I checked all the stupid stuff.

[bort]

I recently got a 97 4.0 4x4 5spd that I am very excited to dig into. But since it is my DD for work and college I live by the rule "maintenance before modification". That said ive got an electrical problem that I cannot track.

Engine misfires at low rpm, and sucks above 4500 (propably 300000 on factory cats), the 4x4 lights come on but it does not engage. According to my computer I have: misfire cyl 1, misfire cyl 6, lean bank 1, lean bank 2, upstream dpfe off, and an ABS light (dont care). When viewing live data; vechicle speed is always 0 (dash gauge is accurate), all three o2 sensors read 0.000 volts and all fuel trims read -100.0. I still have accurate readings of iat, tps, maf, and rpm.

So far I have checked fuel filter, air filter, and cleaned every plug (with the stuff At&t uses) between the computer and transfer case. I cannot find any bad grounds or open wires, bad plugs or dead ends. And I have checked all the stupid stuff. I came across some post discussing fuel pressure regulator playing havoc on O2 sensors but a flat 0.000 constant makes me think electrical.

I am open to any and all input and ideas. Thanks in advance.

[RoidedRanger]

check any harness that may have been touched while working ont he tranny. this may be related or might not but i played hell tracing this down ,luckily a member on another forum had the same problem that turned out to be mine too...

my 94 4.0 5spd ran like shat when i got it, i was down to throwing ALOT of parts at it trying to fix it to no avail. long story short, it ended up being the dam o2 sensor pigtails being switch around (left plugged into the right, right plugged into the left) from when the guy before me put a new clutch in it.

just an idea of something simple to look for.

[rkyroadrcr]

I know this may sound dumb. I was having the same running issues with my '01 after letting someone else tune my truck (bad idea). After chasing egr codes and such and replacing parts that did not need replacing, I put Motorcraft plugs in. Never thought to check, since I told them to use them to begin with and they didn't. What it boils down to is for some reason anytime I have seen other plugs in these Rangers they don't seem to run as well.

[bort]

update... well not much of one. Between work and school im trying to tackle one problem a night with this truck. Ive got some of the small stupid stuff fixed but not the big issue.

I plugged it into a high end snapon scanner and got no information that my actron didnt give me. I have replaced the plugs and triple checked the O2 sensors. It is not possible to cross the sensors in this particular truck the harness' will not reach, and the O2 for the passenger side bank is actually on a seperate harness. The VSS still registers 0 mph at any speed on the computer but the dash is still accurate. All O2 sensors still read 0.000V in any situation and all fuel trims still read -100.0 in any situation. I was however able to get the 4x4 to engage briefly but then it faulted and gave me the blinking light 6 times. Then after looking at the conection to the computer again it gave me the blinking light 4 times and would not go into 4x4 again.

Most of the functions on that wiring harness running down the driver side frame rail seem to work so I'm beginning to rule out the harness and connectors not to mention that the right bank O2 is a seperate harness. Could it be that my computer has had a lobectomy? I checked the numbers and it is the correct computer for the truck.

Thanks for your input guys, every opinion is helpful. Please keep the ideas coming.

[66POJ]

Originally Posted by bort

update... well not much of one. Between work and school im trying to tackle one problem a night with this truck. Ive got some of the small stupid stuff fixed but not the big issue.

I plugged it into a high end snapon scanner and got no information that my actron didnt give me. I have replaced the plugs and triple checked the O2 sensors. It is not possible to cross the sensors in this particular truck the harness' will not reach, and the O2 for the passenger side bank is actually on a seperate harness. The VSS still registers 0 mph at any speed on the computer but the dash is still accurate. All O2 sensors still read 0.000V in any situation and all fuel trims still read -100.0 in any situation. I was however able to get the 4x4 to engage briefly but then it faulted and gave me the blinking light 6 times. Then after looking at the conection to the computer again it gave me the blinking light 4 times and would not go into 4x4 again.

Most of the functions on that wiring harness running down the driver side frame rail seem to work so I'm beginning to rule out the harness and connectors not to mention that the right bank O2 is a seperate harness. Could it be that my computer has had a lobectomy? I checked the numbers and it is the correct computer for the truck.

Thanks for your input guys, every opinion is helpful. Please keep the ideas coming.

Pull the ECM and pop the cover off. Look for burnt areas and solder splatter around the capacitors.

[bort]

new 4.0, new o2 sensors, new ecm, still have flatlined o2 sensor readings and -100.0 fuel trims.

the 4x4 is a mute point since i scored a BW1354 manual.

please help, anybody got any ideas outside the box? im so frustrated with this.