Misfire & Eating Fuel

[PCC]

Hi all,

For those mechanic types...............

My 302 EFI has just started playing up. Symptoms...............

Misfire - although does not seem to be impacting too much on the performance

Eating fuel - Eating fuel with smell of fuel at rear of car including heavy black (carbon) deposits

I think it is ready for a tune up. However not sure where the diagnostic plug is

Any advice what the problem may be.

Oh and its a Ford - sorry Oval gang

[cameron02]

My guess is a faulty lead or spark plug. This would account for missing as well as carbon deposits due to unexploded fuel.

[PCC]

My thoughts too Cameron, but have 8.0 leads and titanium plugs (less than 6 months old).

It has only just started misfiring although has been eating fuel for some time.

Checked the leads - seem okay. Will check the plugs tomorrow. Not an easy job on a blue oval in a Cobra

[cameron02]

You could try running it and pulling off one lead at a time. If it doesnt run any worse....thats the one.

[boxhead]

Pulling leads and seeing if it runs no worse will tell you whick cylinder is not making power, then pull the plug out for that cylinder - look at the plug end (the end that goes in the head) and see if it is black and shiney (wet)
If it is then you have no spark at that cylinder - No spark can be caused by.
(1) dead plug
(2) dead lead
(3) failed distributor cap (faulty pickup for rotor button)

If the plug is clean and white then there is no fuel getting into the chamber.
To test this you will need to first buy a "Noid light" remove the connector from the injector on the faulty cylinder and plug the lead into the light, start the car and watch the light - if it blinks quickly then the ecu is sending the signal to the injector to make it fire.
I doubt that it is a fuel pressure issue if the fault is only in 1 cylinder.
So if you have clean plugs and a flashing noid light then it may be a clogged injector.

Hope this Helps Pete

[PCC]

Thanks Dave and Cameron

She's booked in for a diagnostics day so hopefully the "professionals" can cure it.

Hopefully its a dodgy plug or lead or may be even an oxy sensor playing up. Will let you know.

Been meaning to get the steering aligned for quite some time so that will be done to.

Hardest part - leaving it with a Garage

Ah well a bit of worry for the right result - Gotta be worth it.

[jess]

Hi pete
sounds like a dodgy air flow meter see if you can borrow one to try
cheers
jess

[venom0427]

also try some airostart, spray it around the lower pleum chamber, inlet and any area that could leak air into the engine, the car can fuel up to compensate for the extra amount of air. PS: do not spray it if you do have a faulty lead etc, so do the above first. and also is the engine surge. hope it helps. david

[PCC]

Jess.

Airflow meter is only a year old.

Starting is fine, idling is fine, and general performance is fine.

Previous Airflow failures resulted in flames at the back end and cold start problems.

[venom0427]

02 censor, map, bap, ???, can you get a fault code

[PCC]

Still waiting on full diagnosis, but dodgy manifold gasket is a start.

Tomorrow should be fixed - will advise

[PCC]

Just an update on my trials and tribulations..............

Replaced exhaust intake gaskets and cleaned injectors (rated 42 out of 50 before the clean). Misfire gone (so I'm told).

Only remaining work is that a hairline crack was picked up on the intake plenum so that will be replaced once its replacement has been alloyed (couple of weeks time).

Also took the opportunity to have the car aligned so handling should be vastly improved.

Getting there

Oh and to all you builders with EFI motors - DON'T CUT THE DIAGNOSTICS PLUG OFF - Why oh why do people do that as fixing such faults without one only leads to searching in the dark

[PCC]

Picked the car up last night and was amazed with the difference.

Engine is tight and responsive and now handles as it should - very satisfied