4L60E not holding first gear when shifter set at 1st.

[barbermi]

Hi all.

I am trying to sort out an issue I am having with my 4L60E.

As the title mentions I have the shifter set on 1st and do a power run (drag run) but the car will automatically shift to 2nd at 3900rpm (44km/h) which is way too early!
Ideally I would like the car to hold first until approx. 6000rpm.

Any ideas where I should be looking in the tune to adjust the shift point for first gear hold?
I have attached my tune for you to look at. I have also attached a screen shot of when it all happened. Could it possibly be that I had not achieved WOT? I had 63.9% throttle but I would assume the car would hold 1st if first is selected.


Thanks in advance.

Mark

[joecar]

D0913: set this higher.

[Taz]

Hi Mark,

Are you running a 32 inch tire with 4.11 gears ?

Do you have an OEM gear position switch (PRNDL) assembly mounted on the 4L60, and wired to the PCM ?


Cheers,
Taz

[barbermi]

Hi taz.

Yeah its a 31" tire and 4.11 lsd. Your right about the gear position switch also. All stock and wired to the pcm.

Why do you ask mate?

Thanks.

[barbermi]

Hi Joe.

I looked at that earlier after doing a search on the forum. D0913 is set at 88kmh already. My car is shifting at 45kmh odd. I had ignored this parameter as I thought this wouldnt be the issue?

[Taz]

... its a 31" tire and 4.11 lsd. Your right about the gear position switch also. All stock and wired to the pcm.

Why do you ask mate? ...

Hi Mark,

Just attempting to eliminate variables. If the gear and tire information is correct, the reported / calculated vehicle speed should be correct. If you have a PRNDL switch wired, the PCM should "know" what gear position the shifter has been placed.

Your WOT TPS thresholds are defined by D1206 to D1211. Given your TPS% was in the 60% range in the attached screenshot, the PCM would have been using the part-throttle shift speeds.

The attached tune should rectify your selected gear position issue - and should now hold whatever gear you select - as all 4L60s will do (unlike the 4L80s).

Also, I sanitized some of the shift speeds, but did not go through your tune completely.


Cheers,
Taz

[barbermi]

Thanks Taz.

Ill give the tune a shot tomorrow.
Had the tune I been running set up as a 4l80? I didn't think that would be possible?
I am confident the speed calibration is accurate as I have checked the Vss against a GPS speed indicator and it looks within a couple km/h.

Thanks again for your time.

Mark

[Taz]

No sir - was not setup as a 4L80 - was correctly setup as a 4L60. I was just highlighting platform differences for anyone following along, as 4L60 vs 4L80 can present different tuning challenges.


Cheers,
Taz

[barbermi]

TAZ your a true gentleman!
Thankyou for your help with the first gear hold. It works an absolute treat. At WOT it holds gear until the limiter! Now I need to stop it spinning the wheels! Haha.

Out of curiosity? could the tune be set up to do the following at the drags:
Shifter in D1 take off and the car automatically shifts to second at say 6200rpm. Once it shifts I move the shifter to D2. It holds second until 6000rpm then shifts itself to 3rd I move the sifter to D3 and so on. In theory wouldnt this make for the most consistent ET's? Provided traction etc is constant.

Just a thought anyway.

[joecar]

...

Out of curiosity? could the tune be set up to do the following at the drags:
Shifter in D1 take off and the car automatically shifts to second at say 6200rpm. Once it shifts I move the shifter to D2. It holds second until 6000rpm then shifts itself to 3rd I move the sifter to D3 and so on. In theory wouldnt this make for the most consistent ET's? Provided traction etc is constant.

Just a thought anyway.You will get more consistent ET with hands-off... i.e. set up the WOT RPM and MPH tables to shift at the RPM you require.

[barbermi]

Hi TAZ,

Just wondering if you can please help me out again?

I am doing some tuning on the LS1 and it appears the gearbox is slipping. If you have a look at Log_0011 I have attached at 13:40:26 I have done a power run. The car spins the wheels but I also feel that the VSS is going high while the engine RPM aren't. I noticed a big slip at 13:43:17 going from second to third.

Another issue I seem to have is the gear jumps in and out of first as it pleases if I try to hold first gear. If you look at Log_0010 at 13:24:25 I am attempting to do another power run. The Engine RPM are following exactly how the car lunged in and out of gear. I shifted to second after all of this happened.

Do you have any ideas on how I can fix these two issues?
I have attached my tune for you to look at and modify if you are willing to help me out.

Thanks again Taz,

Regards,
Mark

[barbermi]

The only change I have made since your last tune fixed my limiter and gear hold issue is that I have increased my boost from 8PSI to 12PSI.

I also notice when in first gear and going walking pace it feels as though the car is jumping in and out of gear. It lunges forwards and carry's on as if it has a huge cam in it.