Misfiring under boost

[razmrtwo]

Hi, I drive a 1990 SW20 Turbo. A few weeks ago, the car suffered from misfiring when it hit 0.6 bar (8-9psi) of boost. Below that boost level, the car runs fine. What could be the causes for the misfire? I already check the ignition lead and it is still in good working condition.

Can it be caused by a dying fuel pump? The reason I asked that is because I can hear a hissing sound coming from the fuel tank which lead me thinking that the fuel pump is on its way out.

[dantheman]

Spark plug gaps might be incorrect.

[razmrtwo]

Spark plug gaps might be incorrect.

If so, what is the correct spark plugs gap for a stock 3SGTE?

[Peter Gidden]

Spark plug gaps might be incorrect.

If so, what is the correct spark plugs gap for a stock 3SGTE?

Coppers should be gapped to 0.8mm. Iridium and platinum should be pregapped out of the box and should not be manually corrected if worn.

[razmrtwo]

What is the correct spark plugs if I am to buy Bosch Platinum plugs?

[Peter Gidden]

What is the correct spark plugs if I am to buy Bosch Platinum plugs?

They'll most likely be pregapped to 0.8mm.

[Harold]

Have you checked your rotor arm and dizzy cap?

[Baker]

Ignition timing worth a check.

[razmrtwo]

Peter Gidden, do you know which of the Bosch platinum model should I buy?

Harold, rotor arm and dizzy cap had been checked and they're fine.

Baker, good that you point that. I will send the car to my mate to check the ignition timing

[Peter Gidden]

Peter Gidden, do you know which of the Bosch platinum model should I buy?

If you want Bosch, FR7DPX.

[razmrtwo]

Peter Gidden, do you know which of the Bosch platinum model should I buy?

If you want Bosch, FR7DPX.

Thanks a lot for the help mate

[razmrtwo]

I had changed the spark plugs with the correct 0.8mm gap however the misfiring is still present. It does improved things a bit though.

[Peter Gidden]

Suspects are distributor cap and rotor arm. But unlikely if replaced recently during routine servicing.

And coil has habit of cracking with age and letting moisture in.

You checked the leads - how? Looking at them will not reveal any weakness in the core conductor.

[razmrtwo]

Today, my mate and I did a compression test to reveal a massive leak which came from the BOV flange. And to our surprise, the flange of the BOV was damaged

Good news is that it was an easy fix We will continue to check for leaks again tomorrow since it was already late. Hopefully the car will be ready by tuesday