Car is on a feeding frenzy again. Had to replace the power booster last week, flushed brake system and got her going. All was well for a couple of days. Now I have a problem of her just stumbling and dying. It starts right up cold and runs great, plenty of power. A while after she is up to temp, it stalls out. By stalling, I mean it sputters, backfires, misses and you have to play with the gas to get it to the side of the road. The problem occurs at idle as well as moving down the road. If you let it sit for a couple minutes, she fires right up and runs fine for a while and then does it again.

I checked the fuel pressure. It is 42 lbs when you turn the key on without starting car and holds when you switch off without bleeding off. I started her up and drove with the gage on it. The problem occured and the pressure remained solid. I was hoping on the pressure dropping and it being the fuel pump, no luck there.

I installed 22lb ford injectors from fiveomotorsports in the spring and they have been working fine. When problem occurs, I checked the injectors, and they are all pulsing steady even though te cas is not running steady.

I suspected the ignition module or coil. I removed cap and rotor. Whoever replaced the module before I acquired car broke the cover on the capacitor and set it in place (the way plastic was bent you could tell it was pryed loose) So I replaced the module, capactor,cap, rotor and coil while I was in there. Problem remains.

Plugs and wires are good. I turned lights out with car running in garage and saw no arcing of any kind and see no obvious problems.

Also, the SES light comes on and stays on when problem occurs, but registers no code. When you try to pull codes right after problem occurs, you have to wait a few minutes for the SES light to stay out, or it wont let you enter diagnostics mode. When in diagnostic mode, all you get is code 12.

Any suggestions ? Thanks Rich

 

I had this problem while back. Mine was a vacuum leak somewhere. You also might wanna check the TPS. When the car starts losing power and bucking, does it just stall the engine when you press the gas pedal?

 

Yes, the engine stalls unless you pump it. Even then, it is hard to keep running until it gets off the road. I don't understand why the SES stays on while it idles really rough but gives no code.

 

So basically you're keeping your foot on the pedal for it to run? Unplug the MAF and see if it runs better. If its running better, your MAF sensor is the problem. MAF problems usually result in codes 33, 34, or 36. Are you running the car in field service mode, aka jumped a and b ALDL terminals? If you are, and when the problem happens, the ECM will not store a code. Run it for a bit and see if the SES light comes on.

 

I will try unplugging the MAF next time it occurs. Thanks for the suggestion. As for the field service mode, no, I run car without the ALDL jumpered and try to pull codes after it sets a SES light. Problem is, it doesnot store a code. I will still try the MAF though and see if it makes a difference. I am starting to suspect the ecm. The problem occurs with the stock chip and the hypertech chip so I can rule out the memcal.

 

Does the car have cats?
(sounds like plugged cats)

 

Yeah, it still has cats. I didn't think of them. Is there a sure way to tell if they're bad? Kind of expensive to replace if they aren,t bad. Thanks for the help. Rich

 

I know someone in here has a service manual to determine if you have clogged cats using an air pressure meter through the A.I.R. pipe or O2 bung to determine if the cats are clogged or not. From idle to 2000 rpms, the back pressure cannot be more than 1 psi, correct me if I am wrong...

 

Thanks, I can check my manual to verify the psi, I just don't have it at hand. It is in the garage.