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Unread 08-03-2005, 07:24 PM   #1
skocheroni
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Hesitation on acceleration

Hey all,

Sometimes while driving my 1997 Wrangler SE, I will have a slight hesitation while accelerating. What I mean by this is that after starting up the car and backing out of a driveway or something, it'll be in first gear and if I am giving it light to moderate gas, it'll sputter.

Only once I have either a) turned off and turned on the car, or b) slowed down and then hit the gas harder will the car respond normally to giving it gas. After this, all works fine whether it be from a stop, or any other form of acceleration.

What would cause my car to have this sputtering problem only within the first minute of driving (till I give it hard gas)?

Could it be timing, fuel pump, etc?

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Unread 08-05-2005, 08:31 AM   #2
skocheroni
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No one has any input on this?
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Unread 08-08-2005, 03:48 PM   #3
98JEEPTJ
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Mine does the same thing and nobody knows what's going on good luck getting help with it I got no where....I have replaced all the sensors and everything still no different I even changed injectors and no change....
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Unread 10-09-2005, 08:00 PM   #4
wildflowerjones
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Well lets work this out...

Mine does the same thing... '02 TJ

What is crazy is that once it happens... I t does not do it again until the next time the jeep sits a cools off... like over night. It runs great... I have gone off road, mud, dirt, gravel, 4wheel high, low, back and forth to work 40 miles round trip daily... everything seems solid as a rock and runs strong.

I have put on 31x10.5x15 BFG A/T ko's... Surly new tires could not cause this...

I have replaced the TPS Sensor... No change... actually the idle gotten worse. So I am thinking of putting the old TPS sensor back on. The sensor was from NAPA and it is the exact replacement.

I have change the spark plugs. 4412 Champion Spark Plugs... The old plugs were so bad... they were gapped to like .50 or greater... This is no exageration. My jeep runs better, however, there is still that rough at "first crank" idle and the hesitation on the first acceleration.

On a side note, since changing the plugs I have noticed an increase in the mpg... an additional 3mpg... which gives me 18mpg.

I filled up with Cheveron with Techron in the attempt to clean the fuel injectors... 2 tanks so far.

I changed the oil and oil filter... I did not figure this would make a difference, but it needed it anyway.

Tomorrow I am planning on cleaning the throttle body with some Valvoline throttle body cleaner I picked up a AutoZone...

I am not sure what will be next... I have priced the sensors and they are extreemly expensive... I cannot afford to throw money at this like a crap shoot until I hit something that works. I also don't want to throw a bunch of additives in to the fuel supply, etc. On thread mentioned putting "Seafoam" in to the throttle body... I don't know...

I have done a search on these issues... Several things have been discussed in the forum... O2 sensors, TPS sensor, MAP sensor, New Gas, New Plugs, cleaning the throttle body... who knows?

I will let you know what happens when I clean the throttle body... perhaps it is just cabon build up? This jeep has 39000 miles...

Any suggestions are welcomes
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Unread 10-10-2005, 08:11 PM   #5
wildflowerjones
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I cleaned the Throttle Body. There was lots of carbon build up. The engine seems to be idling better.

I will know for sure in the morning... I will keep posted...


I did take the carpet out and reinstalled my HAM radio... No change
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Unread 10-11-2005, 06:23 AM   #6
wildflowerjones
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No Luck

Well crap...

Rough idle this morning... Hit the gas a couple of times and then it smoothed out...

Still searching... Suggestions are welcomed...
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Unread 10-11-2005, 09:14 PM   #7
RockPaws
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If your getting a rough idle after the first start of the day and it lasts maybe 30 seconds or so. It sounds like you need the computer flashed. Their is a TSB that covers this problem, or rough idle after start. My 01' had this problem, and the new updated software fixed the rough idle. Of course the dealer needs to do the re-program.
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Unread 10-12-2005, 10:24 AM   #8
98JEEPTJ
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Well here is a weird wrench in things it didn't do it when it was in the mid 30's last week stared the first crank, now back to the same old chug...I don't think it's a software prob because after you rev it up a fiew times it stops.
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Unread 10-13-2005, 06:03 AM   #9
wildflowerjones
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I pulled the the IAC Valve and sprayed the bejesus out of it with TB Cleaner. Wiped it down. Cleaned the Throttle Body where the IAC goes in.

The Jeep runs better, however, this morning is still got a rough idle until I hit the gas a couple of times.

This also happens when I leave from work every afternoon.

One of the Advanced Auto employees suggested I might have a leaky fuel injector. Through out the night/day it drips enough gas into the engine until it is "flooded". Once the excess is burnt off, everythinf runs like a champ.

Any thought about this? Is there a way to check the injectors.

Someone else suggested that the o2 sensors were crapping out, however, I figured this would give an "check engine" light. However, I may replace them anyway.

Anyother suggestions/solutions would be appriciated...
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Unread 10-13-2005, 04:05 PM   #10
RockPaws
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They both still sounds like they need a software update. Mine did exactly what you both describe. Right after the first start when cold, it would run rough. You could rev it up, or just let it run thru the rough idle. Then all normal. May be worth checking with your local jeep dealer to see if theirs a update.

The only other time I have seen the rough idle, is when the battery voltage is very low during start. The computer may have lost its memory. They tend to run rough for they next 4-5 starts after the battery problem is fixed. The OBD II readyness tests will show not ready also. But this does not sound like the problem... just FYI.
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Unread 10-14-2005, 07:01 AM   #11
wildflowerjones
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Here is the fix...

IAC valve... The old one was stuck in one position. Put the new one on I picked up from NAPA.

This morning problem solved!!!

rock on
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Unread 10-16-2005, 03:07 PM   #12
SEALLogan
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Quote:
Originally Posted by wildflowerjones
Someone else suggested that the o2 sensors were crapping out, however, I figured this would give an "check engine" light. However, I may replace them anyway.

FYI an O2 sensor shouldn't go bad until 50000+ miles, but are usually getting lazy by 60-70000 miles.

When they do start to go, they will give inaccurate reading to the computer, but will not set the CEL. An exception to this is the O2 behind the cat, which will throw a code. This sensor should not effect performance though, as it is only there to make sure your CAT is doing its job. The POS 1 sensor probably won't set a code until well after it is shot.
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Unread 01-17-2007, 11:47 AM   #13
Mark Cline
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What is an IAC valve and where is it located. I have hesitation all the time from idle.
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Unread 01-18-2007, 07:48 AM   #14
alexrule123
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mine was kinda like this, and it was the map sensor. there was a tear in the tubing, so i just fixed that and good as new
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Unread 01-26-2007, 02:35 PM   #15
sonofa
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I am having the same thing happen to me. Only thing is it wasn't doing this until this week right after I changed the oil. My oil pressure is little higher now, could high oil pressure cause this?

This same thing happened last winter to my 93 Explorer, but that time I was leaking transmission oil.
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