May have shifting problems

**ChevyZ76** · 06-10-2014, 12:59 PM

I have a 9 Z28. Today just messing around I got to about 115mph. The car felt like it wasn't going any where and was working it butt off but would not shift to the final gear. Now it shifts usually under WOT around 6K. I have had it for a few months and this is the first time it has been pass 80mph. The reason I ask is I have had 3 3rd gen Fbodies that would not shift into 4th gear at WOT. Some people say speed governor but the car didn't just die. It wanted to keep going but not shift. i do not want to end up with a blown motor. But when I take it to the track I don't want this to be an issue.

***SMWS6TA*** · 06-10-2014, 01:30 PM

M6 or A4?

**ChevyZ76** · 06-10-2014, 01:31 PM

98 z28 a4

**Firebirdjones** · 06-10-2014, 03:33 PM

The only 3rd gens that would shift into 4th gear at WOT were the L98 350 TPI examples. That 700R4 had the valve body and governer setup a bit different to allow it.

On our 4th gens, I would assume they also have the ability to shift into 4th at WOT but that may be based on which speed rated tire your car came with. I never had any of our automatic 4th gen's going that fast, but looking at the tune I see nothing in HPtuners that would limit it, and as far as the shift tables (rpm/mph) it appears that it's setup to hit 4th gear at WOT.

However I'm looking at SS tunes which had larger and higher Z speed rated tires. Not sure if that's a factor but it could very well be possible that if you have a Z28 with a lower speed rated tire you might be running into a speed limiter that is programmed in the tune from the factory based off which tire option your car came with.

**theorangeguy** · 06-10-2014, 03:41 PM

this sounds like a governor from the factory that was set because of the tire they were using...I had it happen on my 99 camaro. It may have Z rated "or higher" tires now, but it probably came with tires that were only rated up to 110-115mph from the factory "which was pretty common" so the manufacturer set a limit on how fast the car can go for safety reasons. Need to get it tuned to get rid of it.

**ChevyZ76** · 06-10-2014, 04:43 PM

My code is QFZ for Z rated tires. So not sure what the issue is now. I didn't want to push it. It shifts at about 6K rpm under WOT. Which seems really high and a little scary at that.

**Firebirdjones** · 06-10-2014, 06:37 PM

If your door tag shows Z rated tires then you should have a tune in there that allows 140ish mph or so. 6,000 rpm under full throttle is pretty close to a stock shift point, so no worries there. I'd have to look at a base tune to be sure but I know it's right at or very close to 6k.

**0rion** · 06-10-2014, 07:40 PM

Originally Posted by SMWS6TA

M6 or A4?

I see we have a new entrant for the "dumbest question of 2014" award.....right now you're in 1st place.

are you bouncing on the rpm limiter or does it get there and just kinda bog down? It really would almost have to be the speed limiter I would think. The speed limiters were kinda all over the place.....115ish, 140ish, 160ish. My 98 in stock form was 160. Tires typically determined the limiter like most have said already but yours wouldn't be the first time I've read about someone having z rated tires and a 115 limiter (I believe it was actually 118). Maybe you have a pcm out of a different car that had T rated tires or something? The quick answer would be to get your file pulled and see what the pcm says. Know anyone with hptuners or efilive? Wouldn't have to buy the credits just to read the file but you would if you wanted to modify the tune.

***SMWS6TA*** · 06-11-2014, 08:00 AM

Originally Posted by 0rion

I see we have a new entrant for the "dumbest question of 2014" award.....right now you're in 1st place.

what? honest question....I know more about M6's then the A4's. Automatics are some Voodoo device that works on magic....to me.

**0rion** · 06-11-2014, 08:45 AM

Originally Posted by SMWS6TA

what? honest question....I know more about M6's then the A4's. Automatics are some Voodoo device that works on magic....to me.

read that first post again and tell me what part of it would make you think an m6

**ChevyZ76** · 06-12-2014, 05:56 AM

Car isn't bouncing or dying. Just sounds like it is working its butt off and nothing is happening. I could be I left off before it shifted. Just sounded to working to hard. Just got skewered. i know it was in the 6K range

**GoldenFlame** · 06-12-2014, 12:23 PM

Are you saying it wouldn't shift into 3rd or into 4th? Also what gears do you have? If it's all stock and 2.73s they take what seems forever to get up to 6K in 3rd gear.. Eventually it will shift to 4th but you either have to back off the gas or be at 163mph.. This from personal experience.. I don't remember the shift point for 2nd into 3rd... And not sure how the speed limiter works on these either..