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4l80e to manual

Jspohr

Jspohr

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I looked around for an answer to this, but couldn't find. Forgive me if I missed it:

1999 Suburban 2500 2wd 7.4

Is the computer going to care if I put a manual transmission in it??

Thanks.
 
The 4l80e is computer controlled and should have the #1 speed sensor in it so, yes, it could hate the swap. Depending on what trans you use and what all you do along with it, it should be do-able it's just not a mindless swap like in a square body.
 
nvrenuf said:
The 4l80e is computer controlled and should have the #1 speed sensor in it so, yes, it could hate the swap. Depending on what trans you use and what all you do along with it, it should be do-able it's just not a mindless swap like in a square body.
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But the electronic controls to the engine aren't going care are they?

I understand the speed sensor part.

The 4l80e gets talked to, yes, but it really doesn't have much control over throttle and fuel management?? or am I missing something else??
 
Jspohr said:
But the electronic controls to the engine aren't going care are they?

I understand the speed sensor part.

The 4l80e gets talked to, yes, but it really doesn't have much control over throttle and fuel management?? or am I missing something else??
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It has to “see” it and there are items in the computer that may have to be fussed over.

So this 7.4 is the L29, multi port?
What transmission?
 
Yeah, the computer is going to want feedback from the trans. Without the speed sensor it'll probably go into limp mode trying to prevent trans damage. You may also get a hand full of trans related codes causing the check engine light to stay on (not a big deal except that you won't know when there's an engine code triggered).
 
nvrenuf said:
Yeah, the computer is going to want feedback from the trans. Without the speed sensor it'll probably go into limp mode trying to prevent trans damage. You may also get a hand full of trans related codes causing the check engine light to stay on (not a big deal except that you won't know when there's an engine code triggered).
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Again, I get the speed sensor part. But is there anything beyond that that needs to be addressed?
 
A 90’s era truck won’t go into limp mode. The only input missing is the speed signal to the ecm. The ecm does not make any decisions based on speed when it comes to the engine running. Yes, it may set a vss code for the trans and that other sensor inputs from the trans are missing too, but it won’t keep the engine from running.

Keep in mind it’s all mechanical throttle on all small blocks and big blocks back then. They couldn’t limit throttle control since it wasn’t controlled by the computer.

A 7.4 Pfizer (Vortec) or Tbi will run when the auto is removed. Though it would be worth talking to a tuner to turn off the auto trans stuff.
 
ZooMad75 said:
A 90’s era truck won’t go into limp mode. The only input missing is the speed signal to the ecm. The ecm does not make any decisions based on speed when it comes to the engine running. Yes, it may set a vss code for the trans and that other sensor inputs from the trans are missing too, but it won’t keep the engine from running.

Keep in mind it’s all mechanical throttle on all small blocks and big blocks back then. They couldn’t limit throttle control since it wasn’t controlled by the computer.

A 7.4 Pfizer (Vortec) or Tbi will run when the auto is removed. Though it would be worth talking to a tuner to turn off the auto trans stuff.
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This makes sense, because you can put the thing in neutral, push the gas to your hearts delight, and it's nothing but a cable pulling the throttle open.

Any suggestions on who could do this cheap?
 
Howell EFI could do tune pretty easy. That’s where my ecm and tube came from for the 8.1 in my truck that has a manual.

I would prune the trans wiring from the factory harness except for the vss sensor. Put the vss sensor back in the manual you put in the truck.
 
Bent77 said:
No, what transmission are you going to use?
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I have a lot of apprehension about answering because I don't want or NEED a lecture about why I shouldn't use the trans that I've chosen, and that's usually where that question leads to on these forums even though it may not be you that does it. This vehicle won't be a daily driver, and I have my reasons and I've put more time reading up on it than most people ever would. I just came looking for facts about the swap. I won't be rude and not tell you since you asked, though. SM465.
 
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ZooMad75 said:
Howell EFI could do tune pretty easy. That’s where my ecm and tube came from for the 8.1 in my truck that has a manual.

I would prune the trans wiring from the factory harness except for the vss sensor. Put the vss sensor back in the manual you put in the truck.
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So, at that point the VSS's only purpose would be the speedo and maybe ABS, right? Or is ABS working solely off of WSS's?
 
Jspohr said:
So, at that point the VSS's only purpose would be the speedo and maybe ABS, right? Or is ABS working solely off of WSS's?
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All three. Abs depending on which version uses vss for the rear wheel speed since they don’t have individual sensors out back.
 
Jspohr said:
I have a lot of apprehension about answering because I don't want or NEED a lecture about why I shouldn't use the trans that I've chosen, and that's usually where that question leads to on these forums even though it may not be you that does it. This vehicle won't be a daily driver, and I have my reasons and I've put more time reading up on it than most people ever would. I just came looking for facts about the swap. I won't be rude and not tell you since you asked, though. SM465.
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I doubt anyone will criticize your transmission choice around here. I run the same combo however I ditched the OE EFI after reviewing aftermarket options including the Howell option noted by @ZooMad75
 
Jspohr said:
I have a lot of apprehension about answering because I don't want or NEED a lecture about why I shouldn't use the trans that I've chosen, and that's usually where that question leads to on these forums even though it may not be you that does it. This vehicle won't be a daily driver, and I have my reasons and I've put more time reading up on it than most people ever would. I just came looking for facts about the swap. I won't be rude and not tell you since you asked, though. SM465.
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I don’t think bent cares what you put in but depending on what you use it may have a vss option or not. Which would make all this discussion pointless because you’d run the vss so your speedo worked.
 
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