Renix no spark after blown radiator hose - Crowd Source Diagnosis

[88trailcrawler]

Yes, square connector with wire retainer.

Is that the knock sensor? I'll need to replace it.

Still don't think it's contributing to the no spark condition?

Test the CPS: http://cruiser54.com/?p=50
Clean ICM contacts: http://cruiser54.com/?p=41

That sensor that crumbled is not like the CTS, but the knock sensor. Does it have a plug like an injector?

 

[88trailcrawler]

Still dead.

New CPS from Napa. Drilled upper mounting hole to 3/8" and pushed down on install. Tested at .26~.28 VAC at crank. Higher than removed CPS but not the desired .5 VAC.

Still no spark at the coil.

 

[88trailcrawler]

Update:

Drilled out both CPS holes to 3/8". Now getting up to .4 VAC at crank. Pretty sure CPS is not the issue.

Tested coil + to - inputs got a pretty solid .6 ohms (read that .5 is minimum spec.?)

Coil - to HV tested only 2.8 ohms (read that 6.0 was minimum spec.?)

Possible shorted coil?

Still dead.

New CPS from Napa. Drilled upper mounting hole to 3/8" and pushed down on install. Tested at .26~.28 VAC at crank. Higher than removed CPS but not the desired .5 VAC.

Still no spark at the coil.

 

[Ecomike]

Some test data from this morning.

CPS: only getting .18v while cranking on the ACV setting.

Confirmed no spark coming out of the coil with an adjustable ignition testing tool. (Eliminated distributor/wires/plugs for now).

I guess that data indicates a CPS issue. Plus I am dreading trying to reach that damn CPS.

That is the lowest reading CPS value I have ever seen. Surprised it worked at all. I fought believing mine was a CPS for months, had .35 V cranking and it would start one day, get across town, then no start and had to tow it home, then no start for days while testing...Finally got a brand new, from rock auto Standard brand made in Italy CPS (OEM is probably the best option), and drilled it out and then pushed the CPS down from the top side as I tightened the 2 screws and got up over 0.50 volts. Once the engine is running the voltage is more like 5 volts output at say 2000 rpm. I must admit that months latter the ICM went bad on that same jeep.

 

[Bent]

My money is on the coil. Have you pulled it off and looked for cracks or signs of swelling? How does the socket for the primary wire look? Any burns or signs of arcing?

 

[Ecomike]

Still dead.

New CPS from Napa. Drilled upper mounting hole to 3/8" and pushed down on install. Tested at .26~.28 VAC at crank. Higher than removed CPS but not the desired .5 VAC.

Still no spark at the coil.

Make NAPA replace the CPS, that is crap voltage for a Renix CPS after the MOD, or just buy an OEM CPS. Chrysler AMC had real problems since day with the low CPS cranking output voltage and TSBs on it. Cruiser54 worked as service rep at a dealer back then, knows all about the problem.

I went with ones made in Italy by Standard Products about 6 years ago for mine and both have never missed a beat in 6 years. No assurance they are still made there or the same quality. The CPS and ICM/coil could both be the Issue.

Did you clean and tighten up the snap clips between the ICM and HV Coil?

 

[Ecomike]

Yes that is the knock sensor, not needed to start or run the renix jeep. Some claim the MPGs are better with a working on. I have an 87 rig that has not one for 12 years. Round to it project.

Yes, square connector with wire retainer.

Is that the knock sensor? I'll need to replace it.

Still don't think it's contributing to the no spark condition?

 

[Ecomike]

>0.4 volts may be enough to get it start 1 out of 10 attempts, depending on the rest of the wiring. I have never had a bad Renix HV coil, yet, and mine look like they are 30 years old. I have had one bad ICM. Curious which one Cruser thinks is more prone to failure. 8Mud may have the HV Coil and ICM test data, may be in an old thread or 2 where he and shared that data and test data here in this forum.

Update:

Drilled out both CPS holes to 3/8". Now getting up to .4 VAC at crank. Pretty sure CPS is not the issue.

Tested coil + to - inputs got a pretty solid .6 ohms (read that .5 is minimum spec.?)

Coil - to HV tested only 2.8 ohms (read that 6.0 was minimum spec.?)

Possible shorted coil?

 

[Ecomike]

My money is on the coil. Have you pulled it off and looked for cracks or signs of swelling? How does the socket for the primary wire look? Any burns or signs of arcing?

Interesting, why bet on the coil?

 

[88trailcrawler]

DONE!!!!!!

in one final Sunday evening Hail Mary I dropped in a new ICM, Ignition coil and MAP sensor. Boom spark confirmed and it fired right up.

Proud to say the side of the road radiator hose and coolant refill seems to have been successful too. (My kids did it with me on the phone 450 miles away).

Now what I think I learned:

Doesn't the CPS also trigger injectors too? If so, I could have eliminated the CPS by confirming the injectors were firing.

Pretty sure the no spark was due to coolant damage to the coil and/or ICM. The coil tested pretty low resistance from the negative terminal to the HV output, I think indicating a short in the coil. I had a hard time getting any consistent voltage reading out of the ICM (coil terminals) during cranking, possibly indicating coolant damage in the ICM. If I recall correctly, my tests at the ICM in coming connectors were OK.

And so now another strong running Renix (past 200k in this recent road trip) remains on the road.

Thanks to all who contributed to this thread!!!

 

[Ecomike]

Congrats may your Renix live long and prosper LOL.

"Doesn't the CPS also trigger injectors too? If so, I could have eliminated the CPS by confirming the injectors were firing."

Never really thought of it that way, but yes, using a noid light to see if the injector signal is there to fire the injectors sounds like a valid tool. Thanks!!!!

 

[8Mud]

Where the coil mounts on the ICM is a poor design, water, coolant, mud or whatever can collect there. The contacts from the coil to the ICM aren't protected.

Possible if you separate the coil from your old ICM and clean the contacts and the surrounding area (like Cruiser mentioned) it may work again. Nice to have a spare around.

Possible the coolant got into something critical and fried the electronics in the ICM or the windings in the coil. You might want to ohm test your new coil and compare it to the ohms form your old one.

 

[88trailcrawler]

the contact points were still covered with grease from when I did most of the Cruiser tips a few years back. Removed coil tested less resistance from - to HV. I didn't do a comparative test, but I couldn't get any consistent output reading from the removed ICM at the coil terminals.

My theory is that the upper hose failure saturated the coil and ICM with HOT coolant that likely seeped into one or both. Add to that the time to allow the coolant to dry out/gum up in the heat - internal short/corrosion seems likely.

In hindsight, it might be a good idea to rinse coolant off of critical/sensitive parts in the event of a coolant spray like they had.

Where the coil mounts on the ICM is a poor design, water, coolant, mud or whatever can collect there. The contacts from the coil to the ICM aren't protected.

Possible if you separate the coil from your old ICM and clean the contacts and the surrounding area (like Cruiser mentioned) it may work again. Nice to have a spare around.

Possible the coolant got into something critical and fried the electronics in the ICM or the windings in the coil. You might want to ohm test your new coil and compare it to the ohms form your old one.