How do I keep the truck from downshifting?

green02crew · Post by **green02crew** » Sun Dec 16, 2007 8:17 pm

I'm very used to a standard and when on the highway going up hills I would keep it floored in fifth gear rather than downshifting. Is there any way to keep my CC in 4th gear and just floor it on the highway? I live where the highways are constant up and down hills so I hate when it keeps having to downshift... the sound of money being thrown away! I don't mind slowing down a bit on the uphills because its in too high a gear. I just don't want the truck to choose a gear related to how far my foot is down on the accelerator. I'd prefer a cheap and easy fix but wouldn't everybody?

Post by **HenryJ** » Mon Dec 17, 2007 3:22 am

I bought a Hypertech Power Programmer II to make shift point adjustments as well as firm up the shifts.
Do a search for that as well as TCC , Torque Converter Control switch.
Another good topic would be the corvette servo thread.
All of those deal with transmission shifting and ways to alter it.

Sorry, no cheap or single answer.

green02crew · Post by **green02crew** » Mon Dec 17, 2007 7:31 am

I looked at the HPPIII and I could alter the shift points but not really prevent it from downshifting at WOT. I just miss the option of a standard to floor it without having the vehicle downshift. I want to remain in control and when I don't want it to downshift it shouldn't. I don't really see anything out there that would give me quite what I am looking for.

killian96ss · Post by **killian96ss** » Mon Dec 17, 2007 9:08 am

The shift point changes made with the HPPIII are only used @ WOT, which means changing them will do nothing for normal every day driving.

The only part that might help keep the transmission in OD at higher speeds is a new shift valve that only allows the transmission to downshift when more than 3/4 throttle is applied.

I belive the stock shift valve downshifts around 1/2 throttle.

TCI and B&M both make these shift valves, but if you decide to try this I would contact both companies to see if the valves are compatible with the 4L60E since they only list the 700R4, 200R4, and 4L60 (non electric) transmissions in the application guide.

Steve

green02crew · Post by **green02crew** » Mon Dec 17, 2007 11:17 am

If these did work would they be difficult to install? I'm having more problems now than worrying about my gas mileage but I am not that mechanically inclined. I'm used to working with a clutch.

green02crew · Post by **green02crew** » Mon Dec 17, 2007 11:25 am

Well scratch that last post I called and it does not work with electronic transmissions. The only thing he could offer as advice is to actually open up the transmission and change the gearing or getting an $800 electronic shifting kit to operate by computer to basically tell it when to shift. At those prices I might as well install a standard into it! Thanks for the help though.

Post by **HenryJ** » Mon Dec 17, 2007 3:40 pm

The HPPIII alters shift points based upon miles per hour. You can alter other than the WOT shift points.
Paul and I both did this to correct the 3-4 shift point.
You do set them using a WOT run. This way you do not have them hold too long, or shift short.
I know that you argue this point each time, but there is some correction available.

green02crew · Post by **green02crew** » Mon Dec 17, 2007 4:45 pm

So for example I could set 3rd to a maximum of 60mph so when on the highway at 65 if I floor it than the truck would not downshift to 3rd but rather remain at 4th?

Post by **HenryJ** » Mon Dec 17, 2007 4:59 pm

Not exactly how it works. You can adjust + or - in 1 mph increments. Making a pass at WOT you make adjustments to achieve the best results.
You really won't notice any differences in the lower gear shift points.
I did find adjusting 3-4 did make a difference tough.
I have mine set at -12
I can not say it makes all the difference. Paul said it helped his too.
I would say the shift firmness is part of the equasion and the vette servo , longer pin and billet fourth.
Mine no longer searches for a gear down shifting all the time on hills. I did add the TCC to give me a few rpm and prevent a down shift. All together the mods are working great for me.

No single chaep answer though.

killian96ss · Post by **killian96ss** » Mon Dec 17, 2007 5:13 pm

HenryJ wrote:The HPPIII alters shift points based upon miles per hour. You can alter other than the WOT shift points.
Paul and I both did this to correct the 3-4 shift point.
You do set them using a WOT run. This way you do not have them hold too long, or shift short.
I know that you argue this point each time, but there is some correction available.

