'04 WJ stalling in reverse

[heyhar]

I just replaced the TPS and O2 sensors in a friend's '04 Grand. It was running crappy, and once warmed up, would stumble and try to stall when placed in reverse. It now runs forward and shifts through the gears just fine, but when you try to back up, it immediately runs rough and stumbles into a stall if you don't two-foot it. The original TPS was toast, and the new one seemed to make it happy, and it reversed out of my garage just fine. But once it came up to temp, started the stumbling act again. I'm tempted to try another TPS, but before I go back under the hood, is there anywhere else to look? Thanks in advance, Ray.

 

[shelbyluvv]

What engine?

 

[heyhar]

Oh, sorry...Our favorite-the 4.0. About 125k miles.

 

[shelbyluvv]

I personally do not like the 4.0, lol! Thus the reason I went with a 5.2 V8 in my MJ. Is the check engine light on? Any stored codes?

My WJ stalls in reverse every now and then. Mine has a 4.7 and the convertor lock up solenoid is going out of the range sensor in the trans. Check your grounds first. They have been know to cause a lot of weird issues on the later model Jeeps.

 

[heyhar]

Touche on the engine choice...Oddly enough, this HEEP has had grounding issues, to the point of toasting the computer and finally not starting. I'll have to look in that direction.

I'm still leaning towards the TPS, as it has exhibited some of the bad behavior that my '96 XJ showed when the TPS was acting up, and it only took FIVE, one new and four used, until it was happy!

 

[larsen]

Runs fine in forward gears and you're thinking TPS? The gear position (neutral safety) switch might be a better place to start.

 

[heyhar]

I am furiously grinding through the web trying to find out which tranny an '04 GC Laredo 4.0 might have...45RFE, 545RFE, 45RE...all I'm finding is conflicting info. All this to find out if it has an NSS similar to the AW4, where the selector switch does more than just interrupt the starting circuit and turn on the reverse lights. and it's wealth on knowledge tends to spoil the inner tech in all of us! Probably the closest thing is NAGCA.com, and it's nowhere near this level of expertise!

 

[shelbyluvv]

The 4.0L WJ has a 42RE transmission. Only the V8s got the 5/45RFE tranny. The 45 and the 545 are the same trans. Just one has a different flash to turn 5th gear on.

The NSS is a good place to start for troubleshooting on the 42RE.

 

[heyhar]

Thanks...That's what I've been waiting to hear. I'm getting more play on than from ZJ/WJ sights.

 

[Tuffnuttz]

Try this:


stalling, mostly when shifting to reverse. no codes. found main wiring harness rubbed through on left rear of valve cover stud. orange wire from map sensor rubbed through. repaired and re-routed wires, problem solved. thanks

 

[heyhar]

I certainly will look...Thanks!

 

[heyhar]

Try this:


stalling, mostly when shifting to reverse. no codes. found main wiring harness rubbed through on left rear of valve cover stud. orange wire from map sensor rubbed through. repaired and re-routed wires, problem solved. thanks

You hit the nail on the head...My friend, out of desperation, took it to a dealer, and they had it fixed in no time! Charged an hour's labor, and all was good. Thanks.

 

[OverlandZJ]

Making a mental note of this symptom and cause..

Glad you got it.

 

[Tuffnuttz]

Glad he got it fixed.

 

[jeeptech1]

glad its fixed. quick thing though. a 45 is not the same as a 545rfe. not even close

 

[heyhar]

Another problem was the turn signal relay under the dash. Right signal was OK, left worked only sometimes. It was a black icecube relay under the dash. I'd previously heard about it, but I don't understand what it does. My friend researched it, got one off ebay, swapped it, and all was well. My question is, What does it do? I don't think there's anything like it in an XJ. Between these silly problems, and the dual-zone blend doors in the dash going bad, I'll not be lusting after a WJ anytime soon!

Oh, and did I mention the power windows only working sometimes?