Speed Issue auto transmission (Page 1/2)
Will.145 OCT 25, 12:11 PM
I recently drive a 5 speed v6 fiero and noticed how much more power it has to my auto V6 Fiero. Long story short, my auto transmission seems to really suck. I floor it and it will max out around 3,000 maybe 4,000 if it's downhill. It's not my kickdown cable because I just adjusted that properly and made it so it would shift as late as possible. So what could this be? Governor in the tranny, spark issue, timing issue? It shifts too early and doesn't down shift either.
olejoedad OCT 25, 01:27 PM
Throttle Valve cable adjustment - follow it exactly as the Factory Service Manual describes!
Downshift is controlled by the TV cable - you do not have it adjusted properly.

The TV cable doesn't control shift points, that is the governor's job.
Will.145 OCT 25, 01:32 PM
I am pretty sure I've adjusted it properly. Manual says to depress the button on the cable to allow it to come out and then depress the gas pedal fully. I did this to the point of getting stuck under the "butterfly intake" thing. So it's shifting as late as possible but still won't go over 4,000 unless I break the cable.
olejoedad OCT 25, 04:20 PM
The governor controls shift points.
Have you checked the vacuum line to the solenoid?
Patrick OCT 25, 06:26 PM

quote
Originally posted by Will.145:

I floor it and it will max out around 3,000 maybe 4,000 if it's downhill.



It's been awhile since I've driven an automatic Fiero. Can you keep it in a lower gear at a higher RPM if you select the gear manually?

Also make sure you're not being misled by a faulty tach. As our Fieros age, it's not uncommon for the tachometer to be very inaccurate.

[This message has been edited by Patrick (edited 10-25-2025).]

Will.145 OCT 25, 08:05 PM
Hey yeah I can't find the solenoid I've tried looking online for a diagram but can't where is that?
Will.145 OCT 25, 08:07 PM
My Tach is absolutely messed up because it's the 4 cylinder tach I just did an engine swap. But I'm familiar enough with the engine to know it isn't matching up RPMS and I double checked with an RPM conversion chart and when Tach says it's at 4,000 it's really at 2,800
olejoedad OCT 25, 09:03 PM

quote
Originally posted by Will.145:

Hey yeah I can't find the solenoid I've tried looking online for a diagram but can't where is that?



My bad, there isn't one on the TH125C.

GM added that when they upgraded it to the 4T60.

Apologies.
Will.145 OCT 25, 09:43 PM
No worries I appreciate the help
Patrick OCT 25, 09:59 PM

quote
Originally posted by Will.145:

My Tach is absolutely messed up because it's the 4 cylinder tach I just did an engine swap. But I'm familiar enough with the engine to know it isn't matching up RPMS and I double checked with an RPM conversion chart and when Tach says it's at 4,000 it's really at 2,800.



So you're relying on a 4-cyl tach of unknown condition to indicate to you what the RPM is of your 6-cyl engine? Okay.

You also seem to have missed my earlier question...


quote
Originally posted by Patrick:

Can you keep it in a lower gear at a higher RPM if you select the gear manually?


[This message has been edited by Patrick (edited 10-25-2025).]