Marino

hello guys i 've a small question.
can a worn camshaft cause detonations?
I have problem of detonations only on middle throttle and when I accelerated brusquely, I already checked timing (12 degrees at idle) and afr (14.6 on light/middle throttle 11.8-12.2 wot full boost). the engine is standard with standard boost pressure.
the detonations disappear only if the retard the timing to 5-6 degrees
any advice will be appreciated
thx
Marino

edit: today I was in 4 gear at 2500 rpm, i have accelerated and, over the detonations, I noticed that after the peak, the boost started to decline according to the rpm. in 4500 I was only 2 psi boost

Karl @ FPT

Shouldn't do no, a worn cam means less air will be entering the engine.
Your ECU may not be retarding the timing on boost though, perhaps try another if you have one or can borrow one and is the vacuum hose connected to it too?

Chas

It depends.

I have seen a friend's Rover SD1 popping from the exhaust alot in addition to backfiring via the carb which was suspected initially down to worn valve springs. It was the camshaft in the end.

OTOH (it was a diesel mind you) my old PD Passat misfired terribly upon throttle. I have to this day not seen an intact camshaft quite so worn.

Marino

good morning,
at the beginning i also thought it was an issue of ECU that does not retard the timing but I tried 2 different ignition ECU (one without knock sensor) but nothing has changed. also i have tried to change the act sensor, metering unit, fuel ECU and fuel pump but nothing .
i have already spent more than $ 500 in spare parts and equipment to control the AFR and timing. the only things that i have not changed are the dizzy and the camshaft.

Karl @ FPT

None of that is detonation though mate, it sounds like valves opening/closing at the wrong time in relation to the spark event.
The diesel is not comparable as it doesn't have a spark in the first place and essentially detonates all the time.
What pistons do you have? What fuel are you using?

Unless somehow the cam has worn in such a way it has increased your dynamic CR, but I don't know if that's even possible?! lol

Marino

this morning I removed the camshaft and it does not seem consumed.
I always use petrol with 100 octane (Eni super blue).
the pistons are AE +0.5 and were changed when I rebuilt the engine 18000 miles ago.
what else can I check?

Red_bull

Is it det or misfire? Cause misfire could be something different! If you hear det without monitoring it then the issue is pretty bad or are you using something like headphones?