Ok, one thing I've been noticing.

 

Cruising at say 3500 rpm in 3rd, and then punching the throttle - My car will usually ping a little. If I slowly build boost in second and keep it through the gears (i.e., slowly press down at and then gradually go WOT) I never hear ping.

 

Seems like the fuel system has a hard time keeping up when boost goes from 0 to max in a short amount of time. Anyone have any luck in getting more fuel in the engine when the turbo is spooling?

 

Also: anyone ever notice a hesitation/stumble at part throttle, low boost (1-5 psi?) Is that likely to be fuel related as well?

The fuel system (from the pump to the regulator) stays at a constant pressure. It should have no problem supplying fuel to the injectors, no matter how the boost is changing.

 

Maybe your fuel pressure regulator has issues. I think it's tied into the manifold pressure, so it will deliver fuel to the injectors at a constant PSI above whatever the manifold is at. If it were responding too slowly, you might have fuel problems.

 

Is your O2 sensor okay? I've heard that as they get old, they also start to respond more slowly. That would affect your a/f mixture when the boost changes quickly.

 

I never had any pinging issues with my turbo wagon, no matter how hard I pushed it.

My first thought is that its timing, with the quick stab you are probably out running the ECU/knock sensors ability to roll the timing back, with the slow pull the system can keep up. What grade fuel are you running? My stock RX does the same thing on low octane. As a test, set the timing back 5 Deg or so and see if that helps the ping (overall performance may suffer a bit).

 

If it is fuel related a pressure gauge should tell the tail, make sure you tap it in at the end of the line at the regulator so it show the pressure at worst case.

 

Just some thoughts

Gary

Also: anyone ever notice a hesitation/stumble at part throttle, low boost (1-5 psi?) Is that likely to be fuel related as well?

 

I have been having that problem ever since I went to the TD04. Part throttle, stumbling starts at 1-2in/hg and goes to 3-5psi.

 

If I just nail it and go WOT, it doesn't happen.

My first thought is that its timing, with the quick stab you are probably out running the ECU/knock sensors ability to roll the timing back, with the slow pull the system can keep up...

My thoughts exactly.

I agree timming. I was having a similar problem turned out my timming was advanced by a couple degress. Pushed timming back to where it was supposed to be and not a single ping (89) octane. If you cannot get your timming to where it is supposed to be you may have the distributor off a tooth. That is what happened to me.

 

So give your timming a good once over.

Good luck