Full throttle "hesitation"

[1993RT/TT]

I own a 93 R/T Turbo that will not rev past 4000rpm at full throttle. When driving it nicely it can rev all the way to redline but after going about 2/3 throttle is sputters and actually slows down. Logging the car shows no knock and I did notice the injector duty cylce actually went from high 60% down to 40%. It also makes a very loud popping sound that sounds like its coming from way over on the passenger side. Any help or ideas would be appreciated. I should also mention that the ECU is freshly rebuilt and switching ECUs makes no change. Thanks

Jake

[B-Man]

Change your spark plugs/wires recently?

[YoshiBishi]

You might want to check the gap of your plugs. Try something around .030 or .028.

[DK77]

Could be a boost leak

[iceorphen]

I just sorted out a similar problem, i chased it down and found it to be a pretty bad vac leak causing me to lose ~6hg of vac.

[1993RT/TT]

I did change the plugs recently but not the wires. What is a good way to check for a boost leak?

[dpartinvr4]

those IDC's, if they are "true IDC's" are way to low. your ECU must to be advancing the hell out of your timing. what timing does your log show?.........is your FPR broke? or do you have bigger injectors in without a piggyback system to adjust afr?

[3000GTCSULB]

Spark plug wires. I had the same problem.

[3KVT]

I'm dealing with the same issue pretty much and Hans thinks its spark blow-out. So I'd check plugs, wires, and coils too (one of mine has way more resistance than the others do, which could be causing the blow-out). Here's a good write-up on homemade pressure testers if you're mechanically inclined. courtesy of stealth316.com

Stealth 316 - Intake pressure tester

[1993RT/TT]

those IDC's, if they are "true IDC's" are way to low. your ECU must to be advancing the hell out of your timing. what timing does your log show?.........is your FPR broke? or do you have bigger injectors in without a piggyback system to adjust afr?

I'll hook the logger up again tomorrow and see what it says for sure on the timing and IDC