Gear ratio change question
Thread Starter
Racer
Joined: Nov 2008
Posts: 279
Likes: 2
From: Cabot Arkansas
Gear ratio change question
I just got my car back from a gear change. It's a 99 vert with an a4. I went from 3.15 to 3.73. After a few miles I got a p1870 code. I reset and again after about the same mileage I got it again. The performance of the car was not altered. I have been reading and it seems it is caused by the gear change. I have ordered and will soon receive a Predator programmer. My question is will it adjust the shift points and eliminate this code setting or should I take it back to the shop for them to diagnose and deal with?
Race Director
Joined: Mar 2007
Posts: 18,308
Likes: 21
From: Marlton. Increasing performance one speeding ticket at a time! NJ
I just got my car back from a gear change. It's a 99 vert with an a4. I went from 3.15 to 3.73. After a few miles I got a p1870 code. I reset and again after about the same mileage I got it again. The performance of the car was not altered. I have been reading and it seems it is caused by the gear change. I have ordered and will soon receive a Predator programmer. My question is will it adjust the shift points and eliminate this code setting or should I take it back to the shop for them to diagnose and deal with?
You did a gear change without a re-program. What shop did that?
Yes you'll get that code, and probably hit the rev limiter and other small annoyances.
The predator will absolutely be able to change the gear ratio for you. However, I'd recommend that you don't open it and send it back.
If your not technically inclined, contact one of the forum vendors here such as ECS and get a mail order tune. It's a very simple procedure and costs much less than a predator and you'll get hands down much better results.
If you really plan on doing a lot of mods in the future, get a full tuning suite like HPTuners. It costs the same (base package) and you get the ability to do full tuning on 4 cars out of the box vs the predators 1. Plus if you upgrade to a Torque Converter later on, that's something that the predator can't handle.
Predator is fine to do some simple things, but most find its limitations quickly and upgrade.
Drifting
Joined: Nov 2006
Posts: 1,682
Likes: 2
From: Plano Texas
St. Jude Donor '08
I had the same thing on mine when I got my new differential installed. I got the p1870 code. For me, it only came on after driving a while, like an hour or so. But you need to get it tuned and either have them adjust the slip/pwm table, or I think on mine they just tuned it out completely.
quite a change I bet going from 3.15 to 3.73 huh? I went from 3.15 to 3.42 and that was a nice improvement in itself!
btw, here is my thread where I had the same problem:
http://forums.corvetteforum.com/c5-s...ing-p1870.html
quite a change I bet going from 3.15 to 3.73 huh? I went from 3.15 to 3.42 and that was a nice improvement in itself!
btw, here is my thread where I had the same problem:
http://forums.corvetteforum.com/c5-s...ing-p1870.html
Thread Starter
Racer
Joined: Nov 2008
Posts: 279
Likes: 2
From: Cabot Arkansas
Thanks for the input. I ordered the Predator as a first step learning tool. I already know someone that will buy it from me when I have reached its limitations. I don't really intend to do a lot of mods but i suppose everyone says that at first. I think the shop did not reprogram because I mentioned that I had ordered the programmer and would be using it as soon as it arrived. And yes the 3.73 gears really woke up the throttle response !!! My RPM at 70mph is only 2350 or so and theres no way I will ever touch top speed anyway. So far my MPG is not really affected but I drive mostly on rural 2 lanes.
