General TechHave a question that is not covered by one of the other categories? This is the forum for all other items not specifically covered in other categories.
Got a car here (Xc) with a 302C on petrol / gas,
When on petrol, and the motor is hot, you turn the key off, and the motor keeps running on, and 'pinging' as it does so.
It only does it on petrol, and when hot.
On gas its fine
Plugs are BP6FS and new
Fuel Pump has been replaced (the old one was leaking)
The motor was rebuilt some years ago, although its only done around 50,000kms
The possibility's im throwing around are
1) Some fuel in the sump, and its running on vapours
2) Possibly leaking intake manifold gaskets, and sucking air / oil
3) The fuel line and soleniod (gas / fuel cut) get hot when the motor is hot, the brass bit of the solenoid is to the point you dont feel comfortable holding it for too long, Therefore the fuel could be boiling in the carb and the motor is running on the vapour.
The thermaquad carb on it has been reconditioned to try solve the problem, but made no diff.
I doubt it is due to carbon deposits in the cylinders, it has had top engine cleaner through it and also given a hard run...
Any other posibilities or people with similar probs?
What donuts said!. My mate has advanced the timing on his XF with gas a bit, and he has also (at some stages) advanced it too much and it doesn't shut off. Retard the timing
__________________
Alex
"Give me any task to do, and I will find something else to do in it's place." Plato - a definition of procrastination
Umm, why would the timing cause it, once the keys off, theres no spark anyway... Its igniting itself.
The timing is correct anyway, the balancer is in perfect cond.
It also does / did it at true 4* advance.
Anyhow, its sorted, it was idling too high, although it wouldnt idle down any more at all (idle solenoid was loose and idle screw right out)
It is a common problem with thermaquads (idling high), so the carb place is replacing the primary butterflys with ones with no bleed holes, and modifying the base to block some of the air bypass vanes, therefore it will idle correctly, and stall when the solenoid turns off.
Its a std 302 with thermaquad etc, so those that know the carb, will know what i mean.
Umm, why would the timing cause it, once the keys off, theres no spark anyway... Its igniting itself.
The timing is correct anyway, the balancer is in perfect cond.
It also does / did it at true 4* advance.
Because it just does... has something to do with excess heat in the chambers or something caused by timing being too far advanced I think.
Common knowledge that advanced timing causes run on after the motor has been turned off. But now you mention idle speed I do remember my brothers celica had a little run on when it was turned off, but he had a mechanical fuel pump and it would have been well above normal idle.
Umm, why would the timing cause it, once the keys off, theres no spark anyway... Its igniting itself.
The timing is correct anyway, the balancer is in perfect cond.
It also does / did it at true 4* advance.
Because it just does... has something to do with excess heat in the chambers or something caused by timing being too far advanced I think.
Common knowledge that advanced timing causes run on after the motor has been turned off. But now you mention idle speed I do remember my brothers celica had a little run on when it was turned off, but he had a mechanical fuel pump and it would have been well above normal idle.
Anyways glad you got it fixed.
WTF???
Have you ever done this before? 9psi EB was spot on! lower timing.
98% of the time this is the case. timing very rare.
have tested both on same engine with holley and thermoquad.
The AutoGuide.com network consists of the largest network of enthusiast-owned enthusiast-operated automotive communities.
AutoGuide.com provides the latest car reviews, auto show coverage, new car prices, and automotive news. The AutoGuide network operates more than 100 automotive forums where our users consult peers for shopping information and advice, and share opinions as a community.
Linear Mode
