Running bad UNLESS the Check Engine light is on????

[Paddletrucker]

OK, so my Jeep has been doing this crazy thing the last few days. Shifting through the gears, there's what I'd call a hesitation before I shift. I can feel her drag and slow, but the RPM always stays constant. Then, just like I punch the gas pedal, she'll come back to life. This last less than a couple of seconds in each gear, all the way into and including fifth.

At highway speed with the cruise set between 55-60 (Yes, I drive like my Grandpa, but get 20+mpg's:D) it will do something that's not quite a sputter. Again, less than two seconds and it'll come right back around. It almost feels like I hit the coast setting on the cruise for a brief moment. Again, the RPM never moves.

At an idle, it will go from 1,000 down to about 600 and idle rough. After a couple of seconds, it comes right back.

It's never died. It seems like it does this at pretty regular intervals. Every couple of minutes on the highway. Sometimes the problem is worse than others, but it never lasts any longer. Here's what's odd...It WILL NOT do it very many times before I get a Check ENgine Light, and then it runs just fine. Going down the road, I can just turn off the key, wait a second, and turn the key back on and the engine will restart (5-speed manual) and the CEL will go off. She goes back to "cutting out" a little bit every once in a while until the CEL comes back on. Same thing idling in the driveway. It'll do it until the CEL comes on. I can kill it and it'll start doing it again.

It'd done this for a couple of days. Then, the other day, I had to put new battery terminals on it, because the cables were hanging on by a few strands of wire. It didn't do this for a couple of days after I'd done this, so I thought it was related to not getting enough power to something. Then last night, it started doing it again. So far, it hasn't done it with the CEL light on. I guess I need to see if I can find a code reader for the '95 and see if that will tell me something.

A little more info, if it matters. '95 model, 5 spd manual, 237,000 miles. Oil pressure seems to stay constant at around 60psi going down the raod all the time. The volt meter stays consistent. The springs are still sagging SOB's:p (I NEED to take the lift out of the shop and put it ON the Jeep!!!!!!!:bang::bang:) All stock, never has had any problems since I've had it other than the water pump. Fuel mileage is great, usually around 20mpg's. That hasn't seemed to change. Last summer, I put new plugs, wires, etc. on it. It's always ran great before this, and still does, once the CEL comes on.

Any ideas are appreciated. I've got some errands to run, and I'll be going to my local mom and pop back woods parts store to see if he's got a code reader. If not, I guess I'll run by one of the bigger chains I try to stay out of and see if I can at least see what code it's throwing.

[4.3LXJ]

Might want to replace that throttle position sensor Nate

[Paddletrucker]

OK, thanks. On my semi, which is what I'm used to messing with, that would be under the gas pedal and costs about $200. I'm not much of a car mechanic, and usually don't work on anything I can't STAND next to and work on at chest level that's totally unobstructed. I'm thinking that the XJ's would need to be behind the dash somewhere? When I get a TPS failure on my big truck (about once every two years) I get a different hesitation while shifting. The pedal goes dead for a split second when I shift. Every time you let off the throttle, you can put your foot back into it and get nothing, until it fires again and then i'll jerk the daylights out of you, making you look like a two week rookie truck driver. My Jeep isn't doing that. THe pedal is effective the whole time. The engine just feels really weak for that second, second and a half. Also, my semi is fine once I've got my pedal back. The problem only presents itself at the beginning of each shift. The throttle isn't used to take off, so I can't really say or remember if it does it then. It's NEVER done it at highway speed with the cruise set, like my Jeep's doing. Is that perhaps a better explanation of what I mean by hesitating? And am I comparing Apples to Oranges here, using the TPS in my semi? Also have a speed sensor in my big truck that goes out after most particularly wet spring or winter seasons that acts real similar. Does the XJ have a speed sensor that could cause this. Jeeez, I need to learn NOT to think of my Jeep wearing Caterpillar goggles. Just never really worked on much else, I suppose. Always paid to have my personal vehicle fixed and enjoy my days off, or save them for wrenching on the vehicle that's paying the bills. LOL

I was wondering about 02 sensors, but won't know until I can get the code, I suppose. I can't see it being related to the distributor, plugs, wires, etc. or I'd think it would be doing it consistently and would not quit when I get the CEL.

ONe more comparison of my tractor to my Jeep. Most big trucks have an ECM that will give you the codes. Newer ones have a small screen in the instrument cluster that tells you all kinds of stuff. Mine's an old '96 with one of the first styles of ECM's they put on those big engines. No fancy computer screens or anything, just turn the cruise off with one old style METAL toggle switch and hold the 'set/resume' momentary toggle switch up to set the cruise and the CEL will begin to flash. Count the flashes. If it flashes 5 times twice in a row, all is good. If you get, say a 6 then a three, it's low on coolant. If it gives you any other code, refer to the chart of fault codes in the Cat book that is in the glove box. Pretty simple. Why, oh, why can't my little beloved XJ have something similar???:rolleyes: I need to find one of those iPhone apps and a cord that'll work with the OBD1, I guess.

[4.3LXJ]

This one is on the shaft of the butterfly. On the outside of the throttle body. You will only get an O2 sensor code if the heater in it doesn't work. Might be a good time to pull any stored codes before throwing parts at it.

