KA turbo WOT hesitation + spark plug Qs

[AceInHole]

I just turned the boost up to 7psi today and took it out for a few quick tests. It was all fine and dandy for a while, then I got a hesitation of sorts. At WOT it'll keep going, but it feels like it's on a rev limiter. Basically I just lose a lot of power. It accelerates slightly, but there's a sudden large drop in power.

What I'm thinking:
1. Spark plugs. I'm using Bosch Platinums at the gap they came in. Was gonna switch plugs but after swapping heads I had trouble starting the car. I ended up trying to revert to the "old" setup, and never went back to the new plugs. Gonna try the NGK Copper plugs tomorrow at a .030 gap.

2. It might be the fuel pump, but I'm doubting that since it used to hesitate every once in a while. If it was a lack of fuel I don't think the power would drop so suddenly, and I don't think the problem is consistent enough to be the fuel pump. I've heard the fuel pump is good for like 10+ psi of boost when not using an FMU....

3. Would the TPS have an affect on it? Tip-in retard maybe?

4. Knock sensor? I'm not really hearing a knock or ping (there is a clicking sound for a small RPM range... thought it might be a noisy injector, but i'll pull the valve cover to see if it's the timing chain...)

Finally: spark plugs:
Denso Iridiums are supposedly the best... but how are the NGK Iridiums? Not as good? Still worth it? Would I just be better off sticking with NGK copper plugs or platinum plugs?

Thanks in advance,
PJ

[sykikchimp]

the copper plugs spark better than the platinums, and iridiums.. those expensive plugs are made to last a long time. i.e the 100,000 mile tune ups with cars using the platinum plugs...

you might even try running a little colder plug... plus your running rich might be fouling out the plugs.

I would also check the timing, and make sure your injectors are working properly, and make sure your MAF is still tight, and not having problems.

( i think that hits all the big stuff.. fuel, air, spark... )

[AceInHole]

Originally posted by sykikchimp
the copper plugs spark better than the platinums, and iridiums.. those expensive plugs are made to last a long time. i.e the 100,000 mile tune ups with cars using the platinum plugs...

you might even try running a little colder plug... plus your running rich might be fouling out the plugs.

I would also check the timing, and make sure your injectors are working properly, and make sure your MAF is still tight, and not having problems.

( i think that hits all the big stuff.. fuel, air, spark... )

Yeah, my guess is the plugs are fouled.

Timing was checked yesterday and set to 18deg BTDC. Injectors are working fine up untill WOT. MAF is on tight. It's gotta be the plugs.