8.1 vortec l18 / nv4500 swap. lean mode ?

[Walker william]

Hey all, forgive me if this was posted in the wrong area, this is my first time visiting the site as a member.
I'm looking for info on a " lean mode" that I've heard is actuated by the fifth gear in the nv4500.
I have a 1990 k3500 that came originally with a tbi 454 with a hydraulic sm465. I recently swapped in a 94 nv4500 sucussfully and am now setting my sights on swapping in my recently acquired 8.1 vortec. I am still in the market for a stand alone harness and ecu for the swap.

My questions:
Did the vortec 8100 have a lean mode?
Is there a lean mode controlled by the ecu or did I get misinformation?
What controls the lean mode actuation?
What model years had this lean mode
Incorporated?
What can be done to make my cruise control work with the newer ecu?
Any insight into the topic would help. Thanks

 

[Supercharged111]

You're referring to lean cruise and I don't think it's gear dependent. It takes some trickery to engage it as the PCM needs to think it's a non-US truck because of emissions.

 

[RichLo]

Im no expert in this but hopefully one of the 411 swap guys can chime in on this. In the mean time though do some searching on '411 ECU swap' this is the go-to computer swap for doing these types of things for the average guy without an electrical engineering degree.

 

[someotherguy]

Dunno about the 8.1 having this, but the much older GMT400's equipped with the SM465 4-speed have their own version of that transmission where the top cover is aluminum instead of the older model cast iron, and has a switch mounted that enables a lean cruise mode when in 4th gear. I wonder if that's what you heard about?

For it to be initiated by 5th gear selection, the 8.1's PCM would have to know what gear you're in - the NV4500 doesn't have a provision for that.

Richard

 

[Mark Gilbert]

The 8.1 will not have lean cruise enabled on any US made vehicles. There are ways to play with the tune to give you a sort of "Pseudo lean cruise"

As for the cruise control, if you have a Drive By Wire throttle body the cruises control will be handled by the PCM without the box that your truck currently has.

Honestly I wouldn't use a standalone harness and ECU, unless you don't have the original that came with the engine.

 

[Christian Steffen]

The 8.1 will not have lean cruise enabled on any US made vehicles. There are ways to play with the tune to give you a sort of "Pseudo lean cruise"

As for the cruise control, if you have a Drive By Wire throttle body the cruises control will be handled by the PCM without the box that your truck currently has.

Honestly I wouldn't use a standalone harness and ECU, unless you don't have the original that came with the engine.

With the 0411 you can do real lean cruise. You just have to make the computer think its a holden.

 

[Supercharged111]

Dunno about the 8.1 having this, but the much older GMT400's equipped with the SM465 4-speed have their own version of that transmission where the top cover is aluminum instead of the older model cast iron, and has a switch mounted that enables a lean cruise mode when in 4th gear. I wonder if that's what you heard about?

For it to be initiated by 5th gear selection, the 8.1's PCM would have to know what gear you're in - the NV4500 doesn't have a provision for that.

Richard

The PCM should know what gear it's in based on RPM and VSS. Toyota did this back in the 90s.

 

[Walker william]

The 8.1 will not have lean cruise enabled on any US made vehicles. There are ways to play with the tune to give you a sort of "Pseudo lean cruise"

As for the cruise control, if you have a Drive By Wire throttle body the cruises control will be handled by the PCM without the box that your truck currently has.

Honestly I wouldn't use a standalone harness and ECU, unless you don't have the original that came with the engine.

I actually didn't get a wiring harness with the 8.1 is the only reason why I was in the market for the stand alone harness. I was planning on doing drive by cable throttle because I had the option with the aftermarket harness that I was looking into and the truck was originally a drive by cable truck, so I was thinking that would be easier. I have the option of sourcing an oem engine harness off line but the only one I can find is for the newer body style with an Allison and drive by wire set up. Which one would be more practical the stand alone for 600$ or trying to gut the 500$ oem harness?

 

[L31MaxExpress]

The PCM should know what gear it's in based on RPM and VSS. Toyota did this back in the 90s.

The PCM does know what gear it is in. That is how the upshift light has worked forever. I know the earliest TBI engines had them and fairly certain even the CCC Q-Jet ECMs knew gear they were in too.

 

[someotherguy]

The PCM does know what gear it is in. That is how the upshift light has worked forever. I know the earliest TBI engines had them and fairly certain even the CCC Q-Jet ECMs knew gear they were in too.

Good to know. Someone should tell those dummy engineers that made a whole new top cover and added the sensor to the last of the SM465's..

Richard