1SlowFormula

that is the stock setting... and that parameter has nothing to do with this.

myltwon

iTrader: (1)

so since I have a 3000 stall I should set to 3200rpm?

95FbFormula

iTrader: (25)

Does every obd1 car experience this I was planning on a 3200 to 3600 stall but I don't want to lose my 2-1 downshift

myltwon

iTrader: (1)

well according to some there are fixes that don't compromise the 2-1 downshift

1SlowFormula

yes all ODB-I cars will experiance this when they go to a higher then about 3200 or so stall speed, there is no real set stall because it depends on how loose it is and the supporting mods... Also you will not completely loose your 2-1 downshift, but only at WOT. You can learn to drive the car with it set this way because you never notice it on the street, the only time it bit me in the A$$ was at the track, my rear peg-legged and spun the car shifted to 2nd and then caught and bogged down because I was only going 10-15MPH now in 2nd gear at full throttle. but then all I had to do was throw the shifter to 1st for it to downshift, then I was good to go for the rest of the run and only lost ~.3 ET but my MPH was still showed a good run. Too bad that was during an elimination round in my local racing series points cup...

And that was the only time I had an issue with this fix in the 2+ years I have had the high stall...

95FbFormula

iTrader: (25)

so it only effects the 2-1 auto downshift I would still be able to shift it my self. LOL i was only worred because that was 1 of my favorit things about the auto was the high rpm 2-1 downshift.

Shon Herron

iTrader: (25)

Well, I am not under the impression that ALL OBDI cars have this problem.
When I was doing testing SEVERAL years ago, I had a yank ST3500 and it would only cause a problem if I stalled it up before launch, leaving off idle was fine and actually produced the best 60's for my car.
Some have seen it with 3000 and others have not seen it till the 3800 range. it all depends.

1SlowFormula

Ok let me clear up my statements above, it will only happen to OBD-I cars, not ODB-II... It happens when the higher, no set speed due to other factors, doesn't allow the computer to do it's processing correctly to perform the shift... Historically those stall speeds are over 3200, but at times do not show, as you stated, till about 3800 or more, and some have seen it with stall speeds as low as 2800, but those are very rare. Your converter manufacturer, vehicle combo, weight, gearing, and many other factors go into it...

buffman

iTrader: (9)

it's a hit or miss kind of thing for OBD1 cars. It can happen and it cant. My converter is rated for around 3000ish. Stalls to around 3400 based on my datalogs. I've never had the stall Wall problem...

Some guys have stated the issue comes from flexing the output shaft on launch, loosing VSS signal etc. I would believe upping the min VSS diagnostic rpm could help, or you can completely turn it off in the switch table..

slowmofo

iTrader: (6)

Its a 94-95 problem, I never got around it in my 94.

buffman

iTrader: (9)

^^^ OBD1 = 94-95 cars

1SlowFormula

I always understood that VSS diagnostic RPM was just that a diangotic RPM setting, one of a couple that tell the computer to run the DTC32 Test, for the EGR... I don't see that helping or effecting this issue since it does not have any impact on the parameters around shifting...

From the tunercat refernce manual page 14:
Constant Type Calibration Table
The Constants Table is used to present calibration values that represent single values or calibration constants such as fuel cutoff RPM or injector flow rates.

buffman

iTrader: (9)

I have no experience whether or not it is helpful, I was just relaying information that was presented in another thread. I've already made other necessary changes to my tune that have so far prevented any issues..

Ed Wright

iTrader: (1)

Fixed correctly you won't loose your downshifts.

dhdenney

iTrader: (53)

Subscribing. I am working on my 4l60e combo right now.

TwoFast4Lv

iTrader: (8)

Ed fixed mine(years ago) and it works perfectly

I spent thousands on transmission testing and verified it was in the PCM but could find no one to hack it up for me. Ed Stepped up to the plate and did it. he put his personal car together and tested code until he got it fixed.

IF you call him he may give you the converters to look for that cause this problem the most

I did go back to a OBD-II for the street. I like the 3rd gear select Lock up

2nd3rd4thgen

is it only in 94-95 what about 93

Michigan Skip

Well, I could care less who gets pissed at me.
People think it's taboo or something to tell how to fix a problem. Especially this particular problem. Here's What I do and it works every time. Change the VSS Diagnostic Enable Min from 3000 to more than your converter flashes to and try that.It's under the ECM Constants table

buffman

iTrader: (9)

^^ That doesn't work everytime.

CamaroRacing12

iTrader: (5)

john p. why the 3500 vig not the 3600?