Hello everyone,

I got myself a really nice 1998 Grand Cherokee Laredo I've wanted to fix and clean up and everything's been going well so far except for this issue I can't solve for the life of me.

When coming to a stop, like at a stop sign, or when the engine's RPM lowers to near idle (sub. 1000), the engine starts to rumble then a few seconds later, unless I give it some gas, will stall out - struggling to startup again.

I've replaced MAP, TPS, and IAC sensors. Starts up with no troubles, drives flawlessly, and puts out no codes other than the ABS light on dashboard. No misfires. Engine was replaced with the same 4.0L somewhere around 100k miles ago, not sure exactly.

Haven't checked fuel pressure yet, will get back soon with that.

Any help would be much appreciated.

 

Just throwing out an idea ... checked for Vacuum Leaks yet?

 

Yup, this was probably the first thing I tried. It did have one initially running to the HVAC controller, which is also what conveniently fixed the AC from blowing out of the defrost vents, and now sits at around 15 PSI (which to my understanding is normal at idle).

 

I forgot to mention there is some sort of electrical problem causing various issues. The door locks will trigger when accelerating from a stop in first gear and lately the interior lights have been staying on - even with the car off and doors closed. The electric windows won't work sometimes and then work other times.

 

That stuff is because of BCM issues/connections.

 

Is that diagnosed by using a multi meter on each fuse, or do you mean potentially replacing the whole panel? Do you think this could be causing an engine issue like that?

 

No, it's not about fuses or multimeters. It's not a panel to be replaced, it's a module, called a "body control module" and yes it could cause goofy issues as it does many things. They can go bad or maybe they only need cleaned connectors. You should always make sure your battery is fresh and strong first.

 

Oh my mistake, I mistook that for the fuse box near the fender. Where is the BCM, anyway? I do have a brand new battery as well.

 

 

Ah okay, good to know. Any way to diagnose this other than just replacing it?

 

The simplest approach is to run diagnostics using a scan tool. Short of getting a scan tool you can reseat (disconnect/reconnect) each of those two big connectors to wipe the pins of oxides/contaminants. If you can, clean them with electronics cleaner spray and let them dry before reconnecting. If the troubles recur after that then you need to replace it.

 

Well running the scan tool is amongst the first things I tried, as I mentioned in the initial post, and it runs no codes. Might have to do a visual inspection.