lhpdiver

It is 2:30PM and the temperature is maybe 85 but the sun is HOT. The car has been parked all day in the hot sun. I just tried starting it and I had to turn the key maybe 5 or 6 times.

Bought the battery at Costco August of 2018. Last time I had a similar issue I pulled the battery and had Costco test it. They said the battery was fine. (I miss the old days when you could just pull into a Sears and they would test the battery in like 5 minutes. Costco insists you take the battery out of the car and they test it for 2-3 hours).

Anyway - the weather will probably be about the same for the next few months. I've read that one thing to try is using premium gas in warm weather. Unfortunately I don't have a shady spot to park the car.

Any other ideas ? Thanks.

BlueRidgeMark

Well, lets' figure out if you have a fuel problem or a spark problem, and go from there. It's probably not fuel, unless you are getting that dreaded injector heat soak problem. Do a search on it here and you'll find plenty of info.

Could be the CPS. They can get cranky when they get hot, and a no-start is the primary symptom.

If you can grab a can of freeze spray, you can use it to find the culprit. Next time it won't start when hot, spray the CPS down with a few bursts, and see if it starts. If it does, test your CPS,, and proceed accordingly.

BTW, Autozone will test a battery in their parking lot in 5 minutes, for free.

lhpdiver

Well the Jeep is behaving better today - but it is a little earlier in the day.
The spark plugs were replaced a week ago and the injectors were cleaned.

I think the last time I had this problem and mentioned it on this forum some suggested the CPS. I picked one up on the internet and never got around to doing anything with it... Actually it was sold as new but when it arrived the box was pretty beaten up.

As for 'freeze spray' - might the spray I use on my computer equipment fit the bill ? That stuff is pretty cold. Of course, I would have to watch a video or two to see where the CPS is on our Jeep...

I used to take the Jeep to autozone to read the check engine codes, until I picked up a computer. I'm not sure our store checks batteries, but I will ask.

BlueRidgeMark

The CPS is located at the back of the engine, driver's side. If you were looking at the engine from the front, it would be at about 1 or 2 o'clockish. It actually mounts on the bell housing. It reads a notch on the flywheel. See the video below for the location, test proceedure, and how to replace it. He uses my method, which works better than others I've tried or seen described.

(Bleepin Jeep is well respected in the Jeep community. His videos are excellent.)

It's a bit difficult to get to, but with a long 'straw; on your can of spray, you can get to it. I'm not sure the computer spray (canned air for dust?) will be cold enough. Freeze spray is easy to find, though.

If a good chilling makes the beast start again, the next step is to test the CPS. OR you could skip to that step.

That said, here's a caution: The 4.0 engine is VERY picky about sensors, especially the CPS. Stories abound on every Jeep forum about people installing aftermarket CPSs and having them bad out of the box, or in a few days, weeks, or months. If you buy one, buy Mopar/NTK/NGK only. (NTK/NGK makes them for Mopar.) Just save yourself some grief.