Renix CPS ? No spark

Ecomike said:

Got my 1987 AW4 dropped today, and got a look at the OEM renix CPS mounted in the spare AW4 I am about to use, and the AW4 I just pulled on the 87 (the 87 was the one that always starts, but only has .27 V AC signal strength).

Turns out the stock distance from the flex plate has a huge clearance in the neighborhood of 1/8" on my 87!!!!!!!!!!!!!!!!! Lots of room to move the CPS closer!

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what's that measurement based off of? Did you attach the flexplate to the torque converter? There's a decent amount of space between the torque converter and the CPS. Also - if you weren't holding the tranny vertical when you did this measurement there's a decent chance some of that free space was from the torque converter sagging down a bit. Not all of it, but some of it.

kastein said:

what's that measurement based off of? Did you attach the flexplate to the torque converter? There's a decent amount of space between the torque converter and the CPS. Also - if you weren't holding the tranny vertical when you did this measurement there's a decent chance some of that free space was from the torque converter sagging down a bit. Not all of it, but some of it.

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Torque converter has nothing to do with it that I know of. The metal tip of the CPS is closest to the holes in non-teeth part of the flex plate. It is the wide hole spacing that the CPS sees, not the teeth or the TC.

The 1/8" was eyeballed between the flex plate part with the timing holes, and the CPS tip.

Opps, miss read your question, yes, the flex plate was attached to the TC!!!!! Sorry. It was in its normal mounted position, so I will recheck that for sure and repost!! Thanks for the heads up. I was told before that there was no play in there, but that was when mounted to the crank shaft!!! So I see your point.

I got to do some testing on the TC slop, movement versus the CPS location, and you were right, if I lift up on the TC the flex plate will hit the CPS tip when the AW4 & TC are not attached to the engine and it's crank shaft, and the AW4 is horizontal. In fact if I really forced it, it would rub, but that was at an extreme that would not be reached with the crankshaft holding the flex plate in place.

I did the CPS mod, increased the right mounting bolt hole diameter, and installed it on the 87 Jeep while I was swaping AW4s this weekend, and after drilling the hole about 1/16" dia larger in the new CPS, I still had about 15 to 20 thousandths of an air gap minimum, if not more with the AW4 standing up vertically.

Now, back to the old battle. The CPS gremlins returned and were sighted for the first time in nearly 2 weeks today!

The 89 jeep, new CPS had nearly infinite resistance and no voltage output, when I tested it after six 10 second cranks and non starts. It worked fine on daily test starts the last 2 weeks or so, and I tested the connection after the no starts today (soldered in CPS) and got 9,300 ohms (apx), which means I was reading the ECU, but not the CPS, as the ECU was reading 9300 ohms, and the CPS was reading 275 ohms (apx) before the soldered connections a month ago, and the combo (parallel cicuit) was reading about 280 ohms the last month.

I connected the DMM on volts AC across the same CPS-ECU contacts and cranked again.

1st crank, 0.01 volts
2nd crank .05 volts
3rd crank .18 volts
4th crank .30 volts
5th crank .7 volts and started in 1 second of crank time.
Restarted 4 times in a row with no problem
Turned it off, and ohmed the ECU-CPS solder joint and got 270 ohms!

I am wondering now if there is not a solid state cold joint (intermittent conductivity, electrical connection) inside this new CPS that has dogged me all along?????

Where are you buying the CPSs?

cruiser54 said:

Where are you buying the CPSs?

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The one on my 87 that has worked since 2005 was from Autozone (which last tested at .27 V). The new one on the 89 was from Autozone as well. I have 3 news ones from Rockauto, Standard brand. One just went on the 87 during the AW4 swap this weekend. Another will go on the 89 today, weather permitting.

What I am puzzling over is where inside the internals of the CPS could it have intermittent conductivity, and why? I may dissect this one when I get the chance. I am not sure exactly what the guts are. If it is just a coil, magnet and wire connections, then a poor wire connection is all it could be, but once it turns on it works perfectly. It acts like a sometimes bad solid state switch IMHO.

I swapped out the CPS today. I bought 3 new ones, Standard products brand, from Rock auto 3 weeks ago. The one I installed on the 87 Sunday (while swapping the AW4) was made in Italy, stamped. The second one had Standard products name and logo on it, and I installed it today on the 89 with the sometimes no start CPS gremlin. The one I had fought with last 10 weeks had no source markings, just 2 little circles, and was from Autozone.

