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Very strange thing happened...

J

jmeti000

NAXJA Forum User
Location
san antonio,tx
So driving home from work tonight on the highway the jeeps engine suddenly cut out for a couple seconds. No warning, guages fine, full tank of gas and no funky smells. It drove home the rest of the way just fine...like nothing ever happened. Its an 87 with a 97 block and renix electronics and this is the first time its ever happened...any ideas?

Thanks
 
The cps was replaced about a year ago, and the TPS about 2 years ago. As far as I know the MAP sensor is still the original one. Seeing as how its the cheepest and the oldest on the jeep think I will try that one first. REALLY wishin I had OBD II right about now lol.
 
I had a similar 'WTF' moment in my renix about ~3-4 years ago... its an unerving feeling not knowing whats up... mine crank crank crank'd for rougly 2-3 minutes, then started up when i pushed the gas pedal during startup. Then dissapeared.

JUST FOR REFERANCE, this evolved into ECU problems that masqueraded as an occasional cps-related no start. It was later diagnosed as a bad ecu, replaced it and it was good to go. I am not saying this is your problem, just putting it out there in case you develope a no start.
 
Good to know, thanks xcm. I didnt hafta crank anything though, and it starts up just fine right now...course its a manual so being that it was in gear and rolling at 65mph when it cut out on me, it might have just force started it...I dunno. Guess I might as well pull out the voltmeter and check the TPS while im tinkerin with it tomorrow though...and just when you think its running good too lol.
 
jmeti000 said:
The cps was replaced about a year ago, and the TPS about 2 years ago. As far as I know the MAP sensor is still the original one. Seeing as how its the cheepest and the oldest on the jeep think I will try that one first. REALLY wishin I had OBD II right about now lol.
Click to expand...

Where did the CPS come from?

I just picked up a new CPS from the dealer because the new CPS I put in a year ago is starting to fail and gives me intermittent problems.
 
There have been a lot of problems reported from CPS sensors that did not come from the dealer. I would definately test it.

If you unplug the CPS from the harness and test for AC voltages between the 2 wires on the cps while cranking you should get 5 volts.
 
Monster Mopar said:
There have been a lot of problems reported from CPS sensors that did not come from the dealer. I would definately test it.

If you unplug the CPS from the harness and test for AC voltages between the 2 wires on the cps while cranking you should get 5 volts.
Click to expand...

.5 volts AC-- not 5 volts:gee:

thank Cruiser54 for the following copy-n-paste:

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.
 
Update...tested the TPS and its fine, and replaced the MAP sensor today. Low and behold on the way home from the river it did the same thing...cut out for 2 seconds and came back on like nothin ever happened. Again, still had all my lights, gauges, and radio blaring. This is going to drive me crazy till I figure it out lol.
 
never seen a map sensor do that anyways. if it's a clean shutoff, no sputtering, it's likely ignition related, which means probably cps or something
 
x2 on CKPS.. sounds like one thats on its way out..

I have done a couple dozen from XJ's to ZJ's and TJ's Its the only thing i insist be bought directly from the dealership.. They are not fun to replace.. Doing it twice in one year due to inferior parts failure is annoying..
 
I was getting similar problems, started of real intermittent then more regular, replaced both cps. Was still happening till one day just stopped on the side of the road, ended up tipping a can of coke all over the coil, fired right up. Thermal fail on the coil. Which took a while to get bad enough to diagnose. Good luck with it.


---
I am here: http://tapatalk.com/map.php?eytchp
 
Well, After reading everything everyone wrote, I decided to change the coil...and while I was at it since they are connected I figured I might as well do the Ignition module too lol. Anyways, its been two days and it hasnt stalled out on me (knock on wood). Just wanted to say thanks to you all for pointing me in the right direction :)
 
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