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200 TJ 2.5 automatic won't go over 40 mph with 4.11 gears

ASE-TRANSMISSIONS

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GEARS? 2000 2.5 AUTOMATIC w/33's 40mph max speed unless pedal 2 floor! Another shop put 4.11 gears in and she still doesnt want to go over 40mph! We disconnected the exhaust to make sure cats weren't clogged. I don't believe that shop put enough gear but I wanted to get y'all's opinion before we say it out loud
we own a 89 YJ 4.0 manual transmission and we put gears in it and 36s and she screams on the interstate.
 

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Keister Bunny
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I would have guessed the 2.5 already had 4.11 gears from the factory? Maybe with an auto they went to a different ratio?

But yes with 33's and the 2.5 4.11 gears it's going to be a dog. You need to regear or live with it. This is assuming that everything else mechanically is in good shape
 

Chris

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So much information is missing here.

First off, was this issue present before the shop installed the new gears?

Secondly, do you realize that a 2.5 automatic is the worst possible combination you could have in terms of drivetrain? I wouldn't have gone any bigger than 31" tires on that, certainly if you plan on any interstate driving.

So it's going to be a dog no matter what just due to the drivetrain. Even with the correct gears it will still be a pig. My 2.5 automatic was barely able to get up to highway speeds and that was bone stock without any mods whatsoever. I'm wondering how much of it is related to that.

I'm sorry but you picked the wrong drivetrain to modify, that's for sure.

Keep in mind that I am not saying that this is normal. It should definitely go over 40 mph. What I am saying is that with that 2.5, an automatic transmission, 33s, etc., it's going to have a hell of a hard time getting to higher speeds, that's for sure. You're dealing with maybe 70-80 hp at the wheels.
 
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TJ4Jim

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If you had a Factory auto then it would have been equipped with the 3.73 and as Chris mentioned 31" tires with the 4.11 gears would be the best choice.
 

CharlesHS

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GEARS? 2000 2.5 AUTOMATIC w/33's 40mph max speed unless pedal 2 floor! Another shop put 4.11 gears in and she still doesnt want to go over 40mph! We disconnected the exhaust to make sure cats weren't clogged. I don't believe that shop put enough gear but I wanted to get y'all's opinion before we say it out loud
we own a 89 YJ 4.0 manual transmission and we put gears in it and 36s and she screams on the interstate.

Unless the engine was replaced in the 89 YJ; the YJ came with a 4.2L 87-89.
The 4.0L was not used in the YJ until later 89.
The YJ could have come with an AX-15; if it was a later production YJ 89-95.
The YJ could have come with a Peugot BA10; if it was an early production YJ 87-89; which is a undesirable transmission.
 

TheBoogieman

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I drove my neighbors 2.5L auto on 33s once. I still have the pic. :unsure:
p.s. This was on the street.
snail jeep (2).jpg
 
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ASE-TRANSMISSIONS

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Sry I'm wife trying to get info for husband. Customer brought their 2000 2.5L automatic Trans cause it was overheating and would not go into would not go past 40 miles an hour so he brought it to our transmission shop prior the customer took it to four wheel drive parts and had 411 gears put in it it originally came with 3.78 I just called the Jeep dealer and asked with the VIN what gear ratio came stock and it came with 3.73 so four-wheel drive parts put for 11s in it the customer does not know anything about big trucks so he brought it to my husband and yes it's a dog just trying to make sure we explain it to the customer properly because we do not have any experience with this particular comeback kind of issue don't want to tell the customer that a big company like that did him wrong unless we are sure so I reached out to the gurus I've owned our 89 Wrangler for over 15 years and she's perfect however my Jeep is different than this guys yes my husband would have never put this size tire on this Jeep without a larger engine. Thank you so much for your quick reply we just don't want to steer this guy wrong they took the tags off the rear end my husband rebuild rear ends and he would have never went with 411s on this Jeep he would have went higher but that's his personal opinion that's why I wanted to get y'all's opinion so I could let the customer know

So much information is missing here.

First off, was this issue present before the shop installed the new gears?

Secondly, do you realize that a 2.5 automatic is the worst possible combination you could have in terms of drivetrain? I wouldn't have gone any bigger than 31" tires on that, certainly if you plan on any interstate driving.

