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Old 11-22-2010, 12:55 PM   #1
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Engine Hesitation Under Certain Circumstances

I recently acquired a 97 TJ SE 2.5L w/o AC Manual that was give to my step son. NO codes are being thrown

It worked great (no real obvious issues) until he started tinkering and did a tune up that included new plugs, air filter and oil change. Now, that is ALL I WAS told he did. After that the engine ran like crap! The old plugs had a huge gap (they were correct Autolite plugs) and he gapped the new ones to .035. Anyways, I intervened and had him change the dist cap and rotor. That gave no change. I did some searching and found that the IAC might be bad. I replaced it, because the old one WAS BAD (valve was stuck). That, along with new plugs and coil, fixed the prob MOSTLY.

However, what happens now is:

When was a warmed up idle....IF IT FLOOR the throttle, the engine misses, hesitates and bogs down but DOES NOT STALL.....

If I SLOOOOWLY increase throttle the engine is fine and once past about 2,000 rpm I can floor it WITHOUT any hesitation!

THAT IS STRANGE!

I was also told, the hesitation sometime occurs now as speed when in 3rd gear.

ANY IDEAS??????

Fuel Pressure? (BTW - any links with pictures on how to check that)
TPS?
Crank Poss. Sensor?
Bad Distributor Switch Plate?
O2 Sensor(s)?

Thanks for any help!!!!!

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Old 11-22-2010, 02:40 PM   #2
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Crank and cam sensors that was the problem with mine!

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Old 11-22-2010, 02:54 PM   #3
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Fuel Pressure? (BTW - any links with pictures on how to check that)
TPS?
Crank Poss. Sensor?
Bad Distributor Switch Plate?
O2 Sensor(s)?

None of the things you asked about are things that he could have damaged easily.

But - the coil wire - it can break inside, making an extra gap for the spark to jump across. Under acceleration and under load - like lugging in 3rd gear makes it evident.

Try seating it again, if no help, try putting on another from a different car, or a new one from a parts house $2-3.
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Old 11-22-2010, 03:01 PM   #4
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I would change all the wires first.
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Old 11-22-2010, 03:11 PM   #5
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Changed all WIRES - Double Check Seating.

NEW COIL installed.....

It runs good and strong other than when the throttle is QUICKLY floored or with low RPM and it is floored while in motion....

Almost sounds like the timing is not advancing but I can not adjust the distributor.....

I checked for vacuum leaks, but could not find any obvious ones.

This is testing me almost to my personal breaking point.
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Old 11-22-2010, 03:48 PM   #6
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By any chance did he wash it or spray cleaner around?

Water or cleaner can get inside the TPS, it's not sealed. Maybe take it off and spray it down with a good contact cleaner - not wd-40, oils or carb cleaner. Even rubbing alcohol will work. Put it back and try it.

They aren't expensive - just don't get it from a cheapie parts house like Autozone. They are often worse than the old one. NAPA or a quality place.

Let us know.
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Old 11-22-2010, 03:58 PM   #7
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I will try that 2nite - in the mean time, any other options or ideas from anyone?

Please feel free to chime in!!!!!

Thanks in advance!!

Chris
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Old 11-22-2010, 07:27 PM   #8
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I checked the TPS and water intrusion IS NOT an issue...

I have a basic Haynes Manual for the Wrangler. Does anybody have the testing paramaters (Ohm readings) for the TPS, MAP and O2 sensor, and Distributor Switch Plate. This manual does not include any testing parameters.

It seems that the timing does not advance fast enough when the throttle is open quickly. Slow increase has no hesitation.

Anybody have experience with the distributors with this year Wrangler?
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Old 11-22-2010, 08:24 PM   #9
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Quote:
Originally Posted by cthies View Post
I checked the TPS and water intrusion IS NOT an issue...

I have a basic Haynes Manual for the Wrangler. Does anybody have the testing paramaters (Ohm readings) for the TPS, MAP and O2 sensor, and Distributor Switch Plate. This manual does not include any testing parameters.

It seems that the timing does not advance fast enough when the throttle is open quickly. Slow increase has no hesitation.

Anybody have experience with the distributors with this year Wrangler?
I dont even think there a variable timing.
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Old 11-22-2010, 08:31 PM   #10
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OK, kinda makes sense. I am a Chevy man, the jeep is much simplier in many ways but also very different. I am used to the ability to adjust timimg.

OK, I got some Info on testing the TPS and I will do that tomorrow.

I am also going to check codes and see if maybe the CEL is burnt out.

