My car is a 1986 Z-28, I replaced the stock 305 TPI with a race built 10.5 : 1 compresion over bored 350 making it a 355cid TPI using the same intake with some machining and honing done to it so it would breath better. Before I had the engine done I instaled headers and a full exaughst with bigger pipes, also had a 410 rear instaled along with a race built transmition, and I am also running a NOS Nitrous system.......It has just been painted Candy Apple Red and got a bran new interior.....It looks great and makes alot of power....my problem is at wide open throttle the car dosen't shift when it should unless I come off the throttle a tiny bit.....
Could this be a problem with the throttle position sensor?
ANY HELP OR SUGGESTIONS WOULD BE GREATLY APPRECIATED!!!

 

what do you mean it doesnt shift when its supposed to, in other words does it just keep going until you let off, or does it eventually shift, just too high in the RPM band?

 

I havent let it go far enough to find out if it will eventually shift or not, but if I let of the throtle abit it will shift it almost as if i need a little stopper under the pedal so its just a fraction before wide open throttle and everything would be great!!!

 

Mines been doing something similar since I had my trans redone.Will not shift into 2nd at wot....most of the time.If I let up on the throttle a fraction will get it to shift.I/we have tried adjusting tv cable and it really doesnt help much.I havnt held it past about 5500 or so but thats too high considering all the other shift points are on time.Trans shop is about to go back through it.

 

Mine did the same thing going into third gear. All I did was kick the throttle valve way down and now it's fine.

 

sounds like a misadjusted TV cable

 

Is this only 2nd to 3rd, or also 1st to 2nd? How does it do in "normal" driving?

The TV cable should never be adjusted to "solve" a problem. It should be adjusted properly only. I'd guess your "race built transmission" was improperly built.

 

Mine is only on the 2-3 shift.I agree with shifty.Guy who built it was saying we need to keep adjusting the cable.I`m like no,something is wrong.Not to mention if I`m at highway speeds 60 & up if I floor it or close it acts like it trys to shift into 2nd.I think it may be a slip thouigh.I think mine is just FUBAR.Hope the guy gets it right this time.

 

Either of you do a higher stall converter and/or changed the rear gearing?

Anyone checked the Governor yet?
TV doesnt get 'adjusted' it gets reset. There is only one way to do that. The TV cable mainly controls the line pressure rise.

 

Yes,Governor is last thing to try that I`m aware of before they go back through mine.We are gonna try that first.