Jump to content

Heatsoaked CPS?


Recommended Posts

It's incredibly hot here right now, but I didn't have much choice to do the bulk of my moving today. Got up, picked up the help, grabbed an enclosed 5'x8' U-haul trailer, and went out to the house. Had no problems on the way there, or the way to the self storage place (~35 miles one way with a 45 minute break in the middle to load the trailer.

 

We got to the storage place, unloaded, and the truck wouldn't start. Just cranked and cranked, acting like it wasn't getting spark. Let it sit an extra 10 minutes, unplugged the CPS and plugged it back in, and it fired up. We to the new place about 1/2 mile away, unloaded the rest, and left to get the second load. The truck died in the middle of one of the busiest roads in Springfield right at the start of rush hour. Pushed it into a parking lot, let it sit about 15 minutes, unplugged the CPS and plugged it back in, and coaxed it back to starting. Instead of making the second trip, I dropped off the trailer and the help, and went home.

 

According to my temp gauge, the truck never overheated. However, my fingers got a little scortched when I popped the hood.

 

Heatsoaked CPS? Bad CPS? Overheating when the gauge said it was fine?

 

Edit: forgot to mention this is the XJ, 99 4.0HO/AW-4

 

Rockauto's showing CPSs ranging from $38 to $166. Should I even bother with the cheaper one?

Link to comment
Share on other sites

When you mentioned this happened on your 99, I remembered there are a couple of TSBs floating around dealing with injector heat soak on 1999 and above intake manifolds causing hard starting and rough idle when hot. The "cure" is an intake manifold heat shield or a wrap around the affected injector, usually #3. I don't remember the TSP number, but the heat shield is available for $3 from your friendly Jeep dealer. The part number is CBXCB060. I put one on when I installed my 2001 intake manifold.

 

Link to comment
Share on other sites

Would soaking one injector cause it to shut off fuel and spark completely? It wasn't even coughing or sputtering when I would try to start it... just spin, like they do when you unplug the CPS. I know a 4.0 will idle on 2 cylinders, I imagine the stupid thing would at least try to start on 5.

 

I'm sure there's a Jeep dealership somewhere in this city, I'll grab one of those. I'll also go out and check the CPS with my ohmmeter for the hell of it.

Link to comment
Share on other sites

Picked up a new CPS today, and actually had the sucker changed out in 10 minutes on a hot motor. I guess that's another plus to the 99+ intakes.

 

It started, idled, and revved just fine. Now I just gotta wait a few days of driving around to make sure all is well and good again, then get another trailer on Tuesday and finish moving.

Link to comment
Share on other sites

My '88 started acting like this, and now that I've read this thread I realize that it started cutting out only after a new CPS was installed. How many of you have encountered such behavior with a new CPS? I've never thought about the possibility of it being bad from the box. This was an official Jeep part that I put in, too.

 

Same symptoms. It started when the weather got hot. It'll run for 10, 15 or maybe 20 minutes, then just ... die. It won't restart when it dies, but if I sit there for a half hour or 45 minutes, it starts right up and I can drive it home.

Link to comment
Share on other sites

This is my first new CPS, so I can't say. I bet if I tested my old CPS, it would ohm out just fine. When it did work, it drove fine. Then it would just either not start or die. I'm going to keep my old one in the truck as a last-resort spare, now that I know I can change it out fairly easily on the side of the road if I were to need to.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...