push down pedal - slow acceleration (HELP!)
 

hi

every 50-100 miles, my supra has a problem, which none of about 10 mechanics could repair yet, nor tell why it occurs. i hope someone here can help me.

the problem:
if i push the pedal down in "D"-position after the car has fully stopped, it accelerates very, very slowly. as if it were a vw golf or it's running only on half of the cylinders. the rpm meter climbs at around 500rpm in 2 seconds. this problem will last 1-5 seconds. no matter if i kick down or gently push down the pedal. after this, power sets in immediately.

i drive an automatic '89 supra mk3 with turbo (7m-gte).
transmission oil has recently been changed, motor oil too.
except this problem, there are no more symptoms. it runs absolutely well.
mileage: 130'000 km, thats about 90'000 miles, i think.

sounds strange. you'll need to start checking all yur sensors to make sure they are within specs. Sounds like the computer is not allowing enough fuel needed during that senerio.

That means you're going to have to start metering all that you can and probably even the ecu.

I would think that if you started with the ecu and worked your way out you would find it more quickley.

As opposed to starting from a choice of places under the hood.

Am I wrong? If so please correct me.

thank you, i'll try this.

someone told me, the supra has a "steering box", containing a chip which calculates best shifting points for the automatic transmission. how do you really call this box? it isn't the ecu, am i right? they told me, the replacement of this box would cost me about 500 swiss francs, that's 500$.

Try starting off with doing a diagnostic on your engine and transmission.
Link for engine diagnostics is in my signature. Transmission is similar but you put a paperclip between TT (89+) or ECT (pre89) and E1 and your o/d light will flash the codes.

Good luck

And don't buy the "steering box" :)

no diagnostic codes showing up...
now there are 2 new problems:
first, the automatic transmission ignores position "2". if i select position 2, the transmission stays in D-mode.
the other problem is, that it doesnt decelerate normally if i take my foot off the pedal, the rpm meter goes down a bit, up a bit, down a bit and so on.

check your throttle position sensor (TPS), make sure its within spec.

Well if you want an honest opinion on this from a guy that worked with a ASE certified master mechanic rebuilding autos you have a problem. lol. It sounds like you are having a slipping issue and the tranny is not engaging in 2nd gear at all. I am not to familiar with the auto in mark 3's because I will only buy a stick because a real sports should only have one type of tranny. Now that is out of the way if you feel real adventurous have someone pull the pan on the tranny and check the seals around the pistons in the valve body. They may be wore out and leaking causing the transmission to have problems building pressure. Seeing as a automatic is more of a pump than anything else without pressure you have nothing.
A slow build of pressure would probably not throw a code so that is why you arent finding any on this issue. I have seen it many times on a lot of different transmissions doing the same thing and pretty much every time it was the the seal around either the 1 2 piston or the 3 OD piston leaking and messing up the whole works.