I have a 2000 4.0 aw4. about a year ago my cam synchronizer shaft grenaded and ate the cam sensor. I got it all back together but ever since the jeep hasnt ran well. it drives fine but does this weird thing when i stomp on the gas it feels like it is going to die, idles real rough, but then is fine. If i tap on the gas it will sputter and almost die, rpms drop to 200, and then be fine. If i tap on the gas when the rpms drop to 200 it will stall out. I have checked tps, cam and cps are new, cleaned iac, clean TB, checked for vacuum leaks, re indexed the cam sesnor, fuel pressure is 45. I really dont know where to go from here. I have a live data scanner but i really dont know what i am looking for. Ive learned to drive it like this but i really would like to fix this issue. any help would be great.

 

If you have a live scanner, watch the throttle position reading as you slowly press the pedal to the floor. (engine off). It's the TPS that detects you stepping on the gas and ups the fuel momentarily, like the old accelerator pumps used to do in carbs.

 

TPS checks might be easier with an analogue meter, on which you can easily detect 'dead' spots in the meter "sweep"...

 

Sounds like you may have a short in the cam sensor wires. Check and see if anythings melted on the harness side. Good luck~

 

Ill check it out. I was searching around and found the fsm for the 2000. it looks like when installing the new synchronizer you need to align the pulse ring and the outside part with a toothpick that fits in a hole. well the dorman part doesnt have that. also, it looks like it is a hit or miss with the dorman part fitting and i got lucky. is it possible though that i got a bad sychronizer shaft and its some how out of spec? the sensor is original mopar. ill also check the wires. I did some scanning and found my o2 sensor was giving very funky readings and that is only 2 years old and a ngk. my mechanic friend is postive my air/fuel mixture is off and firing/ignition is also off. Im leaning towards that cam sensor synchro because this started when my old one broke and i put the dorman one in.

 

Swapped out a known working tps and it had no effect. Still at a loss here.

 

So I did a fuel pressure test today. 45 at idle. When I press on the gas and it does the stutter thing it still holds at 45. When off and primed it holds above 40 for 5 minutes but after a 30 minute period it dropped to 0psi. has no problem starting I don't have to prime it.

 

Make sure the cam synch is "timed" correctly. That vane has direct input on cam position and injector firing time in relation to the crank. If its off it will effect a wide variety of engine operation. I find when doing them in the shop I set them up with a lab scope stacking cam and crank sensors under over to show the relationship of the sensors and timing. There are YouTube videos explaining this if it helps.

 

Okay so I'll redo the cam sensor and synchronizer and try to index it all correctly. I don't have a scope or anything unfortunately so I'm just gonna reindex it and hope for the best.

 

Wasn't that synchronizer pinned to the block? Because of the age and mileage components wear so it may be necessary to widen that gap slightly to give you some adjustment room. You can try turning slowly to find best spot like turning a distributor way back when.

 

It's bolted down with a little retainer but if lossened I can twist it around. Would I do that if the motor running or off?

 

Take a look at this video on You Tube. Very good explanation. Of course you are doing it in the vehicle and looking for the mark on the front of the crank. But finding yourself on compression is still done the same way; feeling pressure at the plug hole or watching rocker arms. Note the indexing and positioning of everything.


good luck....Ron

 

so i did that exact thing, got it at tdc on compression and lined everything up. still have the issue. i turned the sensor a bunch of ways and it only made it worse. this is driving me crazy

 

If the sensor is now lined up properly and you have checked the other things we talked about ( previous post) how about driving it and looking at fuel trims? When the problem happens where does the fuel trims go? Lean? Where is long term fuel trim now? But to be accurate you need to set the cam sensor, clear codes if any and then drive it to develop history. Of course it would be nice to verify cam/crank sensor relationship since this started right after the sensor failure.

 

I dont know how or what i did but i finally fixed it. I probably indexed it 4 times today after nothing worked and then all of sudden it started working no problem. no more hesitation or anything