From the owners manual:

"The shift point option allows you to change the RPM at which your transmission shifts at wide-open throttle".

Shouldn't this statement be different if you are also able to change part throttle shift points?

Steve

Post by **HenryJ** » Mon Dec 17, 2007 5:28 pm

Try it. Lower that 3-4 shift point radically. IIRC Paul set his to -18
Mine is set at -12. That helped lots with it searching when pulling a slight grade.

I know, I read the manual too. It doesn't say anything about this and it does state it just as you quoted, but it does work. Try it. Mine has the servos and pin now, so it is not as good a test. The improved holding power alters the performance. In fact the gearing and tire size affect the system as well. Loading better be added too. Lots of factors to consider. Mine is loaded heavy all the time and runs big tires.

green02crew · Post by **green02crew** » Mon Dec 17, 2007 7:45 pm

So say for example your truck shifts to 4th at 12mph sooner and you have your torque converter locked to prevent unnecessary loss of power by way of the torque converter spinning needlessly so it is just a direct line from your engine to transmission? I just wanted to make sure I'm getting this right. In theory you would gain a few horsepower by locking the torque converter and therefore transmission directly to engine, then the lower shift points would make it shift sooner and in theory you would use less throttle to keep the same speed?

Post by **HenryJ** » Tue Dec 18, 2007 3:18 am

I don't think it is that simple. For one , you do not choose when the converter locks. You can choose to unlock it. Locking too soon will bog the engine and you will lose mileage.
Best mileage and performance run in a curve. Ideal is to maintain the point at which both of these peak.

1337vending · Post by **1337vending** » Tue Dec 18, 2007 1:34 pm

In order to do what you want you'll need tuning software like HPtuners or EFI Live. The parameters that the Hypertech programmer modifies is the WOT shift RPM, not the part throttle shift points. The way it works is under part throttle, the computer uses vehicle speed and throttle position to determine shift points. Once the vehicle throttle position gets above a certain value (I believe it's 95%), the computer only uses RPM to determine when to upshift. Using the Hypertech might be able to make it shift sooner at WOT, but wouldn't be able to prevent a downshift.

Also, if I remember correctly, overdrive is weaker on our 4L60Es and isn't designed for prologned heavy loads and towing. HenryJ? Not to mention, peak torque for our 4.3 is at 2800RPM (conveniently around 65 in 3rd gear).

My advice? If you want it to hold a gear, downshift to 3rd and leave it there. I do it every day when I drive up a 7% freeway grade.

Post by **HenryJ** » Tue Dec 18, 2007 4:34 pm

1337vending wrote:...overdrive is weaker on our 4L60Es and isn't designed for prologned heavy loads and towing. HenryJ?

The billet fourth servo boasts the holding power needed to tow with. I can not say that is the case, but it can't hurt. I too drop the 3 for towing.

green02crew · Post by **green02crew** » Tue Dec 18, 2007 4:41 pm

Well no question I would tow in 3rd I'm just looking to get mileage out of her. I can always drive slower. But that just isn't as fun!

green02crew · Post by **green02crew** » Wed Dec 19, 2007 8:01 pm

Ok so just to clear this up I'm going for either the B&M shift improver or the HPPIII to firm up the shifts. As for the HPPIII the deciding factor would be shift points if I will get it or not. I'm sort of confused. Does altering the shift points only work at wide open foot to the floor throttle? or does it work for just putting along as well? HenryJ makes it sound like it works for normal shifts other than just wide open. But does it?

killian96ss wrote:The shift point changes made with the HPPIII are only used @ WOT, which means changing them will do nothing for normal every day driving.

HenryJ wrote:The HPPIII alters shift points based upon miles per hour. You can alter other than the WOT shift points.

By the way does firming up the shifts really help with towing and life of the transmission or keeping heat down like it says?

Post by **HenryJ** » Thu Dec 20, 2007 4:15 am

It alters WOT shift points. Radically lowered is does affect the 3-4 shift to keep it from searching when pulling a hill.

