89 Silverado 700r4 to 4l80e swap

wittensville said:

My 89 is the nicer truck especially the interior, the 94 has no title.

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Body swap the 89 onto the 94 frame?

Supercharged111 said:

Body swap the 89 onto the 94 frame?

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That is a thought. But the best frame and motor are on the 89

wittensville said:

That is a thought. But the best frame and motor are on the 89

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Damn. It's too bad the front 8 lug swap basically requires a frame swap.

someotherguy said:

Is MAP input not considered for downshift behavior (and possibly TCC lockup?) Curious, have no experience here, just wondering if that's why tayto mentioned it.

Richard

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@tayto was referring to a diesel engine for some reason. To follow his logic you'd need to ask yourself: How much vacuum does a diesel produce?

the standalone 4l80e controller was only used on diesels AFAIK, that's the reason i brought it up. and yes you are right about map sensors & diesels

Nad_Yvalhosert said:

@tayto was referring to a diesel engine for some reason. To follow his logic you'd need to ask yourself: How much vacuum does a diesel produce?

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They produce some degree of it from a vacuum pump but that would just be me being my argumentative self. Beyond that, they do indeed have a MAP sensor of sorts but it's a 2 bar sensor for boost.. sits right up on the firewall between the wiper motor and cruise module.

Richard

someotherguy said:

They produce some degree of it from a vacuum pump but that would just be me being my argumentative self

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The vacuum pump is a bolt-on belt driven accessory on a Ford, and not part of the diesel engine. It runs truck based systems, like the HVAC, or a vacuum brake booster.
How many GM diesel engines have vacuum pumps?

someotherguy said:

. Beyond that, they do indeed have a MAP sensor of sorts but it's a 2 bar sensor for boost.. sits right up on the firewall between the wiper motor and cruise module.

Richard

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So, its not measuring vacuum, but positive manifold boost pressure...
I could see how it might be called a MAP sensor, but is it used in conjunction with transmission shift logic?

Nad_Yvalhosert said:

I could see how it might be called a MAP sensor, but is it used in conjunction with transmission shift logic?

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MAP = manifold absolute pressure, i.e. relative to a total vacuum. It's 100% a MAP sensor even if only half of it is being used. But I am morbidly curious about MAP involvement with anything transmission related in that era truck. They need something to calculate engine output to determine line pressure, unless it was all TPS back then which would be no different than a TV cable.

Nad_Yvalhosert said:

The vacuum pump is a bolt-on belt driven accessory on a Ford, and not part of the diesel engine. It runs truck based systems, like the HVAC, or a vacuum brake booster.
How many GM diesel engines have vacuum pumps?

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6.5td's do. Have you looked at one? It is used to operate the wastegate, unless one wants to delete the vacuum pump and install a mechanical wastegate controller (Turbo Master for example.)

Edit - heck the 6.2's got one too but I'm not sure of its role other than the HVAC controls on a squarebody. Beats me, I don't get into the GM diesels much. There are listings for 6.2-equipped GMT400's without A/C but have a vacuum pump.

Anybody else? Oldsmobile diesel have one?? You've got me curious, now I need to go check..

Nad_Yvalhosert said:

So, its not measuring vacuum, but positive manifold boost pressure...
I could see how it might be called a MAP sensor, but is it used in conjunction with transmission shift logic?

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No idea if it plays any role whatsoever in transmission operation. Note the smilie and detect some sarcasm; not everything is so serious..

Richard

someotherguy said:

They produce some degree of it from a vacuum pump but that would just be me being my argumentative self. Beyond that, they do indeed have a MAP sensor of sorts but it's a 2 bar sensor for boost.. sits right up on the firewall between the wiper motor and cruise module.

Richard

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Actually that sensor you are talking about is the BARO sensor. The boost sensor is on the intake and has its little stub in a hole to read the boost pressure. In your defense they both look like a MAP sensor on a gasser.

someotherguy said:

6.5td's do. Have you looked at one? It is used to operate the wastegate, unless one wants to delete the vacuum pump and install a mechanical wastegate controller (Turbo Master for example.)

Richard

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The vacuum pump also runs EGR on the 6.5's in the half ton trucks.