RPM change.

[Denny]

Hi guys. Just wondering if someone could change the max rpm in a GM 4.8 E38 bin 12614088 OS? I would like it changed from 5500 to 6000. Any help is greatly appreciated. Thanks for looking and have a great day.

[MPC001]

Hi guys. Just wondering if someone could change the max rpm in a GM 4.8 E38 bin 12614088 OS? I would like it changed from 5500 to 6000. Any help is greatly appreciated. Thanks for looking and have a great day.

I looked at 4 platforms using 12614088 & they are all max rpm = 6000/6100.

[Denny]

HI MPC001. Thanks for your reply. Well now Google is wrong. Bad enough AI gives me wrong answers regularly and confidently. Now Google? I guess AI is controlling it. Now it begins (Terminator). From what I have read it's safe to raise the RPM 500 more than factory. So I would like it raised to 6500RPM. Thanks again MPC001 for your help.

Motor is from a 2007 Silverado Vortec 4.8.

[MPC001]

HI MPC001. Thanks for your reply. Well now Google is wrong. Bad enough AI gives me wrong answers regularly and confidently. Now Google? I guess AI is controlling it. Now it begins (Terminator). From what I have read it's safe to raise the RPM 500 more than factory. So I would like it raised to 6500RPM. Thanks again MPC001 for your help.

Motor is from a 2007 Silverado Vortec 4.8.

You are welcome Denny. I only had LMG, L76, L92 cals to check out. No LR4 cal for 07 Silverado. Yes AI is excellent at confidently sprouting bollox answers with lots of fluff. I started asking a couple standard questions 2+ years ago. It is improving but still not dead right and often claims multiple times with different answers that they are all correct. Grok seemed most accurate so far.

What are you aiming to achieve by raising the rev limit? And is it auto or manual trans? Stock cam & valvetrain?

Most E38 cals have settings for main rpm hi & lo limits (limiter on, limiter off window). Rev limit per gear for auto. Rev limit vs oil temp. Rev limit vs coolant temp/run time (17 x 17 table). And even rev limit reduction when the engine revs too quickly to protect against over rev.

So even though the main limiter pair is at 0x1de34c & 0x1de34e (2 bytes each), there is a lot more than this pair to cover - the start of the rabbit hole .

[Denny]

Hi MPC001, thanks for the help. Achieve more power. I would like the total RPM limit and shift points raised 500RPM. I see it's not going to be easy. The build is a stock 2007 Silverado 4.8 LY2 automatic 4L60e. Has 243 heads (factory), egr delete and rear o2 delete. Plan is to put it in a Audi A5s. They show up for sale here in Canada often, in great shape, with blown motors or turbos fairly cheap $1500-$2500. Just want something fun to drive on nice days. Original plan was a Ford Mustang but they are hard to find in good shape. I use to own a 95 5.0L Mustang. Was fun to drive.

1. Does the TCM hold the shift points?
2. Is there somewhere I can find the addresses needed to do this modification?
3. Am I wasting my time?
4. Is HP Tuners, Or EFI Live the only way?

As always, your help is greatly appreciated. Thanks again.

[MPC001]

Hi MPC001, thanks for the help. Achieve more power. I would like the total RPM limit and shift points raised 500RPM. I see it's not going to be easy. The build is a stock 2007 Silverado 4.8 LY2 automatic 4L60e. Has 243 heads (factory), egr delete and rear o2 delete. Plan is to put it in a Audi A5s. They show up for sale here in Canada often, in great shape, with blown motors or turbos fairly cheap $1500-$2500. Just want something fun to drive on nice days. Original plan was a Ford Mustang but they are hard to find in good shape. I use to own a 95 5.0L Mustang. Was fun to drive.

1. Does the TCM hold the shift points?
2. Is there somewhere I can find the addresses needed to do this modification?
3. Am I wasting my time?
4. Is HP Tuners, Or EFI Live the only way?

As always, your help is greatly appreciated. Thanks again.

Hi Denny, yes it is far more time efficient & safer to leverage a commercially available tuning package for Gen IV cals as both the ECM & TCM need calibrating for matching rpm limits & synchronized shift points. (unless the only targets are maybe a VATS patch byte or enable/disable tests for O2's etc. or some DTC bytes.)

Don't know of anywhere that ECM/PCM addresses can be "found" outside the great "open source" work done for LS1 PCM's (PCMHammer/Universal Patcher) by other gurus on this forum which might be available in XDF format somewhere. Even if a GM definition doc could be "found" for the 12614088 OS, it would take cubic hours to find & confirm the addresses & the math. An E38/E67 alone has thousands of data points to fish through. Then there is the T42 as well. An LS1 PCM parameter list I saw years ago had over 9,000 lines of mem addresses (PCM so included trans).

As for more power, as the Vortec truck motors typically have power peaks around 5500rpm and are meant to be hi torque as you know (long runner intakes), I would venture that revving beyond 6k will only see a reduction in power without a cam (& springs) that move the peak power up in the rpm range for better breathing. A stock motor may even run into valvetrain separation by 6500rpm with stock cam & springs.

Trust this helps a bit.

[Denny]

Thanks for your help MPC001. I'm going to stick with what I have. I thought more info would be available. Thanks again.

[hjtrbo]

If you're willing to get your ecm bin into ghidra I'm happy to point you for things to look for. The trans side won't be possible as there is no public flash tool for bins.

[Denny]

Hi hjtrbo. Thanks for the offer. I am just starting out with programming. I have been reading a lot, here and another site for almost 2 yrs. I got a SM2 pro clone 6 months ago and just got a Ulink Nt a few weeks back.

I have Gihdra but I just installed it maybe a week ago, so I know nothing. I would like to learn if you have the time though. What do I look for?

Thanks again.

[hjtrbo]

First step is setting up the r2 & r13 registers. And post up your bin here.

You'll also need TunerPro and UP if you haven't got already.

As MPC001 said there's a few places that need work. P.S. his commentary on your cam and valve train is excellent.