Thread: wrong gear

Ugh... lol

What are you reading the rpms with, dash or scan gauge?

At 2200 I figured you were on throttle a little since it's a touch higher than 2.93's should be but a touch lower than 3.29's should be. Then again..some dash gauges are reasonably inaccurate.

In a brief way of saying it, you sure did. However we are always in diagnostic mode here and well...I tried to diagnose that since you had a GTP, you shouldn't have any gear ratio other than 2.93.

Now looking back, you could have 2.93's, 3.05 or 3.29. I'm leaning toward 3.05 based on the RPM. Being a dash reading though.. it could be slightly off and according to yoru code, it says it should be 3.29's.

Sooooo back to your question. Theoretically the trans should toss a code, however it won't necessarily light up the check engine light. The code can be stored w/o the light. It's also possible that the difference from input to output isn't large enough to trigger the pcm to report the gear ratio issue. I've seen it go all different ways. The jacked up shifting is likely from the gear ratio though.

The way the trans works is like this. There's a sensor on the input shaft that is drive by the torque converter. Then there's another sensor that reads the output of the differential. Now there is some clutch slippage factored in etc and so there's leeway. but the computer knows how fast the input and output should be reading and it reports a certain level of discrepancy.

Yeah the codes should show up on the Autozone scanner if they are in memory and not lighting up the CEL, because most trans codes are programmed not to light it up. Instead the trans limps and gimps and you take it in for service.

would the torque converter play with it too?
245mm vs 258mm?
is there any way to tell gear ratio and what sprockets are in the trans
without tearing it apart?

You can tell gear based on the tooth cound in the sun input gear. You can get to this by pulling out the diff.

I'd use the code and automatically assume the gear is what the book says it is for the code on your trans. Since you picked it and used it, it's technically not the wrong gear. You have a hybrid of parts etc and it's what it is...

Lockup can happen..uh on a 2.93 car at I think 38mph in third.

I checked yesterday in our GT (3.29 gears) and at 70mph it is sitting pretty much right on 2200 rpm. Pull it down into 3rd and it is at 3100 rpm.

As I mentioned earlier the code could have been shut off if the pcm has ever been worked on and the only way to know that is to have someone with a tuner read it. Also- the easiest way to see if the code should be setting is by watching scan tool data and verifying that in 3rd gear the "Current Gear Ratio" parameter is 1.000:1 +/- about .02 . Much outside of that range and code P0730 should set. Without a scan tool to verify this there is really no way to know what you have. As Bill mentioned you could pull the diff and count the teeth on the sun gear and verify the ratio but also as he mentioned it is probably safe to say that it has the correct ratio unless it was altered and should be a 3.29 ratio. Scanning data is the best and easiest way to see what you have and you dont have to pull anything apart. If the gear ratio is not reading 1.00:1 in 3rd gear then it is not a 2.93 ratio trans. If code P0730 sets, whether it is reporting a code on a scan tool or not from possibly being turned off, the side effects of the code will remain and tcc and shifting will not act as they should.

I'd put the right programming in if I were you.

I plan to. the only guy i have found local (reptile) is currently busy from a move, and working on his house..his computer with the dhp program is still boxed up..know of anybody else around the kansas city area??
if not looks like a zzp pcm is next on my list

I will let Brian know you could use some help and see if he can check it out for you since you are local.

Was going to say, I have DHP. Not really local though.