88_cherokee

The 88 Cherokee was hesitating around 3k rpm and the rpm would go to 0 pop back up and keep running. Sometimes it would stall and have to crank for 30 seconds or so and it would start. A while later it just completely died. Threw a new crank sensor and it started up. I revved the engine and it would rev past 3.5k rpm. It looked like it was bouncing off the rev limiter. I took it for a drive and it died out. So i got a new cps, coil, icu, distributor, and new fuel pressure. I noticed before when cranking, the rpm needle would slightly move while cranking, now it doesn't. I checked all the grounds, conndctions etc and all look good.

Jeepcrazy5722

Have you done Cruisers Tips yet? I posted the link for you, they are a must do before moving on.

https://www.cherokeeforum.com/f51/cruiser54s-mostly-renix-tips-153657/

cruiser54

Unless you have some kind of super-human powers, I don't see how you can tell if a ground is good by looking at it.

Time to take the plunge and do some preventative stuff and quit chucking parts at the problem. See above post^^.

88_cherokee

I know they are good because i went through them and verified them. Also cleaned the c101 connector as well

Jeepcrazy5722

Did you adjust your TPS according to the tips?

88_cherokee

Haven't adjusted the tps, but i think it won't cause a no spark issue

Jeepcrazy5722

You didn't say you had no spark, if you had no spark why would you look at your fuel pressure? Any ways you really need to do all of the Renix tips that Cruiser posted in his link, if you don't you are chasing your tail. I threw a bunch of money into mine since I didn't know about his tips and it ended up being a dirty ground at the dip stick. Then I fought a high idle for years until my wife found his tips about all the ground refreshing, have you added the extra grounds that Cruiser suggests? Have you checked your TPS, did you check the splice in the wiring harness when I moved mine it would effect my TPS, have you checked you CPS if you haven't done then items then you are just wasting your time and money.

cruiser54

Well stated and very true............

DFlintstone

88, they have your best interest in mind. Just one gets a little grumpy sometimes. Interesting detail of the tack no longer coming up cranking.

I believe it operates off a signal from the ECU that is dependent on the CPS signal. I know you changed it, but that doesn't guarantee it's working, and it's signal is making it to the ECU. Do you have access to a digital meter? Check this out>>> (and do Cruisers #5, ground check)(At least).

Anyone with an 87 to 90 Renix Jeep has two or three minutes to see that their
CPS is putting out at least .35 AC volts. I don't mean to come off rude, but if you can't connect a meter and turn the key, we may not be much help.
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 meter set on AC volts. (a 200 scale is lowest on mine).
Crank the engine and note the voltage. (jump it if your battery is low)

Mine somehow works with only .3 my wiring/grounds must be pretty spiffy. .5 seems to be a good mark. One article talked of .5 to .8. **Update, it soon failed. I installed Napa #css980 in my 90, that part will work back to 87. You can also check for 200 Ohm's resistance, +/-- 75, but the ACV is what the ECU is using.

cruiser54

I'm probably the grumpy one..

We are giving tried and true solutions and diagnostic procedures to help. If you choose to ignore these things, we get aggravated. Our experience trumps all your suppositions, suggestions from friends, Uncle Bob's contributions, and what the parts guy thinks. Not to mention the "this worked for me" responses.

DFlintstone

Evening Pete. What do you think on my thought about to loss of the Tack? (reading cranking) Maybe no CPS signal at the ECU?

cruiser54

That's where I'd start.

88_cherokee

I'm not being grumpy. I just said i have gone through the grounds, tried 3 crank sensor, measured them with a meter, checked the wiring, and have done just about everything i can thing of, and what you guys said. I have 2 88 Cherokee and have swapped parts over so i know they are good working parts. Apparently the problem lies within the wiring harness since i haven't been able to find the problem

cruiser54

How did you test the CPSs?

Post 27 of my Tips is something you should look at if you suspect wiring issues. Have you done #2?

Flintstone was referring to me being the grumpy one, I think.

88_cherokee

Problem ended up being a pinched wire in the harness.