Lumpy as me old grannys custard!!

[clarky5150]

Help! Since buying my griff last week it has idled like a bag of sh&*e. The previous owner said the stepper motor was knackered. Ive took it out and cleaned it (no joy). The problem seems to be more when the cars hot though. At 1100rpm tickover the car hunts and runs really lumpy and on occasios will not tick over at all. I have disconnected the Stepper motor and tried to adjust the air flow meter but this seems to make no difference. Are these simpoms concurrent with a duff stepper motor or should i be looking elsewhere. Ive tried an air flow box from a V8S on the car - no difference. The car is a 4.3 and has a semi wild cam in it. It apparently has a Mark Adams chip and head work. Any thoughs would be appreciated.

[kevinday]

May well be the stepper motor, also consider that if it does have a wild cam (you do not say which it is) it may be caused by the cam itself.

[clarky5150]

The problem is intermittent ranging from poor to bloody awful. I can blame the poor on the cam at a push but not the big fluctuations.

[apache]

could be dodgy injectors, apparently they get buggered up quite quickly these days and a clean won't break the bank. I guess you'll have to gradually eliminate the less expensive items like dizzy and leads, new stepper etc (if it don't fix it you'll have a spare)

[HarryW]

Silly question if you've borrowed the AFM from a V8S can't you try the stepper as well Can you hear the stepper make a noise particulary when switching off i.e. a little buz when swtitching of , just proves the stepper is alive but not necessary OK though. Is the base idle set ok on the bypass on the plenum? (only to be done once your happy hte stepper is OK otherwise the ECU will chase it's own ass (as it may already be doing).
Finally as you've already said it does have a wild cam fitted, whilst this will give you a ragged tick over it should not give ou an erractic one. All IMHO and certainly not definative or probably acurate .

Harry

[buzzsaw]

Lumpy idling when hot only....possibly Lambda sensor. Has fuel consumption increased as well?

[clarky5150]

1992 4.3 so no cats or lambda. Wondering if the metal shrouds on the end of the plugs could be breaking down. anyone had that??

[simon.b]

I’ve not had the metal bit’s breakdown, but I have had the rubber end caps turn brittle and start cracking which then allowed the HT to arc across to the exhaust manifold. This was quite easy to spot though so I guess you’d have already found this.

Cheers,

Simon.

[rbfisher]

That is what it is that it is being - them pesky plug shields. Poor running when hot but OK at warm up.