42RLE transmission reprogram/shift kit??

[resistance]

J-thompson, TJKJ; when I hit the gas at about 55 mph (90 kmh) I don't get such an instant response everytime. I said "everytime", because sometimes I floor it and absolutely nothing happens, I don't know why. I've tried many other ways to get the most out of it and oddly enough, I only get the boost each and every time when I press the gas pedal 2/3 of the way down and hold it right there. Does that sound normal to you?

Another thing is, when I need instant acceleration on the highway, or better traction driving uphill, I reach high RPMs like 5000-6000, but can't feel enough power output. The engine roars loud, but no impressive acceleration occurs. It feels like forcing the hell out of an old 1.4 lt. engine.

Do you think there are other issues, or am I expecting too much??

 

[tjkj2002]

J-thompson, TJKJ; when I hit the gas at about 55 mph (90 kmh) I don't get such an instant response everytime. I said "everytime", because sometimes I floor it and absolutely nothing happens, I don't know why. I've tried many other ways to get the most out of it and oddly enough, I only get the boost each and every time when I press the gas pedal 2/3 of the way down and hold it right there. Does that sound normal to you?

Another thing is, when I need instant acceleration on the highway, or better traction driving uphill, I reach high RPMs like 5000-6000, but can't feel enough power output. The engine roars loud, but no impressive acceleration occurs. It feels like forcing the hell out of an old 1.4 lt. engine.

Do you think there are other issues, or am I expecting too much??

You got other issues.

When was the last time the trans fluid was changed? If has been done was ATF+4 used? If not that is one of your issues.

Last time spark plugs changed? Should be every 30k.

Last time PCV valve changed? Should be every 30K for best performance.

How does the air filter look? If your playing alot in the sand most of that sand(call it moondust) will make it past the air filter and reduce compression in the engine which = major power loss.

Every had the fuel system professionally cleaned? Should be done once a year as carbon buildup is a major issue in modern FI engines.

Might want to have the fuel pressure checked under high load(power braking) to make sure it's not a pump or fuel filter issue.

Oh and one last thing,does your speedo work?

That is just a few things to start checking.

 

[osufans]

I'd say you may be having some issues with your transmission. When I press the pedal all the way down, mine goes. I originally started this thread with the issue about OD being too quick to shift, and since it was so tall, I would almost immediately downshift after going into OD because the Jeep would start losing momentum.

I have since learned to deal with this issue, but even still, the darn thing sometimes wants to upshift too soon, and will often times have to hunt for a gear because I'll be slowing down to turn, complete the turn, then press the accelerator again, and the transmission will find itself confused as to which gear to go to. That's my only beef with autos...I can't say it's just this one, as every auto I've ever owned (save for one 5R55E by FORD!!!) has done that.

But your issue sounds entirely different...I would have to say, I had a Pontiac Grand Prix GT (wider is better...lol) and it was showing signs of sluggish acceleration, and sloppy shifts...turned out the planetary gear was about gone. Ended up with a rebuilt transmission (compliments of GM, thanks to Certified Pre-Owned).

 

[resistance]

Thank you for the informative replies. They've been very helpful. Now back to the checklist:

You got other issues.

When was the last time the trans fluid was changed? If has been done was ATF+4 used? If not that is one of your issues.

Last time spark plugs changed? Should be every 30k.

Last time PCV valve changed? Should be every 30K for best performance.

How does the air filter look? If your playing alot in the sand most of that sand(call it moondust) will make it past the air filter and reduce compression in the engine which = major power loss.

Every had the fuel system professionally cleaned? Should be done once a year as carbon buildup is a major issue in modern FI engines.

Might want to have the fuel pressure checked under high load(power braking) to make sure it's not a pump or fuel filter issue.

Oh and one last thing,does your speedo work?

That is just a few things to start checking.

TJ, in the last two months, spark plugs, all fluids and air filter were changed. The old air filter was not in very bad condition though, not much dust or sand around here actually.

If I'm not mistaken, clening the fuel system is called "carbon-clean" process. No, I didn't have it done. I'll take care of it as soon as possible.

I didn't know what a PCV valve is, so I did some research and learnt what it is. Good idea, thank you. But the main problem is, I don't know and can't find what the "PCV valve" is called in my language If I can explain the mechanics what it is (maybe show them a pic), I'll have it changed.

My speedo works, no issues there. But my problem would still continue even without a speedo, because as I've said, I just can't feel the power of the 3.7 lt engine. I don't get that "being pushed into the seat" feeling. Do you?

 

[osufans]

I don't get that "being pushed into the seat" feeling. Do you?

Definitely. I was surprised the moment I took my Liberty for a test drive how zippy it was. I wouldn't say "balls to the wall" push you back in your seat and you can't sit forward until you let off the accelerator...but definitely brisk.

So if you think you have an engine issue, rather than a transmission, have you had your engine compression tested? Why did you change the plugs, and did you look at the old ones? They could indicate improper combustion in the engine (or even the existing ones could show some indication, depending on how bad the issue is.)

