Gene Wolf

I'm looking for a programmer which will allow me to modify when my A4 downshifts. Right now, it takes too much throttle before it downshifts, and I would like to modify this.

Will either the predator or the hypertech allow this?

RPOZ4Z

From what I recall, I believe the predator is the better of the two.

you might want to checkout thier websites, It should state what each one will do.

rickw6sr

The Predator will allow you to program the up-shift and down shift points at WOT in both RPM and speed, in each gear, and uses an internal algorithm to shift it during normal (less than WOT) conditions. It also allows you to set the shift-fitmness and shift-speed + and -. I'm using it on my 2001 A-4 coupe and can recommend it. PS: They re-flashed the software in mine for free and paid for return shipping. No I am no a dealer, just a user. GL........ Radio Rick.............

Gene Wolf

Thanks for the replies. I guess I'd like to get the Predator because it's less expensive and I don't need to do any super sophisticated tuning. Right now my 2000 vert is at Corvette Specialty getting a Vararam intake, Bassani exhaust with X pipe and 180 thermostat, so I think the Predator should do enough tuning if it can modify my downshift points

dorickw6sr, does your predator allow you to set the downshift points based upon throttle position and speed? Or do I have to look to the HPtune or EFILive to do this? Right now, I have to go to WOT to get the thing to downshift into 1st if I'm getting on the freeway and doing about 25 or so. If I'm going 35, it won't downshift into 1st at all, which is funny because it stays in 1st until around 55, so it wouldn't hurt anything to downshift into 1st at 35, but it won't.

Mike Mercury

be careful here, not all C5 Predators are created equal. Some do more than others - and it'a all based on the year of Corvette.

best to visit the DiabloSport website. Then I'd telephone them with specific questions. Why ??? Because their web description of a specific model predator will list what it can adjust - but some of these fields are for F-Bodies - and may not be available on the C5.

http://www.diablosport.com

Beer99C5@FastbirdPerf.com

I found the Predator useful. I loaded custom tunes from RWTD (RWTD did not provide the tunes in a timely manner but did eventually provide the tunes), and used the Predator to monitor KR while playing with Nitrous as well as using the Predator to pull timing for the Nitrous shots. I also had a code pop up and readily cleared it without having to go to the dealer.

Dyno Gain from the factory tune to a RWTD Tune was 299 HP (Stock) to 308 HP (RWTD) far short of the 17HP (Default Predator Performance Tune)claimed by some vendor sites.

I am moving on to EFI Live Scan now (I want hardcopy logs), and will see what else I can do with the Predator Tune wise. But for entry level modding I have been pleased with it.

rickw6sr

Yes, the Predator will allow you to set the points at which your transmission will be up-shifted under WOT, and at which "it will allowed you to down-shift", it's set by speed in MPH.
In my case, my Vette' was recently modified from a 2:73 rearend to a 3:42 and it was necessary to change all the shift points, up and down, for proper operation. No problems with anything (so far).
PS: Be sure that your "year" Vette' is supported by the Predator, and that you purchase a current unit with the latest software, or, like me, you will have to send it back to them for a re-flash.
GL, Radio Rick, Located in the Tahoe foothills.

Gene Wolf

Thanks for the reply, rickw6sr. I read the Predator manual for my year and although it says you can adjust the downshift points based upon rpm and mph, I'm a little confused. I'm still locked into the old days where you had a shaft connecting the throttle linkage to the tranmission which would operate the downshift mechanism, and this could be adjusted by shortening or lengthening the shaft to, in effect, change the downshift point based upon throttle position in conjunction with the manifold pressure as measured by the vacuum modulator.

I am having a hard time understanding how by defining the rpm and mph at which downshifting should occur can, by varying just those two parameters, control all possible throttle situations. For example, in my getting on the freeway scenario, I'm at about 1/4 throttle, pulling up the onramp in second gear doing about 35-40 and accelerating moderately and I see that traffic is coming and I need to punch it to merge, but it won't jump down to first gear. It just stays in second and pulls the best it can against the mechanical disadvantage of second gear and the 2.73 ratio rear end. I know it's safe to downshift into first at that point; first gear takes me to 55 or so under WOT, so why not downshift?

I don't remember looking at the tach, but say I'm at around 2,000 rpm and doing 35-40mph at that point. If I tell the Predator to downshift at 2,000 rpm and 40mph, I can't see how I can define those two parameters alone without also defining either the throttle position or the manifold pressure so it knows what kind of acceleration situation it's involved in, and whether it seems appropriate to downshift. It sounds like the Predator doesn't allow a way to define throttle position in relation to downshifting, but does it allow you to define manifold pressure in relation to downshifting,? Just either one of these two parameters along with the rpm and mph definitions would seem to provide enough control to accomplish what I'm after.

The pdf manual file on the Diablo website stated that it allows shift adjustment based upon rpm and mph, and makes a statement that these work "in conjunction with each other, based upon load" I guess this means that the Predator defines the throttle postion and/or manifold pressure behind the scene automatically??? And because you've chosen "performance tune" that means you're probably looking for somewhat more aggressive downshift points??

Okay then, real world experience is where the rubber meets the road (literally): rickw6sr, did you notice that your downshift points were any easier to reach as a result of your Predator tuning? I guess that's the real question.

rickw6sr

Your next to last sentence says it all, it's based on throttle position, computer input and how quickly you mash your foot on the throttle. Throw-away all your analog thoughts, this is a "wire driven" throttle system that measures lots of paramaters via the on-board computer, and the computer is programed via software to respond based on "many variables". What do they do, and how exactly they do it? I don't know, as a retired enginner, I can imagine how they would approch it.
As to your last question, yes, it will down-shift as soon as I mash the gas or (if I'm below the programamed MPH maximum for that gear) go directly into the lower gear if I manually select it. Hope that answered your question. Radio Rick, just cruzin' in the Moter Lode...............

Gene Wolf

Yep, that about sums it up! I just have to assume that it will downshift more responsively, and based upon your experiences, it sounds like it does, so 'nuf said.

I am still waiting to get my vert back with the new Vararam, Bassani and 180 thermostat, and am anxious to see how much of an improvement these little mods make. I'm planning on driving it for awhile as it is, letting the computer adjust and then see is it's close enough to what I'm after. Who knows, I may not even need the Predator tuning......(yeah, right!)

"Honey, you know we can't really take advantage of the new intake and exhaust unless we UNLEASH the potential with a performance tune!!" (mentally practicing speech to wife.....)

Thanks again.

Mike Mercury

that's an interesting perspective.

pawngod

SOMETHING IS WRONG THEN !! my vette will downshift to 1st gear at 40mph...and you better be hangin on and not in a corner.....not a mechanic but ...it should easily downshift at 35mph