Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
I need some help. 1999 Jeep WJ 4.0. To give a little history, The Car started dying may run down the road a few miles then die. It would start right back up but would die again and again. After searching the web most folks claimed it was the PCM or Crankshaft sensor. Well I started throwing parts at it with a PCM after a NEW PCM the car did the same thing. Next i order a Crankshaft sensor and was looking for the cable of the crankshaft sensor plug and I cut away some tape on the wire harness and cut 3 wires into, not the 3 to the crankshaft sensor., I repaired those wires and unplug the crankshaft sensor Now the car won't run. It turns over but acts like its out of time as it turns over slow and almost back-fires.It sounds just like the Jeep ScannerDanner was working on in one of his video's where he was using a test light to show RPMs on his scope. Then i found ScannerDanner's Video's and I got me a Mutl-meter, I know I should of done this first. Then after I probe the 3 wire plug to the crankshaft sensor and Found Ref 5 Volt. center Ground, and the outside pin show .003 Volts plugged in. When i un-plug the sensor the 3rd pin would go to 5 volts. So i order another sensor. Put it in and still get the same reading. It has a New Batt. Oh and a New Coil Pack and Spark plugs. Where should i look next?
I would check the harness that runs behind the valve cover for cut wires from the valve cover bolts. Also chk the asd relay make sure its good . chk all 3 connectors to pcm unplug clean dielectric grease and plug it back in, these are known to have bad or loose connections etc also move the harness around see if that fixes it first. And chk your iac valve known to get stuck leak etc.
Backfiring suggests ignition spark occurring with intake valve open so maybe it's a jumped timing belt. Can you do a clear flood mode crank and listen for odd sounding cylinders?
Do you have spark? Can you smell fuel? Is injection pulse present?
I'm repairing two wires that was patched in the harness then putting the harness back in place and doing all my checks again. Will post as soon as i'm done.
99 was a one year fit for many parts on those Grand Cherokee engines. I have personally been bit by this and have seen other very good techs go down the rabbit hole (so far as to pull the timing cover to check the chain) after changing the ignition coil. It must be for a 99 model year. The other ones will plug in, but the connector is upside down. It fires the plugs in the wrong order and you get the back fire, no start.
I'm not saying that's definitely what's going on with yours, but it's worth a look.
Its a Coil-over-pack. today my new Coil-over-pack came in and i installed it. It only backfired. Update on Crankshaft sensor. Key-on. I have my 5volts ref, I back probe the signal wire and hand cranked the crankshaft watching the Meter. I have my on and off 5 Volts. Now, Should or can i do some checks on Cam sensor?. I know i have my 5 volts This was a running car when i parked it The reason i stated working on it it started dying driving down the road. I broke the elect connect to the coil-over-pack Trying to get room on the wiring harness was why i changed it out. After putting all the parts on. It now only backfires. I hope i've given all the info i can. But if more is needed Please ask.
I'm starting to feel like Noah on the Coil over plug. Even tho I've replaced to 2 times and still does the same thing. I don't have the old one its in the trach. Does anyone have a diagram of the wiring to the Coil over plug. ?? If so can you send one to me at rocketmancars@yahoo.com thanks
Good News the Jeep started. I found on youtube a guy with the same problem, he had a new Coil over plug pack and it was wired backward. I tried two new coil packs and both where wrong. So watching this guys youtube he reversed the elect pins and it ran, I did the same thing. Man you know how long I've been trying to fix this thing and all the time it was the parts i was buying. It now does show #4 plug not firing i have a new plug going to hope that's all it is.
Rocketman wrote: Good News the Jeep started. I found on youtube a guy with the same problem, he had a new Coil over plug pack and it was wired backward. I tried two new coil packs and both where wrong. So watching this guys youtube he reversed the elect pins and it ran, I did the same thing. Man you know how long I've been trying to fix this thing and all the time it was the parts i was buying. It now does show #4 plug not firing i have a new plug going to hope that's all it is.
Those are the worst type of faults to fix - when brand new parts are causing the problem you starts doubting your skills.
Getting involved in discussions because I have a lot to learn still.
