3 (E38) engine swaps/conversion's rev limiting at 5,500RPM's

[GAMEOVER]

(2) 2007 5.3ltr & (1) 2008 6.0ltr
Originally rev limit's were set to 6300-6500RPM's but none of the engine's would rev past 5,500RPM's...so I went thru and set every rev limiter function to 8,000RPM's to try and figure which function in the Tune was causing this and nothing...All 3 vehicles are mated with TH350 transmission's
I attached a 2007 5.3 file

[ScarabEpic22]

Hmmm, hate to say it but is there any way you could run a manual OS, like one from a Vette? Wonder if thats messing with anything running an auto OS without having a TCM to communicate with.

[GAMEOVER]

I don't know Erik, but I can't figure it out...

[ScarabEpic22]

Oh I know what it is!

With an auto OS and no TCM, the ECM thinks its always in Park or Neutral! Change those limiters and Im willing to put $$ on that being the issue.

[Tre-Cool]

if there running a turbo 350/400 i would run a manual os for sure.

[GAMEOVER]

Oh I know what it is!

With an auto OS and no TCM, the ECM thinks its always in Park or Neutral! Change those limiters and Im willing to put $$ on that being the issue.

Already tried that, I changed all those limiters to 8,000RPM's and it didnt make a difference...

[Taz]

Hello Gameover,

I'm guessing that with the TCM communication being absent the ECM is coming up against a torque limiting table that we do not have access to. The ECM will also not be receiving a VSS signal - as the TCM sends the VSS via GMLAN / CAN BUS.

A manual tune in the ECM would allow for direct VSS input, and should resolve your RPM issue.

Just a guess ... still the Gen III guy ... working on Gen IV R&D day by day.


Regards,
Taz

[GAMEOVER]

Ok, gonna need to find a Manual Pinout for the E38 ecm because all I have is automatic pinout's...

[Taz]

Hello Gameover,

Let me know what ECM manual tune you are going to use (i.e. 2007 Corvette LS2, etc.), and I will get you the pinouts.


Regards,
Taz

[GAMEOVER]

Taz, I guess I'll try a 2007 & 2008 LS2 6.0 manual tune if you got them...

Thanks in advance...

[ScarabEpic22]

Dang, was hoping that was the issue and it would be simple to take care of.

Running a manual setup is probably easier going forward for swaps not using a factory-pared engine and trans, good to know the manual OSs let you input the VSS directly into the ECM. Didnt know that.

[GAMEOVER]

Yeah, I didn't know that either...just waiting to get ahold of a manual OS pinout & tune file...I went over the automatic E38 pinout that I have and there isn't a vss location!

[gmh308]

Yeah, I didn't know that either...just waiting to get ahold of a manual OS pinout & tune file...I went over the automatic E38 pinout that I have and there isn't a vss location!

If you cant find a manual OS drop me a line. Am pretty sure I have a fix for this. :) Limiting on a CAN failure. Just need to try it out on a willing field test candidate :).

[tunedportcj5]

I was having the same issue last night on the dyno. I am running a E38/T42 with a 4L80e. I am still struggling with getting a VSS signal. We noticed we were hitting the rev limiter around 55-5700rpm and couldn't figure it out. Each time we would make a change, reflash and hit the limiter. We did back to back runs w/o any changes and it never hit the limiter. Very odd... after making additional mods and reflashing the tune it hit the limiter again. Another pull after that and it was fine...

I don't want to derail this thread but can anyone advise me on my VSS issues?

Thanks,
David

[Taz]

Hello David,

A little more information would be helpful. What is the problem with your VSS signal ? The T42 was intended for use with the 4L80, and should be sending a VSS signal to the ECM. Also, E38 and T42 pairings were common in GM trucks and vans - so I'm not sure what the issue is, without some details of your particular application.


