LLY: over revving

VinceGU05

VinceGU05

duramax lover downunder
May 20, 2011
164
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Melbourne, Australia
i have been having WOT shift problems since day one after the engine conversion.
have tried just about everything. different trans. new fuel filter. difference set of tunes.
but no matter what it will rev to 3800 rpm. even in neutral which i was very surprised about.
shouldnt it stop at 3300 ( factory rev limit)? the tuner tells me he hasnt touch this part of the tuning, therefore its my issue.
can any one help with where or what to check? whats allowing it to rev so high.
i think this is the key to my hanging shifts.
thanks in advance.
 
TDFDiesel

TDFDiesel

I'm That Guy
Jan 6, 2011
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Mesa, AZ
You physically changed your trans out and you are still having the same issues? I'm not going to be of much value here, but was just trying to clarify.

Do you have all the factory speed sensors?
 
x MadMAX DIESEL

x MadMAX DIESEL

<<<< No Horsepower
Dec 30, 2008
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Lexington, Ky
Can you change the shift to make up for the difference? If its shifting at 3500 and you want it to shift at 3000 ie try adjusting it to say to shift at 2500-2600 and see what happens.

Sent from my PC36100 using Tapatalk 2
 
messejme

messejme

Jazzy, Me and Max
Mar 7, 2008
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Branchburg NJ
Could it be a problem with the reluctor wheel being wrong tooth count or loose bolts or broken teeth causing a misreading of the actual RPMs?
 
VinceGU05

VinceGU05

duramax lover downunder
May 20, 2011
164
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0
Melbourne, Australia
TDFDiesel said:
You physically changed your trans out and you are still having the same issues? I'm not going to be of much value here, but was just trying to clarify.

Do you have all the factory speed sensors?
Click to expand...

physically a new trans.
got all 3 factory speed sensors on the trans. all checked ok with mike L .

[What does it do with a stock tune? ]
last time i checked ... the same.

[Can you change the shift to make up for the difference? If its shifting at 3500 and you want it to shift at 3000 ie try adjusting it to say to shift at 2500-2600 and see what happens. ]
my DSP5 tune is locked.
i could have a look into my stock tune and see if thats locked. if not could try that theory with it but i dont know much more than reflashing tune in with EFILive.

[have you logged rpm to see what it's doing? is the engine free wheeling after the gears decouple? ]
with the T2 rpms match with tacho nothing seems out of the norm. yes engine free wheels like if yr slowing down for lights ( if thats what you mean)

[Could it be a problem with the reluctor wheel being wrong tooth count or loose bolts or broken teeth causing a misreading of the actual RPMs?]

if thats in the trans then no. mike L road tested it before shipping to me.
both new and old trans did the same.. held on to WOT shifts till late 3k rpm.

being an engine conversion i know a lot of things have been switched off.. i can see a few of them thru the T2. perhaps one too many inputs has been disabled. i have checked the throttle with T2 and that is working fine to 100% throttle.
i dont know the logic behind WOT shifts and factory rev limit. once i know some thing with this perhaps i can solve the mystery.
i have known others to try another TCM and that fixed their problem.
think it was "hondarider" that had a similar issue.
 
AKlowriderZ71

AKlowriderZ71

New member
May 14, 2012
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Wyoming
Is it possible that your tachometer is reading incorrectly, and the rpm displayed is not actual engine rpm? You removed a 6 cylinder and installed an 8 cyl. Are you using the 6 cyl tach?
 
VinceGU05

VinceGU05

duramax lover downunder
May 20, 2011
164
0
0
Melbourne, Australia
AKlowriderZ71 said:
Good to know, but my question is still the same.
Click to expand...

reading rpm at idle off the T2 its within 10 rpm of the tacho. even high in the rev say 2500k. its pretty much spot on.

just to add. in the valet tune i asked for 2400rpm 50mph limit.

it revs about 500rpm past that and hence speed can wander a bit higher too.
 
JoshH

JoshH

Daggum farm truck
Staff member
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Feb 14, 2007
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VinceGU05 said:
[Can you change the shift to make up for the difference? If its shifting at 3500 and you want it to shift at 3000 ie try adjusting it to say to shift at 2500-2600 and see what happens. ]
my DSP5 tune is locked.
i could have a look into my stock tune and see if thats locked. if not could try that theory with it but i dont know much more than reflashing tune in with EFILive.
Click to expand...
Shifting is controlled by the tune in the TCM. The ECM tune really doesn't have anything to do with when it shifts.
 
VinceGU05

VinceGU05

duramax lover downunder
May 20, 2011
164
0
0
Melbourne, Australia
ok.. i need some help. i have managed to open up my tcm tune and wander around in there but dont know whats set right or wrong.

can some one send me a tcm tune preferable LLY 5 speed so i can compare the figures within.
thanks
oh and if it matters my OS is 15184109 :thumb:
 
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