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Unread 10-03-2012, 12:31 PM   #1
SPociask
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1999 TJ Wrangler 
 
Join Date: May 2011
Location: Charlotte, NC
Posts: 8
Accelerator Loses Function - Help please

As I'm driving down the road, suddenly my accelerator becomes useless, the Jeep jerks as it drastically slows down and I begin to coast. Pushing on the gas pedal does nothing. The engine continues to run as if in neutral, I still have my power steering and radio. The check engine light goes on only during the incident, then goes off again as soon as the engine "engages" again. There is no other unusual mechanical noise. Actually, I just said it seems in neutral, but upon further thought, it seems to decelerate even quicker than it would, if I had just put it in neutral. It feels more like a downshift from 4th to 3rd gear... but the RPMs don't increase. They decrease.

For the past six weeks or so, it would occasionally happen for about half a second, and the vehicle would jerk (my body would jerk forward). It happened maybe one or two times a week, sometimes less. Normally I'm traveling about 45 mph. One time it happened while I was idling at a red light, but only for that half second; so I couldn't really tell if the engine was going to die.

But last night it got worse, and twice, within three minutes, it happened again... but it lasted a good 4 or 5 seconds. It seems like its instantly shutting down, but didn't completely shut down within those 5 seconds. Slowed down very quickly, and my gas pedal had no effect. Frankly, I was more focused on not getting rear-ended, than I was about observing what was going on. It was quite alarming, as it was on a single lane road with no shoulder, during evening rush hour. Luckily they guy behind me wasn't quite close enough to rear end me during my quick deceleration. I can't count on that luck again.

Had it checked right away with a meter at the auto parts store. They found no bad codes.

I put in some fuel injector cleaner, as it was the only thing I could try quickly and crossed my fingers for the last 6 miles home. Nothing happened during that time. Nor during 15 miles this morning.

The vehicle is a '99 Wrangler 4x4, 6 cyl., 4.0

The guy at the auto parts had some suggestions, but anything he could think of, he says would have showed up as an error code on the meter. (ie fuel pump) I've considered the fuel filter (internal gas tank, sock type). Is there anything I've described that might eliminate the fuel filter as the culprit? Perhaps it's an engine speed sensor? I can check some mechanical issues, but am useless if it's an electrical problem. I have heard that there is a sensor I can plug into computer and drive around with it several days, that will record any intermittant code errors that clear themselves. As I said, the auto parts guy found nothing when he used his sensor. Anyone know what type of shop has the sensor I can leave in for a few days? Would that be a good idea?

Would loose or shorting coil wires cause this? Distributor wires?

Does anyone have an opinion if these symptoms point more to fuel issue, or electric issue?

The situation is somewhat alarming, as there is nowhere to pull over during most of my daily ride. If the fuel injector cleaner didn't fix it, it could eventually end badly.
Suggestions?

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Unread 10-03-2012, 12:46 PM   #2
Jason
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2005 TJ Wrangler 
 
Join Date: May 2009
Location: Eaton Rapids, Michigan
Posts: 6,467
What was the code? Best I can tell, you are describing a hesitation, albeit apparently severe and intermittent.
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Unread 10-03-2012, 12:50 PM   #3
SPociask
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1999 TJ Wrangler 
 
Join Date: May 2011
Location: Charlotte, NC
Posts: 8
Nothing. They found no code. That's the problem.
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Unread 10-03-2012, 01:01 PM   #4
Jason
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2005 TJ Wrangler 
 
Join Date: May 2009
Location: Eaton Rapids, Michigan
Posts: 6,467
You said no "bad" code. I read that to mean there was a code, but they thought it was unrelated. If you do get the SES light again, have it read somewhere else. It's very rare that the light comes on and there are no stored codes.

I assume all the other gauges and lights are normal. (Normal oil pressure, engine temp, etc.) With no indication of a possible culprit, I would start by checking the "easy" stuff first. Check and test plugs and wires. (Cap and rotor? I forget when the DIS started....) Check the electrical connections, particularly to the computer. Take off the battery connections and clean them thoroughly. Check the air filter and intake. Clean throttle body out. Check the accelerator cables for binding or unnecessary play.
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Unread 10-03-2012, 01:53 PM   #5
SPociask
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1999 TJ Wrangler 
 
Join Date: May 2011
Location: Charlotte, NC
Posts: 8
Well that's what I thought, but the guy said he needs the check engine light to be on while he's testing in order to get the needed info. Does that sound right?
I believe I'll just buy my own OBD Reader and leave it plugged in as I drive, til it happens again.
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Unread 10-03-2012, 02:01 PM   #6
Jason
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2005 TJ Wrangler 
 
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Location: Eaton Rapids, Michigan
Posts: 6,467
The codes are stored, even if the light shuts off.
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