Oh, and one other issue I don't recall if you've checked is...the catalytic converter can become clogged, which will really hamper engine output.

And just off the top of my head, have you changed the fuel filter yet? If it is old, it can become clogged and cause fuel flow problems, which also cause top-end (high rpm) loss.

 

[tjkj2002]

I didn't know what a PCV valve is, so I did some research and learnt what it is. Good idea, thank you. But the main problem is, I don't know and can't find what the "PCV valve" is called in my language If I can explain the mechanics what it is (maybe show them a pic), I'll have it changed.

Look on your oil fill tube,there is a hose that attaches to it and what it attaches to on the oil filler tube is the PCV valve,stands for "Positive Crankcase Valve" if that helps any.

 

[eradicator006]

My speedo works, no issues there. But my problem would still continue even without a speedo, because as I've said, I just can't feel the power of the 3.7 lt engine. I don't get that "being pushed into the seat" feeling. Do you?

My '05 is the same way as your Jeep. When going 100kph on freeway and I press the gas 2/3 of the way, the jeep downshifts to 2nd, rpms jump to 5k and it doesn't throw you back like you think it would. I honestly think I get better acceleration if I don't push so ******* the gas and only downshift to 3rd and not 2nd. If I am standing still and floor it, I get some tire squeal and it takes off at a nice acceleration all the way up to the speed limiter.

My friends '04 Rennegade is the same way as mine so I don't think it's a problem. Remember, you're driving a Jeep and not a sports car. Don't expect too much for acceleration.

 

[resistance]

So if you think you have an engine issue, rather than a transmission, have you had your engine compression tested? Why did you change the plugs, and did you look at the old ones? They could indicate improper combustion in the engine (or even the existing ones could show some indication, depending on how bad the issue is.)

Oh, and one other issue I don't recall if you've checked is...the catalytic converter can become clogged, which will really hamper engine output.

I don't know of a dealer who does that test around here. I don' think that they've even heard about it, but even so I'll just ask. I got the spark plugs changed, because I own this vehicle for barely a year now, and when I got them checked, the plugs were black and totally worn out. The dealer thinks that the previous owner never changed them for years. The cats are new BTW, they have been changed two months ago.

Look on your oil fill tube,there is a hose that attaches to it and what it attaches to on the oil filler tube is the PCV valve,stands for "Positive Crankcase Valve" if that helps any.

Yes, I've even learnt how to replace it, and will do it myself if I can find someone selling the valve.

My '05 is the same way as your Jeep. When going 100kph on freeway and I press the gas 2/3 of the way, the jeep downshifts to 2nd, rpms jump to 5k and it doesn't throw you back like you think it would.

My friends '04 Renegade is the same way as mine so I don't think it's a problem. Remember, you're driving a Jeep and not a sports car. Don't expect too much for acceleration.

I always remember that, but at the same time I see equivalent or larger SUV's with smaller engines performing better.. Also considering it consumes even more fuel than a Grand Cherokee V8, sometimes I think maybe the KJ is too heavy for this 3.7 V6 engine.

I turned O/D off today for better response. Wish this was the way it rides with O/D on... It is also interesting that the fuel consumption is decreasing dramatically when I turn O/D off. So what good is the O/D except for long highway trips?

 

[tjkj2002]

My '05 is the same way as your Jeep. When going 100kph on freeway and I press the gas 2/3 of the way, the jeep downshifts to 2nd, rpms jump to 5k and it doesn't throw you back like you think it would. I honestly think I get better acceleration if I don't push so ******* the gas and only downshift to 3rd and not 2nd. If I am standing still and floor it, I get some tire squeal and it takes off at a nice acceleration all the way up to the speed limiter.

My friends '04 Rennegade is the same way as mine so I don't think it's a problem. Remember, you're driving a Jeep and not a sports car. Don't expect too much for acceleration.

I know when I floor it doing 45-55mph I get a real nice burst of acceleration when it drops into 2nd (not 2nd prime),pulls very hard from 4500rpms-5500rpms,well as much as you'd expect for a 6000lbs Jeep though the 5.13 gears helps alot turning those 35" tires.

 

[eradicator006]

I know when I floor it doing 45-55mph I get a real nice burst of acceleration when it drops into 2nd (not 2nd prime),pulls very hard from 4500rpms-5500rpms,well as much as you'd expect for a 6000lbs Jeep though the 5.13 gears helps alot turning those 35" tires.

Just went out and tested this. You're right, and I'm actually quite surprised at how well it accelerated. Going 45-55 and dropping down to 2nd gives nice acceleration. Try giving it 2/3 throttle when going 62-65mph and you'll see what I mean by crappy acceleration. I'm thinking 62mph (or 100kph) is too fast for 2nd and that's why the problem.

