95 RRC 4.2 asking for help w/ diagnoseing an engine problem

[Ed*]

Hi

I have a 1995 LWB RRC, new problem started this week on a rainy day (dont know if that matters)

the engine started running really rough at a stoplight (almost stalling) and then when i tried to accelerate it had very very little power and made a couple of coughing / popping sounds. I pulled into a parking lot and it was at a really low rpm idle, almost stalling. Then the check engine light came on (45 - O2 sensor) and it ran smooth again.

I went to drive home and again really rough, low rpm idle and with no power on accelartion or even the slightest hill.

I know it could be many things, and not just the o2 sensor, but i dont have any idea how to diagnose the problem.

Any help would be great.

Thanks

[rovertek]

check your catylitic convertors, the inner meterial deteriorates and turns to powder and plugs the screens,the easiest way to check is to remove the front o2 sensors and see if it regains the power.....

[kevmcgowan]

Had the same problem with mine. Had a crack in the flange above the cat. Check the manifold for cracks. I replaced the Y pipe and O2 sensors and it ran fine for a while again. Had some other issues with the left bank fuel rail and poor spark. Do these symptoms sound familiar? If all else fails you can always use a can full of gas and a hand full of matches to fix it.

[Dan]

Unplug the O2 sensors as was mentioned before and if they are the broblem the engine should run fine but with a slightly richer mix!

[Ed*]

ok so thanks for the advice
not sure if i was supposed to pull the o2 sensors or just unplug them
but i unscrewed the left one from the exhaust pipe and unplugged it from the wire so it is completely out.

The top 1/2 of the sensor is white, the bottom 1/2 is black and a bit greasy. I have no idea how they are supposed to look. Please let me know, and thanks again everyone.

[Dan]

You can just unplug each one from there own female/male conectors so that when the computer senses them not there it will go into default mode. You moght want to put that one back in or it will get pretty noisy when you start it up. o2 sensors are very complicated pieces of engineering, your lucky you got a code! oh and they can just go when ever they feel like it too!

[Ed*]

ok here is a link (i hope) to a photo of the 02 seonsor
http://www.flickr.com/photos/edrice/2062886906/

[Ed*]

ok so i screwed the o2 sensors back in and left the unconnected
i cleared the codes and let the rover idel for about 5 min in the driveway
everything seemed fine, smooth idel ect.

so i drove to the store about 15 min away and then let it idle in the parking lot as a test. right away the rpms started to fluxuate up and down. it went really far down (almost to 0) for a split second and then bounced back up and the check engine light came on again (45 - o2 sensor)

I drove home and it would idle low at stop lights but no bouncing around of the rpms.

The sluggishness is gone and no poping sounds.

Not sure what to test next.

[Dan]

Ok sounds like the computer sensed the O2 sensors where not there, that was most likely when the check engine light came on. Every time you turn the truck on whithout the O2 sensors it will take a little bit until the computer recodnizes, that is most likly the reving up and down at idle. Now if it drives ok but it idles a bit rough I would get a few new 02 sensors and pop them in.
Pull the sparkplugs and see if the engine has been running rich, if it has it might be more evedence the O2 sensors are bad. At least with my experiance when the O2 sensor(s) go bad they have made my egines run to rich, sometimes almost enough so that the engine won't run!

[Ed*]

Dan, thanks for all of the help.

Can i tell by looking at the o2 sensor if it is rich or not? Also what do i look for on the plugs to tell if it was rich?