So a couple weeks back I replaced the TPS unit, adjusted it along with doing all the other renix clean up and regrounding. Last night it started to shift back and forth at around 50 to 55MPH again. This morning on the way to work it didn't even want to kick down when I stomped on it. TV cable had been readjusted and was working fine. I'm thinking I may need to get a new TCU. I did find one from an 88 here in town and may just go and grab it tonight on my way home from work to see if it solves the issue.

Takes off from a dead start ok under normal acceleration seems to shift really fast if I get on it hard. Does not want to down shift at say 30 mph just bogs down.


Black89

 

Power or Comfort on the switch?

Refreshed trans connectors, right?

 

PC Switch wired to power mode. All your steps have been performed. I just ran an errand for work and it was still doing the same thing. Takes off fine normal load. If I tried to get on it no down shift. I tried a hard launch from a light and it shot through 1st 2nd and fell on it's face in third. Got to where I needed to be and shut it off. Came back out 15 minutes later started off again and it was back to normal. Great hard launches. Down shifted when I stomped on it and took right off. Just like nothing was wrong. I did grab a hold of the TCU while driving and noticed that it is pretty hot to the touch. Not burning the hand hot but hot. I wonder if the heat of the day (Mid 90's again here) is having something to do with it. I'm gonna take off early today and go grab that used TCU and see if that makes a difference.

Black89

 

Try the other tCU. But maybe before that, clean the contacts between the present ECU and it's plugs?

 

Already did that when I refreshed all the other stuff. It almost seems that I have no issues with it in the mornings when I drive in. Temps have been in the low 60's at night. But then after sitting in the hot 90 degree plus sun all day and then heading home is when it seems to act up. Before I left the shop I did it with the TCU fuse out. Pulled the shifter back to 1-2 and when to take off. If felt like it was in 3rd. Didn't wanna go. Put the fuse back in and it was fine again.



Black89

 

OK. Good. Try the tCU.

 

Something interesting to note. I just pulled the panel loose where the TCU is mounted and One of the nuts is just screwed on to the end of the stud. Someone has tinkered with or replaced the TCU at some point. the other other nut was all the way on but only finger tight. Plugs are indeed very clean on both the harness and the TCU unit. Off to the junk yard I go.

Black89

 

Well I drove to the JY and had no issues. Got the Tcu out of an 88 and plugged it in for the drive home. I just shoved it up under the dash for the time being. I went about 10 miles then right back to the same old crap. Kick it down and it it would just do a quick down shift then back up right away. Then again and wouldn't down shift. I'm wondering if I need to drop the pan and do a fluid change and filter? At a loss at this point.

Black89

 

When is the last time you did a change?

 

Never. I've only owned it for a month. The pan has been off. I can see the orange rtv sealer. It was 2 quarts down when I bought it. This issue seems to be when it heats up so maybe it needs a filter and a full load of good clean fluid. What was left of the old might just be that bad. I just did a water pump in my buddy's 00 chevy k1500 and a rear axle in his daughters mustang so it's time to get my ***** fixed. lol

 

You could try changing just the fluid first using the drain plug and see what happens. Use Dex/Merc fluid only. No ATF+.

 

I think just to be on the safe side I'll do the filter as well to be safe.

 

Couldn't hurt. I was just thinking of getting some fluid out of it now, see what happens, and then go ahead with the pan drop as needed. That wuld give you 2 changes .

3.8 quarts per drain.

 

True..

 

I'm gonna grab the stuff on the way to work in the morning and do it when I get home Saturday. We'll see what that does to it.