Black98T/A

iTrader: (5)

Wow you're a smart one aren't you?

Since you're so smart how about answering this question for me?

joecar

If this is the case, then it points to the VSS signal being incorrect... if the wiring is ok then maybe the VSS reluctor is loose.

Black98T/A

iTrader: (5)

yes that is the case which is why I've been shooting down it being the tune. Hell now I even have people bashing my car...lol! I checked the wiring to the VSS it looked ok where is the VSS reluctor inside the transmission?

joecar

Yes, inside the extension housing...

if you remove the VSS sensor, you should be able to see if the reluctor is loose/moved/misaligned/broken, poke your finger in there and wiggle the reluctor.

00 Freak

iTrader: (34)

i feel your pain blk98/TA. I'm having similar issues and i had a trans from performabuilt sent me out a trans from the states to italy. find out its not the trans. still trying to figure out the issue and now the car is on its way back to tx and have a professional tuner look at it. but its weird to me it was working fine and then all of sudden not. maybe the converter? but i hear the same things as its the tune. gone thru 3 transmission and one of them is a now completely different trans. this last one i did the swap and continues to do the same thing. so i hope the tuner can fix it. talk to a few trans guys and tell me its a tune. well see when the car is in tx.

Black98T/A

iTrader: (5)

Hey man..misery loves company. Your problem might very well be the tune. Is your speedometer off? Is the wot shift occurring 1-2? Mine doesn't. I'm 99.9 % sure why my wot shifts aren't occurring...that's because my speedo is off even after having both tuned and untuned pcm's butwhy my speedo is off is my problem.

Black98T/A

iTrader: (5)

I'll check it out..I asked the trans builder the other day if the reluctor wheel inside the tranny could be the problem he said no.

bad6as

iTrader: (17)

My buddies car would not shift 2-3 at wot. I have the mph values wrong in the wot shift. I swore it wasn't in the tune either because it was fine and just started on its own. New trans got put in and still same problem. It was because the engine was making more power to the converter would alow the rpms to go up and the mph wouldent catch up fast enough. Causing it to hit the limiter.

DrkPhx

iTrader: (15)

If this is true...

Then that would point to a mechanical issue such as Joe mentions..

I didn't read the entire thread, so you may have tried this already. Using the scan tool you should be able to command an upshift. This will help pinpoint the problem. Does the problem occur at part throttle as well? If not, are the shifts occuring as commanded? Any DTC's?

Black98T/A

iTrader: (5)

I posted this in my other thread in the transmission section

Black98T/A

iTrader: (5)

No the car shifts perfect 1-2 2-3 3-4 lockup and 3/4 throttle transmission downshifts and upshifts perfect. Any WOT shifting does not occur. If I'm at a dig and floor it it will stay in 1st and hit the rev limiter, if I'm on the highway and floor it it downshifts a gear but will not upshift and hits the rev limiter. Speedometer is about 10 off under 50 and about 15 off on the highway. I've tried a retune, a stock pcm off 98 Z28 with supposed 3.23's, and a vehicle speed sensor and speedometer is still off.

busta9876

iTrader: (3)

I'm just going to list a few things I've learned. I'm not saying issue is in the tune, or in the trans, just sharing some info.

#1 Stall torque converters will slip more rpm, so WOT vs MPH up-shift table is close to red line rpm before the converter, engine could start hitting rev limiter before reaching the needed MPH to let pcm command the up-shift.

#2 A change in tire size or even axle ratio will not effect the WOT upshift speed or RPM AS INDICATED on a scan tool. This is because the speed sensor is on the drive shaft. The PCM has no clue if the axle ratio or tires have changed. With small changes, this does not effect much, however, however, going from 2.73 gears to 4.10's, the engine speed will accelerate much quicker, and could get into a redline fuel cut before the up-shift occurs (this is normally on the 1-2 shift)

#3 Most shop type scan tool a fairly slow at data refresh rates. Using a laptop based such as HP Tuners, you can log data at a much faster rate, and really tell if the shift is being commanded.

#4 Valve bodies in transmissions wear out! There are a lot of replacement valves on the market and repair kits aimed at fixing drive-ability issues. A lot of the tooling required to do the repairs, and the valve kits them selves are expensive. Most small shops don't have the tools to make valve body repairs. When the trans was rebuilt, I would be asking if any valve body repair was done, or if it was even inspected. Working 7 years for a nationwide transmission reman company in quality control I learned a few things. We used specially built equipment to vacuum test every valve in the valve body, to check for wear. If the trans as 100k miles on it, I would be sure you have some worn parts in the valve body.

You might go as far as hooking up some LED's to the shift A and/or Shift B solenoid circuits going to the transmission, and observe the lights during the issue you are having.

1st Gear. A ON B ON
2nd Gear. A OFF B ON
3rd Gear. A OFF B OFF
4th Gear. A ON B OFF

Shift Solenoid A is commanded electrically ON during 1st and 4th gears.

Black98T/A

iTrader: (5)

busta9876 I understand all points about the converter or valve body affecting wot upshifts but those two things will not affect my speedometer and that is my problem. 65 is showing 80mph. Like flame said I'm going to check if the vss reluctor is loose in a little bit.

Black98T/A

iTrader: (5)

looked at the reluctor wheel didn't look broken and felt it didn't seem loose...could the problem be in the cluster?

joecar

Maybe or maybe not...

you will need to connect a scantool to see what VSS reads, and compare this to the speedo on the cluster.

Spellbound

I had a similar situation, it turned out to be the pump in the trans and a few other things. A pressure gauge was used to diagnose. The builder of the trans verified it on their trans dyno.

No expert by any means but it would seem to me that you should concentrate on getting your speedo corrected then go from there. Also, I know you said your APP was pretty accurate but have you had someone pace you to verify?

Black98T/A

iTrader: (5)

Yup that's what I'm now trying to do, if the trans still doesn't shift at wot with a correct speedometer which I doubt I'll go from there. I used 2 different speedo apps on my iPhone both are dead on with my 99 Corvette's speedometer. Speedo says 80 app says 65 and cars are really passing me on the highway. 30-50 range on my speedo its about 10 off. I don't know why all of sudden the speedo became pof with no change in anything.

SladeX

When I was down in Florida last year a guy out in the Daytona area helped me out with a tune issue (which later turned out to be a lifter/cam issue). Check the Florida local board for some help.

It's probably a transmission issue though, but why not get the tune issue sorted out first so you know you've eliminated all other variables?

Black98T/A

iTrader: (5)

I guess this is my next step...

JKB315

iTrader: (9)

Having same issue. I hit my rev limiter twice at the track Saturday. I went from 3:23s to 3:73s since my last tune by Frost. I tried to fix it with my predator temporary . Car still reads about 6-7 mph off. I know it's the tune since it was perfect before gear change. I hope Frost gets back to me soon so I can go racing again. I went ahead and turned my shift points down to 5800 just to be safe.