I just bought a 1998 Grand Cherokee 4.0L
PO had occasional stalling at stop lights so he had somebody else start replacing things, including fuel pump, reman. pcm (computer), timing chain and distributor, but now it wont even start.

When I bought it it had an HEI distributor in it (wrong wiring connectors so it wasn't even attached) I replaced it with a new standard distributor, rotor and coil pack.

It was out of time so I did the TDC cylinder 1 and rotor facing 5 o clock. It would backfire and obviously out of time still. I turned the rotor one tooth at a time (went all the way around at least once).

It would do one of three things
1. Only start and run while holding WOT (Very rough)
2. Backfire no start
3. Start with no throttle and hold an idle, wont increase RPM (Very rough)

I looked at the timing marks when I could get it to run and it is way above (counter clockwise) the zero mark (approximately 12 degrees). This is the reason I think it may be a sensor making the computer trying to compensate.

I have not tested the fuel pressure (no tester) but there is plenty of fuel coming in I fouled a set of spark plugs working on it today and have replaced them. I also cleaned the Oxygen sensor.

So, basically is it my timing still? I've tried adjusting it all day with no luck are there any tips? Could it be my timing chain off a tooth? How hard is it to check? What sensors could cause this and how do I test them?

 

From researching I have found it could be any of the following:

Any kind of timing (distributor, wires, chain)
CKPS
CMPS
PCM
Upstream Oxygen Sensor
Exhaust header crack
Knock Sensor
Clogged Cat

I'll start testing them when I can but are there any other thoughts or tips? Im not 100% on how to test these since I'm getting mixed results while searching so any clarification would help

 

Double check the firing order.

 

Am I correct that the firing order for the GC is the same as the Cherokee?

I'm using a Cherokee Haynes manual and have triple checked the firing order but I am using the Cherokee firing order and distributor install procedure

 

I forgot to mention when I have it started it has black smoke coming from the exhaust

Another tidbit, I have the belt off of it right now (it was removed when I bought it as well as the power steering pump) I dont think this will effect anything?

 

Black smoke is unburned fuel, so you may have fouled plugs. As long as the battery is fully charged it should not make much difference that the serp belt is off, but a code may be set because the alternator is not charging.

 

Is there a way to check that the timing chain is on right?

I have never changed one or had it apart so I'm not sure. But the PO said it was changed so I want to make sure it is on right and not whats giving me problems

 

The best way would be to pull the timing cover off and see if the timing marks on the sprockets line up.

 

Well I adjusted the distributor some more, It feels a lot better and cranks a lot faster with no backfiring now. But now it isn't hardly firing. You can hear maybe one or two fires in 3-4 seconds.

The timing light on cylinder 1 will flash once every couple seconds, is this normal or is it not sparking every time?

Thanks for the help so far bustedback I appreciate it

 

It sounds like you just might have a crank sensor problem.