stumbling in first gear

Nathanael Rusciolelli

Nathanael Rusciolelli

TJ Enthusiast
Joined
Dec 4, 2016
Messages
118
Location
North Carolina, United States
Not even sure what to call this issue really but my jeep is doing this weird thing in first gear every now and then where it all of the sudden stops accelerating for a split second and then jumps up again and continues to accelerate. It's really hard to describe. It almost feels like when an automatic transmission shifts gears (mine is manual however). It's very quick and it doesn't feel like the engine is missing or anything. For some reason I keep thinking that the serpentine belt is slipping or something. Would that cause an issue like this? If I turn the A/C on the problem is worse and more consistent (it's actually done that with the A/C on for a while now but i've just ignored it and turned off the ac). This is the first time it's had this sort of issue without the A/C on. It's not a big issue yet and it doesn't do it in any other gear but it's just making me nervous and I like my jeep working properly. Btw, it's a 99' 2.5l. Your advice is much appreciated.
 
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Nathanael Rusciolelli said:
Not even sure what to call this issue really but my jeep is doing this weird thing in first gear every now and then where it all of the sudden stops accelerating for a split second and then jumps up again and continues to accelerate. It's really hard to describe. It almost feels like when an automatic transmission shifts gears (mine is manual however). It's very quick and it doesn't feel like the engine is missing or anything. For some reason I keep thinking that the serpentine belt is slipping or something. Would that cause an issue like this? If I turn the A/C on the problem is worse and more consistent (it's actually done that with the A/C on for a while now but i've just ignored it and turned off the ac). This is the first time it's had this sort of issue without the A/C on. It's not a big issue yet and it doesn't do it in any other gear but it's just making me nervous and I like my jeep working properly. Btw, it's a 99' 2.5l. Your advice is much appreciated.
Click to expand...
Do you have a check engine light on in your dash?
 
Nathanael Rusciolelli said:
Not even sure what to call this issue really but my jeep is doing this weird thing in first gear every now and then where it all of the sudden stops accelerating for a split second and then jumps up again and continues to accelerate. It's really hard to describe. It almost feels like when an automatic transmission shifts gears (mine is manual however). It's very quick and it doesn't feel like the engine is missing or anything. For some reason I keep thinking that the serpentine belt is slipping or something. Would that cause an issue like this? If I turn the A/C on the problem is worse and more consistent (it's actually done that with the A/C on for a while now but i've just ignored it and turned off the ac). This is the first time it's had this sort of issue without the A/C on. It's not a big issue yet and it doesn't do it in any other gear but it's just making me nervous and I like my jeep working properly. Btw, it's a 99' 2.5l. Your advice is much appreciated.
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Have you worked on your Jeep recently? Or has anyone worked on your Jeep recently? Any changes at all recently?

Note: seriously. Issues can stem from a previous modification or repair or recent change.
 
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Fouledplugs said:
Have you worked on your Jeep recently? Or has anyone worked on your Jeep recently? Any changes at all recently?

Note: seriously. Issues can stem from a previous modification or repair or recent change.
Click to expand...
The most recent work done to it was transmission fluid change and about a month ago I had the cooling system overhauled (new everything). I'm starting to wonder if maybe the clutch is slipping a little bit, I've never experienced what that feels like so I can't be sure. From what I've read, if the clutch slips, the engine would rev up but I wouldn't feel any acceleration. That's not exactly what this feels like. It's just like a very quick hiccup and than it jerks forward again.
 
Nathanael Rusciolelli said:
Not even sure what to call this issue really but my jeep is doing this weird thing in first gear every now and then where it all of the sudden stops accelerating for a split second and then jumps up again and continues to accelerate. It's really hard to describe. It almost feels like when an automatic transmission shifts gears (mine is manual however). It's very quick and it doesn't feel like the engine is missing or anything. For some reason I keep thinking that the serpentine belt is slipping or something. Would that cause an issue like this? If I turn the A/C on the problem is worse and more consistent (it's actually done that with the A/C on for a while now but i've just ignored it and turned off the ac). This is the first time it's had this sort of issue without the A/C on. It's not a big issue yet and it doesn't do it in any other gear but it's just making me nervous and I like my jeep working properly. Btw, it's a 99' 2.5l. Your advice is much appreciated.
Click to expand...

That wouldn't be the serpentine belt. It almost sounds like your clutch is slipping. A good way to test if the clutch is slipping is to put it in gear, give it full throttle, and if the RPMs shoot up super fast but the clutch fails to grab, you'll instantly notice.

It only does it in 1st gear, and it only does it sometimes, or all the time?

When you say it continues to accelerate when it does this, does that mean it accelerates without your foot on the pedal?
 
Chris said:
That wouldn't be the serpentine belt. It almost sounds like your clutch is slipping. A good way to test if the clutch is slipping is to put it in gear, give it full throttle, and if the RPMs shoot up super fast but the clutch fails to grab, you'll instantly notice.

It only does it in 1st gear, and it only does it sometimes, or all the time?

When you say it continues to accelerate when it does this, does that mean it accelerates without your foot on the pedal?
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I'm starting to think that it's the clutch slipping too. I've heard that if the clutch is slipping really bad than it wouldn't stall if I tried to start in a high gear. Mine does stall so I know it's at least not too far gone. If I was more experienced I could say with more certainty but it really only seems to occur in first gear and its inconsistent (does it every two or three times I set off in first).
 
My guess is ignition or fuel. Plugs, wiring, fuel filter, fuel pump.
You need an engine analyzer. Take it to a shop and have them hook it up.

If it is intermittent it might be hard to find but turn the AC on, try to duplicate the conditions, cold or at full temp. Might be the ignition module too.
 
