96 Lumina shifting problems

I have a 96 Lumina 4T60E automatic transmission.
what is happening is it does not want to shift into 2nd or 3rd unless I let off the gas pedal for moment and then give it gas again. I had the car scanned today at Advance Auto and no error codes showed up. Could this be a TPS even though it is not showing up on the scan?
Thanks

I'd lean more towards a bad vacuum modulator or the hose/line going to it....

I have a 96 Lumina 4T60E automatic transmission.
what is happening is it does not want to shift into 2nd or 3rd unless I let off the gas pedal for moment and then give it gas again. I had the car scanned today at Advance Auto and no error codes showed up. Could this be a TPS even though it is not showing up on the scan?
Thanks

I'm guessing it's your PCS solenoid.
Mozilla/4.0 (compatible; MSIE 6.0; Windows CE; IEMobile 7.11) Sprint PPC6850SP

Are the Vacuum Modulator and PCS Solenoid both located in the transmission?
This car shifted fine before I replaced the Head Gaskets, after putting the car back togather and took for a test drive is when I noticed it. Engine runs smooth and fine on interstate just getting to the interstate is where I'm having my shifting problems.
Thanks

I think I found the vacuum modulator, is this the unit that the upper intake vacuum line hooks into?

I think I found the vacuum modulator, is this the unit that the upper intake vacuum line hooks into?

Yes. Make sure the line isn't sucking air, and pull it off the modulator. If there's any fluid in the line, the modulator's diaphragm is blown. That will cause it to fail to upshift until you snap the throttle shut and build some vacuum...

I checked the line and it is not sucking air, The line and in-line filter looks very clean and dry.
I also wanted to note that I changed the trans filter and filled it back up to level with Valvoline Max Life yesterday to try and fix this problem , but of course this did not help.
Thanks

Inline filter?

You may be looking at something else then.

This line goes down to the front of the tranny down low, roughly under the airbox area?

I have included some pictures for you to look at. hope I did this right


the vacuum line shown in the pictures run from #9 (vacuum diagram) and connectes to the Vacuum Modulator.

you can also see the filter I was talking about in the pictures, I guess I could get rid of this filter, it could be restricting the flow and see what hapens.

Thanks

37367

37368

37369

Huh. Never noticed that screen before. Cool.

Sucks that wasn't it, would have been a simple, cheap solution.

I might still pull the modulator off and test it with a vacuum pump, make sure it holds suction and moves the pin as it should...

I will try that, Thanks for your help

Test

I was just checking to see if my new signature worked