1999 WJ pops thru Throttle body won't start - Page 2 - Jeep Garage - Jeep Forum

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  #13  
Old 01-20-2016, 11:51 AM
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Re: 1999 WJ pops thru Throttle body won't start

What do you mean with " its definitely better but it still doing the same thing"? Does it run now?
Regarding the flywheel, on the 5-45RFE i can remove a cover on the lower side bell housing and see the flywheel, donīt know how this is on the 42RE.
Also it is firing, but does it fire at the right time? Did you check the oil pump drive shaft assembly, where the cam sensor sits on top? Already heard about wear on there, causing the ignition timing to be (too)far of and causing backfire.

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  #14  
Old 01-20-2016, 02:33 PM
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Re: 1999 WJ pops thru Throttle body won't start

Quote:
Originally Posted by Frango100 View Post
What do you mean with " its definitely better but it still doing the same thing"? Does it run now?
Regarding the flywheel, on the 5-45RFE i can remove a cover on the lower side bell housing and see the flywheel, donīt know how this is on the 42RE.
Also it is firing, but does it fire at the right time? Did you check the oil pump drive shaft assembly, where the cam sensor sits on top? Already heard about wear on there, causing the ignition timing to be (too)far of and causing backfire.
with respect to doing the same thing, its definitely not stopping forward motion of the starter motor as much but still igniting fumes in the intake manifold and sometimes it sounds like its gonna start but wont. I have had the cam timing out and the gear is in very good condition. I paid the mechanic to set the cam timing again.

Here is an interesting find:

I went back to look at the film i took of the coil pack with plugs installed and grounded during cranking. I found instances where 4 plugs were firing at once. I need to wait till I get home to really watch this in slow motion but I was able to stop the film several times were 652&1 plugs were all firing at one time. Also on another occasion 543&2 were firing at the same time. Now I know the coil pack works in pairs but quads is a different animal here. This is a very plausible cause of my symptoms but now I have to figure out why it's happening. I plan to go back and look to see if they are triggering at the same time or if one of them is random and the other is correctly following the firing order.
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Old 01-20-2016, 05:00 PM
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Re: 1999 WJ pops thru Throttle body won't start

4 Plugs firing at the same time is indeed strange. The PCM supplies or breaks the ground for the 3 coils, so if two coils fire at the same time (4 plugs), then it almost looks as a PCM problem. This happened with the new PCM? Or both? If with both, then there must be something wrong with one of the speed sensor. The pulse ring from the cam sensor was checked?
Just red that there is a torque converter cover, which gives access to remove the torque converter bolts. Probably you can check the flywheel via this access hole.
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  #16  
Old 01-20-2016, 06:50 PM
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Re: 1999 WJ pops thru Throttle body won't start

ok I think I'm on to something. A while back I videotaped the coil pack with 6 plugs grounded with bailing wire. I was happy all six plugs lit up. I went back today to see if I could do it in slow motion and check the firing order to see if it was random or in the right order because something is lighting the gas in the intake. I mentioned the four plugs at once above but I was watching the cadence of cylinder 6 playing the video clip in a loop for a while. When I looked for the cadence on cylinder 5, 5 is blasting all over the pace. It is hitting the cadence but also firing quite randomly as is cylinder 2 as you would expect. 6/1 and 3/4 are firing off at the correct cadence.

I was able to upload the movie, its short, run it in a loop and check it out if your curious. Focus on cylinder 6 at first at the top of the screen. You can see the spark the best there, it trains your eye for what to look for. This one was a real bear to find.

First thought is a grounded wire since the PCM shoots ground signals to the coil pack. Any thoughts you have on this one are welcome.
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Old 01-20-2016, 06:53 PM
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Re: 1999 WJ pops thru Throttle body won't start

BTW, the new PCM seems to work just fine, although it did not fix the problem, it hasn't injected any problems so far. I want to see the motor run longer than 3 seconds before my final decision.
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  #18  
Old 01-30-2016, 06:39 PM
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Re: 1999 WJ pops thru Throttle body won't start

THE FIX: defect in new coil pack. Replaced coilpack and it runs well. How to diagnose: turn the coil pack upside down with it plugged in. put spark plugs in an use bailing wire to ground all the spark plugs, wrap it around the threads and ground it somewhere. Then use your cell phone to take a film of the plugs while you crank it. see if the firing order is good and that non of the plugs are misfiring multiple times more than the others. Bad coilpack! I accidently stopped the film when 4 plugs were firing. Hmmmm...

One guy took a bath selling this car and I dumped $500 chasing a bad coilpack. Oh well, I'm in about $1200 for a nice WJ with ~110k. Finally got a ride in it today around the block twice trans seems solid, no noise from gearcase so fingers crossed.

I'm used to low slung good handling cars, touring in a Jeep is like being in a motorhome. Gonna take some getting used to.

Best,

M
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