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Nathanael Rusciolelli said:
I'm starting to think that it's the clutch slipping too. I've heard that if the clutch is slipping really bad than it wouldn't stall if I tried to start in a high gear. Mine does stall so I know it's at least not too far gone. If I was more experienced I could say with more certainty but it really only seems to occur in first gear and its inconsistent (does it every two or three times I set off in first).
Click to expand...

I'd bet you could take it to any clutch / transmission shop (i.e. AAMCO) and they would drive it with you in it. They'd be able to tell in 5 minutes if the clutch was on it's way out or not. They probably wouldn't charge you either, because they'd want the potential business.
 
Alrighty then @Nathanael Rusciolelli, once you eliminate a slipping clutch here is a little more info for you to check into from another "four angry squirrels" herder.

The 2.5 has two additional features that the 4.0 doesn't. One is that the ECM will kick the RPM up approximately 250-300 RPM under two specific conditions. The first is when the AC is turned on. The second is when you load up the power steering, such as when turning sharply at low speed in a parking lot. This is normal behavior for an SE. If the RPMs are "popping up" on the tachometer only in first gear and mostly with the AC on then this may be the cause. As strange as it sounds, cleaning the IAC may diminish how much you notice this feature. If the IAC is a little "sticky", it will increase the RPMs more than normal and make the increase more noticeable.

Go here for instructions on cleaning the IAC: https://wranglertjforum.com/threads/how-to-clean-your-iac-idle-air-controller-valve.662/

Report back if this improves things, or even if it doesn't.
 
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StG58 said:
Alrighty then @Nathanael Rusciolelli, once you eliminate a slipping clutch here is a little more info for you to check into from another "four angry squirrels" herder.

The 2.5 has two additional features that the 4.0 doesn't. One is that the ECM will kick the RPM up approximately 250-300 RPM under two specific conditions. The first is when the AC is turned on. The second is when you load up the power steering, such as when turning sharply at low speed in a parking lot. This is normal behavior for an SE. If the RPMs are "popping up" on the tachometer only in first gear and mostly with the AC on then this may be the cause. As strange as it sounds, cleaning the IAC may diminish how much you notice this feature. If the IAC is a little "sticky", it will increase the RPMs more than normal and make the increase more noticeable.

Go here for instructions on cleaning the IAC: https://wranglertjforum.com/threads/how-to-clean-your-iac-idle-air-controller-valve.662/

Report back if this improves things, or even if it doesn't.
Click to expand...
Thank you for the insight on the 2.5l engine. My iac should be pretty clean as I cleaned it out recently when trying to track down another repair. When you say that the ECM will kick up the RPM, are you referring to idle speed only? It always idles up about 200 RPM when I turn on the AC, which I know is normal. It's during acceleration that this issue occurs.
 
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Nathanael Rusciolelli said:
Thank you for the insight on the 2.5l engine. My iac should be pretty clean as I cleaned it out recently when trying to track down another repair. When you say that the ECM will kick up the RPM, are you referring to idle speed only? It always idles up about 200 RPM when I turn on the AC, which I know is normal. It's during acceleration that this issue occurs.
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Yup, that is normal. It is idle, and just off idle RPM only that gets modified by the ECM. If the IAC is slow to react to the ECM signals it will maintain a higher RPM off idle as well. For a short period of time. I thought it was worth mentioning.
 
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The fact that it happens during acceleration really does sound like a slipping clutch to me. Sure, it could be something else (and I wouldn't know without driving it), but anytime I ever had a slipping clutch, that's exactly what it did.
 
Nathanael Rusciolelli said:
Not even sure what to call this issue really but my jeep is doing this weird thing in first gear every now and then where it all of the sudden stops accelerating for a split second and then jumps up again and continues to accelerate. It's really hard to describe. It almost feels like when an automatic transmission shifts gears (mine is manual however). It's very quick and it doesn't feel like the engine is missing or anything. For some reason I keep thinking that the serpentine belt is slipping or something. Would that cause an issue like this? If I turn the A/C on the problem is worse and more consistent (it's actually done that with the A/C on for a while now but i've just ignored it and turned off the ac). This is the first time it's had this sort of issue without the A/C on. It's not a big issue yet and it doesn't do it in any other gear but it's just making me nervous and I like my jeep working properly. Btw, it's a 99' 2.5l. Your advice is much appreciated.
Click to expand...
Check the transmission and transmission fluid, then check the differential and its fluid. your gears could be slipping. check your air intake and throttle body. make sure ur not overheating, check coolant. and check your oil. you could also have a fuel pump or fuel injector issue... and last if all, make sure your alternator is working properly.
 
Nathanael Rusciolelli said:
Not even sure what to call this issue really but my jeep is doing this weird thing in first gear every now and then where it all of the sudden stops accelerating for a split second and then jumps up again and continues to accelerate. It's really hard to describe. It almost feels like when an automatic transmission shifts gears (mine is manual however). It's very quick and it doesn't feel like the engine is missing or anything. For some reason I keep thinking that the serpentine belt is slipping or something. Would that cause an issue like this? If I turn the A/C on the problem is worse and more consistent (it's actually done that with the A/C on for a while now but i've just ignored it and turned off the ac). This is the first time it's had this sort of issue without the A/C on. It's not a big issue yet and it doesn't do it in any other gear but it's just making me nervous and I like my jeep working properly. Btw, it's a 99' 2.5l. Your advice is much appreciated.
Click to expand...
Check the transmission and transmission fluid, then check the differential and its fluid. your gears could be slipping. check your air intake and throttle body. make sure ur not overheating, check coolant. and check your oil. you could also have a fuel pump or fuel injector issue... and last if all, make sure your alternator is working properly.
 
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