quadracer

Desperate, Need help.


194k mile 1999 WJ, 4.0, 42re, 242;

I just swapped in a 94k mile 1999 42re from the junkyard. I drained completely, changed fluid and filter using Mopar ATF +4. The engine ran great before the swap and I had just done a fuel filter, NGK plugs, K&N filter, and a throttle body and IAC valve cleaning a couple months ago. After the swap it drove fine for about 10 miles with some minor slippage and shift issues that I just chalked up to it working itself back in. But then I started having engine trouble. The engine:

-Wrecks of unburnt fuel
-Idles low and rough, shakes, misses, sputters and nearly dies but doesn't
-While driving it has low power and also misses
-Same condition hot or cold
-It will only rev to about 2500 rpms before having a condition that acts almost like a rev limiter.
-The transmission is a little shifty, lol, but I can’t really focus on that yet due to the engine problems which may be causing it. I do have all my gears so I don’t think I’m in limp mode. The main transmission problem is that it doesn’t want to disengage soon enough when coming to a stop. Kinda like forgetting to push in the clutch for a second and almost stalling a manual vehicle.
-I have code 171 (“I’m running too lean so I’m grossly overcompensating with fuel”).
-I had code 131 before reseting it, but I think that was just thrown due to the above condition
-I have checked all fuses, OK
-I have installed my CPS with the mopar 0.035” spacer
-I have checked voltage to the CPS connector. I get 5.19 volts from either of the side pins to the center.
-I have checked the resistance of the CPS. It is 1 everywhere except from pins 2 to 3. There my multimeter flashes 16000 ohms (16.xx in the 20k setting) for a split second before going to 1. I’m gonna probably break down and replace it, just to eliminate it. But all the info I can find indicates the Jeep won’t run at all and will also throw a code for a CPS problem.

Questions:

-Is there any possibility that two different 1999 42re’s may not be plug and play in the same 1999 WJ?
-Do I need an ECM or TCM reflash or something?
-Could a bad torque converter make it act like this?

quadracer

I have a borrowed scan tool that I just ran on it. With it idling like crap about 90 seconds after starting dead cold, its about 60 degrees out, these are my numbers:

S.T Fuel trim B1 32.8%
L.T. Fuel trim B1 32.0%
Intake M.A.P. 48Kpa
Engine Speed 833rpm
Ignition Timing 10 degrees
Intake Air Temp 17 C
Throttle Position 18%
O2S B1, S1 0.040V
O2S B1, S1 STF 32.8%
O2S B1, S2 0.080V
O2S B1, S2 STF 99.2% <---------- Possibly the problem?

Can anybody make sense of this?

ol"blue

Welcome to CF.
Is there a chance you pinched an O2 sensor wire when installing the trans?

quadracer

Oh yeah, always a chance. I was super careful with all the wires but you never can rule that out. The o2 sensors sure are throwing out some crazy numbers tho, Im gonna check the voltage to them today and also ground resistance. I'm also gonna re re install the air box and check for leaks, I removed it to access the manifold to downpipe bolts

quadracer

Some weird things going on... but I’m getting somewhere:

I removed the airbox and throttle body to check for anything out of order:
-Checked IAC, clean and OK, I have 5.19 volts at the connector
-Checked voltage @ MAP connector, 5.19v
-Checked voltage @ TPS, 5.19v
-Checked resistance of TPS, in 25k mode 1 @ closed 4 @ open, OK
-Checked voltage at B1 S1 o2 sensor connector, 4.25 volts, OK
-Checked ground resistance @ B1 S1 o2 connector, 0
-Reset all codes and reassembled everything

1st start: runs rough still, gauges, warning lights, interior lights going crazy like never before, scan tool won’t connect
2nd start: Starts for 2 seconds and dies, gauges still going wild, scan tool won’t connect
3rd start: same thing
4th start: Same as 1st

I disconnected the scan tool, because It seemed like every time I hit the connect button, the gauges went crazy or did something different.

5th start: Starts and runs great, plug in scan tool and it connects, It drives great and I drive about 3 miles (no further one way then I wanted to walk home, lol) until warm, pull in the garage and it idles great. Now my o2 numbers look like this:

Engine speed 713
MAP 36Kpa
ST fuel trim B1 -2.4%
O2S B1, S1 0.420, moving around from 0.2 to 0.8
O2S B1, S1 STF -2.4%
O2S B1, S2 0.040V
O2S B1, S2 STF 99.2%

So now I have a reasonable o2 reading so I decide to drive it some more. It runs great and shifts great for about 10 minutes like several times before. Then on my scan tool I lose voltage on my #1 o2 sensor signal, back to the 0.040v ( a mega lean signal) and therefor a super rich 32% fuel trim and it runs like crap. I crawled under and unhooked the #1 o2 sensor and the idle returned to normal. I was able to replicate the whole experience a little while later.

So I’m waiting on a new o2 sensor and hoping that will fix it, and the electrical gremlins will go away. I ordered an OEM NTK 23122 for $40 from rock auto.

FYI, Im using an iobd2 wireless tool by xtools, it broadcasts wirelessly to any idevice. It works great, you can watch every sensor on the vehicle at the same time live while you drive, although I don't recommend it, very hard to drive.

quadracer

Replacing the front o2 sensor took care of it, runs and shifts good now.

ol"blue

That's good to hear. Thanks for posting your results.

quadracer

Still running and shifting well, the wife has been driving it to work for about 2 weeks now. The check engine light is on saying now the rear sensor is failed which is no surprise since the scan numbers above indicate that, but it doesn't effect usability. The replacement transmission seems to have gotten worked back into service and is noticeably less worn than the one removed.

I'm not sure what I did to the o2 sensors? Both came out with medium thump of my fist on a 21mm wrench, no beating or impacts, and I was careful with the wires. Then I left them lying on my work bench for a month. A buddy of mine says you gotta wrap them up.??? Anyway, I'm gonna replace the rear one soon.