A quicker shift and more holding pressure are good for towing.

green02crew · Post by **green02crew** » Fri Dec 21, 2007 6:08 am

Could a wait4me performance tune do what I am looking for here?

Post by **HenryJ** » Fri Dec 21, 2007 6:11 am

Yes. You would still need the hard parts install to help out the transmission.

green02crew · Post by **green02crew** » Sat Dec 22, 2007 6:28 pm

The wait4me is on its way! Supposedly he says that he can get what I am looking for so we'll see... I think I am in need of the hard parts though like you said but I'll give the software a shot first before dismantling as I am not so good at that. I usually break things haha.

Torskdoc · Post by **Torskdoc** » Thu Dec 27, 2007 4:18 pm

One other thing you might want to consider is removing the restrictor baffle on the throttle plate.

I did this over a month ago. Drivetrain was hunting 3-4 and back again on normal highway driving (w & W/O cruise). Acceleration from 35 to 65 in cruise control usually was accomplished with a downshift to 2nd.

TOTALLY different ballgame now.

55mph to 75mph doesn't hunt from 3-4 and back again. also noticed that less throttle is required to hold a certain speed. Cruise control is smoother WITHOUT downshifts due to less throttle used to maintain speed. Throttle response is more crisp, and I don't have to mash down as hard or as much to accelerate.

Also gas mileage on highway went from 16.5 avg. to 18.0-18.3 avg over the last month. This is before the last fill up. I've since added new plugs and Cap/Rotor.

A smaller throttle setting now gets the same power out of the engine that a larger setting would before. The tranny is shifted based on settings from the computer. If the RPM, LOAD, TPS, and other parameters haven't been set, then the trans will not shift.

Plus it's CHEAP. Either take your's and modify it, or find one at the junkyard and modify it.

Larry

Post by **HenryJ** » Thu Dec 27, 2007 4:28 pm

Good tip!
I totally forgot about the change in TPS that occurs when you remove the diffuser or go to a clean blade. That was part of the equation I forgot about.
I fine tuned my TPS too. That could affect it a little, maybe?

green02crew · Post by **green02crew** » Thu Dec 27, 2007 8:24 pm

Ok first things first TPS? huh? And Is this an easy thing to do by any chance? Are there any negative sides to doing it? Would I just be cutting off the crescent shaped part on the throttle blade to allow more airflow? I have an 02 so would a change like this mess anything up with the EGR gasses I have been reading about or anything running lean? Sorry lots of curiosity and I have been reading about doing this I just don't really understand it all.

roadrunner · Post by **roadrunner** » Fri Dec 28, 2007 2:07 am

I find this interesting too but am kinda lost too. Anybody got any pics of what baffle you're talking about. Is this year specific or 4.3 general. Mine's an 01 4.3. Not having problems but always interested in performance/mileage mods.

Post by **HenryJ** » Fri Dec 28, 2007 6:13 am

Throttle Blade Diffuser and EGR limiter

TPS=Throttle Position Sensor

TPS Sensitivity Adjustment (fine tuning)

Those topics should help clear things up.

green02crew · Post by **green02crew** » Fri Dec 28, 2007 8:22 am

This seems like a good idea but might be just a little too in depth for me. I could trim the throttle blade myself but the rest of it seems lost to me. I don't know if I want to risk messing anything up. If I were to trim the throttle blade would the other mods have to happen as well?

Post by **HenryJ** » Fri Dec 28, 2007 9:00 am

Can you do one without affecting another? Everything you do has pros and cons. You have to decide what makes sense to you.
The manufacturer puts together a package and if the configuration is satisfactory, you use it as it was presented.
Is it right for everyone? Is anything?

Any modification has risk. Many work well with others. many require others. It is a vicious circle.
We have tried to test quite a few here and let you know what works for us. Will it work differently for you? Maybe. Driving conditions, habits, circumstances are all different.
Read the topics. If your questions are not answered, ask in the topic so that others may benefit as well. If I am a new member looking for information on the throttle blade mod or the TPS adjustment, it is not likely a topic named: "How do I keep the truck from downshifting?" would be where I would look.
That is what I am trying to do here. Keep the information together.

roadrunner · Post by **roadrunner** » Fri Dec 28, 2007 5:13 pm

Thanks for the threads. A lot of GOOD reading and more than a few ideas popped into my head. Always a good thing. Thanks again Brule.

