Dr J

Long post, persistent intermittent problem. 96 GC, limited, 4.0 automatic 4wd quadratrac. 16 year old daughter’s DD, so needs to be reliable. Sputtering problem, mostly when driven less than a mile since starting. 3 months back, was 1) sputtering when driving at constant speed (30 mph), seeming like it was going to die, bogging down, then recovering, and 2) bogging down then surging engine speed when slowing down at stop signs. Never an issue idling when in park, though. Last month, it has started straight out dying (under a mile from starting driving) – no sputtering, just like someone turned off the key. Happens like one to three times over the course of her one mile drive to work, one day out of three. I have read the forum a whole lot, and cleaned the IAC, and cleaned the electrical connections to the IAC and TPS. In May, I put in new dist cap, rotor, denzo (?) wires and champion copper plugs. Last week, it was acting up and if finally threw codes – it had never done so before. Three codes– IAC, TPS and Crankshaft sensor. I read the forum some more, read that all three had one thing in common – the PCM. So, I read some more, cleaned the three connectors at the PCM, replaced the two screws in the PCM cover and zip ties the PCM connectors in place. This week, it did something it never has done – died as if the switch was turned off when going 35 mph, then restarted itself and ran a hundred yards, repeated this trick and ran fine the rest of the way to work. It did not throw a code.
So, my question is this – If it were you, what would you replace first? I am leaning toward a new PCM from Rock Auto, screw it in place, leave the old PCM wired up, and drive it to the dealer to ask them to connect and flash in the new one.
I’m trying to do my homework, guys, I’m just stumped on this one. And I’ve got a limited amount of time until school starts back up. Your help, advice and/or thoughts would be appreciated.

Creature85

Cleaning the IAC doesn't always work. I've seen a lot of guys clean them and then a month later it craps out. Do you have a rough idle? I'd be checking the voltages to all those sensors before throwing down all that cheddar for a new PCM and flashing.

Dr J

Thanks, Creature.
Start the beast up, idle is fine, smooth - in park. She has never had a rough idel while in park. 5 times out of 6, you pull up to stop sign or red light and things are great. It is that 6 time out of 6 that she bogs down, over reves, then comes back to normal. Roger, that. Don't want to throw a bunch of money at her, but I gotta keep my daughter safe. That help you figure anything out?
John

Dr J

Sorry ... voltages. I checked the TPS engine off, key on, 5 volts. Read about checking TPS voltage, but was unsure about what I read. Simple/clear instructions would be greatly appreciated. If not simple, then clear is great ;-). Didn't check anything else. Don't know specs, have good multimeter. Since it is an intermittent problem, didn't really know if that would be tellting. whaddya think?
J

JJCIII

I had to resolder the removable circuit board which is the large cover that'd removed to open it. And as for a reflash, chrysler/jeep pcms don't get flashed. They just get reset. Not sure why they designed that way.

Bustedback

No, they need to be flashed.

JJCIII

I'm not sure exactly how its different from other makes but I've been told and read that its not done the same way. Something about the chrylser pcm not being writable or something.

Bustedback

All OBDII Chrysler PCMs are able to be flashed. I've done it first hand.

Dr J

Thanks, Busted. Traveling now. I'll get on the Crank Sensor this weekend and post results.
J

Creature85

Here's a nice write up for testing the CPS.

https://www.cherokeeforum.com/f51/testing-cps-5563/

And for your TPS.

http://autorepair.about.com/library/faqs/bl232i.htm

I can't seem to find the link for the IAC test.

As JJCIII said it could also be poor connections on the PCM. The connections on those are easy enough to reflow without issue.

Dr J

Thank you, Creature. I'll be back home this weekend and will post results. I appreciate your help.
J

Dr J

Thank you folks. Got back home, replaced crankshaft position sensor and cleaned MAP sensor. All seems well, been a week. Keep your fingers crossed for me.