Tranny problems


#1

4 days ago tps code tripped. drove without issue, next day didnt want to go without really tromping on it. then it didnt want to shift out of 2nd, finaly got it to shift. now after replacing tps i still have no 3rd “D” or “od” Im not brave enough to tear into the trans. any thoughts?


#2

98 olds lss 3800 n/a


#3

ok… more to add. took it to auto parts store, no check engine light but p1406 egr valve pintle position code. could this be the issue? when i left i jumped on it a bit and it will now shudder then shift if i am mean to it, but not if im nice?


#4

You probably need to get it on a better code reader than the ones that auto parts stores normally use. They often use generic readers that don’t pull all codes. There very well may be transmission codes that are hiding from the AP store scanner. Unfortunately, this probably does mean paying someone.

Those 4T65Es are very complicated in computer control terms. Lots and lots of things can mess with them including even the EGR. I’d say that in the short term it doesn’t matter much. You have the EGR issue, so diagnose it and see what happens. Note that I said “diagnose” it - no code can tell you that the valve itself is bad. Here’s a handy site: http://easyautodiagnostics.com/gm_egr_test/gm_egr_valve_1.php

Edit: I think the '98s still had a vacuum modulator. They do fail, create havoc with shifting, and are easy to check and fix.


#5

i think the egr was because i had unplugged a vacuum that was in the way. i think that may be a completely unrelated issue.


#6

i plugged it back in. i guess we will see if the code returns would you suggest a mechanic or a transmission shop


#7

The EGR is electronic rather than vacuum actuated. Whatever that line was, it’s probably unrelated. But if you had the codes cleared and it doesn’t return - then yes, skip the EGR.

If that’s the case, the only thing I can say is to track down every single ground point you can and clean and tighten all of them. Other than that, going without codes is shooting in the dark. It sounds like you are being stuck in limp mode. If that’s so, then there are codes. The magic word is “Tech II scanner”

What was the TPS code? Is it safe to assume it it gone? There aren’t any codes that can tell you the TPS is bad. Check the wiring and the TPS operation.


#8

Im unsure what the code was. i knew it had produced that code. googleing it told me it could cause issues so i grabbed one off of my properly functioning car and the check engine light went away but the problem persisted. i will swap egr valves tomorrow most likely (pricey part) just to be safe. mechanic on Monday i guess


#9

Well, glad you didn’t actually buy a TPS. Note that pretty much all codes refer to the entire circuit - not just to the part. If you want to test the suspect TPS, it’s easy if you have a voltmeter - install it; there’s a 5V power wire; 1 ground wire; 1 signal wire. Make sure you get 5V on the power wire. The signal wire should read about .5V at closed throttle and about 4.5V at WOT. Most importantly the transition between the .5 and 4.5V should be smooth and steady as you slowly open the throttle plate.


#10

A 16 yr old 4t65e trans is right at fail point. Actually probably past it. Service such as fluid/filter change might prolong life but usually will not cure anything.


#11

had a rebuild 25000 miles ago. functioned great until this.


#12

appointment for friday, i will find out then