OK, car starts fine and drives great but after driving it for a while and shutting it down, it will stumble and almost stall upon starting it up again. I read that the injectors can get hot and cause gas evaporation so I went ahead and wrapped the injectors and fuel rail in reflective thermal shielding.

It seems to have helped a little but I am still getting the stumble/stall after the car is started up minutes later. As you guys can see I replaced a LOT of stuff on this car and just want it to run right.

Car has new parts as follows:

Cooling System: Water pump, Stat, radiator
Fuel: Ford 5.0 injectors, Fuel pump
Electrical: Starter, Alternator, battery, Cables, Extra Grounds
Ignition: Rotor, Cap, plugs, Wires
Exhaust: New Stainless Header, o2 sensor, exhaust system, cat
Air: K&N cone filter

The vacuum lines look good, some of the rubber connections look a little dry rotted but other then that good. The TPS is stock and so is the IAC, I pulled the IAC and cleaned it up and it def helped the idle of the car, but my problem is when it gets hot.

 

Any ideas??

 

My guess would be your crankshaft position sensor could be going out. But then again, there are people here that are FAR more experienced with Renix motors than I ever will be. I'm sure they'll chime in momentarily

 

I bought a new crank sensor a few weeks ago but have not installed it yet. Any other ideas?

 

Well get that thing in there then! I bet that's what it will be.

 

I've replace the cps in a 1990 chreokee laredo and it wasn't too bad, just be careful with the little dust cover when you remove/replace the sensor. You can actually reach it with your fingers to get the screws out/started but you'll need about 18 inches of ratchet extensions to make the job easier
.

 

Test your CPS when hot with the following instructions.



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