The map sensor is critical to delivering the proper fuel/air ratio. It could result in a no-start, but would not be involved with an overheat and it is not suspect for dying while driving.

Don't get ahead of yourself. Check for spark. No spark? Crankshaft position sensor is absolutely your primary suspect.

Be sure vacuum line leading to the map sensor is good.

Then see where you are at.

 

Just make sure that map line is flawless. It goes to the rubber plug on the inside of the TB. You can hook it to manifold vacuum anywhere, but I kept mine as designed. If the brittle little tube breaks off in the plug, you might use a small screw or even an extractor if you happen to have one. Of course if you hook it up somewhere else, you need to make sure there is not a vacuum leak there at the rubber plug.

Supper crucial, that one. The map. "hogs out" the fuel mixture for the computer. The other sensors then try to improve on it from there.

It's 90 or earlier? check the cps. Only takes a couple of minutes with a $5 meter.

 

Howdy Tom! Guess we doubled up there. Gonna use the last of the light to try to loose the squeak from my f-ng kregan belt. Twice didn't work, maybe the the third time....

 

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He he. I'm with you Rusty. (with exceptions) 02? I got that thing tight enough to fry every bearing. Idler, Alt, water pump bla bla. still chirps!

Clearly Kregan/ORielies, sells belts with a team of trained gerbils built in. Next week I will need an alternator, or a water pump.


I eddied/deleted a comment because the 2011 date threw me.

 

Ok finally got back out to the jeep on saturday...There was no spark. Where is the best place to buy the cps online? How hard is it to install?

 

moparpartsonline

factorymoparparts

tapco

Buy a MOPAR sensor unless you like doing things twice.

SEARCH this forum and the web; there are lots of threads on how to install the crank sensor. Here is one of them to get you started...

http://www.go.jeep-xj.info/HowtoCPSchange.htm

 

You might want to first test yours before buying and installing a new one. A $5 DVM that measures AC volts from HF is suitable for that, and handy for other stuff. IN my sig there is a thing Cruiser did on that. Really the test only takes a minute, although, yea, CPS IS the most likely suspect.

 

thanks!

Can these jeeps be towed? I may just try to get it into town 10 miles away to have a local mechanic take a peek..wasnt sure if i needed a trailer or if a tow strap would work with 4x4...seems like when my grandpa had his motorhome he had to have the front axle of his jeep altered to tow?

 

I certainly don't disagree with testing DFlintstone; thanks for that reminder as there certainly are other possibilities for lack of spark (coil, ignition control module, etc).

It is easy to test the RENIX crank sensors; testing on the H.O can be inconclusive. Here's how to test your crank sensor.
--------------------------------------------------------
Renix (87-90) Crankshaft Position Sensor 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 crank sensor directly from the Jeep dealer for best reliability and longevity.

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.

 

http://www.ebay.com/itm/Crankshaft-P...385#vi-content 36.50 sound about right for a mopar part?

 

Good price it it is OEM Mopar part. I'd confirm, but Tapco sells mostly OEM parts.

But use the above TESTING procedure before ordering. Don't get ahead of yourself.

 

Ok will do. I need to pickup a voltmeter as I dont have one currently...looks like on ebay they are pretty cheap so assuming autozone would have one for 10 bucks or so. Thanks again everyone for the help

 

Walmart has cheap meters and so should any parts store. You can get them for $10 or so, but don't be afraid to spend $25 or so as the quality is much better.

A meter is required test equipment for ANYONE working on their XJ! It is very possibly the best money you will spend. I have too many of them to count!

 

Transfer case in N. Trans in P if it's an auto. Be sure it rolls freely a few feet before just taking off.