Why does my car shift so early

69stanger

Founding Member
Oct 20, 2002
102
0
0
CA
my car seems hell bent on shifting between 3.5-4K rpm even if Im flooring it. Whats the deal, why wont it rev to atleast 5K.

oh yeah I have an automatic.

any help would be apprecitated thanks
 
On the FMX, it's on the back driver's side of the main housing.
It looks like a medium sized gold mushroom with a vacuum hose going to it from the intake manifold. If you pull the hose off the modulator, inside the stem of the modulator, there will be a small allen screw. Turn yours counterclockwise about 1 to 1 1/2 turns. Reconnect the vacuum hose and go for a drive. It should affect your shift points, not a great deal, but perhaps enough. Continue to adjust as nessesary.
 
Great68 said:
Where is it located on a C4?

Same size, shape, adjustment, vacuum hose, etc., but on the passenger's side of the transmission.
Always check the fluid levels when troubleshooting any kind of hydromechanical unit---power steering, transmission, rear differentials, etc.
It sounds obvious and stupid, but almost 50% of the times it turns out to be something simple.
 
I just tried adjusting the vaccum modualteor and now my car shifts at 4.5K rpm. thank you so much.

I will do some for adjustments tommorow and hopefully I can get it to shift at 5K.

thanks again.
 
you can manually keep it in gears 1 and 2 as long as you want
but watch out, i blew out my 2nd gear clutch on my c4

if your on the highway, throw it all the way down, and the tranny will shift into second
if you have it in low from a start, it wont shift out until you do it
but what i did, was id shift into second, then put the shifter back in low and it would stay in second gear as long as i wanted

this will really help your acceleration, by making the transmission kick down