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Old 05-19-2010, 09:17 PM   #1
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Engine hesitates!!

While driving my 97 TJ (manual transmission) the other day I felt a slight hesitation when trying to accelerate. It has progressively gotten worse in the last week. I thought that it had something to do with the fuel filter or possibly the pump but I didn't want to spend any undue money on something that I wasn't sure would fix it. Does anybody have any suggestions as to what it is?

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Old 05-20-2010, 09:50 AM   #2
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Could possibly be your cat. 13yrs. old and all. Check the exhaust flow and or drop your muffler and take a look inside.

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Old 05-20-2010, 10:09 AM   #3
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x2 on the catalitic convertor, or its just bad gas. Before spending anything, run it about empty then fill 'er up with 100% gas.

Mine has been having trouble with the 10% ethenol gas. Nothing major, just a little hesitation on start up...
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Old 05-20-2010, 02:11 PM   #4
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I thought magicians pulled rabbits and birds out of their hat, not cats.

The cat guesses were just that - wild guesses with no basis. BTW, a plugged cat does not just cause hesitation, but many more symptoms as well.

There's probably at least 50 things that can cause hesitation.

Lets start with ignition - anything done to it lately? Ignition - plugs, wires, cap, rotor etc. What plugs are in it now?
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Old 05-20-2010, 02:30 PM   #5
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as far as "no basis", my basis was on the fact that it progresively got worse over the period of a week. Same basis that made me think it could just be bad gas.

Check the free stuff first, then dive into the other things suggested. As well, rrich has a good point on the plugs/cap/rotor, they are made to fail. If it still does it regularly after the next fill up, do the tune-up first. Those consumables are made to fail over time and are often overlooked.
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Old 05-20-2010, 07:06 PM   #6
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Thank you for the suggestions. I will definitely try the cheaper way first and run the gas out of it. Then I will try the next two. I was planning on giving it a tuneup this spring anyway.
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Old 05-21-2010, 12:38 AM   #7
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Quote:
Originally Posted by rrich View Post
I thought magicians pulled rabbits and birds out of their hat, not cats.

The cat guesses were just that - wild guesses with no basis. BTW, a plugged cat does not just cause hesitation, but many more symptoms as well.

There's probably at least 50 things that can cause hesitation.

Lets start with ignition - anything done to it lately? Ignition - plugs, wires, cap, rotor etc. What plugs are in it now?
Wow trying to flame someone on this site!? Lets see here hmmm within a week it got worse. Now Cats can cause hesitation do to exhaust flow and back pressure and yes loss of power and so on........ As far as tune up parts and fuel filters it becomes a progressive thing. Sometimes we get part of the story or someone does not notice the progession until it is bad. I have a problem with you jumping in here and saying our suggestions have "no basis". I did not want him to run out and buy a cat. I suggested inspection. Seven services also chimed in with possibly bad gas. We could also have said check the other items that you have stated but we did not but, hey there are others here with opinions that could have chimed in and gave their opinions also.....with out bashing others ideas.
Oh and tlief82 I almost forgot a dirty throttle body can cause hesitaion also. Keep us updated on your progress and if you need anything else just let us know.
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Old 05-21-2010, 01:53 AM   #8
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Not trying to flame anyone - but there's always someone that comes up with ridiculous ideas. Some seem to get a perverse joy in misleading folks that ask for help.

If it wasn't a guess, was it intentional misleading?

There was nothing said that would support a bad cat - especially when cats don't act that way.

THINK!

Cats rarely fail in a week. Ask anyone that's ever dealt with a cat. The only exception might be if the cat got crushed - but that wouldn't take a week to notice.

If the cat was plugged enough to cause hesitation the exhaust would be so restricted it wouldn't run at even medium speed. Then obviously his complaint would have been different. ie: "Won't get out of it's own way!"

As suggested it could be simple like a dirty throttle body, or in need of some plugs.

Need more information to be much more definitive.

There are lots of things that can cause hesitation - exhaust problems are way down the list near the bottom.

Maybe if I didn't jump in so soon the comments would have been the "engine needs to be rebuilt?"
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Old 05-21-2010, 10:17 AM   #9
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rrich I'm not going to get into a pissing contest with you. Like I said the problem I had is that you jumped in and bashed a couple suggestions. They were a couple suggestions. I do not get on this site to mislead anyone. I get on this site because enjoy helping others and from time to time a little ribbing and banter amongst us. I do not get on this site and tell people (especially when I do not know them) that their suggestions/opinions or the like are without basis and or rediculous and that they have a perverse joy in giving wrong info. Now lets get off the high horse there homer and stop with rediculous I'm right your wrong crap.
You are correct that there is usually other factors that can cause hesitation. Never said cats can fail in a week. It is usually progressive. He could have just noticed it because it was getting worse. Same thing with tune up parts and filters. Also with tune up parts you usually get a rough running engine when they start to fail not just hesitation. See where I'm going with this?
I have had a cat problem that did have flow issues that caused hesitation. (or at least felt like it. Perception) Exhaust flow at idle felt decent. After tune up it was the same. Dropped exhaust and found the cat had started coming apart. Changed the cat and WOW what a difference.
With that I am done.
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Old 05-21-2010, 10:39 AM   #10
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^^ You mean that sometimes people have something happen to them, and once they learned to fix it they add it to their arsenal of causes of different problems?

