1-2 Shift Flare

Ktown6.0

Ktown6.0

I can't remember
Joined
Jan 31, 2007
Messages
635
'99 truck. PPump conversion, using 12v TPS. On start up first gear holds solid too 3k rpms and has a hard shift. Shifts right to second if I keep throttle pedal, or quick shifts 2nd then 3rd if I let off. Trans is a Garmon unit, Stage 2. Not yet a year old.

This issue only happens on start up. After this, it doesn't happen again. 1-4 shifts are fine, and all works well. If I pull over, shut the truck off and restart, I have the extreme first gear shift, and then all is well.

There are a number of threads with first gear issues, but none say the issue goes away.

Fluid level is good, color is normal. I have not checked with a gauge since it only does it once per start up.

Ideas?

Thanks Everyone
 
idle it in neural for s bit before driving, see if that helps,
Also, do you have the factory heat exchanger under the turbo still?
 
I tried the idle before moving. That didn't help.

Factory heat exchanger.

I found one single post from someone who had this issue and fixed it with an Output Shaft Speed sensor. But, I assumed that only overdrive was controlled electronically?

The issue is only on the initial start up. Once it goes through the first 1-2 shift, problem is gone.
 
OSS has trans fluid coming from around the plug after inspection. I'll replace tomorrow, and report back with results.
 
Could have a sticking valve, speed sensor will create all kinds of havoc.
Based on wheel speed and gov pressure is how it decides to shift..
 
You are describing this wrong.

Since first gear is the rear clutch and the sprag, it either holds or not. Second gear is just adding the front band to the above. It can't flair. If the band doesn't hold it stays in first.

Unless, the band is applying, then slipping and grabbing. Which I've never seen. Are you having a late shift issue?
 
Flare was the wrong word. I apologize. First holds long on first start up and drive. Hits hard for second. After the run through the gears on any given startup, it shifts fine from then on, until shut off. I looked at the OSS after some deep reading, and mine has fluid leaking through the plug. No other leakage around to be coming from another place.
 
My nephews 01 did that too. I'm not sure what we did to fix it but I think it was the trans transducer/temp sensor.
 
Problem solved.

Output-shaft Speed Sensor was the culprit. Tip was split, and magnet was sitting sideways. Replaced, and all is well.

FYI: Some parts houses have issues looking up this part on a dodge for some reason. I found the part number online, and was able to get them to find what they had in stock.
 
No one really seems to have a good idea what role it plays at the programming level.

Monkey Fist Rage
 
BigPapa said:
Mine has done this since I put my 12V in the 98.5. I've asked for help a couple of times:

http://www.competitiondiesel.com/forums/showthread.php?t=133560&highlight=shift

http://www.competitiondiesel.com/forums/showthread.php?t=132865&highlight=shift

http://www.competitiondiesel.com/forums/showthread.php?t=137386&highlight=shift

I've always suspected a bad APPS. Just never got around to replacing it. I'll have to check the OSS. You have a part number?
Click to expand...

Sorry for the slow reply.

I do not have the part number handy. I just went to the O'reilly Auto website.

On edit, here are the #s from the website.

MasterPro (their brand): # 2VSS45 and then Line Code MPI
BWD: # S8023 and then Line Code BWD

I don't remember which one I purchased. I remember vaguely giving them the S8023# and then they were able to look it up.
 
biggy238 said:
No one really seems to have a good idea what role it plays at the programming level.

Monkey Fist Rage
Click to expand...

I can confirm it makes a really nasty 1-2 shift on initial start up, and then doesn't come back until truck is shut off and restarted if the OSS goes bad.
 
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