Regards,
Taz

[GAMEOVER]

I noticed the same issue with the 5.3 truck engine...If I would try and hit rev limiter it would go to 5,500...but if I turned engine off and on real quick, it would shoot past 8,000rpm... But most of the time it would only go to 5,500rpms

[tunedportcj5]

Hello David,

A little more information would be helpful. What is the problem with your VSS signal ? The T42 was intended for use with the 4L80, and should be sending a VSS signal to the ECM. Also, E38 and T42 pairings were common in GM trucks and vans - so I'm not sure what the issue is, without some details of your particular application.


Regards,
Taz

The problem is that I have no signal in the scan tool - in addition, i'd like to hook up my speedometer. I have tried all of the relavent PIDs but no luck. Does the T42/E38 communicate over anything besides the CAN +/- connections that could be the issue? I do know that when new tunes are written to the TCM (upshift/downshift speeds) the changes work. The TCM has to know the VSS then....?

Thanks!

[ScarabEpic22]

In this setup, I believe someone on here said that the TCM sends the ECM the VSS signal on the CAN bus. So if you want to see VSS, log it on the TCM. Currently the only way to do this is via BBL as the V7.5 scan tool can only scan one controller at a time (V8 will be able to do both).

This is a weird issue though, wonder if Ross has any insight on it?

[Taz]

Hello David,

Are the ECM & TCM tunes from the same vehicle (i.e. matching tunes) ? Is the wiring harness from that vehicle, or a custom harness, and have you confirmed the pinouts / wiring connects to the components / locations that it should ?

If you need schematics to confirm the wiring continuity I can help with that. Also, some ECM & TCM pairings may have odd speedometer parameters to arrive at a proper signal (i.e. tire diameter of 6 inches, etc.). Looking at the stock, never altered tunes should provide some insight.


Regards,
Taz

[Taz]

... I believe someone on here said that the TCM sends the ECM the VSS signal on the CAN bus ...

Those were my comments … they are not completely accurate all of the time … they were intended more to get people thinking, and checking schematics and GM manuals, than to be taken as gospel.

I am still self-educating with respect to Gen IVs, so the following is merely my understanding at this point in time, and subject to correction …

Gen IV VSS communication is often platform or option (manual vs auto) specific.

Corvette’s output a direct VSS signal from the ECM to the IPC (Instrument Panel Cluster) – at 4K pulse per mile.

If the Corvette is a manual – the ECM receives a traditional VSS signal (high & low) from the T56. If the Corvette is an A6 (6L80) then the ECM receives the VSS signal from the T43 over the GMLAN / CAN BUS network.

Trucks are a hybrid of the above.

Truck ECMs output the VSS signal via GMLAN to the BCM, then the BCM sends this via GMLAN to the IPC (Speedometer).

Truck ECMs output a non-serial data VSS signal to the EBCM, and the Nav Radio.

Truck ECMs receive a Replicated TOS (Transmission Output Shaft) signal directly from the TCM. This is a single wire signal (high only) output roughly at 25 Hz per MPH.

As you can see, VSS signals with Gen IVs are very different than with Gen IIIs.


Regards,
Taz

[tunedportcj5]

Hello David,

Are the ECM & TCM tunes from the same vehicle (i.e. matching tunes) ? Is the wiring harness from that vehicle, or a custom harness, and have you confirmed the pinouts / wiring connects to the components / locations that it should ?

If you need schematics to confirm the wiring continuity I can help with that. Also, some ECM & TCM pairings may have odd speedometer parameters to arrive at a proper signal (i.e. tire diameter of 6 inches, etc.). Looking at the stock, never altered tunes should provide some insight.


Regards,
Taz

They are not from the same vehicle. I have no idea what the original source was (I don't have the tune in front of me to verify). The E38 OS thinks I am running a 4l60 which could be an issue? The T42 is definitely a 4l80e OS. Do you have schematics handy that I could use to verify my wiring is correct? The harness was originally built for a 4l80e. I had to swap some pins and add the ISS connector.

