2000 Jeep Cherokee stalls after warm-up

[Talyn]

I think he meant file the holes in the CPS it self

 

[Chris627]

I think he meant file the holes in the CPS it self

Oh!! OK that makes more sense. I was getting worried for a minute. Thanks

 

[winterbeater]

Oh!! OK that makes more sense. I was getting worried for a minute. Thanks

Yeah, exactly! Sorry if I wasn't clear. I meant to elongate the unthreaded holes in the Crank Position Sensor bracket that the bolts pass though before the bolts engage in the threaded holes. Well, it seems that you didn't file out your threaded holes, so no harm done. And (obviously) you realize that if you position the Crank Position Sensor too close to the flexplate (rotating), it could be destroyed. But too far away could be a weak or lost signal. And sideways would change your timing.

 

[Chris627]

So, if you pull the two bolts out and try pushing it down closer???????????? If it's not real close, you could file the holes open bigger.

I just tested the CPS and I took picture, but I don't know how to attach them. So, I'll discribe the results. I hooked up the blacl lead to the C-Terminal and the Red lead to the B-terminal. I guess it doesn't matter which color lead goes where. The reading I got was 33.40M Ohms!! I shouldn't be reading anything at all. If this has been my problem all along I am pi**ed!

 

[winterbeater]

Did you see somewhere that there should be no resistance? The only thing I could find in the FSM is that it should go from 5 volts to 0 once it passes the last slot. I figured that you would have to put your voltmeter into the ground side (probably the black, and crank the motor watching for the voltage swing. A test light would probably work better. And you would probably have to pull the coil or something so that it would just crank slow and not start.

 

[Chris627]

Did you see somewhere that there should be no resistance? The only thing I could find in the FSM is that it should go from 5 volts to 0 once it passes the last slot. I figured that you would have to put your voltmeter into the ground side (probably the black, and crank the motor watching for the voltage swing. A test light would probably work better. And you would probably have to pull the coil or something so that it would just crank slow and not start.

http://www.jeepforum.com/forum/showthread.php?p=6079423

This is where I got the test procedure for the CPS. Take a look and let me know what you think. Thanks

 

[Chris627]

Did you see somewhere that there should be no resistance? The only thing I could find in the FSM is that it should go from 5 volts to 0 once it passes the last slot. I figured that you would have to put your voltmeter into the ground side (probably the black, and crank the motor watching for the voltage swing. A test light would probably work better. And you would probably have to pull the coil or something so that it would just crank slow and not start.

Sorry, I meant CKP not CPS. It gets confusing sometimes which term to use!

 

[winterbeater]

OK, now you're teaching me. But a couple of observations. But I'm not an electronics expert.
1.) On that link, he says to set the ohmeter on the 1k-10k scale and that you should have infinite resistance. You are measuring 33.4M. Is that not 33400k? That may be relatively close to infinity. What do you get if you hold one ohmeter lead in one hand and the other one in the other hand? You will get a reading, but I don't think the conductivity is very high.
2.) You probably noticed the test for the 0 to 5 V fluctuating voltage that I suggested form the manual.

aperwork

 

[Chris627]

OK, now you're teaching me. But a couple of observations. But I'm not an electronics expert.
1.) On that link, he says to set the ohmeter on the 1k-10k scale and that you should have infinite resistance. You are measuring 33.4M. Is that not 33400k? That may be relatively close to infinity. What do you get if you hold one ohmeter lead in one hand and the other one in the other hand? You will get a reading, but I don't think the conductivity is very high.
2.) You probably noticed the test for the 0 to 5 V fluctuating voltage that I suggested form the manual.

aperwork

I should have never thrown out the factory installed CKP that went bad. I would have something to compare this one to. The old one had resistance, which, according to this test it shouldn't have any resistance i.e. open. The way I'm figuring if I'm getting any resistance it is a bad sensor. I'll try holding one lead in each hand and see what I get! I plan on doing the test 2 tommorrow and see what happens. Thanks

 

[winterbeater]

You are looking for HIGH resistance (close to infinity). Low resistance is the opposite which would be high conductivity. High ohms number = high resistance. What keeps it clear, though is when you say "open", which is very high resistance. Low resistance is what you have when you touch the two ohmeter leads together (ie.closed circuit). I think we mean the same thing though.

