Engine Miss - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

XplodEd EA · 07-02-2003, 03:30

My car has developed a very noticeable miss at idle, sometimes even stalling. It's a CFI 3.9 on dual fuel. The miss happens running on either gas or petrol and its no worser than the other. I've swapped all ignition components over from my dads car besides the dizzy itself and it still has the miss and with my ignition gear in my dads car his runs fine. It's not the head gasket, I just replaced it and re-coed the head about a month ago, I just did another test today at work and its all good. I've checked for fault codes, all I get is code 11 which is no fault codes. I've also retensioned all the inlet manifold and throttle body bolts. The timing is spot on, spark plugs are ok. I've also reset base idle and re-checked the timing, I can't find a damn thing wrong with it.

Does anyone else have any other suggestion on what else to check, this one has really got me stumped and I can't for the life of me figure it out.

mongrelEB · 07-02-2003, 03:41

Could be a blocked injector in the throttle body?
How about fuel pressure - flat spots anywhere? (well, flatter than usual

)
Is the coil lead rubbing on the dipstick? Sometimes it can leak onto the dipstick.
Umm can't think of anything else right now, good luck man

AusCaRnAgEr · 07-02-2003, 03:48

Maybe just out of some small chance, the exhaust could be restriced to some extent.

XplodEd EA · 07-03-2003, 00:45

Well I did some more fiddling round today and now it runs nearly ok on gas, there is a very very slight miss still but if you didnt know I dont think u'd notice it. On petrol tho it is still really bad to the point of nearly stalling still.

The miss is only really noticeable at idle, once your away and under full throttle it goes like anything and you cant really feel a miss. Anyway I'll see how we go at work tomorrow and if I get some time I'll throw a fuel pressure gauge on it and see what happens.

94EF_Ghia · 07-03-2003, 05:39

Oh yeah checked your lead's ?

You did say u checked ur plugs

XplodEd EA · 07-04-2003, 01:42

I've swapped leads and plugs between two cars, my leads and plugs run fine in my dads car and with his in my car it still runs like shit. I can safely say its not within the ignition now cos gas idles pretty damn good now.

I didn't get a chance to throw a fuel pressure gauge on today so I'll have to wait till next week now

jjj · 07-04-2003, 02:01

It could be your TFI, hall sensor(crank angle sensor) or you will have a worn bush in your dizzy. swap over your dizzy with your dads and see how it runs. It could also be the coil breaking down.

XplodEd EA · 07-04-2003, 02:25

That doesnt explain why when its on gas the miss is gone and it idles like it should and has more power than running on petrol as it is at the moment.

I'm certain something in the petrol side of things has shat itself. And as to why it was running bad before on both fuels I think was partly to do with the inlet manifold bolts being loose, I let it sit overnight after tightening them and gas hasn't played up since.

Walkinshaw · 07-04-2003, 06:16

Check for cracks in your dizzy cap. I had this same problem and found a few small cracks in the cap, replaced it and it was all sweet.

Check it first before buying a new one though.

Walkinshaw · 07-04-2003, 06:18

upon further reading, id be looking more for fuel problems, intake leaks etc.