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99 PCM replace/update

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Old 11-25-2019 | 08:30 AM
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Originally Posted by Dave51
I suppose what you're really asking is



and I do not know that. But since 1391 can be generated by


I think we're REAL close. With an otherwise normal and synced CPS signal that artifact (I believe it's coil) would seem to be the culprit. I think it's either the CPS, the distributor cap, rotor or somewhere along the harness to the ECU.
being pretty inexperienced with a scope myself, it would seem this artifact is sticking out like a soar thumb. Wouldnt this be something apparent to someone that performed my "diagnostic"? that dip between the 3rd/4th ckp spike had me curious from the beginning of being hooked up.

by "coil" you mean "pickup coil" yes?
Old 11-25-2019 | 10:18 AM
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Originally Posted by 4x4jeepmanthing

by "coil" you mean "pickup coil" yes?
This thing:


I believe the artifact is either from the coil or the signal to the coil.
Old 11-25-2019 | 10:51 AM
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Hmm, my ignition coil is only a few months old echlin brand, replaced while on the hunt in this thread( stock ohmed good but had a crack in the insulation), the new one didnt change anything.

Is this something the scope can check? Don't want to fry it lol


Last edited by 4x4jeepmanthing; 11-25-2019 at 10:55 AM.
Old 11-25-2019 | 10:58 AM
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Originally Posted by Dave51
This thing:
I believe the artifact is either from the coil or the signal to the coil.
Because it appears in every set of reluctor windows, it has to be either all 6 spark plug wires (TTBOMK, impossible), scatter from the high voltage side of the coil, or perhaps contamination from the wire that signals the coil to fire (I'm away from my stuff again for the holiday, but see if the CPS wire is in the same harness as the coil signal supply wire). Since the artifact looks to be only about 7-8 volts, it can't be a direct shot from the secondary coil (which would fry everything).

You can fiddle with this with the Hantek by using the attenuator probe on the secondary coil and it should match up with the artifact in the CPS (don't be standing in a puddle of water while playing with the secondary coil).
Old 11-25-2019 | 11:05 AM
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Originally Posted by 4x4jeepmanthing
Hmm, my ignition coil is only a few months old echlin brand...
I'm sure it's fine.

1. Check the distributor cap and rotor for any signs of arcing.
2. Folllow the CPS signal wire all the way back to the ECU to see if it has any contact with the coil supply wire.
3. Change out the CPS.
4. If the CEL remains on, cover with the aforementioned black tape.
Old 11-25-2019 | 11:16 AM
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Originally Posted by Dave51
Because it appears in every set of reluctor windows, it has to be either all 6 spark plug wires (TTBOMK, impossible), scatter from the high voltage side of the coil, or perhaps contamination from the wire that signals the coil to fire (I'm away from my stuff again for the holiday, but see if the CPS wire is in the same harness as the coil signal supply wire). Since the artifact looks to be only about 7-8 volts, it can't be a direct shot from the secondary coil (which would fry everything).

You can fiddle with this with the Hantek by using the attenuator probe on the secondary coil and it should match up with the artifact in the CPS (don't be standing in a puddle of water while playing with the secondary coil).
a bit ignorant here sorry, but this secondary coil, is this one of the wires of the ignition coil harness that i should monitor? and do so while monitoring the cam sensor also?

im trying to dig up wiring diagram for this coil
Old 11-25-2019 | 12:09 PM
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Originally Posted by 4x4jeepmanthing
a bit ignorant here sorry, but this secondary coil, is this one of the wires of the ignition coil harness that i should monitor? and do so while monitoring the cam sensor also?
Big fat wire from coil to distributor and the cam sensor.
Old 11-25-2019 | 12:13 PM
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Originally Posted by Dave51
I'm sure it's fine.

1. Check the distributor cap and rotor for any signs of arcing. will do!
2. Folllow the CPS signal wire all the way back to the ECU to see if it has any contact with the coil supply wire. out of two wiring harnesses I can confirm the current, which I fully gutted and reworked, has no wires touching.
3. Change out the CPS. headed to the JY to see if I can get lucky with a mopar cps, otherwise I can stop by napa on the way home.
4. If the CEL remains on, cover with the aforementioned black tape. did you one better, ive already pulled the light haha.
ive got a good brick of time off for the holiday, hopefully I can bury this thread in that time. thank you for all the help, ill post up later with replacement cps.
Old 11-25-2019 | 12:16 PM
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Originally Posted by Dave51
Big fat wire from coil to distributor and the cam sensor.
ah figures haha, im happy to check it though. does this require back probing or is this strong enough for the scope from the sheathing. I know its enough to zap you good lol.
Old 11-25-2019 | 12:18 PM
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Originally Posted by Dave51
Big fat wire from coil to distributor and the cam sensor.
Or, one of the small wires will be the one from the ECU telling the coil to fire.
Old 11-25-2019 | 02:00 PM
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I would obtain a complete used Distributor, and slide that in
Old 11-25-2019 | 04:08 PM
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Originally Posted by awg
I would obtain a complete used Distributor, and slide that in
everything distributor wise is new now. this happened with mopar distributor assembly and aftermarket.
Old 11-25-2019 | 04:18 PM
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1.

Pcm coil out

2.


Under acceleration
Old 11-25-2019 | 04:36 PM
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Isn't this fun?
Old 11-25-2019 | 04:52 PM
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There is that thing where the major spikes only occur when CPS is sending 5 volt signal. Is that diagnostic of a faulty CPS? IDK, but certainly something to ponder on...


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