I ran the car 4 days ago and it ran incredible. I started it today and the idle is inconsistant. I gave it 5 minutes to warm up and took it for a drive. It runs ok if you drive it normal but the second you give it any gas it goes no where and the rpm's barely move. I put it in nuetral and reved it a little and it is better but bogs a little but under a load. Please help! Headers installed 3 weeks ago. I know of the burnt wires and such. Looking for the less obivious ideas to check.

 

I need to add this since it never happened before. I had a fuel pressure gauge hooked up for the last 3 months and it will run at 36 to 37 psi at idle. The pressure will bleed off to 0 after a few hours avery time after you turn it off. Today it had 10 psi with the car off and when i started it the pressure was to 40 while warming up and stayed above the usual. Very weird since 100 times it does the same thing and the day it runs horrible the gauge reads different.

 

Now does this fuel pressure change happen when the car is acting up? Have you checked the fuel pressure w/out the vacuum line attatched to the FPR?

 

I have not checked with the hose disconnected. The fuel pressure stayed 3 psi higher than normal. It only has happened tonight in 10 minutes of driving. I blew a head gasket in my 79 z28 and it had the same power loss. The difference is the idle is not real bad and the cruising speed is somewhat smooth but i don't dare give it much gas.

 

Also check that your intake for leaks after MAF, clean MAF if dirty. Check for vacuum leaks, I had 2 that were causing some very bad hesitation and bogging. One was the PCV fresh air tube going into the valve cover. The fitting was leaking air so I bought a new fitting. The other one was a dry rotted elbow for the EVAP solenoid coming off the throttle body.

Monitor your fuel pressure, as pumps have a tendancy to just die out of no where.

Also check simple things like you said, arcing and burnt wires. Pull a plug and see how it looks. Oh yes, also new header coating burning off on breakin can ruin O2 sensors so dont rule those bastards out either... though I dont think they would cause bogging.

 

I waited 2 weeks to put new 02's in so they should be fine. It does it cold and warmed up so it will eliminate a lot of things. I am suprised no red light codes are coming up. I had 2 plug wire reversed and the car ran better than now. I had great acceleration right up to the point i parked it and the second the car starts the idle sucked. Very strange just sitting it went from 100% smooth with full power to very rough idle and zero power and i mean zero!

 

plugged cat?????

 

It turned out to be a plug wire was burnt like i thought. It was in the heat sleeve but still destroyed the wire. The sleeve was hard as a rock where it touched the header. I had to use an old plug wire and run it over the top. I guess when they say headers get extremly hot they mean it. Good news except the track was closed tonight.