I drilled the left hole out one size larger, and got it closer to the FP. It ohmed out at 209 ohms. I got a peak AC cranking voltage of .29-.30 volts and it started 5 times in a row at about 3 to 4 seconds of cranking. The first crank was no start in 3 seconds, but fired up in 1 second of second cranking.

The peak voltage at higher rpms seems lower with the newest cps, but then again the one I replaced I had up to .77 V while cranking after beating on it repeatedly.

I am planning to pull it, and drill the other hole larger next. I noticed in all this multi CPS work that my 87 had all thread bolts (loose fit to CPS holes), while the spare AW4 and the 89 had shoulder bolts that are a very tight fit in the AW4 hole and the CPS holes!

My new CPS is installed with the weather pack for now, not soldered... yet.

I started to dissect the AZ CPS I pulled off the 89 today. It uses a huge (wire length) copper coil of angle hair fine wire, wrapped around 3/8 long steel (iron? or SS?) core tip. Separate but butted up to the metal core is a magnet behind the non magnet metal core. The tip inside the wire coil is a separate piece of metal, not the magnet itself. Assembled the tip acts like a magnet.

I will try to get the back side apart tomorrow, to see how the wire is connected to the coil ends.

Pulled the new (new) CPS, drilled out the right side hole (had already drilled out the left side hole), reinstalled, now have close to .50 volts, about .47 avg, .50 peak, .45 minimum, versus .33 V yesterday, reading it while attached to the ECU on the AC volts of my DMM.

It started before and after moving the CPS closer. Taking about 3 seconds to start today after the mod.

joe_peters said:

Well, if you are getting power to "A" on the 3-wire ICM connector then the B Latch relay is working.

Any chance you have a used ICM/coil you could swap in for a quick test?

Just guessing, but the primary side of the coil should have resistance of something like .90-1.5 ohms depending on ambient temps, and the secondary side something like 11,000-13,500 ohms.

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How did you measure the secondary resistance? I have a non start, and am suspecting the coil (or ICM), and I have .90 ohms across the isolate primary, and 4,800 ohms from the secondary post (spark post) to either of the primary connections. Is that good or bad?

87 Jeep, Renix.

Ecomike said:

How did you measure the secondary resistance? I have a non start, and am suspecting the coil (or ICM), and I have .90 ohms across the isolate primary, and 4,800 ohms from the secondary post (spark post) to either of the primary connections. Is that good or bad?

87 Jeep, Renix.

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I found this on post 22 from my prior work about 2 years ago:

I checked from the input side to the HV output and got 4000 ohms. I expected a short, or infinite? So I check the working coil off the 87 Jeep (2-3 year old coil) and it reads 7000 ohms?

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One mystery solved, one unsolved. I swapped out the ICM/HV ignition coil assembly between the 87 and 89. Then I got what sounded like a jumped timing chain, or serious mechanical issue inside the engine, but then it would crank fine for 3,4, 5, 6 seconds, then thunk (like it wanted to fire, but had no power) nearly stop rotating then cycle again.

Seems I did not have the rotor back in locked down in place, it was riding too high up, keeping the cap from bottoming and it was turned off about 30 degrees as well. It felt locked in place, but it was nightime with a flash light....and I was in a hurry.....and so on....

But now with both are running, I am still not sure why it died twice this week in the first place and refused to restart the second time it died, before I removed the rotor and cap and reinstalled the rotor wrong.

Thought I would an update here. Cyl #1 and #2 had fouled plugs that added to the problem, and closed loop O2 system was swinging the idle up and down to miss fires I guess. I started other threads on the oil fouling plug problem.

Ecomike said:

One mystery solved, one unsolved. I swapped out the ICM/HV ignition coil assembly between the 87 and 89. Then I got what sounded like a jumped timing chain, or serious mechanical issue inside the engine, but then it would crank fine for 3,4, 5, 6 seconds, then thunk (like it wanted to fire, but had no power) nearly stop rotating then cycle again.

Seems I did not have the rotor back in locked down in place, it was riding too high up, keeping the cap from bottoming and it was turned off about 30 degrees as well. It felt locked in place, but it was nightime with a flash light....and I was in a hurry.....and so on....

But now with both are running, I am still not sure why it died twice this week in the first place and refused to restart the second time it died, before I removed the rotor and cap and reinstalled the rotor wrong.

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