And then use said arsenal to give suggestions?!



I'm with you, there was no need for the playground, I'm right, you're stupid BS.
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Old 05-21-2010, 10:42 AM   #11
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And to answer the original and go along with the others, yes, definitely check the cheap stuff. Dropping your exhaust is free, why not try it?!

I have seen hesitation issues in the past where it was fuel filters and fuel pumps. But like you said, wait to do that last. Hesitation can be the start of a clogged filter or a bad pump, but after a while, the pump won't even work anymore and you can't even idle, let alone accelerate.
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Old 05-21-2010, 01:41 PM   #12
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Change spark plugs and wires. THat might help or fuel injection cleaner, or fuel filter.
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Old 05-21-2010, 03:04 PM   #13
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plugs, plug wires, distributor cap and rotor are all very quick and easy to check when you start having engine issues/hesitation. They are fairly cheap to replace if needed too. Dirty throttle body as well.
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Old 05-21-2010, 04:14 PM   #14
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hm, having the same issues with my 97 tj as well. It only does it after a cold start and not enough time to warm up or when I stop to say eat lunch and just jump in and go. Does it at the bottom of 1st gear mostly unless I run out the clutch a bit to stay up in the RPMs. Just did plug and wires yesterday, but like a dumb-@ss forgot to get the cap and rotor (and I used to sell parts wholesale, though in my defense cap, rotor, and wires used to come in a tri-pack at our shop lol)

I know I need to replace my exhaust manifold cause it leaks like a siv, but I didn't think about cleaning the throttle body.
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Old 05-21-2010, 04:25 PM   #15
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I changed plugs, wires, dist cap, and rotor. It starts right up but it makes an awful noise like an engine with a cylinder down does (loud ticking). Not exactly sure how to describe it. I did notice the gap on the plugs were not the same but they are the exact same number on the plugs that I pulled out. Do I need to change the gap or is that something that would not cause that much problem? Also, the plugs that i pulled out were for a 99 wrangler (the plug that I was supposed to have in there was from years 91-98). I don't know if that makes much differ because i tried both thinking that would help but it didn't.
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Old 05-21-2010, 06:03 PM   #16
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Gapping the plugs is very important or you will have misfires. The gap should be .035. Even if the box says pregapped to .035 ... double check it anyway because sometimes it might not be correct. It happened to me and I was going nuts trying to figure out what is causing a misfire in cylinder #1.
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Old 05-21-2010, 06:12 PM   #17
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Forget that last comment about the bad sound. I crossed the plug wires somehow and that fixed the problem. The tuneup also fixed the hesitation problem and it only cost me $50. I noticed it has a little more giddyup too. Thanks for all of the help and suggestions from everybody!!! But I still want to know if the difference in gap in the plugs make a difference?
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Old 05-21-2010, 06:55 PM   #18
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""""But I still want to know if the difference in gap in the plugs make a difference?""""

YES!


Using the correct plugs also makes a difference. Using aftermarket "performance plugs" like splitfires, multielectrodes or the others can cost you an engine.

Look at the underhood label - it will tell you the plugs it was designed to use. Wouldn't you think the engineers that designed the head know a little bit more than an "armchair mechanic?"

Never trust what the box says is the gap ---- ALWAYS CHECK IT YOURSELF!
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Old 05-22-2010, 06:51 AM   #19
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gonna pick up the cap and rotor today. Wish I had the new exhaust manifold though. I hate that sputter put put put.
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Old 05-22-2010, 08:02 PM   #20
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Congrats tlief82. Yes always check your gap Bro. Someone at the factory or the parts store could have dropped them and these things are mass produced. There is room for error there. I also agree stay OE.
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Old 05-22-2010, 11:02 PM   #21
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Just because a plug works great in a Yugo or Moskovich, it doesn't mean it'll work in a Jeep - even if it does fit the hole.
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Old 05-23-2010, 07:09 AM   #22
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I drive a 97 4cyl and I've been having similar issues
So far I changed the plugs, wires, cap and rotor, removed and thoroughly cleaned throttle body, and new air filter.

I'm thinking the tps needs to be replaced as I also have a slightly rough idle in addition to the hesitation, but I can't find the correct tps. Everywhere I go they try to sell me one that has three flat terminals in the connector, where mine has three round connectors .


Has anyone else had issues replacing their tps? Any suggestions?
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Old 05-23-2010, 07:51 AM   #23
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You must have been going to parts houses like AutoChina or the like.

Try the dealer! Make sure theirs is in the original MOPAR box. Some dealers buy and sell you the same Chinese crap that AZ sells.
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Old 05-24-2010, 04:57 AM   #24
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Yeah...autozone, pepboys, advance auto, etc. They all carry the bwd part with the three flat metal terminals in the connector, not the three round terminals like are in my stock part.

Has anyone else had this issue?
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Old 07-19-2010, 10:06 PM   #25
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So what is the "ideal" spark plug, I replaced rotor/cap plugs and wires, used autolites and now I am getting a 'ticking', valve tapping sound. I did find that my distributor vacuum advance line was clogged - replaced the entire vaccum line now things just aren't right - runs pretty well - drivable, no noticable decrease in power... Maybe a timing issue?

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