I am pretty sure I tried to log VSS while connected to the T42 on the scan tool. I'll try it again.

thanks for the help!

[Taz]

Hello David,

On the road for the day ... checking in remotely. The tunes not being matched could cause an issue. When you get a chance post the ECM & TCM tunes. What year range TB (throttle body) are you using ... "05-'08 (silver blade) or '09+ (brass blade) ... will check and see if I have a set of matched tunes ... don't see too many Gen IV 4L80s ... lots of Gen IIIs though !


Regards,
Taz

[ScarabEpic22]

David, chiming in with what Taz said, if you're running an E38 originally equipped with a 4L60E (ECM says 4L60E as trans type) with a T42 running a 4L80E OS. Mismatch there could be causing issues.

Post your tune, I havent seen any Gen IVs aka E38s running with a 4L80E (doesnt mean they dont exist), so I might go back to running the T42 with a 4L60E OS then swap the few pins needed to control an 80E with a 60E OS.

[joecar]

David, are you physically running a 4L60E or a 4L80E...?

[ScarabEpic22]

David, are you physically running a 4L60E or a 4L80E...?

80E, post #14 and in his sig. :D

[Taz]

... I havent seen any Gen IVs aka E38s running with a 4L80E ...

The 4L80 was not widely used with the Gen IV engine. Used briefly in 2007 Gen IV HD trucks. Mainly used in 2008 & 2009 Express / Savana (2500 & 3500 series) full size vans.


Regards,
Taz

[tunedportcj5]

Here are my tunes.. 12395

[Taz]

The tunes are both 2007 MY. The TCM looks like an authentic 4L80 tune. The ECM uses OS12614088 - I don't believe that OS was ever paired with the 4L80. I think 2007 4L80 trucks used ECM OS12608677. I don't have this ECM tune on file.

You will either need to locate a 2007 MY ECM tune compatible (originally paired) with the 4L80, or move to 2008 MY tunes. If you change to 2008 MY tunes the TCM can be reflashed with the newer OS, the ECM will need to be replaced with a 2008 (service # 12612384).

The 2008 MY is more swap friendly - most platforms used ECM OS12617631 - Corvette / Truck / SUV / VAN.

Once you settle on what tunes you will use, then we can help confirm the wiring harness continuity - it may vary slightly across applications.


Regards,
Taz

[GAMEOVER]

I can't find a corvette pedal...working on a standalone harness for a 2008 LY6 6.0...Wanted try the Corvette Manual OS...:frown:

[GAMEOVER]

Local salvage yard had quite a few(corvette pedals) a couple months back...:shock::shock::shock:

[Taz]

I can't find a corvette pedal...working on a standalone harness for a 2008 LY6 6.0...Wanted try the Corvette Manual OS...:frown:

GM part # 25835421 ('05-'11 Corvette). GM list price = $98.37 .... GM Parts Direct (www.gmpartsdirect.com (http://www.gmpartsdirect.com)) = $58.62


Regards,
Taz

[GAMEOVER]

Thanks Taz, I just ordered one...Didn't think they were that cheap NEW:w00t:

[gmh308]

(2) 2007 5.3ltr & (1) 2008 6.0ltr
Originally rev limit's were set to 6300-6500RPM's but none of the engine's would rev past 5,500RPM's...so I went thru and set every rev limiter function to 8,000RPM's to try and figure which function in the Tune was causing this and nothing...All 3 vehicles are mated with TH350 transmission's
I attached a 2007 5.3 file

If you are still having trouble try this and see if the rpm limiter is fixed:

12401

[gmh308]

If you are still having trouble try this and see if the rpm limiter is fixed:

12401

Happy New Year! :) Any luck Mr Gameover?

[GAMEOVER]

The holidays kinda put a hold on everything...I should be able to try your fix early next week...:D

[GAMEOVER]

Finally got to try your fix gmh308, and it worked...Doesn't rev limit at all...
But I can't find what was done....Or was it something behind the scenes...:D

[gmh308]

Finally got to try your fix gmh308, and it worked...Doesn't rev limit at all...
But I can't find what was done....Or was it something behind the scenes...:D

Glad to hear it did it for you. Yes "behind the scenes" one might say :). Cheers.

