KJamesJR

So my Jeeps had a rough year and is now getting the attention its been desperately craving. For a while now I've been having some rough idling along with a misfire on cylinder 6. Rewind a few years when I purchased a dirt cheap CPS off ebay to fix my no start issues and my jeep hasnt been running right since. However it cranked over and was once again reliable so i left it until I had the finances to purchase a proper cps.

I partially suspected the cheap CPS to be part of the issue with my misfire and rough idle and purchased one via the stealership which came with an exceptionally short wire... wierd. I also decided to replace my cap/rotor/wires/plugs so I picked those up as well. Just for giggles I purchased a new fuel injector for that 6th cylinder too as all of them are most likely 17 years old or so.

Next issue was re-wiring my down stream o2 sensor wires. My cat fell off one day and pulled all the wires down and were rubbed through on the driveshaft. They've been previously rewired/spliced though in a half-*** fashion. I kept getting a periodical o2 sensor code which came and went so I took my time and did it right. I didn't actually belive its the sensor as its less than a year old, rather my wiring job.

I installed everything periodically and tested for start up between each once. New cap, rotor, plugs etc... started just fine. New CPS... started just fine. Rewired the o2 sensor wire pack, started just fine. I have not put in the fuel injector as I'm waiting to see if she'll even keep misfiring. The Jeep was running good. Idle was still a bit rough, but vastly improved as I dont feel it shaking in my seat. I drove it about 15 miles and threw it in park at the drive through when suddenly my RPMs jumped up to about 2000. After that point even when in drive stopped at a light my RPM would hang around 1200 when typically it was around 800 and rough. As i got home things seemed to normalize, but I'm not sure if it's over. Before someone says air control valve, it's also brand new... or just over a year old and wasn't the cheap ebay sort either. I haven't lost any power either.

Maybe I knocked a vacuum hose loose, but I wasnt even working around an area with vacuum lines at least not a lot of them. Perhaps the comp is still adjusting to the new parts? I'm going to take a shot at it again tomorrow and will update. Until then I'm open to suggestions. I will update if I find anything.

Radi

Hats off to you for that. Too many folk change everything at once, then when the engine won't start...have no idea what new part did it.
Have you done anything with the throttle pos. sensor? Might be at least worth checking it's sweep with a DMM.

KJamesJR

TPS is new. Was replaced along with the air control valve. I don't know what a DMM is but I can test it if necessary.

Anyways hold today on account of the rain. The RPMs seem to throttle now between 800 and 900 RPMs. It's not a regular occurrence. Just a little bit this morning. I'll take it over 2000 rpm.

KJamesJR

Now my RPMs are all over the place. Occasionally bogs down and will rev up higher after driving for a while. I've got a sneaking suspicion it's the cps I was given the short wire should have been a dead giveaway. Going to replace it tomorrow. Currently we've got about 12 inches of snow on the ground. So I will update when completed.

KJamesJR

Quick update.

The idle seems to have normalized but I was still having problems with the o2 sensors. Thought it was my wiring job again. Kept getting o2 sensor heater code. After some diligent searching I came across a thread here where a guy had the same issue with his down stream o2 sensor wires being chewed through. Same problems with the codes being thrown.

Turns out it's a fuse in the box under the hood. Blue 15 amp fuse located in the top row, second fuse in from the passenger side. Sure enough mine was blown. Had a spare so replaced it. Didn't clear the code yet but I'll give another update when I do and put some more miles on it.