Rev limiter question. 4.0 I6

[Deadman 94 xj]

Is it possible to remove/max out the rev limiter on my engine? It's a noob question I know and I get the dangers of doing this, but it seems like mine (maybe the yr?) is set really low.

Thoughts? How, if it can be done?

[BUZZINHALFDOZZEN]

You might be able to do it with a superchip tuner type thing and gain a few horse while you're at it.

[Deadman 94 xj]

You might be able to do it with a superchip tuner type thing and gain a few horse while you're at it.

Thats a good point. I haven't thought about engine electronics in a long time. Thanks, I'll look into that.

[BUZZINHALFDOZZEN]

Not really sure what's out there for jeeps. I have a few stacked on the cummins.

[Deadman 94 xj]

I know there are some things out there. I was looking more for altering the stock engine, opposed to aftermarket.

I come from the frame of mind that not adding more fuel or air to the engine will help it last longer. I still run the stock air box lol.

[JeepSteeler]

My rev limiter is the ungodly noise and vibration it makes at about 3500 rpm.

[mxg342]

Not really sure what's out there for jeeps. I have a few stacked on the cummins.


If you're stacking, get a smarty and be done with it.

[Deadman 94 xj]

I found this:



1. The only way to do it is to either burn a new chip into the stock PCM or add a programmeable piggyback computer such as the Unichip. I didn't want to spend the $$$$ to do it.

2. Anything above 5500rpm would be suicide and even if you raise the limiter to 5500rpm, the performance advantage over the stock 5200rpm limiter is minimal.

3. The torque curve starts to drop off more quickly above 4500rpm and by 5200rpm the engine's already well past the peak HP point as well.


Based on that I'd say I'll just have to accept that it's no V8 :D. Maybe I'll still throw a chip in it...

[BUZZINHALFDOZZEN]

If you're stacking, get a smarty and be done with it.

Edge and smarty at the moment

[XJchris98]

Hypertech makes a programmer that lets you alter the rev limiter +/- 500 RPMS, raise your top speed limiter, etc...but I dont think it would work with your 94 (non OBD II).

http://www.hypertech.com/Default.aspx
If you contact the company, they may have something that would work for you. However, you might be screwed due to the lack of an OBD connection.

[Deadman 94 xj]

Hypertech makes a programmer that lets you alter the rev limiter +/- 500 RPMS, raise your top speed limiter, etc...but I dont think it would work with your 94 (non OBD II).

http://www.hypertech.com/Default.aspx
If you contact the company, they may have something that would work for you. However, you might be screwed due to the lack of an OBD connection.

Thats good info! Mine's a 96 FWIW. I never changed the user name lol.
http://www.hypertech.com/products-results.aspx

[tjblair]

I found this:



Based on that I'd say I'll just have to accept that it's no V8 :D. Maybe I'll still throw a chip in it...
You change your rev-limiter and you will be doing a V8 swap sooner than you would like............lead foot:biggrin:

[Krod]

why?

[tjblair]

why?
Have you seen Tom drive that jeep?:icon_eyes:
just kidding Tom:047:

[Krod]

lol Yes.

...but I meant why would you want to raise the rev limiter with no other mods? The power has long dropped off at that point, and you're risking kaboom for no real reason???

[tjblair]

lol Yes.

...but I meant why would you want to raise the rev limiter with no other mods? The power has long dropped off at that point, and you're risking kaboom for no real reason???
Oh, lol. In that case I agree.

[Deadman 94 xj]

LOL, thanks Jeff.

I get what you're saying Krod. It just comes down to me not knowing any better. I did a little research and understand that the engine needs to be able to breath and higher flowing injectors can be used with the air and blah blah blah. (that's an example. I wouldn't put injectors in an otherwise stock engine. A stroker, yes)

The way I was thinking was that I could just eliminate the thing that's keeping it from going past the line without harming anything. I was wrong.

Aside from the obvious engineering oversite, I thought I could just use my judgement to not kill the engine. But my judgement kinda sucks right now.

[wozz]

hmm they wouldn't put it there if you weren't supposed to hit it right?

[Deadman 94 xj]

hmm they wouldn't put it there if you weren't supposed to hit it right?

Riiight! :042:

[Krod]

hmm they wouldn't put it there if you weren't supposed to hit it right?

Oh believe me I hit mine like a cheap whore in Vegas all the time!
Never said you shouldn't hit it!!! But moving it is another thing

[fmlyof4whlrs]

Why are yo hitting the Rev limiter so much? If you are looking for more performance without engine work regear for better response. If you are constantly hitting the limiter will doing hill climbs or something of the such try a different gear or high range.

Also and I am not sure on this as I have not done it myself....but if you have an AW4 you can modify the torque convertor lockup to that you can lock it with a flip of a switch. This helps with engine braking on down hills as well as prevents some lose of power through the convertor....just make sure you turn it off before you try to stop or you will stall. Nice write up about it on Gojeepin.

[Deadman 94 xj]

Why are yo hitting the Rev limiter so much? If you are looking for more performance without engine work regear for better response. If you are constantly hitting the limiter will doing hill climbs or something of the such try a different gear or high range.

Also and I am not sure on this as I have not done it myself....but if you have an AW4 you can modify the torque convertor lockup to that you can lock it with a flip of a switch. This helps with engine braking on down hills as well as prevents some lose of power through the convertor....just make sure you turn it off before you try to stop or you will stall. Nice write up about it on Gojeepin.

Thanks, I'm pretty familiar with the shift kits. The latest one is a really nice kit.
The jeep is already geared. I'd like to get into engine work but I'd like to get the rest of the jeep up to par first. :) I doubt I'll ever do anything like a V8 swap though. Maybe one day when I have more time and $$, if the jeep lasts that long.

To answer you question though, I don't know why it hits the limiter so much. I'm not flooring it in Low. It's just the way it is I guess. I plan to take it easy on it for a while :D.

[PAFirefighter49]

My friend has a Jet Stage II chip on his TJ that helps gain power (along with high flow intake and exhaust and throttle body spacer) and also raised his rev limiter.

[Deadman 94 xj]

My friend has a Jet Stage II chip on his TJ that helps gain power (along with high flow intake and exhaust and throttle body spacer) and also raised his rev limiter.

I'm going to do a little more research on it. I did a lot of that stuff to my last jeep. Bored TB, aftermarket filter, and little stuff like that. The engine ended up developing a loud knock and it wasn't the lifters. I'm not saying that was the cause, it more than likely wasn't, but after all that, I decided I just wanted to leave this one be.

Now, I would like to get a little more power out of it though. The problem is a lot of this stuff is hit or miss as far as gains go. I have a free flowing exhaust on it, but not being opened up at the other end (intake) sort of renders that pointless.