cblu007

It was definitely 4.10. I counted the teeth on both the ring and pinion gear, I installed 3.23 in the hope of getting rid of the high RPM on the highway. I am beginning to believe the transmission won't shift out of 3 rd. At what kph should the transmission shift into it;s gears?

cblu007

Would a servo issue cause this? Pushed in the servo and it goes in about a 1/4 of an inch or more.

Injuneer

I'll give this one more try, and then leave you alone. If you had 4.10 gears and it was locked in 3rd gear, at 100 KPH the RPM would have been 3,332. If you swapped in 3.23 and did nothing else, the RPM would have dropped to 2,625.

So your gear swap info and theory about it not shifting out of 3rd gear is not supported by your reported drop from 2,800 RPM to 2,600 RPM. Something does not compute. And at this point, if your speedometer was correct with 4.10 gears, and you did not update the PCM, the speedo is now reading 79 KPH at a true 100 KPH. Is that what you are seeing?

Injuneer

Shift table, from factory manual - had to use 96, because 95 and earlier manual has a page for truck applications, not passenger vehicle. The shift is based throttle position percent and is shown as output shaft RPM. You would have to convert output shaft RPM to MPH based on the rear axle ratio and tire diameter.

cblu007

Just purchased this car so not sure what the original owner done to car. I know that he did do the gears in the rear end. Not sure if he done anything to the PCM. The car just seems like it is searching for another gear on the highway. Would the servo do this? I don't have access to a scanner. which sucks.

gaedbo

In post #14 I explained how to access the Free Scanning Program.

If you activate the engine and transmission portions of the program it will tell you your RPM, Speed in MPH, and what Gear you are in, besides Problem Codes that are active along with a lot of other information.

Read the Info in the Scan9495: Free OBD1 scan app for 93/94/95 LT1 posting and you will see.

cblu007

Gaedo. What type of cable do I need. It has an OBDII connector but has a OBD1 PCM.

gaedbo

cblu007 it was in post #14, but here it is again -

One of the places you can get a cable from is (click on the following link)

http://www.aldlcable.com/

Your other choice is to make your own. But you NEED TO READ the information in the link about the Scan software like I stated in post #14 and #21 to know how to do it.

cblu007

I discovered today that my speedo isn't reading correctly. about 18kph off higher than it should be. speedo reading about 82 kph when I am going 100 pkh hence the high revving that I was experiencing at 100 kph. Which was more like 125kph. 3.23gears with 17 inch tires. The PCM is from a 2.73 gear ratio with 16 inch tires. Would the change in gear ratio and tire size make that big of a difference in speedo readings?

gaedbo

Your 275/40R17 Tires have a 25.7" diameter. So using Injuneers information in his Post #5, you should be at

3.23:1, 25.7" tires, at 100 KPH/62 MPH:
3rd = 2,619
4th = 1,823

cblu007

I am closer to 2000 rpms. What could be causing my speedo to be off. The difference in actual speed and the speedo reading seems to increase with speed. Is this a PCM issue?

gaedbo

In Injuneers Post #15 he explained that....... You need to program the new gear ratio into the PCM if the PCM was programmed for other than what you now have installed. Otherwise the speedo will be off.