Help - Engine Knocking above 4000 rpm and under load

[robincoombe]

Can anyone help with this problem:
(1992 3SGE.)

The problem I have is that at higher engine speeds the engine knocks / pings / pinks .... whatever youy want to call it.

* When cold the engine runs fine at both low and high rpm.
* At low engine rpm then engine runs perfectly fine - with engine cold or hot.
* Once warmed up and running above approx 4,000 rpm the engine starts knocking - even worse when the engine is under load - i.e. going up a steep hill.

It's really pi$$ing me off as I've got to ease off the power whenever it does it.

I fitted new NGK Platinum plugs and new HT Leads the other day hoping that the plugs had got fouled and that is what was causing the problem but it still does it even with the new leads and plugs.
The state of the plugs was farily normal - they were a light brown colour around the base of the electrode, nothing unusual.

I don't think it's over-fueling the engine.
I get around 300 miles out of a full tank - I can get it up to almost 400 when driving really carefully on the motorway.
Although having said that - isn't knocking a sigh of under-fueling ?

Anyone have any thoughts as to where I should start looking ?


much appreciated,
Robin.

[Peter Gidden]

Assuming you don't mean knocking big ends, if it's pinging check your ignition timing.

Bridge TE1 and E1 in the diagnostics port, and with engine warm and idling, you 10 degrees of advance.

[Xmun7]

I had something similar, we hooked it up to the computer and found the fuel pressure to be slightly lower to what was recommended, ended up getting a fuel pressure regulator, increased the pressure and all was sorted, no problems now, you should check the fuel pressure