O2 Sensor Replaced still issues
 

Hello All,

I was wondering if someone could give me a hand troubleshooting an issue I am experiencing. A couple of months ago I bought a 95 Grand Cherokee (ZJ). It has a few issue here and there but nothing too crazy. I noticed when I was driving it home the fuel smelt unburnt and it was kinda running a little off. When i checked the codes on the dash (OBD1) I cam u with 12, 23, 21. 12 means battery was uncooked or died within the last 50 key cycles. the other 2 were for the o2 sensor and intake air temp sensor. My immediate response was to change out the o2 sensor and intake air temp sensor. Parts are cheap enough that it wouldn't hurt (engines got 90k miles on it, body has 263k).

The issue I am having is after I changed them out the jeep does seem to running a whole hell of a lot better but I still had the codes pop up but after I had experienced an acceleration issue.


That was during WOT that I had experienced that issue. I also noticed on the rest of the drive home even at maybe 50% it would start but wouldn't be as pronounced.

I am wondering what could be causing this new issue after the intake air sensor and o2 sensor were replaced. No new codes other then the original ones and no codes coming from the trans.

Any help would be appreciated.

Thanks

Bump

bump

interested in knowing what was causing this

I would suspect the TPS.

Thanks. I'll go ahead and replace it and see if it makes a difference. I also still receive codes 23 and 21 when it happens even after replacing the o2 and intake temp sensor.

I'll get back with my results.

I went ahead and replaced the TPS. Throttle response seems to be a little better but the issue still arrises. I also ran some sea foam through the system for good measure. inside of the intake was pitch black.

i wonder if it could be a trans issue. I'm not getting any trans codes and it doesn't seem to be slipping per say.

Stop firing the parts cannon. A TPS can be tested for free.

Which 02 sensor did you replace?

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Haha. I replaced the upstream o2. Doesn't seam to be a downstream. No o2 and I followed the wiring harness back. No plug for a downstream. And I look at replacing a few parts here and there as preventative maintenance lol.

Okay, just checking. I chased a problem like yours for over a year, pulling my hair out. I had had my son replace the 02 sensor, so I knew it wasn't that.

Turns out he had replaced the downstream sensor, which has nothing to do with how the engine runs. It was that upstream sensor the whole time.

Vacuum leaks can also cause your symptoms.

Thanks for the info. My dad was saying the same thing. I'll have to do an ether test one of these days after work.

A 95 ZJ won't have a down stream O2 sensor, it's OBDI.

An unlit propane torch can pinpoint a vacuum leak by concentrating the gas to a fine point. A vacuum leak will suck the propane in and cause a rise in idle speed.

thanks for the info! i'll get back with my results