cutout related to wiring error

[Guest Lenny]

My Trooper has been cutting out when I would let up on the throttle. Just quit then run ok again. It always ran fine when I was down on the throttle, it just happened when I was letting off. Though I had a wire shorting or continunity problem that showed up when a wire shifted forward a speck when letting up. I think I may have found the problem. so far haven't found any wire related issues but did find a wiring error. I replaced the Oxygen sensors on my Trooper and in doing so had to cut the plugs off the old sensors and put them on the new sensors. One wire is a little longer then the other because it reaches to the downstream sensor. Well, I put the longer wired plug on the upstream sensor and vise-versa. It ran fine when accelerating, because both sensors saw extra oxygen so it provided extra fuel for it. But, when I let up on it, the downstream sensor which was now reading from the upstream position would see a shortage of oxygen because there is a speck of time that the engine runs rich when letting up on the throttle. I suspect that normally the sensor that is downstream, after the catylitic comverter, looks for a different fuel oxygen ratio then the upstream one. It probably doesn't care if it's running lean because it only wants to see enough oxygen to burn off any remaining fuel componets for clean emmision. If it doesn't see any oxygen during that instant of letup, I suspect that the computer cuts the fuel until it sees some oxygen. The computer would react differently to the normally upstream sensor's signal. Haven't tested the fix yet, still have some wires I want to check as long as I'm almost thru all of them and apart. Will let you know. Had I not carefully checked every wire and where they were susposed to go from each computer plug pin I could have easily not found this issue and could have been fighting it for ever. Gosh, I hate it when I make mistakes which is more often then I like to admit.

Lenny

[jamesrulz]

My Trooper has been cutting out when I would let up on the throttle. Just quit then run ok again. It always ran fine when I was down on the throttle, it just happened when I was letting off. Though I had a wire shorting or continunity problem that showed up when a wire shifted forward a speck when letting up. I think I may have found the problem. so far haven't found any wire related issues but did find a wiring error. I replaced the Oxygen sensors on my Trooper and in doing so had to cut the plugs off the old sensors and put them on the new sensors. One wire is a little longer then the other because it reaches to the downstream sensor. Well, I put the longer wired plug on the upstream sensor and vise-versa. It ran fine when accelerating, because both sensors saw extra oxygen so it provided extra fuel for it. But, when I let up on it, the downstream sensor which was now reading from the upstream position would see a shortage of oxygen because there is a speck of time that the engine runs rich when letting up on the throttle. I suspect that normally the sensor that is downstream, after the catylitic comverter, looks for a different fuel oxygen ratio then the upstream one. It probably doesn't care if it's running lean because it only wants to see enough oxygen to burn off any remaining fuel componets for clean emmision. If it doesn't see any oxygen during that instant of letup, I suspect that the computer cuts the fuel until it sees some oxygen. The computer would react differently to the normally upstream sensor's signal. Haven't tested the fix yet, still have some wires I want to check as long as I'm almost thru all of them and apart. Will let you know. Had I not carefully checked every wire and where they were susposed to go from each computer plug pin I could have easily not found this issue and could have been fighting it for ever. Gosh, I hate it when I make mistakes which is more often then I like to admit.

Lenny

You are correct you can't have those two sensors switched the one after the cat is monitoring efficiency so it's looking for a consistent value not up down up down like your 02. What kind of o2 sensors did you use and part number?

[Guest Lenny]

You are correct you can't have those two sensors switched the one after the cat is monitoring efficiency so it's looking for a consistent value not up down up down like your 02. What kind of o2 sensors did you use and part number?

I used a Bosch #13007 from Checkers for $89 then bought the second one, same bosch from NAPA for $74. If you have to change them, you will probably have to put the old connector on the new one. That is what I did, The 2 white wires on the new connector are the 12v heater wires. Use a meter to find the two 12 volt DC wires commng from the computer. Check this at the plug for the O2 sensor, not the one on the sensor it self. You can have the sensor unplugged for this and you must have the ignition on. Once established, cut and splice the 12v leads to the two white wires on the new sensor. Then hook the Grey to the grey and the black to the white and youir done.

After changing around the oxygen sensors it did run stronger, pulled harder. However it is still cutting out so now I'm going to look at the fuel system. It is popping a bit when it cuts out so that makes me think it gets lean. I'll be tearing into that this afternoon. I'll post what I find. Hopefully I find something.

Lenny