cheebs

i just got rid of my bmw 540 and got a 93 sc300. when i brought it i test drove it for 1 and a half hours. no issues. 4 days later i drive it to work and the idle drops from 4500 to 3000 and back. i going about 75-80. i slow down it does not repeat. two days later it comes back. you can feel it jerk slightly but i can press the petal with no prob. same speed but i slow down and it now does it at about 40 to 60. it does not seam to do do this below 40. the jerking is so smooth that it feels electronic. i have look in the forums for three days but i have not found an anwser for this. i have found a lot of great stuff tho thanks.

Psionic

Sounds like you need seafoam.

cheebs

where do i need it?

1st-Lex

Sounds like a I.A.C sensor going bad to me.Does it do it while the car is parked?

cheebs

"Does it do it while the car is parked?"


no, not at all

Supra Dr

iTrader: (14)

thank god someone who seached 1st before posting

a brief recap: your going 75/ 80 mph & the tach is @ 4500 rpm &
drops down to 3000. then back & forth. wont exibit the problem
below 40 mph.

auto trans i assume.
my guess it has to do w/ the OD lock up solenoid or the torque
converter.
the trans wont shift into OD "4th gear" untill 40mph or so.
thats why it feels ok @ slower speeds.

to prove my theory: next time it does it on the highway, turn the OD
OFF. it should feel like it down shifted & the rpm should run back
up 4500 & remain stabile.
note: 4500 is kinda high to rev for long periods of time so dont drive
it this way as a remidy.

things to check: the trans fluid level & color.
if its dirty, have it flushed. (not a drain & refill) you may get lucky &
dodge a bullet. the lock up solenoid is eletro-mechanical & sometimes
debris gets stuck to it, flushing sometimes clears it off.
if its still no good, its off to a trans shop. but at least you have an idea
of whats wrong & maybe they will fix it instead of the "blanket rebuild."

post back what happens or if my senareo is incorrect.

john

cheebs

two things the trans fuild is clean and the od button does not work i just brought a new shift lever an ebay guy has the 100 dollar handle for 62 dollars silver and carbon do a search. after reading what supra dr said i went out and set it with the od off.

Supra Dr

iTrader: (14)

even better, could have been an electrical problem w/ the switch causing the problem.
make sure the OD switch & indicator light both work. if not resolve that 1st.

cheebs

right after you chimed in i went out to the car took off the shift handle and put a wire in the connection for the od and the light came on took it out it went off. so i put it back and put hte handle back on and the light stayed on. went i got the car the od button did not work so i brought a new shift handle.

cheebs

ok just got home from work it is just as you said supra dr. how much do you think it will cost to fix? or can it be diy?

Supra Dr

iTrader: (14)

sorry man, this is where i bow out to the trans shop. i'll play w/ some GM & honda
solenoids, but i really haven't had the need to mess w/ the toy rear drive trans.

its 1 or the other, possibly both.
1) the lock up solenoid may be electrically weak, it may engauge lock up & then
"kick out" then engauge again. giving the rpm up/down you describe of course
it would be less noticeable @ 50/60 than 75/80mph.

2) the torque converter itself may have a issue. were the lock up is engauged,
but the converter mechanically can't hold it & it cycles in/out.

your not complaining about any other trans type problems: slip from stop or
slide between shifts, aggressive or banging shifts, etc. so my money would be
on the lock up solenoid is flaking out. generally the solenoids are positioned
above the valve body, accessed thru the pan or removed externally. this should
not be a remove trans type repair. (i'm only speculating as i have not done this
repair.) try searching around.
as i said before find a trans shop who is willing to repair it, not a blanket rebuild.
provide them w/ what you have tested/tried & how the car acts. this should help them
diagnose it quicker & save you some money.

when you resolve it, please post back here for the others who are searching

cheebs

i asked because as i was searching i found a few post about shift kits. some had a few pics. which showed three noids on the valve body. to replace the valve body you have to take off all the three noids anyway so i thought i might do that since it might need work anyway. the job for putting in the shift kit seemed easy enough. now for my problem i turned off the od and drove it to work that way when i got to work i turned it back on. and the problem has not come back. but i will be look for it and saving to get it fix if it does come back. thanks for your input and help