Hey there - I'm new and praying for help. I've scoured this site before and loved it, but I officially signed up today for a good reason.

I recently bought a 1993 Z28 LT1 that was pretty beat. It ran great, no obvious problems. I'm driving home from work a couple weeks ago, and I realized it wasn't shifting properly. I'm not terribly sure how many shifts it is supposed to do, but I pushed it up to about 42mph and the rpms were around 4 when it finally shifted, and it shifted hard. My dad's a mechanic and he yelled at me for not checking the fluid and all. He checked the transmission fluid and he said it smelled burnt. We spent that evening taking the transmission pan down and checking it out. There was no metal in the pan, and the fluid didn't look all that bad. We changed the filter and fluid and ran it around a bit. I said it still felt funny, but my dad thought it was running great.

The next day, it was still not shifting properly. I replaced the tie rod ends, rotors and shoes, so I took it in for an alignment and balance. The guy that does it is a friend of mine and when I explained the transmission problem to him, he told me to check the TPS. My dad ordered one that day and he replaced it just a couple days ago. After that, it was running great. Shifting with no problems. As he was driving it home, it did it again. No shifting. I took it out for a bit and it shifted just fine for me, until last night and this morning.

Sorry for being so long-winded. I'm just completely at a loss as to what the problem could be. I'm no gearhead, but if you need any info, I can get it. Anybody else ever have this problem or have any idea what I should check now?

Thanks for having such a great forum!

 

My car did the same thing with the new setup, but after I took it to the tranny shop they said my 2nd gear was out. My trans would shift from 1st to 3rd or 4th which was the reason why it would hit hard.

Im not saying you blew your tranny, but its something to take a look into. Also check the TV cable at the TB and look for kinks as well.

 

Awesome. I'll check that stuff out. Thanks so much for your help!

 

do you have to let off on the gas for it to shift? if so thats what mine is doing right now

 

Can you say...

T56 Swap????

-Ivan

 

Thats funny I get at least a couple calls a week from t56 guys with big power switching to autos so they can go faster and so they can quit spending 1400-1800 every three months or so on clutches lol

Ok first the TPS has nothing to do with shifting in a 93 , Its not a 4l60e like in the 94 cars its a 700r4/4l60 No E . With intermittent harsh and late upshift problems I would have to suggest you take a look at the TV cable. Some would call it a passing gear cable make sure its not binding, The other possibility is the Throttle valve itself could be sticking in the valve body. But I would check that cable first it hooks to the throttle body ,

 

Ok. Here's the bad news. Your 1993 F-Body uses a 4L60 (700R4) transmission. It's cable controlled, not electronically controlled. This means that your TPS has nothing to do with your shift scheduling.

You may be looking at either the governor or the throttle valve hanging up.

If your dad is a mechanic, he should be able to help you establish when your car is shifting. Your transmission is a 4 speed with a lock-up converter. Your 1-2 shift should occur at 15-18 MPH, and your 2-3 shift should be at 35-38 MPH. Your 3-4 should be around 45 MPH. This is all under normal throttle. If your car doesn't have a 3-4 shift, or has no passing gear (kickdown), you're probably looking at a stuck throttle valve. There's also a chance that the MTV valve could be stuck. If a valve is stuck, it'll require removal of the valve body to free it up. A stuck valve is usually a sign of a larger problem, though. The contamination had to come from somewhere. There have been rare occurances where we've freed up a stuck valve and the transmission work fine for a long while after that, though.

If there's anything I can help with, please feel free to give me a call. 302-250-1202

Frank
CPT

 

You probably need to adjust the throttle valve (TV) cable. It's a cable that goes from the throttle linkage to the transmission and is adjusted at the throttle body.

There is a tab and a slider on the throttle body end of the TV cable. With engine off, press the tab and move the slider toward the rear until it stops.
Release the tab and push the throttle linkage to WOT. The slider should "ratchet" forward with the throttle wide open. Release linkage and operate to make sure everything moves freely with the engine off.
Road test and recheck with engine hot.

 

wow, i am overwhelmed at the awesomeness of you guys!

i talked to my dad today and he said he was looking it up with some of his friends and coworkers and they all agreed it may be a governor or tv cable issue.

i'm taking it over to his shop tomorrow after work. luckily he is king of spare parts and has a couple trannies around with governors. i'm hoping that is the problem and also that i haven't successfully burned the hell out of the transmission trying to manually shift it.

i'll post the results tomorrow night after we put her up on the lift. its just such a great car...i'm really in love with it. my dad loves it, too. he's got a 1967 camaro rs ss that is completely modified. he's taken best in show a few times at car shows. i thought it would be fun to have my own camaro, so it could be like a father/daughter effort, you know? but of course, the 1993 z28 i got is so beat up. the guy that had it prior to me just beat the crap out of it. it's got a lot of body damage and needs paint badly. the headliner is falling down and the driver's seat has a tear and the foam is coming out. i found some pleather custom seat covers on ebay that i'm considering. it's going to be a project, and i'm really excited. my goal is to get it race ready. i'd love to take it down the 1/4 mile and see what happens. after i fix the shifting issue, of course! =)

 

Hey thats my favorite kind of car, Starts out as a lump of coal and a little elbow grease and of course dollars and you make a diamond out of it

 

I can say it, but I have no idea what it is.

 

So we checked the TV cable last night and switched out the governor for a new one. Still not shifting properly. I'm looking at a new transmission now.

Sadness.....