So it's going to be a dog no matter what just due to the drivetrain. Even with the correct gears it will still be a pig. My 2.5 automatic was barely able to get up to highway speeds and that was bone stock without any mods whatsoever. I'm wondering how much of it is related to that.

I'm sorry but you picked the wrong drivetrain to modify, that's for sure.
 

P man

Keister Bunny
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The customer screwed up by having 4.11 installed should have went much lower (numerically higher). Is there any check engine lights or codes present?
 
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Fouledplugs

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Too much information is missing as @Chris already stated.

Even with the 2.5L, 33inch tires, and 4.10/11’s it should still easily go over 40mph on a flat road.

What’s the airbox look like. Someone needs to open it up and check for obstructions, same needs to be done to the airbox plenum leading to the intake manifold.

Check the throttle body for obstructions. I’ve seen rags and other things left in them or even large chunks of debris from the filter get past and cause issues. Air filter could of came apart.

Any number of things could be wrong, a proper diagnostic needs to be performed like fuel pressure at idle and while driving, comparing them to what the manual has for standards.

I’d start with a detailed visual inspection and start taking a few things apart.
 
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ASE-TRANSMISSIONS

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Unless the engine was replaced in the 89 YJ; the YJ came with a 4.2L 87-89.
The 4.0L was not used in the YJ until later 89.
The YJ could have come with an AX-15; if it was a later production YJ 89-95.
The YJ could have come with a Peugot BA10; if it was an early production YJ 87-89; which is
I drove my neighbors 2.5L auto on 33s once. I still have the pic. :unsure:
p.s. This was on the street.
View attachment 349892

Funny 😁 😂 lol. Yall are awesome.
 
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OP
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ASE-TRANSMISSIONS

New Member
Joined
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Location
Orange park, Fl.
Too much information is missing as @Chris already stated.

Even with the 2.5L, 33inch tires, and 4.10/11’s it should still easily go over 40mph on a flat road.

What’s the airbox look like. Someone needs to open it up and check for obstructions, same needs to be done to the airbox plenum leading to the intake manifold.

Check the throttle body for obstructions. I’ve seen rags and other things left in them or even large chunks of debris from the filter get past and cause issues. Air filter could of came apart.

Any number of things could be wrong, a proper diagnostic needs to be performed like fuel pressure at idle and while driving, comparing them to what the manual has for standards.

I’d start with a detailed visual inspection and start taking a few things apart.

The customer screwed up by having 4.11 installed should have went much lower (numerically higher). Is there any check engine lights or codes present?

Thank you so much. My husband doesn't have anyone to bounce his ideas and thoughts off of. He took things apart looking for obstructions 3 days ago nothing out of place. Only 1 code for PO135 O2 Sensor Heater Failure. Radiator busted on top replaced Radiator and thermostat cleared code drove didn't come back. No other codes. I'm waiting for husband to finish what he is working on to ask the fuel pressure he got so I can post it to you. I did call dealer and get the gears she came with and you were right 3.73 stock. Thank yall! I read your responses to my husband and he is VERY thankful! He has been rebuilding transmissions and rear-ends for over 30 years he knows his stuff however you guys know your jeeps (inside and out) and we value your opinions. We consider our customers family and we thank yall for each and every thought you send our way! I will post the fuel info as soon as he comes out of his build room. My husband questions why would the other shop go with 4.11 gears or this large of a tire like you said 2.5 and automatic Customer doesn't know that's the shops responsibility to guide customers correctly. Yes customer purchased gears and tires at same place. Customer called shop and told them issues jeep will not gain speed will not maintain speed unless pedal to floor the shop said it's transmission that's why the customer came here. No transmission issues. Hold pedal to floor yes will down shift. The customer has been jacked around enough.
 
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Gilaguy23

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Sep 21, 2021
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A'holeville
IIRC I saw the name 4wheel parts wholesalers as the shop who did the mods. Been my experiance more than a few of their shops dont know their bungholes from a hole on the ground. About as reliable as having your jeeps engine rebuilt at Autozone. Pretty much the same general consensus of 4PWP's "procomp" line of stuff. For comparison many of us have 4 bangers and manuals with OEM 4.10 gears. Running 33's renders 5th useless basically,offroad is doable but its no pavement pounder. Even as 4th, or an autos 3rd is a 1 to 1 ratio, Id think your 2000 would do a little better than 40 mph. Good luck getting it sorted out.
 
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