High RPM, doesn't shift into next gear

[slick]

So... all electrical problems fixed, and most of my gas mileage problems fixed, my car is running really good. But.... only one big thing wrong I am noticing right now. At higher RPM's (above 6000 RPM), it doesn't want to shift into the next gear. I actually have to let off of the accelerator and let the RPM's drop before it will shift.

I have a few things in mind what could be wrong, but I'd just like some of your guy's opinion's.

Thanks.

[z34_nut]

:shock: ...lets just say thats EXACTLY what my tranny started to do before it took a shit....um...fluid change?

Also, check your vaccum lines, just to be sure, and do a pressure check if you can find the tools. This could also be electrical, but more then likely its not.

[Regal_GS_1989]

I've had my old 88 regal hit the Redline a few times before it would shift into the next gear :shock:

I''ve never had to read a tranny data stream off an OBD1, nor do i know if its possible, but if you can get a scanner to read the tranny data stream, drive the car and see what happens when it doesnt shift. If a shift has not been commanded, than there is an electrical issue. If a shift is commanded, but it doesnt shift until you back off, than there is a fluid/mechanical issue.

[slick]

Well... I know I am due for a fluid and filter change, so I will go ahead and do that. And, I know of a few connections that I need to check up on, so I could do that as well.

Could anyone provide me with a tranny vac. diagram?

[GOT2B GM]

How's your fluid look? Is it foamy? Underfilled? Overfilled? Pan drop and filter change would be a good start.

I'm having issues in my auto Z right now too. No 3rd gear, on a tranny that's only 40,000 kms old, thinking it's electrical related.

[z284pwr]

My trans is doing the same thing, shortly before it started doing it in every gear, I heard a pop while trying to manually shift it into 3rd at high rpms. This is with brand new filter and fluid as well. I don't think it likes running 6500+ RPMs when it used to be 5700 or so?

[patgizz]

vacuum diagram:

1 line from vacuum modulator up to engine vacuum

no more vacuum lines.

[Canada]

Low fluid can do this.

I'm sure you know this....BUT...check with the engine and trans hot, in park, and at idle.

Just changed fluid in my friend's 2000 GTP with 80k on it....fluid looks brand new.

[slick]

Thanks Pat and Chris.

Yeah, so I'm figuring it's probably the overdue needed filter and fluid change (about 30,000 on the rebuilt tranny), so she's about due for another change.

I'll check the vacuum tomorrow between classes.

[mihela816]

Another thing that can cause this is a misadjusted or broken throttle valve cable. It's the cable that loops from the throttle body, behind the plenum and attaches right by the tranny vent on top. It basically tells the transmission what throttle position is to control shift points.

[Canada]

I don't think that car has a TV cable.

The vacuum line would just would only effect shift firmness....as its only controling transmission pressure.

[94CutlassXtreme]

When you say the car won't shift at high RPMs, do you mean it won't go into forth during crusing. If so, is your service engine light on? I had a similar problem, and it turned out to be the neutral safety/MLPS (manual lever position sensor) switch. Once I replaced it, the car shifted fine.

[patgizz]

Another thing that can cause this is a misadjusted or broken throttle valve cable. It's the cable that loops from the throttle body, behind the plenum and attaches right by the tranny vent on top. It basically tells the transmission what throttle position is to control shift points.

there is no TV cable on any 3.4 equipped car or any of the electronic trannies.

[z284pwr]

Doesn't the TV cable just control the down shift points, doesn't the vac. modulator control line pressures and shift points on the Non "E" trans?

[Anonymous]

Try the fluids. Mine was having a problem shifting (very similar to yours) and it turned out my fluid was very low.