I've checked, replaced, and added new ground wires and I am still having hesitation/bucking problems @ 2,200 - 3,000 rpms. I've pulled codes from the ECU and get code 51, which is the fuel pump relay. So I switched the fuel pump relay from my other 7, checked the resistor and got .6 ohms, which is in tolerances, checked the fuel pump fuses inside the car, and checked the circuit relay. Everything checks out OK!

Also, the downpipe glows red almost immediately after starting up. Do I have a clogged cat? I don't know what else it could be. Maybe the fuel filter? I've searched and it's hard to tell exactly what the problem is.

If it is a clogged cat would it be safe to run open exhaust after the downpipe? I know I would have to watch the boost carefully, but just to go around the block a couple times?

 

not only would u have to watch your boost (lol if you can keep up) if u just ran a dp, youd have to hold your ears......

 

usually a glowing cat does mean its clogged and if you just run the downpipe it would probably hit boost cut

 

Only if you have a pre-cat.

If not, you might be running very rich or have a bad misfire. Check the plugs/wires.

 

Spark plugs are new. I have now ruled out a clogged cat because I don't have any horrible odor from the exhaust. The downpipe appears to be some cheap stainless steel eBay pipe, so I think I was just over-reacting to the change in color.

Today I tested the voltage at the fuel pump and I am getting 11.4 volts when I bypass the resistor, and 5.4 volts with the resistor. Everything appears to be OK. I drove around with the resistor bypassed and 11.4 volts going to the pump and still had bucking issues.

Next up to check is the TPS, fuel filter, and injectors to see if they are leaking. Is there anything else I should check?

 

I am having similar issues. I have a 4 page thread going on about it. I am bucking and rough under 2500 RPMs and it cuts out bad as soon as I free rev or take off accelerating. It just cuts out, then finally catches and revs. I have yet to find the issue. Idle is good though. I am checking fuel pressure next. All of my sensors check out and no vac leaks found...

 

i've been having a similar issue. as soon as a put any load on the engine (usually when i hit between 4-10 psi boost even when free reving), the engine runs very rough and backfires like a bastard. when i let off the gas, the RPMs drop to about 500 and then go back to the normal 830 or so as if the fuel pressure is catching back up to it. i do not have a pressure gauge so i don't know what my fuel PSI is, but i replaced my fuel pump and it made no difference so i put the old one back in since the new one was OEM anyway, but i remember the plastic ring was cracked. i thought nothing of it but maybe thats my problem. where can i get a new ring? and how come it makes such a difference even if the O-ring is properly sealed?