Pinking under acceleration.
One of the MR2 club members asked me what would cause this on his '90 model NA
He has just had a timing belt change, new water pump etc, and distributor reco to stop an oil leak.
 
He says the problem was not there before the work was done.
Btw the spark timing has been properly checked, and it still does it even using 98 fuel.
 
Anyone got any ideas?

sounds like the timing belt might not be installed correctly 

Thanks Andrew, that's what I would have thought too, unless anyone else has any ideas.
 
 

Mine sounded like it was pinging for a while too.  I had the spark plugs changed that helped a bit, then also had the leads changed when the new clutch went in.  Fixed...... 
Altho you probably already checked them.

Thanks Shaz, I'll pass that info on to the owner.

How do you know its actually pinging? Is it just making a pinging noise because I'd be very suprised if it is actually 'pinging' (detonating).

track_mr2
How do you know its actually pinging? Is it just making a pinging noise because I'd be very suprised if it is actually 'pinging' (detonating).

AFAIK pinging and detonation seem to be defined differently.
 
Anyway a stock gen2 3sge should not even give light pinging, even on 91 RON, so something is out of whack.
Although I know the gen3 motors can have a problem with pinging and run best on 98 RON.
 
 
 
 
 

Pinging, detonation, pre ignition. My understanding it is all essentially the same thing, uncontrolled combustion occurring prior to actual ignition timing and can be very damaging if prolonged under high loads , especially on turbo engines.

It's most likely to occur at revs where peak torque is developed and is a unique and distinct sound.

If you timing is too advanced it will cause it. Are your temp sensors all ok? Even if your base timing is ok if the ecu thinks the engine is always cold it it will alter the actual timing.

Are Spark plugs the correct heat range and gap? Maybe you have carbon build up which can cause it.

Does it do it all the time? Only during certain conditions? Easy to turn it on and off with throttle application? Would be worthwhile confirming correct cam timing as it is odd the problem only surfaced post replacement.

Cheers

Because MR2 NA's don't run very high compression or have particularly agressive cams and tuning it is really hard to have them pinging. When most people say there car is pinging it really isn't, its just a rattle noise comming from something like a cracked exhaust bracket or timing belt cover etc....
Worst possible case considering they just had the timing belt done is the cam gears aren't aligned properly but that will give you an odd noise all the time not just under heavy acceleration plus your car will be noticably slower.
If your not dropping any power it will be something else.

Sound like the timing is advanced....try backing off the dizzy abit