Serious cut-out problem...
 

About a week ago, the motor wouldn't idle while cold. It would surge up and down 3k-250 rpms then cut-out. It wouldn't happen after the motor got warm. Now, it violently cuts-off almost like a sudden fuel cut out or ignition failure while I'm driving at random intervals.

I have just replaced the 02's, and IAC, and reset the tps. After it cuts out, I heard the fuel pump kick on and off at least 4 times. The starter solenoid is new too. I hear the solenoid trip but I haven't moved the key. The fuel pump seems to charge the lines just fine when I turn the ingnition.

Do ignitions do that when they go bad? The fuel pump is a aftermarket 255lph model that is 3 yrs old.

I am at a loss on this one...appreciate any input.

Re: Serious cut-out problem...
 

My first guess is the ignition switch. The last time I had crazy things happen in my stang, it turned out to be the ignition switch. It was barely making contact in the "on" position. If I held my fingers on the ears around the key it would stay running, but as soon as I let off the ears, it would die. The only thing that gets me in your situation is the idle surging. I don't know if that's the beginning of your problem or pure coincidence.

Re: Serious cut-out problem...
 

I re-torqued all of the intake manifold upper and lower bolts and checked for vacuum leaks. I also said to heck with it and replaced the tps, o2's, ECT and ACT. Fooling around I found the electrical harness to a thermactor relay completely corroded. No relation though. One of these days I'll rip all remaining smog crap out of the engine bay and really clean it up.

After all of that, it is runnning fine. Honestly, I think I wasted some money on those sensors and it was the GT-40 intake that just needed a re-torque. I haven't retorqued anything since my engine rebuild :eek:

but then, it's more fun just to drive the heck out of it!

Re: Serious cut-out problem...
 

Damn I'm having the same stuff happen I just replaced my coolant temp sens tonight its not cutting out anymore but it is still jumping between rpm's man its blowing me. I ran it on a scanner at work and it wouldnt give me any codes but it was running rich so I guess I'll take it back up to work again tomarrow and see what it says now

Re: Serious cut-out problem...
 

My cut-out is back...
I have changed the ACT, Fuel Pump relay,TPS and reset to .98, IAC, and cleaned the MAF, ECT, and K&N filter.
I am now going to drop the tank today and check/clean all fuel pump connections and put a new coil on. Maybe just put a new pump on to be sure...

New symptom though...it cut-out a couple of times this morning on the way back from work when it was idle up to 2k rpm. When I drove it hard, no problem.

:D I love intermittent electrical problems, don't you?

Re: Serious cut-out problem...
 

Ah-ha!.....
looks like a good suspect to me! :eek:
I should put a picture of the coil too, man it was nasty!

Re: Serious cut-out problem...
 

Looks like a good cut-out candidate to me. Aren't you glad you dropped the tank?