JZ'sTA

iTrader: (23)

Well, after yesterday's events at Bradenton (sucky time slip, car felt like crap) I decided to take the car out today and do some logging so I could adjust my PCM fuel trims at part throttle, then move on to full throttle again.

I found that when I get the car up to around 4500-5000RPM at part throttle (about 20% to 30%) the car just falls on its face. It's like it hits a brick wall and doesn't want to go any higher. I have to give it quite a bit more throttle to increase the RPMs. Happens in gears 1 2 and 3, didn't try the other gears, but at least that shows (hopefully) it's not a drivetrain thing.

The RPM it hits at changes, it seems like at lighter throttle I can get it to hit at around 5000, at heavier throttle it hits earlier.

Would valve float, related to bad springs maybe manifest itself this way?



Car is a 383 stroker with 9.0 compression, Turbo kit, heads cam etc.


Plugs seem fine, and I gaped them correctly.
Not a boost leak because I am only at part throttle.

Thanks

METAL MAN

You need to check your fuel pressure while your driving. Tape a gauge to the windshield and have someone watch the pressure when you go WOT. The pressure shouldn't drop at all, if you have a boost referenced regulator it should go up with boost. I'd say this is probably your problem. If you don't have at least a Walbro 255 your long over due.

METAL MAN

One more thing, make sure that plug gap is tight, you'll want to be around the low .30's and not over .37.

JZ'sTA

iTrader: (23)

Thanks Metal MAn, however the problem is at part throttle.
Fuel is there, and the plugs are gaped at 0.30.

Armageddon

iTrader: (41)

is the car showing any other symptoms?