Programmed for wrong gears question
Programmed for wrong gears question Okay, so a few months back, me and a buddy were cruising on the highway. I was cruising at 75mph, and he was cruising at around 68mph. Yet we were cruising side by side. I cruised to 68mph as he was, and he started pulling away at his 68mph. So today, I tested out a method people had told me to spin your tire 1 revolution, and count how many turns the drive shaft turns to calculate the gears the car has. If it is accurate, I have 3.73 gears. (Side note: my car when I bought it was pre-modded. I didn't know much of these cars, and the dealer told me it was stock). So when I got some mods for the car, I had it tuned from madz28. He asked for the gears, and since I did not know, I also told him it was stock. Stock being GU5(3.43 gears).
My question, I had it tuned last year, what can be the results of driving it tuned to 3.43 gears but actually having 3.73 gears? What can I expect when I get the car tuned to the correct 3.73 gears?
Any help is appreciated, thank you.
My question, I had it tuned last year, what can be the results of driving it tuned to 3.43 gears but actually having 3.73 gears? What can I expect when I get the car tuned to the correct 3.73 gears?
Any help is appreciated, thank you.
TECH Senior Member
Joined: Dec 2001
Posts: 5,399
Likes: 3
From: Jacksonville, FL
Well GU5 is 3.23, not 3.42 (GU6). Did you just give them the RPO or tell them 3.42? Get someone next to you on the highway at say 70 MPH who you know has a factory speedo setting, note your RPM and bounce it off a calculator like www.f-body.org/gears/
Oh we have done that before on the highway. Me and a buddy of mine were cruising at 60mph at around 2k RPMs. He was pulling away. And for me to go even, I had to do almost 64mph. When I do 75mph, he does 68mph to stay even. I had all the RPM ranges before, but I think I threw it away cuz I was told it wouldn't matter. When I did the tune, I told them GU5. He knew from that.
But that's not the point, I am wondering what are the outcomes of being programmed wrong. Like 00PewterSS said, will all that happen is just a right speedo?
But that's not the point, I am wondering what are the outcomes of being programmed wrong. Like 00PewterSS said, will all that happen is just a right speedo?
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I have a Predator handheld tuner...went from 2.73 to 3.42(gear only change).. My predator tuner(old model) didn't change the setting correctly so was off... Car would shift into D at around 15 mph and drove like crap..shifted horrible.. I am pretty sure that the pcm uses mph for shift changes and there is a big difference when it is off like that. Another way to check is look at what others have quoted they run at certain rpms on the highway. That is the way I checked that my settings were correct.
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Sounds about right.
You are doing 75, he is doing 68. That means your speedo is 10% too high (assuming his car is correct
). That would be about the same change from 3.73 to 3.42. (Note: Stock on your car is 3.23). So yeah, you probably have 3.73 installed.
The effects are your car will shift hard, because the shift points are all messed up. Also, as you noticed, your speedometer is off. Worst of all, your odometer is going 10% faster, too. So in the last year, if you racked up 10K miles, your odo will show 11K.
No damage will be done, however.
You are doing 75, he is doing 68. That means your speedo is 10% too high (assuming his car is correct
). That would be about the same change from 3.73 to 3.42. (Note: Stock on your car is 3.23). So yeah, you probably have 3.73 installed.The effects are your car will shift hard, because the shift points are all messed up. Also, as you noticed, your speedometer is off. Worst of all, your odometer is going 10% faster, too. So in the last year, if you racked up 10K miles, your odo will show 11K.
No damage will be done, however.
I had the same problem when I bought my car. It was programed for stock 3.23, but had 3.42's installed, so it wasn't off quite as far as yours. The biggest problem I had was the car pulling out of it's power range at WOT. I've made some other changes, so I'll never know just how much it was hurting, but it was very noticeable that the car would quit pulling at the top of each gear.
I drove to Texas and back, as well as plenty of driving around here(1,2,3 etc hour drives). I know for sure I've put about 14k miles on the car since the tune. Would that put me at around 17k actual miles? Or 12k actual miles?
Originally Posted by squirrelishere
I drove to Texas and back, as well as plenty of driving around here(1,2,3 etc hour drives). I know for sure I've put about 14k miles on the car since the tune. Would that put me at around 17k actual miles? Or 12k actual miles?
When it was tuned, didn't they see what was already there in the stock tune?
