Fourplants

Hello everyone. I recently bought my z32tt and have been having a misfire when warm. At first we thought vacuum leak so we traced the system and fixed the leaks (3 of them) and no help. Then we thought boost leak, made a tester and tested everything seemed ok. Then I thought plugs. come to find out that the car has NGK iridiums. Did some research and found that the supposed correct plug is the NGK PFR6B-11B with a gap of 0.35 with my mild mods. My question is will the iridiums being a shorter plug cause a misfire at temperature? Should I go with the platinums? Never hurts to have another opinion. Thanks

Rupe

There must be a reason for "requiring" a specific plug. Couldn't hurt to try.

Big Zed

What set of Iridiums are they? It's possible that they are too "hot" of a plug compared to the factory ones.

Also, dont assume plugs are the issue. It could be low compression, bad coolant temp sensor, etc.. If it's only missing when it's hot, then use that info to your advantage. What changes when the motor warms up? Then look those places for abnormalities.

hoov100

Check fuel pressure, you could have a bad FPCU which isn't turning the fuel pump on high.

Fourplants

They are the Iridium IX. Much shorter than the PFR6B-11B. Wouldn't the shorter plug create more volume in the cylinder causing a lower compression? I will also run a fuel pressure test when I install the new plugs. Thanks guys.

hoov100

I run the shorter iridiums in my TT, no problems with them.

Big Zed

Shorter plugs usually indicate a "colder" heat range. Having too cold of a plug isnt' necessarily bad. If you are, look at the tip of the plugs and see if they are sooty and/or black. This indicates an incomplete fuel burn. If they are white, then the plugs are too 'hot.'

Fourplants

Replaced fuel filter installed NGK pfr6b 11b, apexi afc neo and high flow cats to pass emissions test Dyno tuned 329.5 whp at 6450 rpm 345.6 ft lbs torque at 4800 rpm misfire is gone yay lol.

Rupe

Nice man congrats.