I have an 89 irocz with a 305 tpi. it's bone stock with only a set of shorty headers, and a true dual 2.5 exhaust. I took it to the track the other night and was pretty happy with my best run, which was 15.1. There's one thing I'm not understanding though which is why I'm topping out at 92mph. When I'm crossing the line, I'm at 6k rpm. I've been told by many people that something isn't right, but no one has no idea what it might be.

 

So your at 6K in 3rd gear? What kind of gears do you have?

 

Sounds almost like it is stuck in 2nd gear or it is really slipping in 3rd gear.

this is how fast you would be @ 6K rpm with your 700R4 and 3.43 gears,
1st 44mph
2nd 82mph
3rd 133mph
4th 191mph

http://www.f-body.org/gears/

 

My rear end gears are 3.43. it doesn't seem like I'm missing gears. When I watch the tach rpms its shifting at 5500 and it seems to be shifting into all gears but I will recheck on my way home from work

 

Tach could very well be off. This is common on our 3rd gens. See the electronics forum here for a thread on how to fix and calibrate the tach.

RBob.

 

When I get a chance to fix my tach I will, it's got to be about 1000 off. On my way home it shifted as usual when not in WOT and hit 1, 2, 3, and OD. When I got to a long strip I stopped for a second then slammed it. Once again it shifted through 1, 2, 3, 4. My question is, when it's shifting, it's dropping down only 1500 rpms. i.e. (take my tach possibly being off 1000 in to consideration) I hold it in WOT, I shift at 5500 into second, my tach drops down to 4500, shifts into third at 5500, tach drops to 4500, shifts into fourth at 5500, tach drops to 4500, and then just keeps going until i let off when i;m at 6000 and ~92mph. Are the rpms only suppose to dropped 1500 when it upshifts, or is there something wrong there?

 

I can't see how you are getting to 4th gear and still be under 100mph with 3.42 gears.

If you had 4.56 gears, you would hit 100mph in 3rd at 6000rpm, or 84mph at 5000rpm.

 

I think something is up with your transmission.

 

I am not an expert on transmissions at all, but I have had problems in the past with mine, so wanted to share something. I don't think a stock 700R4 will shift into 4th gear at wide open throttle. There is a Corvette servo gear you need for that, which the police car Camaros did come with, and which are available for purchase.

If I am totally out to lunch here I appologize, but thought it may be of some use.

Best of luck figuring it out.

 

to the best of my knowledge, my 700R4 was stock, and had the ability to shift to 4th at WOT which was pretty cool.
I have no RPO codes for the car, but it did have some nice options.
aluminum driveshaft, N64 aluminum spare tire, 3.23 posi rear, 140 speedo.

manual mirror, drum brakes (I have no idea why you'd get a Formula with drums), rear defrost, courtesy illumination, t-tops, power doors and windows.

 

Could it have anything to do with the VSS. I've been throwing VSS code since I put the car on the road, and I read somewhere on here that the VSS not working properly can make the shifts not work properly. Is there any truth to that, or are the shifts only controlled by the govenor?

 

I think the VSS only affects the Lock-Up of the converter.
Shifting is done by line pressure and the TV Cable.

 

I agree, either your tach is wrong or your trans isn't right. Thats really the two most likely culprits

 

same with my vss but no problems with shifting here..