A couple of weeks ago I was wheeling with a club and had two shutdowns on one trail. The first shutdown lasted about 15 minutes. It would turn over but not start. After 15 minutes it started and ran well, no check engine light (CEL). About 30 minutes later it shutdown again. After a 15 or 20 minute wait, which included a tow up the trail by another Cherokee , it started,ran fine, but this time the CEL was on. The codes that popped up are P0301, P0302, P0306 and P0300. I have read what the codes point to, and read a few threads on similar problems. I didn't read anywhere about someones Cherokee restarting after a 15 or 20 minute (cool down period?) wait and it runs great. Could someone point me to the fault? I was thinking that a coil could possibly be breaking down with the heat. My Cherokee Sport is a 2000, 4.0 liter with electronic ignition, 5 speed manual, 2 door and green. Thanks for any help offered.

 

missfire dtc's. Possible crank sensor. Better test 1st.

 

What is the relationship between the Crankshaft Position Sensor and a 15 to 20 minute down time before it would restart?

 

When the CPS gets hot or in your case possible dirt and water at the connection they start to shut down. When everything gets cool the CPS starts to work again. had the same problem 2 yrs back although I wasn't wheeling.

Changed the CPS with one from JEEP- OEM. Checked out the wires and coupling. When I took apart the electrical connection there was all sorts of ming in there--I've seen worse but I shot it out with contact cleaner and packed it electro grease and reconnected. No problems since on my 2000 with that particular issue.

Also I noticed when the CPS was in its "fail mode" I didn't hear the fuel pump energize when I turned the key and was like WTF. Soon as the new one went in I turned the key and the pump came right on so there is a connection from the CPS to cut off energy to the pump when its detected as not working.

 

x2. Also did the dielectric grease on mine.

Another reason why the fuel pump won't work is that's a fail safe, so to speak. If the injectors were firing but there's no spark you'd have fuel washing down the cylinders, which would cause ring issues and oil contamination in the long-term.

 

Thanks for all the information. I'll put a new CPS in as soon as the sun comes out. Have a great day.

 

One more question. Is there any difference between the $60 and $200 models beside cost?

 

did you also have the same code appear as he did none of the above codes are cps related there all missfire codes? hate to see parts being thrown at vechicles

 

p300 missfire infohttp://www.jeepforum.com/forum/f11/2...0-code-977750/

 

I had the p0300 along with some others --the thing that kept getting me is it basically stopped when hot and I didn't hear the fuel pump.

When the jeep finally got home I did some digging and after doing the full tune up except the CPS I still had the same problem. I bought the CPS from Jeep but think paid about $90.00 or so.

As soon as the new CPS went in the fuel pump energized and she started right up no misfires.

I don't agree at all with just throwing parts at something but if his is old enough it should be changed anywho just in case since its a fail part that causes big prblems. $ 200.00 sounds way out of line even for the dealer.

 

seeing you had the codes also id give it a shot then but 200 dollars there crazy

 

cps prices god i love my renix more every dayhttp://www.jeep4x4center.com/cranksh...okee-xj-mj.htm

 

this is a little betterhttp://www.autozone.com/autozone/par...mString=searchbe better of at napa or bennet type parts store though

 

Great information. I forgot to check other forums. Thanks for all the input. I've decided to change the CPS (Delco from the local Autozone) because my Jeep runs great day in and day out. When I had the problem she was working very hard on a level 6 trail and hot (not over heating though). Lets hope this is the problem, I won't know though until I work her just as hard as before. Thanks again.

 

Get the CPS from NAPA, or a dealer.

I believe I read where NAPA carries a higher quality sensor and it will last longer.