Just got 4.10 gears FINALLY installed correctly and man did it pick up the puny stock 305. Now the problem is that the engine has a miss/hesitation/jerking at low mph and rpm. It is not too bad and I have checked all of the usual tuneup stuff. My question is will a gear swap from 2.73 to 4.10 make the computer act funny at low rpm? No others seemed to have this problem but I thought I would ask. My new 383 should be ready in a few weeks to a few months depending on my engine builder so can I drive it like this until the 383 is ready? Oh it is an 88TA with low miles.

 

Automatic?

If so, your trans has a speed sensor in it, which its signal goes to the ECU, and this signal (its frequency) has a function in the parameters of the fuel enrichment, shift points, lock up and timing curves. Most after market chips (replacable e-proms) will take care of this problem since all they really do is change the fuel enrichment and timing curves.........and very little else.

I think that this may be your culprit. But this is not really a common problem........

 

Thanks for the reply. Maybe such an extreme switch confused the computer. Oh well, I will wait for my new motor.

 

Back when my engine was a 305, I did the swap from 2.73 to 3.73 and I didn't experience these problems. Sure, 3.73 isn't a 4.10, but its still a big jump, I had no problems.

On a 700R-4, the ECM has nothing to do w/ shift points.

 

There are 'sensed' pressure ports in the trans that have to do with shifting, downshifting and passing gear shifting. I am not saying that the ECU has control over this, they are just sensed. The other intputs from the trans are from the servo and the valvebody, due to its ability to be programmed.

 

Very rarely will you find a thirdgen f-body 700R-4 with that many switches. The most installed in these trannies was a 3rd gear switch, 4th gear switch, and a 4-3 downshift switch. Not all of these even go to the ECM, some of them are inline to the TCC only.

The only thing I can think of is that the speedo gears are incorrect and the ECM is applying the Torque Converter clutch to soon. If car is doing 30 MPH and the ECM sees its doing 40, it will apply the TCC and probably causing the bog/jerk. Just a thought.

 

Good point!