 

[tjkj2002]

Just went out and tested this. You're right, and I'm actually quite surprised at how well it accelerated. Going 45-55 and dropping down to 2nd gives nice acceleration. Try giving it 2/3 throttle when going 62-65mph and you'll see what I mean by crappy acceleration. I'm thinking 62mph (or 100kph) is too fast for 2nd and that's why the problem.

Well I do have the 45RFE trans and have two 2nd gears (1 for normal upshifting,1 for highway passing,both different gear ratios) so I can still downshift into 2nd when I'm going 62-65mph.

 

[resistance]

One of the worst consequences of having the 42RLE is the power loss during highway passings. It really is dangerous so I often have to abort a passing on 2 direction roads if the other direction is not completely clear. And that is really annoying.

Two 2nd gears.. I'd get a 02 instead of mine just for the 45RFE if I knew that before

 

[spymoto]

I've got an 03' Rene' with the 45RFE ******, I Just got it about a month ago. I put a 2.5" franky lift on it and while driving with the stock size tires, I never had the transmission switch gears while on the highway (I always drive with the O/D on).
I just put on my new wheels, same tires as your running, the Cooper STT's but a slightly different size, mine are 255/70/16, wider but smaller radius. Now while driving my normal 160 mile route on the intersate, it constantly down shifts out of O/D when going up any slight hills (I set the CC at 69 MPH) It is annoying to say the least, so I may just turn off O/D while on the highway. Maybe it's the tires??? I'm currently running 37 PSI and they are Load C tires, 50 PSI max at 2200lbs. I'll have to do the chauk test to find out the right PSI since I couldn't find it anywhere on the net. I'd hate to bring them down to 30 PSI because right now when I let off the gas if feels like the brakes are on... oh yeah Now I can only get 15 MPG driving like a sunday driver :disgust:

 

[spymoto]

Also, I was thinking of re-gearing to the 4.10, how much of a difference is there in gearing between the 4.10 and just driving without O/D on? A free fix would be nicer to my wallet

 

[tjkj2002]

I've got an 03' Rene' with the 45RFE ******, I Just got it about a month ago. I put a 2.5" franky lift on it and while driving with the stock size tires, I never had the transmission switch gears while on the highway (I always drive with the O/D on).
I just put on my new wheels, same tires as your running, the Cooper STT's but a slightly different size, mine are 255/70/16, wider but smaller radius. Now while driving my normal 160 mile route on the intersate, it constantly down shifts out of O/D when going up any slight hills (I set the CC at 69 MPH) It is annoying to say the least, so I may just turn off O/D while on the highway. Maybe it's the tires??? I'm currently running 37 PSI and they are Load C tires, 50 PSI max at 2200lbs. I'll have to do the chauk test to find out the right PSI since I couldn't find it anywhere on the net. I'd hate to bring them down to 30 PSI because right now when I let off the gas if feels like the brakes are on... oh yeah Now I can only get 15 MPG driving like a sunday driver :disgust:

Also, I was thinking of re-gearing to the 4.10, how much of a difference is there in gearing between the 4.10 and just driving without O/D on? A free fix would be nicer to my wallet

It's the tires,you need to get the BCM prgrammed with the closest or exact rpm(revolutions per mile) to gte the trans to shift correctly as the TCM is confused by the different engine rpm and vehicle speed.

And yes 4.10's will help alot but you still need to get the speedo corrected.

 

[spymoto]

It's the tires,you need to get the BCM prgrammed with the closest or exact rpm(revolutions per mile) to gte the trans to shift correctly as the TCM is confused by the different engine rpm and vehicle speed.

And yes 4.10's will help alot but you still need to get the speedo corrected.

Ok , I did not know that. I thought people got that done so they knew exactly how fast they are going. Looking at a calculator i know that it's about +3 MPH off going 67 MPH.

Where is the best place to go for that? And what should I expect to pay to get it done?

Thanks!

 

[spymoto]

Another question... I did the math and the 255/70/16 is 665 Revs per mile acording to Cooper having a 30.31" height. Now do I want to put this number in or put the number in that is half tread wear (675 Revs per mile) for an average? I ask because 665 is as low as it can go because they are new and will only get smaller. Should I do the compromise?

 

[spymoto]

:freak3: ARRRRRR. OK, now I went on tire rack and they say that a 30.3" tire is 686 revs per mile. This doesn't add up mathmatically unless there is a difference because of the flat spot in the tire where the road meets the tire... Can anyone confirm this?

Otherwise:
30.31 * pi = 95.221673330307" around the tire
(63,360" in a mile)
63,360 / 95.221673330307= 665.3947 revs per mile VS. 686 on Tire Rack

 

[spymoto]

Called the dealership today and they said that they can do it for $40

 

[desync0]

The 42RLE is why I'm looking at trading in the KJ for an LJ or JK with a 6 speed.

I have to give it way too much gas getting up to highway speed or it just drops in to overdrive at 40-50mph, and then goes oh wait, we're trying to go faster, and kicks back out again, meanwhile I've lost momentum and have to gas it even more because the rpm is still too low to accelerate in 4th gear.

It's great if you never leave the city though lol