Any other advice before I start tomorrow?
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Old 11-22-2010, 08:52 PM   #11
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Originally Posted by cthies View Post
OK, kinda makes sense. I am a Chevy man, the jeep is much simplier in many ways but also very different. I am used to the ability to adjust timimg.

OK, I got some Info on testing the TPS and I will do that tomorrow.

I am also going to check codes and see if maybe the CEL is burnt out.

Any other advice before I start tomorrow?
CEL should turn on when you turn the key on.

if you said anything above 2000rpm is normal then TPS should be ok otherwise it would be the same all RPM
you said only low RPM could it be MAP?
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Old 11-22-2010, 09:12 PM   #12
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*************UPDATE**************

I used the key and clicked twice to turn on ignition and see if CEL lights up. IT DID NOT. Looks like a burned out bulb....

So, I hooked up trusty Craftsman OBD2 Code Reader and walla....

6 CODES

P0132 - Circuit High Voltage Bank 1 Sensor 1
--------This might be caused by me when I unhooked O2 sensor to see if it made a difference (which it did not).

P0441 - Evap Emission System Incorrect Purge Flow
-------Not sure about this one. Might be the gas cap. I will check this. It is also likely cracked hoses. Good chance the is atleast one but i AM NOT SURE IF THIS WILL EFFECT driveability. ANY IDEAS????

P0300, 301, 302, 303 - Cylinder Missfire
------NOT sure about this one but it might be from the kid hooking up the spark plug wires WRONG when he did his initial tune up. Any ideas here.

Looking for more adviced. I will clear codes tomorrow and drive it around and see what codes are thrown.

Thanks
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Old 11-22-2010, 09:25 PM   #13
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Quote:
Originally Posted by cthies View Post
*************UPDATE**************

I used the key and clicked twice to turn on ignition and see if CEL lights up. IT DID NOT. Looks like a burned out bulb....

So, I hooked up trusty Craftsman OBD2 Code Reader and walla....

6 CODES

P0132 - Circuit High Voltage Bank 1 Sensor 1
--------This might be caused by me when I unhooked O2 sensor to see if it made a difference (which it did not).

P0441 - Evap Emission System Incorrect Purge Flow
-------Not sure about this one. Might be the gas cap. I will check this. It is also likely cracked hoses. Good chance the is atleast one but i AM NOT SURE IF THIS WILL EFFECT driveability. ANY IDEAS????

P0300, 301, 302, 303 - Cylinder Missfire
------NOT sure about this one but it might be from the kid hooking up the spark plug wires WRONG when he did his initial tune up. Any ideas here.

Looking for more adviced. I will clear codes tomorrow and drive it around and see what codes are thrown.

Thanks
I would check distributor cap and rotor.
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Old 11-22-2010, 09:27 PM   #14
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PM me your year if you would like the FSM.
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Old 11-23-2010, 02:06 AM   #15
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Check that firing order again. It's possible to check it several times and make the same mistake each time.

The timing advance is totally by the computer - if it was not advancing fast enough it would not hesitate, but too much too fast might, but very unlikely that's the hesitation.

The plugs - trick AutoChina plugs? - never.

Just use the plugs the underhood sticker calls out - same brands, same numbers. The factory engineers know what works, the ex hamburger onion slicer at the parts house doesn't.

It's so easy to do it right. Why does everyone think a plug that fits a Yugo or Moskovich will make everything work so much better?
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Old 11-23-2010, 04:49 AM   #16
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Quote:
Originally Posted by cthies
I checked the TPS and water intrusion IS NOT an issue...

I have a basic Haynes Manual for the Wrangler. Does anybody have the testing paramaters (Ohm readings) for the TPS, MAP and O2 sensor, and Distributor Switch Plate. This manual does not include any testing parameters.

It seems that the timing does not advance fast enough when the throttle is open quickly. Slow increase has no hesitation.

Anybody have experience with the distributors with this year Wrangler?
Man the Distributor has the camshaft sensor on it and it will throw 301-306 code it needs to be set by oem way if it is not set right then it will always throw the code. This sensor works with the crank sensor for timing that's what I been trying to tell u to check.
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Old 11-23-2010, 04:51 AM   #17
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Hope this helps
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Old 11-23-2010, 07:51 AM   #18
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Thanks JeepFreak - I am going to reset the CEL and see what codes are thrown.....

IF the engine misfire is thrown again, I will prob opt for a NEW distributor.

