stumbling now and then?? - JeepForum.com
 
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post #1 of 14 Old 11-26-2006, 10:04 PM Thread Starter
shierkahn
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stumbling now and then??

OK, I've metered out all my sensors and I found the O2 sensor is bad. I've got a new one but haven't been able to get the dead one out yet.

Question is....... 1- will this cause it to stumble when I go to accelerate?
2- will this also cause it to not want to sometimes not run right
when I start it after it's already been warmed up?

Or should I be looking else where as well?

Thanks for any help/flaming ya'll give, Chris

PS- how long should it take for the new O2 to make a difference?


'92 XJ, 4" Shade-tree lift
33/12.50's, 15x8 Soft 8's/4"BS
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post #2 of 14 Old 11-26-2006, 11:29 PM
olds442
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it can be tricky, it def makes the engine run different, could be running too rich, making it act like that, i would go ahead and change them out

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post #3 of 14 Old 11-26-2006, 11:31 PM
RickyN29
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There are actually a few current discussions on this very topic over at NAXJA. If the O2 solves your problem, then AMEN! Most people have tried replacing everything with no success.

The new O2 should have an immediate effect.

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post #4 of 14 Old 11-26-2006, 11:32 PM
anony91xj
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Sounds like another problem. Check the MAP, ECTS, and TPS.

However if the O2 is definitely bad, replace it. It won't have an effect on how the engine runs but it may cause a drop in gas mileage.

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post #5 of 14 Old 11-27-2006, 12:09 AM Thread Starter
shierkahn
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I'm getting really crappy MPG. If the sensor is covered in the Haynes manual I've checked it. All check out except the O2. I've been working out problems with this XJ since I got it. Seems like nothing was ever done to it maintenance wise by previous owners. So, I'm stuck with all the BUGS. This is my last mechanical hurdle.

Could the stumbling be related to my blow-by problem I seem to be having? Chris

'92 XJ, 4" Shade-tree lift
33/12.50's, 15x8 Soft 8's/4"BS
D30ft, D44rr, 3.55 gears
!!GOT MUD!!

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post #6 of 14 Old 11-27-2006, 12:34 AM Thread Starter
shierkahn
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I forgot to mention that when cold it'll stall a few seconds after starting but usually on the second time around it'll stay running...stumbling for a few minutes unless I hold the idle at about 1800 rpm's for a few minutes. Chris

'92 XJ, 4" Shade-tree lift
33/12.50's, 15x8 Soft 8's/4"BS
D30ft, D44rr, 3.55 gears
!!GOT MUD!!

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post #7 of 14 Old 11-29-2006, 11:34 AM Thread Starter
shierkahn
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Well, I got my CEL working and it's only throwing codes for the coolant system. That's unpluged because it runs like s**t with it pluged in. Worse than with it unplugged.

But now it's not just stumbling now and then, It does it most of the time. sounds like it's not firing on all cylinders. It doesn't do it so much when I first start it, mostly when It's been running and when I'm stuck at a light and have to idle too long.

And it won't communicate with the OBD1 scanner at the dealer/shop. Any ideas?

Thanks, Chris

'92 XJ, 4" Shade-tree lift
33/12.50's, 15x8 Soft 8's/4"BS
D30ft, D44rr, 3.55 gears
!!GOT MUD!!

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post #8 of 14 Old 12-01-2006, 12:52 PM Thread Starter
shierkahn
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Well, still not fixed. Today I checked the plugs and replaced cap&wires.

Checked fuel presure and getting mixed readings, Once it was 24psi and slowly dropped to 0 after shut down.
Checked it again 1/2 hr later and I get 30psi, holding for a few after shut down.
Pinching return line while running didn't cause an increase in presure.
About to go check it again in a minute.
When I give it gas the presure drops RMP depending.
Any ideas on this? Thanks, Chris

'92 XJ, 4" Shade-tree lift
33/12.50's, 15x8 Soft 8's/4"BS
D30ft, D44rr, 3.55 gears
!!GOT MUD!!

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post #9 of 14 Old 12-01-2006, 12:58 PM Thread Starter
shierkahn
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OK, just did a 3rd check on the presure. 31psi with the key on 26psi with engine running. Doesn't make a differance if the vacum line on the regulator is hooked up or not. Still dropping psi when it's given gas. Had a psi increas to 40psi afterr shut down for 5min., start it back up, drops to 25psi. Chris

'92 XJ, 4" Shade-tree lift
33/12.50's, 15x8 Soft 8's/4"BS
D30ft, D44rr, 3.55 gears
!!GOT MUD!!

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post #10 of 14 Old 12-01-2006, 01:44 PM
peyton
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My cherokee does something similar every once in a while. After it has warmed up and I shut it off, then restart it, then give it gas it stumbles. Kinda feels like the fuel pump going out. It throws no codes when it does this. I suspect the trouble is in the wiring somewhere, possibly one of the electrical connectors to the pump not making good contact. One of these days I'm going to go over all the connectors with some dielectric grease to see if that helps.

Have you changed the fuel filter lately?
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post #11 of 14 Old 12-01-2006, 11:55 PM Thread Starter
shierkahn
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Well, problem solved. Fuel pump was DUN.
Peyton; you might want to look into a fuel pump, that's exactly what mine was doing up till it totally went. Wish I would have been on top of it sooner.

Thanks for the help guys, Chris

'92 XJ, 4" Shade-tree lift
33/12.50's, 15x8 Soft 8's/4"BS
D30ft, D44rr, 3.55 gears
!!GOT MUD!!

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post #12 of 14 Old 12-02-2006, 07:11 AM
tangofox007
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Quote:
Originally Posted by anony91xj
Sounds like another problem. Check the MAP, ECTS, and TPS.

However if the O2 is definitely bad, replace it. It won't have an effect on how the engine runs but it may cause a drop in gas mileage.
Here is a quote from Bosch: "A worn-out oxygen sensor can cause excessive gasoline consumption, elevated exhaust emissions, accelerated catalytic converter damage failures and cause engine performance problems such as surging and hesitating." (Emphasis added.)
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post #13 of 14 Old 12-02-2006, 12:43 PM
peyton
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Quote:
Originally Posted by shierkahn
Well, problem solved. Fuel pump was DUN.
Peyton; you might want to look into a fuel pump, that's exactly what mine was doing up till it totally went. Wish I would have been on top of it sooner.

Thanks for the help guys, Chris
Glad you solved your problem. I replaced my fuel pump about 4 years ago. It started hesitating a few months after the pump change. I've put about 50k miles on it since though. I still think it is somewhere in the pump wiring in my case.
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post #14 of 14 Old 12-02-2006, 12:59 PM
BrunoS
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a really clogged fuel filter can cause either sluggish driving problem. change the filter before taking fuel pressure/further diagnosis.

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