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Unread 04-13-2010, 04:03 PM   #1
95GreenWrangler
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Sluggish YJ Suggestions? Common Problem?

I have a 1995 Wrangler with a 4.0 6cyl. Engine and auto trans. Axle ratio is still stock (prob 3.08? i am not near my truck) . Stock wheels and tires, a borla headers and borla catback. However the truck doesnít see to really have any pickup. I can understand if I went to 33ís I would need to change axle ratio, but for now this set up it should be working fine. I see my RPMís climbing as I put the petal to the metal, however my truck doesnít move as fast as it should. Even my friends truck (í89 yj, 4.2 liter 5 speed w/ 35ís) moved better than this BEFORE he regeared to 4.56. Oil's good, air filter's clean. replaced the plugs and wires and such a while back. Is this a trans problem? Something common? Donít get me wrong Iím not expecting a dragster, but I would at least like the confidence to pull onto the highway... Any suggestions would certainly help because I no longer know how to get it to go normal speeds.

Thanks,
Courtney

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Unread 04-13-2010, 04:07 PM   #2
SkullTripper
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What plugs did you put in it? and What kind of oil did you put in it?
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Unread 04-13-2010, 04:17 PM   #3
95GreenWrangler
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Don't remember exactly what brand right now, but I know they AREN'T Champions. I don't like those, at least something basic of another brand.

Oil is Pep Boys brand or Castrol 10W-40, depends what we have in the garage at the time.

But in general it has always been this slow, I have tried different combinations of things and it didn't help. My friend's 89 YJ I mentioned, he just put in whatever oil and spark plugs not caring what brand and his truck always had more pickup than mine.

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What plugs did you put in it? and What kind of oil did you put in it?
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Unread 04-13-2010, 04:32 PM   #4
YJMatt95
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How about an O2 sensor that is going bad? I've been told it can cause the engine to hesitate while accelerating. Maybe, you have a dirty fuel filter??? Just my 2 cents.
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Unread 04-13-2010, 04:39 PM   #5
dirtydan69
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in an auto transmission there is a torque converter that is the link between the trans and the engine. it is designed to slip some, this is why most racing vehicles use manual tranny's with a clutch between them. when a torque converter goes bad it will slip more than it should, and your rpms will rise without much change in power/speed to the rear axle. there is always a possiblity that it could be something in the transmission itself, but the torque converter is relatively cheaper than a transmission rebuild. so i would start there. you may need to take it to a transmission shop, depending on how handy you are with mechanics.
P.S. the only way you can be increasing your rpms w/o speeding up is to have slippage between the engine and axle(s).
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Unread 04-13-2010, 04:47 PM   #6
95GreenWrangler
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Nope had to recently replace my O2 sensor after I got my exhaust done, that was very dirty. How often should they be replaced?

Also replaced fuel filter when I thought that was the cause of a stalling problem, that was last year.

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Originally Posted by YJMatt95 View Post
How about an O2 sensor that is going bad? I've been told it can cause the engine to hesitate while accelerating. Maybe, you have a dirty fuel filter??? Just my 2 cents.
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Unread 04-13-2010, 04:54 PM   #7
95GreenWrangler
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Hmm I'm feeling that this might be the best option to check on, since I thought this was the cause of a problem I had in my Mustang, changed the fluid in that and it didn't help (still had shifting/shuddering issues). Thanks.

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Originally Posted by dirtydan69 View Post
in an auto transmission there is a torque converter that is the link between the trans and the engine. it is designed to slip some, this is why most racing vehicles use manual tranny's with a clutch between them. when a torque converter goes bad it will slip more than it should, and your rpms will rise without much change in power/speed to the rear axle. there is always a possiblity that it could be something in the transmission itself, but the torque converter is relatively cheaper than a transmission rebuild. so i would start there. you may need to take it to a transmission shop, depending on how handy you are with mechanics.
P.S. the only way you can be increasing your rpms w/o speeding up is to have slippage between the engine and axle(s).
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Unread 04-13-2010, 05:12 PM   #8
idaholtby
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I agree with the torque converter scenario. Especially if when you get on it hard and the RPMs increase, but the thrust does not follow suit. As far as the O2 sensor, they typically have a lifespan of 100K miles. The OBDI equipped YJ's have a maintenance timer that triggers around 81.5K miles which is meant to tell the owner it is time to pro-actively replace the O2 sensor before it fails. Pre '91 has a mechanical timer below the dash for this, while a '91 and newer has this incorporated into the ecm.
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Unread 04-13-2010, 06:44 PM   #9
driveajeep812
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A clogged cat perhaps.
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Unread 04-13-2010, 06:52 PM   #10
dirtydan69
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just to get the facts straight, is the engine hesitating, stumbling, really hard to rev in neutral/park? or is it slipping when given gas in gear (drive or reverse etc)? slipping=trans problem, the other is going to be engine related.
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Unread 04-13-2010, 07:18 PM   #11
95GreenWrangler
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Nope, brand new when new borla system was put on.

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A clogged cat perhaps.
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Unread 04-13-2010, 07:22 PM   #12
95GreenWrangler
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No not slipping, just not powerful enough for what it should be at. I shouldn't be worried that my Jeep won't get up to speed enough when pulling onto the highway, but I am because it has no kick (kind of hard to explain in words I guess, without everyone taking a ride in my Jeep) I know it is a Jeep and I'm not expecting racecar like speed.

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Originally Posted by dirtydan69 View Post
just to get the facts straight, is the engine hesitating, stumbling, really hard to rev in neutral/park? or is it slipping when given gas in gear (drive or reverse etc)? slipping=trans problem, the other is going to be engine related.
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Unread 04-13-2010, 08:03 PM   #13
moonshinefuel
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You should have good power with that 6 cylinder. It is a strong engine. I know this is common sense stuff here but I don't recall seeing it mentioned above. Are your throttle body and fuel injectors clean, is your rotor and cap clean? Just want to eliminate this if you are sure.
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Unread 04-13-2010, 08:11 PM   #14
95GreenWrangler
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Yes exactly! I want the power I should have. Well the cap and rotor are recently knew, since I thought that was a solution to another problem. However I can't confirm the throttle body and fuel injectors either way, I would like to say they are clean, but haven't recently checked.

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Originally Posted by moonshinefuel View Post
You should have good power with that 6 cylinder. It is a strong engine. I know this is common sense stuff here but I don't recall seeing it mentioned above. Are your throttle body and fuel injectors clean, is your rotor and cap clean? Just want to eliminate this if you are sure.
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Unread 04-13-2010, 08:34 PM   #15
moonshinefuel
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If it were mine, that's what I would do, run some throttle body cleaner spray down the intake, can says do that when it is off, but I do it when it is running, but I am not advising that. Put some high quatity fuel injector cleaner in the tank also. See if that does it. If not, I would then proceed to the ignition coil, I would not bother testing it myself if I thought it was the factory original, I would just buy a new one. (But that's me). If after that, it still was having a problem, then of course, start looking elsewhere, and go from there.
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