Jeep Wrangler Forum

Jeep Wrangler Forum (
-   TJ General Discussion Forum (
-   -   We found it! (

kellyjo29 08-06-2010 06:03 PM

We found it!
I sweet talked my brother in law into taking the Jeep out for a little jaunt tonight and she was acting up the whole time- bucking and sputtering to beat the band. He noticed that everytime it did that little hiccough the shift indicator light would come on- his diagnosis: since putting on the bigger tires, the gears/RPMs whatever do not quite know what to think about that. He said there is a way to shut that shift indicator off. Anyone know anything about this? It makes sense- the way of driving it has changed as I can no longer go into 5th gear. It happens only after going over 1800 RPMs that the light comes on. I've never paid any attention to that light cuz it's pretty much been on crack since I bought the Jeep. It is telling me to shift when I've just shifted so ignoring it was the way to go. Up until last year I only had a speedometer half time- well that was fixed right after the bigger tires were put on cuz I didn't want to get wheeled as I knew my speedometer would be off. Now that makes sense too- it never hiccoughed when the speedometer wa only working part-time. Don't you just hate it when something about smacks you in the face and you didn't pick up on it?!! Now I'm kicking myself for not noticing it. Anyone know what this little thing is called? Thanks in advance-
Kelly in Michigan

Wildkarde 08-06-2010 06:44 PM

I highly doubt that the shift light is causing the engine to run rough....but with that being said after reading that three times I am not sure thats even what you were asking..........

jeepjones 08-06-2010 07:00 PM

The shift light has nothing to do with it. The only way to shut off the light is to take the cluster apart and remove it. My light does the same thing because of the larger tires, I just ignore it, keep searching. Is your cat plugged up?

JDsDream 08-06-2010 07:22 PM

Is your CEL on? Have you checked for codes?

baja 08-06-2010 07:33 PM

No offense but I am completely lost as to what your question is.Bucking and sputtering sounds like you were in too high of a gear and you are lugging the motor.

kellyjo29 08-06-2010 07:38 PM

New catalytic converter installed today and didn't fix it. I'm not saying the shift light has anything to do with the problem but that since it comes on after the hiccough, that the RPMs are now different. I'm thinking there is a common thread between those two things. Does that make more sense? What is a CEL?

Wildkarde 08-06-2010 07:54 PM

CEL=Check Engine Light....Can you maybe take another shot at explaining the problem start to finish. No offense intended by that first time through was very hard to understand.

kellyjo29 08-06-2010 08:35 PM

No offense taken at all- I appreciate your time and input! :)

I have a 4 cylinder manual 5 speed jeep. After I put 33 inch tires on last year, it started hiccoughing- it would vibrate, then sputter or lose power to engine ( it seems like that anyway). It doesn't matter if the engine is hot or cold. I've installed a new fuel filter, and pump- today a new cat converter was installed thinking it wasn't getting enough airflow. It doesn't stall. Gas mileage is poor 12, down from 16 before new tires. I'm not sure if the worse gas mileage is from the tires or the hiccough. Tonight, my brother in law took the jeep for a drive and noticed that with the vibration, then hiccough, the shift light comes on right after. He thought that since the RPMs are different with the larger tires, the engine is throwing up the shift light because there is a default setting as a protective mechanism to prevent too high of RPMs. Is this feasible? In my mind, it makes sense. He thought there was some sort of switch with that shift light- it obviously works off RPMs right? I truly have no idea but after he noticed the light coming on after the hiccough, I drove it and it was true. The light didn't start coming on at low speeds, but after I picked up speed, the shift indicator light would come on like clockwork after the vibration and hiccough.
There has never been a check engine light with this whole problem and it has been going on for over a year- approx. the same amount of time I've had the larger tires. There has also been a new distributor cap and wires put on as well as a tune up. I'm so close to sticking this thing out to the road with a for sale sign. It is not my daily driver but when I chose to take it, I want it to run well. Is this a better explanation? It's so hard to describe the problem here let alone to a mechanic who's looking at me like I'm half baked.

I cannot describe the bucking and sputtering as anything more detailed then a hiccough- losing power with a vibration. It feels like riding with someone who doesn't know how to shift. I do know how to shift and that's not it but it 'feels' like that.

pokey 08-06-2010 08:47 PM

The shift light has nothing to do with it, just a coincidence. I have almost stock tires and if I shifted with the light IMO I would be lugging the engine. I think they put that light there to try and get people to shift like pansies and get better mileage.

I'll let the guys who know more about lifts chime in, but I know if you are running 33" tires you should re-gear, especially with a 2.5.

Wildkarde 08-06-2010 08:48 PM

MUCH better :)

The shift light is based of RPMS but does not have any effect on the engine,its more of a suggestion on when to shift but other than that does nothing.

Now does it do this hesitation when you give it gas, when you let off or just completly randomly. Does it do it in all gears? Does it make a difference if you are going up a hill, down a hill etc when you notice it?

Can't promise I can pin point the problem but the more info we get out here the more likley some will be able to point you in the right direction.

When was the last time you changed the plug wires etc? It sounds like a misfire, but as you said its hard to tell on a forum and not in the seat of the jeep.

JDsDream 08-06-2010 09:06 PM

Just a couple of points here. first, 33" tires + 2.5 without a gear change are going to give you problems. I'm actually surprised you aren't having worse problems. Second, your speedometer is going to be off, therefore your odometer will not read acurate mileage either.

Wildkarde 08-06-2010 09:33 PM

Disreguard my question about plug wires...somehow totally missed that you had already changed them.

Seems like the gears would make it gutless but not do what he was describing... but if it more like lugging and not actually losing power for a second then I supposed it could be gears as it will lugg out higher in the rpm band with 33's than it did with stock tires....but if it just does it once and goes away than I wouldnt think it would be a gearing issue.

djw97tj 08-06-2010 09:55 PM

so you profile says you have a 4" lift with a lift that high you have to change the driveshaft angles ect. did you do that? also with 33s your stock 4.10 gears are inefective, you should regear to 4.56 or 4.88 i would recommend 4.88 with the 2.5. im in the same boat the biggest you can run without regearing it is like 31s maybe 32s in the fourbanger.

All times are GMT -5. The time now is 05:44 PM.

User Alert System provided by Advanced User Tagging v3.1.0 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.