[Paddletrucker]

Yeah, plan to get the codes before I really start. Found the TPS. Looks pretty dad gum easy. Thanks again. I guess I'm headed to the parts house

[4.3LXJ]

OK, keep us posted

[Mudderoy]

OK, thanks. On my semi, which is what I'm used to messing with, that would be under the gas pedal and costs about $200. I'm not much of a car mechanic, and usually don't work on anything I can't STAND next to and work on at chest level that's totally unobstructed. I'm thinking that the XJ's would need to be behind the dash somewhere? When I get a TPS failure on my big truck (about once every two years) I get a different hesitation while shifting. The pedal goes dead for a split second when I shift. Every time you let off the throttle, you can put your foot back into it and get nothing, until it fires again and then i'll jerk the daylights out of you, making you look like a two week rookie truck driver. My Jeep isn't doing that. THe pedal is effective the whole time. The engine just feels really weak for that second, second and a half. Also, my semi is fine once I've got my pedal back. The problem only presents itself at the beginning of each shift. The throttle isn't used to take off, so I can't really say or remember if it does it then. It's NEVER done it at highway speed with the cruise set, like my Jeep's doing. Is that perhaps a better explanation of what I mean by hesitating? And am I comparing Apples to Oranges here, using the TPS in my semi? Also have a speed sensor in my big truck that goes out after most particularly wet spring or winter seasons that acts real similar. Does the XJ have a speed sensor that could cause this. Jeeez, I need to learn NOT to think of my Jeep wearing Caterpillar goggles. Just never really worked on much else, I suppose. Always paid to have my personal vehicle fixed and enjoy my days off, or save them for wrenching on the vehicle that's paying the bills. LOL

I was wondering about 02 sensors, but won't know until I can get the code, I suppose. I can't see it being related to the distributor, plugs, wires, etc. or I'd think it would be doing it consistently and would not quit when I get the CEL.

ONe more comparison of my tractor to my Jeep. Most big trucks have an ECM that will give you the codes. Newer ones have a small screen in the instrument cluster that tells you all kinds of stuff. Mine's an old '96 with one of the first styles of ECM's they put on those big engines. No fancy computer screens or anything, just turn the cruise off with one old style METAL toggle switch and hold the 'set/resume' momentary toggle switch up to set the cruise and the CEL will begin to flash. Count the flashes. If it flashes 5 times twice in a row, all is good. If you get, say a 6 then a three, it's low on coolant. If it gives you any other code, refer to the chart of fault codes in the Cat book that is in the glove box. Pretty simple. Why, oh, why can't my little beloved XJ have something similar???:rolleyes: I need to find one of those iPhone apps and a cord that'll work with the OBD1, I guess.

Check out this post http://www.xjtalk.com/showthread.php?t=2129

You might want to clean the IAC, and throttle body while you're at it. TPS is about $60

[Paddletrucker]

AWESOME, Tony! Never saw that before. Cool. Thanks!


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[Paddletrucker]

OK. Maybe it's running worse than I thought. I just got smoked my my brother in his automatic tranny TJ. THAT'S NEVER HAPPENED!!!! LOL


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[Paddletrucker]

On my way to a larger town in search of an OBD1 reader. Local guy didn't have one. He did quote me $34.50 for a TPS, though. He'd have to order it. Be here Tomorrow. Think I ought to go ahead and get one?


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[Paddletrucker]

And of course, she's running perfectly. 27 miles so far and it hasn't stumbled once and no CEL


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[4.3LXJ]

I hear ya. Just threaten it with a BFH LOL

It should have stored codes in it from when it did have the light. Start there before buying anything

[Paddletrucker]

Well, I'm having trouble finding an OBD1 reader. Off to store #3. Enjoying driving it around, anyhow. Haven't been getting to do much of that for a long while!


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[Paddletrucker]

Crap. Strike three. In the words of Eric Cartman, "Screw you guys, I'm goin' home!"

Guess I'll see if I can find something on line.

Or maybe, it'll continue to run fine. Lol


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[4.3LXJ]

You can use the key on, key off thing to retrieve your codes. There is a thread here on that

[Paddletrucker]

Hmmmm. Never heard of that. Many thanks yet again!


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[Paddletrucker]

OK, just got home and did the key thing. Awesome.

Here's what I got,

12- Direct battery input to PCM was disconnected within the last 50 key on cycles.

That was when I replaced the battery terminals

The other two were:

21 - Neither rich nor lean condition detected from the oxygen sensor input. Or Oxygen sensor input voltage maintained above the normal operating range.

52 - Oxygen sensor signal input indicates rich air/fuel ratio condition during engine operation

So...it sounds like I need some 02 sensors? I guess all of them? But...would this cause the problem I've been having? Can 02 sensor affect performance intermittently?? This doesn't tell me which sensors to replace, though.

And, with the key on/off trick, is there a way to clear the codes, or will they go away on their own after the problem has been fixed?

Really cool trick. You guys kick butt!

[4.3LXJ]

The codes will go away with 60 or 80 starts, can't remember which. But yes you need an O2 sensor. Personally, I think you should replace both, but you could get away with the upstream sensor. Sounds like it was really worn out. You might see some better milage now too

[Paddletrucker]

Could the 02 sensors cause the stumbling of the engine, 'ya think? MIleage wise, I've been happy. Usually around 20 with the manual and stock tires.

[4.3LXJ]

Yes it could, especially if working intermittently. But before you can find anything else, you will have to fix that.

[Paddletrucker]

OK, thanks so much. I'll work that around my fishing plans this weekend. :D

:xjtalk: saves me more money! Love it!

[Pookapotamus]

I believe a 95 only has the one upstream O2 sensor, they went to 0bdII in 96 and added the second O2 sensor downstream.

[4x4Dalton]

I believe a 95 only has the one upstream O2 sensor, they went to 0bdII in 96 and added the second O2 sensor downstream.

Yep the 95 only has the one O2 sensor.