Iamrowab

Ok, so I swapped motors in my 2003 jeep grand cherokee and have replaced everything in the whole motor, exhaust, o2 sensors... you name it. The truck runs great but I replaced the iac and it keeps throwing the code. And to top it off the truck can't spin tires in sand, and when I go full throttle from a dead stop its slower than a prius. Any help on this would be awesome... this truck has been a nightmare.

CPLSeraphim

I m having the same problem with my 02. Did an engine swap and a lot of other stuff, now has no problem. Just wanted to post to keep track. If I find anything out with mine, I will let you know. Good luck.

Iamrowab

I've eliminated the o2 problems, the junction fuse box under the hood has an o2 fuse which fixed the o2 codes. But now I have an iac code but the iac is new from the dealer last month... and also this truck still has no power off the line. Its like it's being restricted just in first gear.

CPLSeraphim

Mine was finally running enough to drive on the road, then we replaced fuel pump and tank. Wouldn't run, camshaft sensor, injectors, coil paçk, iacv again. No power. Can you drive yours? Just curious as to how bad yours is. I am stopping at. The shop mine is at to see how bad it is. If you can drive yours, does the power kick back in when it shifts up?

Iamrowab

Mine runs and drives fine, it just won't stop throwing codes for everything I've replaced. The o2 sensor codes are being throw again now. But if your in first gear and you give it full throttle it doesn't do anything. It will slowly creep to 2000 rpm then take off. Very strange. But every other gear over 20 mph if you punch it, it'll drop a gear and take off.

dave1123

Just for ***** and giggles, have your VSS tested. It's inside the transmission on the WJ, but it might be able to be tested electrically without opening up the trans. It may be not functioning in first gear, for whatever reason.

I had to turn in my fan to clear the smoke after thinking up that one! The PCM may not be getting a signal to increase the fuel flow.

Iamrowab

I'll try anything at this point! What do you mean you had to turn in yo he fan to clear the smoke? And I think I read there is a shift solenoid could that do it too?

dave1123

No, I was talking about the brain overheat fogging up my room! LOL!

A faulty shift solenoid will just cause a delayed shift or none at all, but it shouldn't limit the rpms or power output. The PCM monitors the throttle position, the manifold pressure, and the vehicle's speed to determine the injector's fuel control and trans shift points. It may also have something wrong with the MAP sensor or the hose leading to it.

What are we talking about, the 4.0 or the 4.7?

Iamrowab

I have a 4.0

dave1123

Okay, I've owned 2 of them, a '97 and my current '00. I'm not really sure of the layout of the 4.7.

Iamrowab

Ya me either I have the 4.0. I've had two jeep cherokees with 4.0s but every time I go in something is slightly different than older models...

CPLSeraphim

Turns out my problem is fuel pump only putting off 16 psi when running. If that solves everything, I will look into this issue more.