 

[Chris627]

You are looking for HIGH resistance (close to infinity). Low resistance is the opposite which would be high conductivity. High ohms number = high resistance. What keeps it clear, though is when you say "open", which is very high resistance. Low resistance is what you have when you touch the two ohmeter leads together (ie.closed circuit). I think we mean the same thing though.

Yes we are speaking the same language. My concern is that I did not expect to see anything but OF. Which, in meter speak for this meter, means OverFlow or infinity, i.e. HIGH resistance. My concern is that I was able to get an actual resistance value. Am I being to picky?

 

[winterbeater]

I think so (but I don't know). We either need someone with greater knowledge than ours, or at least able to check a known good. Sorry, I don't want to crawl under mine in the snow to test. Do they have these in stock at your auto parts place where you could test a couple of them?

 

[Chris627]

I think so (but I don't know). We either need someone with greater knowledge than ours, or at least able to check a known good. Sorry, I don't want to crawl under mine in the snow to test. Do they have these in stock at your auto parts place where you could test a couple of them?

Here is a kick in the butt! I cannot duplicate what I did yesterday!!!! Ain't that some Crap!! The meter is reading exactly the same no matter what range I use to check the resistance. It is now reading infinity, i.e. High Resistance. It is also too cold to play with it today. I cleaned the connection, dabbed on a little di-eletric grease and plugged everything back in. It is outside running right now. Something to note is that this Jeep, and I guess every other 2000 and later, will run with the cam sensor unplugged. How the hell does that make sense? It won't start without it, but as soon as it is up and running you can just pull the plug. It does set-off the CEL. Which is good. At least the computer recognizes something is amiss.

 

[winterbeater]

I come back to the diagnostic point I raised several times. We don't factually know whether you have spark or not when it doesn't run. I suggested popping the coil rail off, when it doesn't run, and putting a spark plug in, then holding the plug base up to the engine to see if you really don't have any spark when somebody cranks it.

I know that the assumption at this point is no spark, but, WHAT IF???????????

 

[Chris627]

I come back to the diagnostic point I raised several times. We don't factually know whether you have spark or not when it doesn't run. I suggested popping the coil rail off, when it doesn't run, and putting a spark plug in, then holding the plug base up to the engine to see if you really don't have any spark when somebody cranks it.

I know that the assumption at this point is no spark, but, WHAT IF???????????

I will do this test as well. Lets, just for a moment, assume I don't get spark when I test the rail; would this then point to the CKP? Is there a test for thermal failure of the CKP?

 

[winterbeater]

Put it on a stove burner and check the resistance???????????? And I do think you won't get spark, but just think you should test. You obviously know what the word assume breaks down to. ass/u/me!

 

[Chris627]

Put it on a stove burner and check the resistance???????????? And I do think you won't get spark, but just think you should test. You obviously know what the word assume breaks down to. ass/u/me!

Amen Brother, Amen!
I'll still do the rail test with a spark plug. It is important to make absolutely sure. CKP thermal failure, from all the posts I've read, is not as common as the CKP just giving out.

 

[Chris627]

I will do this test as well. Lets, just for a moment, assume I don't get spark when I test the rail; would this then point to the CKP? Is there a test for thermal failure of the CKP?

Well, I ran it until it stalled. Almost killed the battery trying to restart it, just to make sure it wouldn't start. As quickly as I could I removed the coil rail and plugged in a spark plug. Starting at the front of the engine and moving to the back I had my son crank the engine while I grounded the plug to the rocker cover. At no point did I not get a spark. I quickly reassembled everything and the damn thing fired up like nothing was wrong! It is now running in my driveway. I also to the time to check the voltage coming from the plug going to the CKP and the CPS, both measured 5volts. Shoot me now!

 

[winterbeater]

You always got spark, so it is a fuel issue. But I would do the spark thing again to see if it starts right back up again. I'd go back through the whole thread to find out, but did you ever verify fuel pressure when it dies?

Time for an exorcism with dynomite! This is just a mechnical device that will respont to logic. This is just a mechnical device that will respont to logic. This is just a mechnical device that will respont to logic. This is just a mechnical device that will respont to logic.

 

[joe_peters]

Borrow/rent a fuel gauge.

Hook it up when dead cold, then start and run engine till it fails while observing the gauge.

I will say you seem to have infinite patience, and I wish you the best of luck.