Cleaned Iacv, Replaced Maf Sensor, Replaced Tps Sensor...what Next?

[prestonj67]

The hard shift problem continues with my 2000 LX300. I have cleaned the IACV, replaced MAF and TPS sensors and it still has a random hard shift at slow speeds (like trans. is going to drop out onto the street). The trans. will make one single bang sound (awful sound!) and the front tires actually chirp. Fortunately, this occurs only randomly at slow speeds (say 5 -7 MPH) and when ether accelerating from a stopped position or slowing down. When I accelerate, the trans. stays in 1st gear longer than normal (to a higher RPM) and as it starts to shift into 2nd gear...BANG goes the tranny. Or when I am slowing down to stop it feels like the trans. is in say 4 gear at 7 MPH and should be in 2nd or 1st then...BANG. It is random and can drive for 15 - 20 miles in the neighborhood without incident and then out of nowhere...BANG. Anyway, here is the history and for the record I am leaning towards this being a trans. problem. Four (4) months ago the car first had this problem and the check engine light did come on. I got the car home, read your Lexus forum, took off the IACV and cleaned it (the magnet was seized with exhaust crud). I re-assembled the components, filled the radiator with fluid, cranked it up (the check engine light was off) and drove it for 3 months without incident until the problem re-appeared (the check engine light did not come on this time either). I got the car home, checked the IACV just to make sure it was clean (it was) and I installed new MAF and TPS sensors (no check engine light cam on). Well I got it back together and drove it for a 10 miles one day then 5 the next on the neighborhood streets. Then I decided to go to the interstate, accelerated hard and BANG. Please let me know what ideas you have. Thanks Preston...

[ESpecial]

What have you done that pertains specifically to the transmission, since that seems to be your problem? I would check the trans fluid level and the color. Should be red, not brown. Drain that fluid, refill with Toy specific atf and see what happens. If that doesn't do anything, probably time for a transmission rebuild. That's $$$.

[prestonj67]

What have you done that pertains specifically to the transmission, since that seems to be your problem? I would check the trans fluid level and the color. Should be red, not brown. Drain that fluid, refill with Toy specific atf and see what happens. If that doesn't do anything, probably time for a transmission rebuild. That's $$$.

I forgot to mention....the first time the problem occurred the engine would not idle at all and we were able to adjust the idle up to a much higher level and limp home.