Post by **HenryJ** » Fri Dec 28, 2007 5:24 pm

roadrunner wrote:Thanks for the threads. A lot of GOOD reading and more than a few ideas popped into my head. Always a good thing. Thanks again Brule.

You are welcome

Having an '01 , I would suggest looking deeper into the EGR limiter to reduce the intake deposits.
My condolences to you as well since we both suffer from one of the tightest PCMs. You will feel like you are dealing with HAL before you are done. I did, but I won.

roadrunner · Post by **roadrunner** » Sat Dec 29, 2007 3:46 pm

Having an '01 , I would suggest looking deeper into the EGR limiter to reduce the intake deposits.
My condolences to you as well since we both suffer from one of the tightest PCMs. You will feel like you are dealing with HAL before you are done. I did, but I won.[/quote]
I plan on mod for EGR but it's pretty cold here right now and no garage so will have to wait for warmth. Part of the threads I read that made me think.

Yeah, I know I've already had a run or two with Hal and probably more to follow.

green02crew · Post by **green02crew** » Sat Mar 15, 2008 7:52 pm

Well I finally got around to doing the throttle blade mod. This tied in with some decent programming and my truck pulls hard on steep uphills now without downshifting, even in cruise! Works great guys thanks for the advice! Now I'll save some green too since it'll keep it at a lower rpm.

Horsehammerr · Post by **Horsehammerr** » Sun Mar 16, 2008 2:43 am

As far as "decent programming" goes, are you talking about Wait4Me programming ? If so, what settings did you get, and tell us about the performance,please.

green02crew · Post by **green02crew** » Sun Mar 16, 2008 10:17 am

Well I did get wait4me, I got the mileage tune and it does help some with gas mileage. Shifts firmer, tire size is corrected and the torque converter locks earlier. Other than that I didn't have much done. I wouldn't get it strictly for performance gains I don't know as though there is much to be had with the 4.3 in programming performance gains. But I enjoyed it and seat of the pants feels better with the shift improvements.

roadrunner · Post by **roadrunner** » Sun Mar 16, 2008 12:36 pm

Just to throw in an additional "two cents worth" I have a little to say about computer controlled downshifting (especially while in cruise mode). I have not tried this for comparison on my CC yet but back when my Caravan was new I proved to my wife that if you are looking for mileage (1) you can't out-mileage the cruise control especially in hilly terrain and (2) though annoying as hell it is more fuel efficient to allow all that 4-3 computer controlled downshifting and convertor unlocking. Please note this van now has 335k on it on original trans with no rebuilds or other work done on it so obviously it wasn't detrimental to longevity. It is also worthy of note I used this van quite extensively for mail delivery on routes of varying length and character such that I did so much stop and go with it I had front hub bearing troubles with it quite frequently. The front rotors would get so hot they would turn blue clear down to the hub centers.
Now as to TPS tuning consider this experiment I tried. On my 90 Buick 3.8L I measured resistance value so I could reset to starting point if needed. I then turned on the ignition with a warm engine and not running and backed off the TPS until the SES light came on. At this point I turned off ignition and unplugged TPS connector and remeasured resistance value. I now had my "not lower than" value. I then adjusted the TPS up a little above the not lower than value. Started engine and drove car. The results were noticeably less objectionable idle exhaust smell, smoother and slower idle, better cold and hot starts, no noticeable performance reduction, and net gains in mileage of city (stop and go) up from 16mpg to 18.5mpg and highway (using cruise combination of 65-70-80 mph driving 800mile round trip) up from 23mpg to 27mpg.
I'll be the first to say I have not yet tried this on my OBDII CC but it certainly improved my OBDI Buick.
I now have my Wait4me PCM, throttle blade, egr limiter, and throttle body spacer (Helix). Weather is warming up lately and I'll let you know results I get with these as I go. Be patient this will be a slow drawn out process I just want to know what each will do or not do on it's own merits.