Ok guys, need some help,
87 Cherokee missing real bad and no power. I cannot even get it to move. I checked all the grounds, did the wiggle test on everything I could find and checked plugs wires everything I can think of,even swapped the iac for another one. Nothing! It was running great last week, and then the next day started missing a little. Today was missing a little then cleared up for a moment and then bam wouldn't even move. Wth?

 

gotta do the basics ,when was last tune up ,check fuel pressure

 

The cap and wires are fairly new but not brand new. Plugs could probably be replaced. Is this common for plugs to go that quickly?

 

Fuel pump brand new.

 

Check the temp sensors on the motor.

 

Explain how you "checked" the grounds.

 

Took them off and cleaned them. Going to get a fuel pressure gauge today.

 

Update: new plugs and wires and no change. Did a compression test. 1-4 were all between 85 and 90. Cylinders 5 & 6 between 100 and 120. Not good. So now my question is will this cause the motor to sound like it is missing and back fire a little through the intake? It still has no power when driving but it will idle. Just sounds rough. Should I just rebuild the motor and start from scratch?

 

Those are not good compression readings. How many times did you crank the engine over while testing each cylinder and did you hold the throttle open?

 

6 to 7 times and yes.

 

I am reading 200 ohms across the cps so I know that could probably stand to be replaced but that doesn't take away the cylinder issue.

 

Here's how to diagnose/test a CPS, but your compression readings are quite low and a bad CPS is generally a crank/no-start condition. Not a misfire.

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 it’s mounting holes with the first drill bit that just won’t fit through the original holes. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.
　
Revised 11-29-2011

 

Thank you. I have been trying to find this procedure in the forum. I will try it tomorrow.
Would the low compression cause the misfire? If not what do I check now. I'm not against doing a rebuild, already have the hoist and stand, but I just want to exhaust all the other options. What about a loose timing chain, or worn dist drive gear?

 

You could always pull the distributor and check the drive gear, I guess. Make sure you mark everything before removing it though.

 

Got plans to pull the front end off the motor and look at the timing chain to see if it jumped a tooth.