[GMPX]

Finally got to try your fix gmh308, and it worked...Doesn't rev limit at all...
Mmm, sounds like if you had run with a manual tune from the beginning none of this would have happened :music_whistling_1: . When the ECM expects to 'hear' from the TCM it will do weird stuff when there is nobody home. Why GM choose to limit RPM (or torque) with a bad TCM is beyond me.

[minytrker]

I have tunes many e38 engine sways. I always use manual os when it has non computer transmission. The very first one I did I tried I used auto os and ran into all kinds of weird problems.

[GAMEOVER]

Thats what im gonna have to do from now on, all manual OS...

[turbo_bu]

For the E38's, does that mean you have to use a car OS then? From what I have read, GM did not make a Gen IV (E38) with a manual transmission since that is when they changed to the GMT900 chassis (2007).

[LastCall]

Bringing up an old thread from the dead. lol

I read where GMt308 fixed the tune, but does anyone know what was fixed specifically? I'm on the dyno now, and stuck at 5400 rpm. I've tried to change all rev limiters without any success. Anybody have suggestions?

[LastCall]

It was a pretty disappointing day on the dyno today. Did not get to make a run past 5500 rpm, regardless of what I changed the tune rev limiters to. Seems that idle allows the RPMs to climb higher, so not sure what that means. If you look at both APP an ETCTP, app stays around 95%. but the etc is cutting it down to 30-40% or less. What would cause this? I changed P1516 to not reported as I was getting the code and though it would be causing the issue.

It feels like a soft limit, and if I stay into the throttle, the ETCTP will fall down, RPMs will go to roughly 4,500 RPM. and then I can rev it back to 5400 rpm. It does not feel like a hard fuel cut off. And I don't think it is reduced power mode as the ETCTP will start working again without having to let go of the throttle and step on it again.

I disabled most of the throttle control tables/test, and some of the MAF/MAP rationality tests as well. Trying to eliminate things, I know this is not the ideal and right way.

Specs are an LS2 with a Maggie at 6 psi with E38 controller and 4L70 with T42 controller. I've attached the ecm and trans tune and three log files (one with basic info and another with ETC PIDs).

Here are the details about OS and hardware:

E38 ECM
08 Silverado OS - 12617631

T42 TCM (posted correct trans tune 09-26-16 @ 6:26 am PDT)
08 Silverado Trans OS - 24239927

Silver blade TB
2010 Camaro Pedal (APP)

[LastCall]

Issue has been fixed. The rev limit was because no transmission range switch was present, and the trans was defaulting to park/neutral tables.

Which brings me to my next question - with no range switch, does the computer ignore the idle in gear (drive tables)? Like coast down and in gear transition tables? Or is that driven off current gear in the trans?

[ScarabEpic22]

Ah that makes sense, I've been pondering this the past few days wondering why it was cutting out at 5500rpms. If you'd said 4000, I'd have immediately gone for P/N/gear selector.

Weird, with a T42+4L70E combo, that should be sending a VSS signal to the ECM. Is the ECM OS looking for a 4Lxx or 6Lxx trans?

[joecar]

Thanks for posting back.

[minytrker]

Issue has been fixed. The rev limit was because no transmission range switch was present, and the trans was defaulting to park/neutral tables.

Which brings me to my next question - with no range switch, does the computer ignore the idle in gear (drive tables)? Like coast down and in gear transition tables? Or is that driven off current gear in the trans?

I had 2 LS3/4l70 swaps that were done at the same time. They ordered 2 of everything, 2 430hp ls3's, 4l70's, standalone harness from same company, literally everything. One cut off at 5500rpm's and one didnt with the same exact tune in both. Swaps can do weird things I have learned over the years.