At WOT feels like I’m running on 6 cylinders. Has no pull what so ever and I can’t roast the tires even at 5,000 rpms. When I launch at any rpm, and I have tried from 6 grand, the car bogs even if I “feather” the clutch. I have new opti, plugs, wires, coil, fuel filter and pressure regulator. My last resort is to replace the fuel pump and/or injectors. Any other suggestions????

 

Has it ever run better since you did the work in your sig or has it always been like that since you did the work?
Have you ever monitored the fuel pressure when the problem occurs?

 

I am experiencing a very similar problem, and my car is mostly stock. I dont bog down until about 4600 or 4800 RPM or so, I can accellerate hard until then and then the RPM's just slowly rise, when the car should pull harder up to my shift point. (K&N, and cut-out.) I also have replaced everything you have stated. I am purplexed as well, hopefully tonight I am going to test the fuel pressure. I did have a LT4 Knock Module in it, which has been removed and since has seemed to help (does not bog as bad now). I did a plug and wire swap this weekend to MSD Superconductors and NGK plugs, which I was hoping would fix it, it did not.

 

The car has ran great after everything that I did in the sig. It has only acted like this since I replaced the head gaskets. I have an Aeromotive adjustable fuel pressure regulator and have it set at 42 psi for idle. At WOT simulation, by removing the vacuum line from the regulator, the psi goes up about 10 psi.

 

You can only guess this way, best you put a OBD scanner on, go for a drive, have it record the OBD information and analyze that.
Just because you up'd the fuel pressure does not mean the injectors are flowing correctly at different engine loads.
It could be the tune is incorrect and not calibrating correctly for PE or WOT.

 

I would suggest a visit back to basics. I'm thinking 2 ways here, either the gasket is still a problem in some way or you created a new problem when you did the gaskets. Do a compression or leakdown which ever is more convenient. Also do a pressure check of the coolant system.

 

Tomorrow when I go to school, I attend UTI, I have two teachers who are ASE GM master techs and on has a Genisys scanner, so I will do some logging tomorrow.

 

I thought about your problem and it sounds a lot like an article that I read about a valve train problem. Take a real close look at everything and if you can look at the pushrods during the full travel. See if they are contacting the heads or if the rockers have sufficient clearance to the valve springs. You may end up checking the springs themselves as well.

 

Had the car scanned yesterday and here is the data stream:

Engine rpm: 671
TPS SensorV: 0.61V
Thr Angle: 0
Spark Adv: 22 Deg.
Idle Air C: 160
BLM Cell: 16
BLM Enable: No
Inj. PW Bank1: 6.0 msec
Inj. PW Bank2: 5.8 msec
Injector Fault: Yes
Knock Retard: 2%
Knock Signal: No
Learned IAC: 42
LT FT B2: 128
LT Fuel 1: 128
Map V: 2.49V
ST FT Bank 2: 128
ST Fuel1: 128

From what my instructors told me is that the PCM is always in WOT. I changed the MAP sensor and cleared the capacitors for the PCM and the car is still flat throughout the rpm range. I did however pulled the injector connectors and found that #2,3,5,8 did not change idle but #1,4,6,7 did make the car idle real rough. So I think I have bad injectors or it just happens that #2,3,5,8 are all on the same circuit. I don’t know just making logical guesses.

 

One thing I notice here is that it's every other cylinder in the firing order! I'm not real sure where to tell you to look but that may be a key to figuring it out! I'm not familiar with that scanner so I'm not real sure but is that saying it's retarding spark by 2%? Move the injectors around to figure out if it's the injector or the computer/wiring causing the problem.

Richard

 

Pulling the vacuum line does NOT simlulate wot because it doesnt put a demand on the pump. Nail the throttle by hand when watching the gauge. Do the pressure test again.

 

Injectors 2,3,5 & 8 are all powered by the 7.5 amp fuse #9 in the underhood fuse box. FYI 1,4,6 & 7 are powered by fuse #10.

I think you found your problem.

Ta Dah

 

Did you notice it says Injector Fault: Yes

 

That is EXCATCLY what the problem was!!!!! Before I even read these post, I woke up this morning and was studying for my electrical test today and it just dawned upon me. I looked at the wiring schematic in my service manual and found that those four injectors were all on the same fuse. Sure enough the fuse was blown!!!! I tell you what I have learned form this, start small and basic then move on to bigger things! Thanks guys for all of your suggestions, I appreciated you taking your time to help!!

 

It doesn't matter how many times you say it or how long you work on anything or even how good you are at it. At some point you'll forget to start with the basics. Why? Because they seem so basic I guess

Glad you found your problem!