golfmiser

Looking for some direction or an avenue that I may have overlooked. I have a '92 limited cherokee 4.0. Recently on cold mornings it would spit or sputter on start up. Never a problem when temperature was 45 degrees or higher. Finally it came to the point it would sputter or backfire upon acceleration when the engine was still cold. It backfired and died on the road. I wasn't getting any spark so I replaced the CPS. It started but missed terribly and sounded like it was running on 2 cylinders. I did all the common checks. Grounds,connections,voltage and vacuum leaks and some I sure I've forgot about. Found the 2 field wires on the alternator needed repairing. Jeep got to starting and running no problem. The next day went to move it out of the garage and it would not start. May come back in 2 hours and it will start. May shut off and try to start again and it won't start. Sometimes I can barely push on the accelerator and it starts. Doesn't run good. Could be the plugs are getting gas fouled. I had a pcm with a bad voltage regulator tried it and it made no difference. I'm getting spark to the plugs. I'm holding 40 psi fuel pressure on start up..49 psi once started. Injectors are pulsing. It looks like the pulse and spark may be weaker at times, hard to tell. I feel like what ever it is that it's affecting the timing and fuel.The intake and headers are getting extremely hot once started. Maybe a intermittent faulty signal from the new CPS.
Any ideas or suggestions would greatly be appreciated. The past 8 weeks have made what little hair I have left turn loose sooner than later.


UPDATE: I finally got the jeep to running normal again this past weekend. I opened the holes up in the CPS so it would sit closer to the flex plate. That seemed to help the no start but I still had issues with the timing being off. I put a new distributor in and it seemed to run but sounded like it had a big cam and would backfire through the throttle body when accelerated hard. I took the distributor out and compared it to the original distributor that came in the jeep. I noticed the relation between where the rotor pointed and where
the plate in the distributor entered the sensor wasn't the same as the old one. I re-installed the new distributor with the rotor pointing just a little past number one on the distributor cap. It started and ran like normal. I know this is long but I thought I would let everyone know what I found. Most of the issues is related to what's becoming a common problem. Poor quality aftermarket parts. I have tried to find a mopar CPS and the 2 dealers we have close said that mopar was not providing them any longer for the '92s.

tech

Have you tried a new coolant temp sensor and maybe a air temp sensor ?

golfmiser

The coolant one is a year old and checks close on the ohm's specs. I have one that was in it before I rebuilt 3 years ago. I will try that and see what happens.
I will have to get another temp sensor. I could see a rich or lean condition with the temp but I didn't think it would effect the intermittent starts.

tech

I think you mite have 2 coolant temp sensors 1 for the computer and 1 for the gauge , the 1 for the computer is the one I'm talking about .

BlueRidgeMark

First of all, "crank" does not mean start, and it does not mean run. It just means that the starter makes the engine go around. You have not described any problem with cranking.

Secondly, what brand of CPS did you install? These things are notorious for not liking after market sensors, particularly the O2 and the CPS. Even quality brands like Bosch. You must use Mopar or NTK/NGK (who makes Mopar sensors) or you are very likely to have problems.

Thirdly, have you looked at your distributor? There is a Cam Position Sensor there that can go flaky, and gives very similar symptoms to a bad CPS. Er, it is a CPS. Yeah, there are two sensors called CPS. Confusing, I know.

golfmiser

Mr. BlueRidgeMark I appreciate you defining what "crank" means and I will try to remember that in the future. My apologies sir. Among us old school guys when we say it won't crank or start we are referring to it not running or starting. When the starter or the crank is not turning we just say "it's not turning over".

Anyway the CPS is a BWD brand. I went to get a Mopar but the dealership said they were unavailable for the '92 model. I will try to see if I can locate a Mopar or NGK brand.

I just replaced the complete distributor housing 6 months ago. I did go ahead and swap that distributor with the old one that originally came in the motor when I rebuilt the engine 3 years ago. Saw no definite changes.

I got home yesterday and went to start it and it started and ran fairly smooth at idle. Let it run for 2 minutes shut it off and it wouldn't start or even hit at all. I tried multiple times until the battery started getting low and it would not start again.

I have been troubleshooting this for 2 months. Due to it starting sometimes and then not starting it's hard to catch it. Just when you think you've narrowed it down. The thing starts.

BlueRidgeMark

Statistically speaking, the odds are I'm more old school than you. But either way, the term "crank" is more old school than both of us put together. Think about the actual meaning of the word. It simply means to crank the engine in order to get it to start. It's meant that since Model T days, when they used a crank (noun form) to crank (verb form) the engine over to start it. So your increasingly common misunderstanding of it is definitely not old school. Tell your buddies they are just wrong.

Yeah, that BWD is bad news. Lots of testimony to that on this forum.

Hmm. Probably not the cam sensor, then, but testing is still a good idea. Might find something useful on Youtube.

Intermittents are the worst!