94 Metro Auto Trans Problem

Hi Everyone,

I recently bought a 94 Metro with 105,000 miles on it. It does fairly well except for one problem. When I am crusing along at or above 40 mph, which means that the trans is in 3 rd gear, if I take my foot off of the gas pedel even slightly, it feels like I just stepped on the brake. Since there is nothing wrong with the brakes, I think that the problem is that the trans downshifted back to 2 nd gear. As I make the slightest movements on the gas pedel, the car seems to jerk back and forth almost as if it can't decide if it wants to be either in 3 rd or 2 nd gear. Everything else seems OK at the lower speeds, when the trans is in either 1 st or 2 nd. The check engine light is OK.

It seems that the trouble is either within the transmission itself, or the AT controller is sending the wrong signals to the direct clutch selenoid or to the 2nd brake solenoid. I was thinking of attaching (2) small 12V lights across each solenoid inside the car where I can see them while I drive the car. I can then observe if the signals from the AT controller look OK or not. I have a shop manual for an 86 Sprint that shows what these signals should be for each of the 3 gear ranges. Even though the ECM and AT controller have changed throughout the years, I think that the basic operation of the automatic transmission has remained the same. That is, the transmission is still shifted through 1, 2, and 3 using the direct clutch and 2nr brake solenoids that get their signals from the AT controller.

Anyone ever had a similar problem or have any ideas ?
Thanks for your help.
graywebdesign

Your idea has merit, it would be a great troubleshooting technique to at least figure out where the problem is arising from.

It sounds simple, but check your transmission fluid, as well. A burnt fluid or low fluid could cause all kinds of strange things to happen with the auto.

I have a spare trans controller and ecm from my 93 parts car if you need it. Email me @ dstuart115@excite.com if you do.

Thanks for your replies, Guys.

Here is an update on my problem. I still have the same problem and I did try the test where I monitored the 2 signals coming from the AT controller while I drove the car. The 2 signals are correct for all of the 3 gears. I guess this means that the AT controller must be OK. I did observe that the problem does not show up when I am driving up hill and is at it's worst when I am driving down hill, ie, engine intake manifold pressure is also low. All vacuum lines seem OK. Could be a faulty MAP sensor or TPS sensor, but the ECM is NOT reporting any problems with them. I will post the fix to the problem, if I ever find it!