It currently has a NEW cap and rotor. I will now more tonight after I reset the codes today and drive it around

Chris
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Old 11-23-2010, 08:21 AM   #19
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Did he, or you, loosen, turn, or remove the distributor?

If not, the chances are very remote that it got out of sync just because he changed the plugs. About the same chance as lightening hitting you in the shower while you are wearing your Tuxedo.

When you replace the distributor you'll have to follow the procedure to get it back in sync - the Haynes generic manual is useless for that.

Did he use the plugs the label called for?
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Old 11-23-2010, 12:19 PM   #20
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No, the Dist was not removed or loosened.

He put in some Platnium plugs. I checked the cross reference and the manufacturer says they work on this vehicle but I might just go back and get the Autolites called for in the manual

I am resetting the codes NOW and going on some errands. I will run the Scanner when I get back again.

Chris
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Old 11-23-2010, 12:23 PM   #21
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If it was not moved that does not mean the sensors are good and even if that one is in time u still need to check crankshaft sensor they go bad very easy test only 2 bolts and unplug it test with volt meter if out of rage this will throw the time off. All jeep disturbers are the same u have to set them in place. they have a key at the end of the disturber that slides in to the oil pump when disturbers are removed u have to put back on tdc and reset.
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Old 11-23-2010, 02:00 PM   #22
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****************UPDATE II**************

Drove jeep to Lowes (aprox 10 miles). Runs fine except:
1. If u try to accelerate QUICK from stop, it hesitates. IF you move fwd in a prudent manner, no issues
2. If u are in gear, and moving (lets say 3rd gear) and u are in a crusing RPM and FLOOR it, it boggs and hesitates but moves fwd. Once to a higher RPM, u can floor it all u want and it responds.
3. I reset the codes, drove to store and checked again....NO CODES. And that was after I forced it to hesitate a few times.

I actually got use to the hesitation and could avoid it easily with simple changes in drive style...but i still need to fix this.

I have not tried the crank and cam sensor yet....I plan to do that. I wanted to post this update however.

Thanks
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Old 11-23-2010, 02:03 PM   #23
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Not the manual -- LOOK AT THE UNDERHOOD STICKER!
The manual is generic, it covers all engines, emissions for all states, all climates. The underhood sticker is for THAT engine in THAT configuration from THAT state.
Use the manual only when the sticker is unavailable.

Autolite plats - were never used in that engine. (Never liked Autolite anyway, nor plats.) I've seen plats cause that exact same problem many times before.

Probably it calls for regular Champion plugs. Could be the whole problem.
Use what the engineers designed to head to use.

Even if the parts idiot tells you different!


Freak - what do you think the chances are the Cam Position Sensor went bad right when the kid put in the plugs?

He He - Was he wearing a tux? Maybe lightening did strike him (see previous post.)
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Old 11-23-2010, 03:14 PM   #24
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Who knows....maybe lightning did strike him along with a sudden attack by a Great White Shark....

At this point, anything is possible.
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Old 11-23-2010, 03:34 PM   #25
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Don't be hard on your self you will get it fixed as for the hanes manual don't go by that one get the oem that's the best one to go by it's what Chrysler uses
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Old 11-23-2010, 05:20 PM   #26
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OK, I ordered the OEM plug and will have them tomorrow...

Champion RC12LYC

Ran the engine some more....checked codes and got another CODE

P0302 - Misfire Cylinder 2

I am now thinking Camshaft sensor in the distributor......
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Old 11-23-2010, 05:36 PM   #27
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I bet it is your plugs. Before putting in the new Champion ones, double check the gap.
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Old 11-23-2010, 05:52 PM   #28
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Quote:
Originally Posted by cthies View Post
I have a basic Haynes Manual for the Wrangler. Does anybody have the testing paramaters (Ohm readings) for the TPS, MAP and O2 sensor, and Distributor Switch Plate. This manual does not include any testing parameters.
the haynes manual is crap-next to useless. you can go on ebay and get the FSM you can put on cd(.pdf files) for like $3.00 and have in in a few minutes. I'm one of those that likes printed things so for $42 i got the feild service manual and drive train dianostics and also have the fsm on cd.
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Old 11-24-2010, 10:31 PM   #29
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Please let us know how those new plugs work out.
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Old 02-25-2011, 02:58 PM   #30
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YAY!!!! Problem FIXED FINALLY! I parked the jeep for quite awhile but felt motivated and decided to tackle the problem....

IT was the CAMSHAFT Sensor in the distributor....

Thanks for all that helped with the problem!!!

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