alright so i had this problem start a few days ago and i cant figure out what it is. havent really tried replacing anything yet but here it goes... i have a 91 rs with the 3.1 and when i get on the highway and i get to about 65 the car starts surging or downshifting sort of and sometimes wont even shift into overdrive.. tried searching on here and couldnt really find anything... but what im thinking it could be would be either the tps or the iac valve... any suggestions would be great

thanks.. Johnny

 

iac has nothing to do with it,and tps would give more issues then just at cruise speed, u say its liek downshifting,u maye have the lockup on the converter cycling on and off, jack up the driver side of the car, on that side of the tras near the front/back of the motor will be a white plug,unplug it and take the car for a drive,if it stops doing it ur converter is going in and out of lockup

 

Does it seem to always happen at about the same RPM and load?

If it more like a soft downshift or is it like you are puching the gas and then letting off?

 

alright so i went and took off the plug that i thought it was... it had 4 prongs in the switch and it was white... and after i unplugged it, it didnt want to go into overdrive on the highway... is that what it was supposed to do? it didnt shift like it did before so im guessing that was the plan...

yea it seems to happen at around the same load and rpm... pretty much after 55 is when it starts to happen or at least thats the only speeds ive noticed it at... and the downshifting is pretty hard but then it goes back to normal and then it does it again for a while...

 

that plug does not control the 3-4 shift, it controls the converter lockup, unpluging it only prevents the converter form locking up. the computer can lockup the convetre in any gear other then 1st as long as certian conditions are met.when i had changed my converter and rear gear ratio i had issues with the computer locking up the converter in 2nd gear all the time on me, it used to lug the hell out of the motor during intown driving.and cycle the converter lockup like mad at around 45-55 mph when cruising

does the transmission shift late and hard? or early and soft etc? if it does i would check the tv cable adjustment

 

sorry for the late replies but ive been kinda busy... but i was driving the car on the highway again and it shifts fine in all other gears but once it gets to that speed (above 55) it will start to do the same thing.. other than the cable adjustment what other things would i be able to do

 

alright so i dropped the pan and changed my tcc solenoid... and so far so good... shifts fine and hasnt surged on the highway yet so im hoping that fixes it..

 

ive had the same problem with my 86 iroc. 700r4/ still cant figure it out. ive posted on here before but noone seems to know what to do. i guess i will try the selonoid that you changed. messed with the tv cable until im just exhausted. and about ready to get out the hammer to it. so i gave up and im just driving it and dealing with it. waiting for the next step of damaging my tranny all togather. how and where and what does it cost to replace that selonoid?

 

i got the solenoid at autozone for about 50 bucks and it can be looked up by asking for the transmission control solenoid.. its the one that controls torque converter lockup im pretty sure the part number is 52-0203... as for where it goes i found this pic that i used when i changed mine..



its the TCC solenoid all the way on the left... right next to the filter neck thing
pretty much 2 bolts and to wires are the only things there after you drop the pan... ive only had it changed for a few days but ill let you know if the problem comes back

 

ok thanks. get back to me and let me know if that fixes your problem. i sure would be very happy if thats the problem that im having.

 

Hey Chevyman did that TCC fix your problem?? i bought one today but havent installed it yet. thanks

 

so far so good... im going on a roadtrip this weekend so i should know if it really fixed it then because thats when it really started acting up.. it did it in town to and so far hasnt acted up like it used to... in town and on the freeway it seems to lock up alot better and easier than the old one did... i just havent put it on a long trip yet to see if that fixed it