Cycokat

Hello all. Pretty new here, found the site when I was looking for a Z28 and have been lurking. I just bought myself an 85 Z28 a couple of weeks ago, and now I have the first of likely many questions. Apologies if it seems like I'm beating a dead horse.

My shift from 2-3 under "normal" throttle seems to happen really early, most times bogging down the engine with RPMs that are too low. It will down shift if I goose it though. Also the 3-4 shift happens around 33-35 mph which seems just a tad early too. When I get on it and am near at or near WOT, the shifts seem to be ok, but 3-4 still happens at around the same speed.

So, from what I've picked up so far is to first check the TV cable and set it according to GM and/or tvmadeez.com. I've done that and the shifts seem to still be the same. I didn't mention earlier that the check engine light would flash when the 2-3 shift bogged the engine, that seems to have stopped after the TV set I did. I will try to set it again, maybe I didn't push it back far enough the first time?

I've also seen the TV Cable Correction Spring. That looks promising, some of the threads I've read seem to describe my situation almost exactly, and it is cheap.

And... On the advice of a mechanic friend of mine (I'm not a mechanic, but am not afraid of turning wrenches), I am going to drop the tranny pan and replace the fluid and filter. Not a full flush, but at least that much. Would it be wise to replace the TV spring while i'm in there and continue this trouble shooting from there? Maybe I could put a new TV Cable on at the same time?

Last thing I'll mention is the governor. It seems that if I change the inside weights or get softer springs it will make the normal throttle shift better?

Thanks in advance for input. This forum seems to have a ton of knowledgeable members and I appreciate any thoughts.

Zach/90\irocZ

iTrader: (6)

1st double check that your ajusting right TV cable right as some people say press gas pedal to adjust it but if you throttle cable has slop it might not be opening the thrittle blade fully so i would suggest ajusting it by manually adjust throttle by hand to adjust TV Cable as that sounds like the issue

changing the weights will only adjust your shift points higher or lower which is a total waste of time if your not making power past 4000rpm and will make your car less efficent and probably slower due to the fact trans not shifting at the right spot where power is mad shifting weights will shift your shift points to higher rpm and in turn out of your powerband

next check to see if you can pull any codes from ecm to see if you have any other issues but it seems to me it TV cable related i would install new one if i had a chance there not much and over the years can develop slop your already there mightest well worst thing is doing double work

you can also do a complete flush by removing the trans cooler line and pour new trans fluid while old is coming out trans cooler line while engine is running after you change filter to get a compete flush theres alot of dirty fluid left in the torque converter think 5-6 quarts i could be wrong

nhgator

I had a similar issue when I resurrected my bird and started driving it,for around $20 at the local chebbey dealer I got a new,correct tv cable,that solved my issues and the car drives and shifts properly now.

Cycokat

I did it by hand the first time and the blade moved all the way to the stop. A local transmission shop advised that I try it using the pedal in case using the pedal doesn't move the throttle blade all the way to the stop.

So leave the governor out of the equation for now?

I tried to do this by jumping the pins, but I don't have any thing wired to #12 and when I tried 5 & 6, nothing happened. I don't have a tool to read them.

The same trans shop that gave me the TV Cable advice, advised against flushing / changing fluid if I don't need to. Said that in an older trans where the history of fluid change isn't known that sometimes changing the fluid can lead to problems? First time I've heard that, does it make sense?

I will get a new cable from Chevy and replace. Both you and nhgator have offered the same advice and I was wondering it myself.

Any opinion on the TV Correction Spring?

I appreciate the replies, I'm learning on the fly here and trying to gather enough information to make the right decisions.

Pro Built Automatics

First, the TV cable has to be right and set right. Once you are sure that you have the right TV cable, which in most cases you will have the right one. Then the TV cable must be set so that it is tight at WOT. You must have max TV with max throttle. Second, the 1982 - early 1987 units had shift timing problems. To solve this, I use the TransGo Senior Shift kit to address the shift timing problems, lockup problems, downshift problems, etc. along with the Corvette servo and the larger boost valves. If you use this kit DO NOT use the 3-4 Orange shift timing spring, as it will make the 3-4 shift very late at part throttle. Use the Green shift timing spring here. I carry the Heavy Duty modified version of this Shift kit if needed.

Zach/90\irocZ

iTrader: (6)

he has alot of good knowleadge and parts fo to his website

for trouble codes it will check engine light will blink 1 time followed by a pause then 2 blinks "aka" Code 12 that will happen 3 times then trouble codes will follow for example code 54 would by 5 blinks pause 4 blinks that will haben 2 more times for a total of 3

alot of good info here https://www.thirdgen.org/faq
engine codes and what they mean https://www.thirdgen.org/service-eng...ht-error-codes

you cant plug up a reader to a ob1 car only ob2 cars and newer unless you did a full ls1 swap readers are for ob2 cars and newer thats how you get codes ob1 only way is to sit and count lol


ive heard horror stories and good stories i cant say if there all true only can tell you whats my experiance and then again theres so many variables on what broke how it broke what they where doing did they change the filter so its all opinions no hard facts all ive seen was i did trans flush and my trans broke havent seen a broke down of trans to see actually what happen there probaly is a detailed storie out there but i never bothered to full look in

heres my storie i had over 230,000 miles on my last last camaro and did a trans flush and had no issues at all ive also did it on a 96 avalon with 250,000 miles leaking oil from heads smoky suspension is worn should die already i change it at 200,000 miles and no issues and i have no proplems going over 100 on the freeway and i didnt change trans oil filter so ive had no bad issues i would recommend changing filter and if your dropping the pan invest in pan with drain plug or you can weld your own drain plug

Cycokat

I will check out Pro Built and that kit. In the meantime, I'm going to order a new TV cable. part #25521263 on rock auto's web site. If the cable doesn't change anything, maybe I will go for that TransGo.

Thanks for the replies; I'll be back with more questions I'm sure!

Cycokat

I forgot to mention that for reading the codes, I did try what was in that linked page. Nothing happened, not even the 12's. I don't have anything wired into #12 so I went with 5-6, no dice. I can certainly try again, it could have been operator error.

Reid Fleming

iTrader: (2)

If you do end up going for a TransGo, please do yourself a favor and get the one that ProBuilt Automatics sells. Their kits are MUCH better than the standard TransGo that everybody else sells.

Cycokat

Thanks.

Zach/90\irocZ

iTrader: (6)

you should see code 12 if you have no codes code 12 should still blink shows ecm is working correctly you connect 6 and 12 the last 2 slots you might try 5 and 6 since you have a later car

one92rs

iTrader: (5)

full TV travel is a must. if you feel so inclined the best way i have found ( since rebuilding my own trans ) was in the superior shift reprogramming kit.

1. with the pan off or pull the pan.
2. with a good cable pull it till the TV valve is flush with the bushing.
3. mark the cable with a sharpie
4. ME ( install trans ) YOU go to throttle body and reset cable to adjust.
5. hook tb cable to tbi and floor pedal. look for mark--make sure mark is at end of boot at wide open throttle.
6. install pan and move on.

we tried this on my buddies truck and it worked perfect. transmission worked a lot better.