ" wrote

I know you say you've checked the resistance, but these are classic symptoms of the HT leads starting to break down. It may be that when you remove them from the plugs, and apply your test meter, that you are temporarily improving the contact through them. Have they ever been replaced?

Reply to
Knight Of The Road

Vince Thanks for the reply. I don't know the history of the leads but I used a spark checker and the sparks jumped a 10mm gap. That's why I haven't changed them, like you I thought of them first. I may just replace them anyway. Dave

Reply to
DJ

Also check the plastic plug that's situated in the centre of the air intake because they melt.

Andy

Reply to
Andy Cap

What a completely pointless tool. How big a gap they jump in normal air is pointless. All it tells you is that power is getting to them. A completely knackered plug can still produce a spark outside the engine and you can't go by the colour of the spark either as it tells you nothing of their performance under typical working pressures.

Reply to
Conor

Plastic thing? Its actually the Air Temp Sensor. And yes they do, which does throw the fuelling completley off.

Tim..

Reply to
Tim..

I'm not quite sure that Plastic 'plug' equates to plastic 'thing' but I'm sure he'll find it whatever ! ;-)

Andy

Reply to
Andy Cap

Conor Not sure I agree with you on this one mate. I used to be an outboard motor maintainer and the manufacturers provide this tool and specify its use to simulate the load by providing a bigger gap but not under the pressure generated in a cylinder. I'm going to change the leads just to eliminate them. Thanks Dave

Reply to
DJ

"DJ" wrote .

My own point is that the leads may be breaking down, but as you remove them from the plugs and use the spark tester, you are altering the angle at which they sit and this may temporarily improve a poor connection. As you say, I think it's wise to replace them anyway, especially as they aren't expensive for this model of car.

Reply to
Knight Of The Road

Clean the multiplug electrical connectors under the air filter - the pins and sockets corrode.

Si

Reply to
Mungo "Two Sheds" Toadfoot

Fair point mate. Very interesting website as well. I managed to go E Germany before the Iron Curtain went. Dave

Reply to
DJ

"DJ" wrote ]

Cheers mate, the website's very amateurish but it was a fascinating job and lots of people have commented favourably on it.........I never got to go there during Communist times- my first trip was 1994 but I would have loved to have visited before- have driven through the old E/W German border many times too. No doubt you will be familiar with the "fun" of driving for a few hundred miles over cobbled roads.........Ooh, me bum!

Reply to
Knight Of The Road

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