matt0106

Or this. Someone could reply, "Yeah, those all look like good replacements. Especially...."

matt0106

This too. Someone could say, "Yeah, if your spark is not very good, your coil may very well be bad/gone/dead or whatever."

matt0106

But instead everyone is on this thread talking about "noggin poking" and pointless other stuff.
Excuse me if I can't get around to checking the tiny amount of suggestions the second I see the post. I do have a job, two dogs, just got engaged, just moved less than a month ago, not to mention anything else that may come up. Just because I'm not a Cherokee veteran, doesn't mean you should belittle me and say that I haven't done a damn thing.

DFlintstone

I'd think that if the CPS checks OK, you've cleaned the ICM-Coil contacts, and the spark is still wimpy, the the coil might be a thought.

I gotta mention, two different posters lately had theirs start, after giving the ICM a whack. (know yours runs).

AC voltage, CPS test; Small clips on the meter leads really helps. (you need contact with those little pins while it cranks)

Unplug the connector at the back of the manifold with wires going down to the bell-housing/cps. (it's a three wire plug, with only two wires)
Probe the two wires to the cps with the digital meter set on AC volts, a 200 scale on mine. Yours meter may have a lower, or “auto range”.
Crank the engine and note the voltage. (jump it if your battery is low). .35 (about 1/3 of a volt) is minimum. .4 to .8 is more like it. I saw one that would actually start and go about a block with just a .1

matt0106

Thanks for helping, I'll do that when I get the chance. Also, thanks for putting it into terms I can understand.


Oh, I forgot to mention, I did clean the contacts on the coil and ICM.

67 GMC

Most of us also have jobs, family, dogs, life etc. That's why you don't get a response to every slight update in 1 hour or less. No one is belittling you or saying you haven't done anything.


Is changing the distributor cap, rotor and wires a good idea-Yes it is. Will it solve your problem? Probably not but try and see. It can't hurt-those are all wear items and it's pretty cheap and easy to try.


Forums are one person broadcasting to a lot of people but if you don't get a response, don't belittle the forum-maybe it's the title or content of what you're posting. How many "Renix won't start" threads are there"? People post that before they have even done a single search and read through a few items. Also don't forget that a 1987 Renix Jeep is getting to be a pretty rare thing so not many people are still working with them. Most have moved on to OBD II vehicles where you get codes that help you figure out what's wrong. Most of this era Jeeps are in the scrap yard-not on the road.


I'll shut up now. I've learned a lot from this forum. I can say nothing but good things about it.


Let us know what you've done.

cruiser54

Well stated and very true.

DFlintstone

Your welcome. I think the 4th holiday is not only distracting, but brings up family and is the tipping point, where you confront what what you didn't yet done yet, this year. I think you did actually post that you had cleaned the coil/ICM contacts. The other two that posted a result by whacking it had as well.

I'm very suspicious when they whacked it they just got a contact they hadn't cleaned well to contact.

You can bet if I ever separate mine I will have a bunch of resistance numbers to post. Primary through, positive primary to secondary, negative primary to seconsary, and each of those three to ground. Why that is not common info here defeats me.

I'm still working on an ECU to ICM signal test that can be done with an LED from the dollar store. Btw, you have a signal, I'm curious what your CPS reads.

matt0106

I understand that. But when no one replys for days, that's when I get annoyed. I've learned a lot too, but this time, I need to figure out what it is, I have no car right now. The other times were just minor, this is major.

Bobolink

Okay, so you want an answer to the question "are these parts any good?" Well sure, if the parts that you're replacing are the cause of your problem, the parts are just fine.


I mentioned before that you had an exhaust leak at the manifold gasket (way back there on page two). Since the gasket is common to both the exhaust manifold and the intake manifold, there's a good chance that there is also a leak at the intake where the gasket mates the manifold to the head. Either or both of these problems, when let go long enough, will kill an oxygen sensor. Yet you've not said a thing about replacing your gasket, or a word about how long you've had the existing O2 sensor, or whether you checked or replaced that. So replace your intake/exhaust gasket (any brand is fine, if it's made for the 87- 90 4.0L) consider replacing the O2 sensor, especially if it's been there for a long time, or you don't know when it was replaced (again, if it's made for the 87-90 4.0L, you needn't ask if it's good).


I also mentioned that it did not sound to me like a misfiring. Now admittedly, I'm an old deaf guy, having fired a few too many rockets and miniguns from my chopper in Vietnam when I was a young stud, but I put on my earphones and cranked up the volume, and I still say, it doesn't sound to me like a misfire. It sounds like an old motor, loose as a goose, with a pretty good exhaust leak at the rear of the motor. It also sounds like you probably need to do Cruiser's distributor indexing. You'd be amazed how far off the distributor firing takes place compared to where it should. This too, will increase the spark at your plugs.


Now, check all these things out, and then let us know how it's going.

matt0106

Well, now it will start but not run for more than a minute. When I took the video it would start and stay running, after a few tries, if I might add.

BruceB

Hey,

Sorry your having problems...
I would check that the distributor shaft has no play. Remove the cap and rotor and see if you can move it side to side. If you can, go to your nearest junkyard and find another one.
How long after you changed the plugs did it not run correctly and did you try reinstalling your old plugs?
Have you visually checked the coil off vehicle for cracks?
Have you checked for any codes from the computer? (free at AutoZone and PepBoys)
There is a key turning method to check for codes by setting off the check engine lights to blink in sequences, you may try that. Probably search this forum for instructions and code descriptions.
Last idea, swap out the O2 sensor with one from the junkyard.

hope this helps

Bobolink

No codes on the Renix ('87-'90)

matt0106

Checked the plug wiring, all good there.
Also, I checked to see if mine had a fuel pump ballast resistor, it doesn't. Nor do I see wires where one might have been.


BUT, most importantly I checked the CPS and it's only .2 of a volt.

cruiser54

I assume you've read this.

Renix CPS Testing and Adjusting



Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark.

Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad.

The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark.

Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected.

You should get a reading of .5 AC volts.

If you are down in the .35 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from Napa or the dealer.

Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off.

A little trick for increasing the output of your CPS is to drill out the upper mounting hole to 3/8” from the stock 5/16”, or slot it so the CPS bracket rests on the bell housing when pushed down. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.




Revised 01-26-2013