91 5.2L 183000mi. Automatic

I'm not sure if I have multiple problems here or not. Intermittent problem, When I am coming to a stop, the Tach starts bouncing and the engine dies. Sometimes when the engine dies, It doesn't want to start right back up immediately, Most of the time it will. I got stranded today in a parking lot for a little while. engine was turning like it wasn't getting fire, you know just free wheelin'. Got out removed top of air flter housing to see if gas was being shot into the TB. hit the remote start and it turned over, gas shot in, and it spit back a little through the tb. Tried starting again, started right up, ran good all the way home. This happened about 2 months ago, I used some Sea Foam through the tb and into the vacuum tube from the booster and it was fine until recently. Sometimes when I am coming off load, meaning coming to the top of the hill or reaching speed, it stumbles a little as well.should I remove the TBFI unit and clean?

Any Ideas???

 

Is it throwing any codes?

 

No codes, found the EGR valve was loose on one side, removed cleaned out the carbon and tightened. Still waiting to see if that is the problem I haven't had time to test drive thoroughly. I removed the air filter and used the vacuum line that operates the warm air valve and stuck my mighty vac into it and it was pullin over 20. Anyone have any ideas if this isn't (EGR Loose) the problem.

 

Because you said it will not start sometimesI would replace the pickup plate in the distributor.

 

Replaced the pickup about 2 months ago.

Sorry so Long

Update. after the last post, I drove about 60 minutes one way to work on a house. anyway, the engine seemed to be running rich or slightly out of time. anyway it was running rough under load at idle. ran good at high rpm. All in all no problems during the trip. On the way back up, close to home I stopped and popped the hood and did a quick visual of the air filter to see if I needed to get one while I was in the store. After getting back in the truck and driving for a short time. It started stalling when I stop again. Anyway finally it wouldn't start again. I popped the hood and touched the wires that go to the temperature sensor for the throttle body. and it started immediately and ran all the way home. Go home and did a voltage check on the wire and did a wiggle test to see if there was a break in the wire. I know that unplugging this sensor will not kill the engine, so a break wouldn't cause the problem. I couldn't find any place where the insulation is cracked or frayed. I am not sure if an intermittent short on that sensor wire would take the sensor control voltage down enough to kill the engine. assuming that the wire is not the problem. any Ideas.

 

The saga continues....

Checked the Map Sensor. Swept it from 0 to over 20 and the voltage varied accordingly Sensor Good. Swept the TPS voltage varied accordingly, Sensor good. popped the PCV unit out and there wasn't any suction.? Pulled the PCV out of the vacuum line, No suction there? Thinking about pulling the TB and cleaning everything out. I don't like to parts change, but It is getting down to that. Anybody have any idea where to start? I think the whole wiring thing was just a nasty tangent that was a coincidence. There isn't a port for checking fuel pressure and I don't have the tubing and fittings to hook up my gauge.

 

you can always do the wiggle test on the TPS. Have the truck running and see if the idle changes when you wiggle the TPS. I have run in to O2 sensor wiring doing the same thing before. If it will ground out on the heat shield and cause the truck to run terrible.

 

I think your along the right lines with the temp sensor. I replace my vavle cover gaskets in my 93 dakota and got the sensor wires under the lip of the one cover. It was doing the same thing with shut down when i tried to stop. My understanding of my problem was that the computer thought that the engine was over heating.


Mopar400

 

Update...

Removed the throttle body and found the port that connects to the PCV and the vapor canister, was plugged with carbon, cleaned out and did an overall cleaning of everything I could without dismantling the tb. I can't get it to die yet, but I haven't gone on any long ventures since. It still runs rough. I changed the O2 sensor, even though the dang thing isn't throwing any codes. The O2 sensor hasn't been replaced in the last 100,000 miles anyway. The timing is dead on, what else could it be. I am starting a Compression test to find out if I have a cylinder or two that has lost some compression. Do you think it could be my fuel pump?

 

Update, Compression test done. Just checking if the engine is getting old or not. Test method. Utilizing a cheap compression tester. Coil wire and shut down relay pulled. TB open all the way. Cranked engine 5 compression cycles per cylinder.
Results

1 175psi
2 170psi
3 165psi
4 170psi
5 155psi
6 160psi
7170psi
8 165psi

test performed on a cold block. just curious do you think these numbers would increase or decrease or stay the same in a operating temp block...

What do you think of the numbers?