Electronic tranny

[53burb]

I am supposed to buy a 454 from somebody north of Phoenix. Anyways, I believe GM started using the electronic trannys in '91. Of course, his Suburban is a '91. He plans on using a carb'd 350 SBC in its place. (Long story). Anyways, can he just have a chip "burned" to have all the engine sensors disabled & still use this tranny?? I told him he could, but that I would check. In the area he lives in, there are no vehicle inspections, so emissions is not a concern for the engine.

[extd56]

If it was a 3/4 ton Suburban in 1991 it would be a 4L80E trans. I believe the engine and trans have to work together on this combo. I have 2 wiring harnesses that I removed from 1991 Suburbans and I was told that If I don't use the 4L80e trans I need a different computer and harness.

[Longhorn Man]

You can get a stand alone computer and harness, but it is super expensive.
You can also get a manual valve body for the 4L80E now, however, that does get rid of all 'automatic' features of the tranny.

[53burb]

So then the tranny cannot work independant of the engine, right, regardless if the chip is "reprogrammed" or not?? He mentioned in the ad that it was a
4L60 tranny. It very well be a 4L80E tranny. He is, self admittedly, not an engine guy. Will a pre-'91 700 tranny then bolt up to his existing transfer case w/o changing the output shaft or using any adapters??

[53burb]

I just received an email back from stating that it is a 3/4ton. So then, like before, is, will a 700 tranny bolt up to the existing TC w/o any problems. I think his transfer case should be a 208. Is this right??

[extd56]

A 4L60 uses a 27 spline transfer case and a 4L80 uses a 32 spline transfer case so you will need a differnet transfer case.

[53burb]

Damn, you are right!!!! This sucks. I was hoping to get the tranny as well with the computer & wire harness. The adapter to mate a 700 in place of a
4L80E to a 208 TC is almost $500 from Advance Adapters. I guess I will call a couple of the chip burners tomorrow to confirm that you cannot use the tranny alone. Anybody have any numbers to try for info??

[shifty]

Originally Posted by Longhorn Man

You can get a stand alone computer and harness, but it is super expensive.
You can also get a manual valve body for the 4L80E now, however, that does get rid of all 'automatic' features of the tranny.

When we're talking about standalone computers, it's several hundred dollars (~$600 last time I checked - for the cheapest one)

[extd56]

Try this link but you might not like what they say.


http://www.howellefi.com/shop/customer/home.php

[53burb]

I understand about the stand alone computer, but a "stock" replacement computer is just over $100 from Checkers. You need to supply your own chip. If he is already using his computer, isn't it as simple as getting the chip burned to disable all the engine inputs?? Maybe, if it was really this easy, everybody would do it.
OK, if he does have to buy a stand alone computer, any other way for me to have him separate the engine w/o too much expense?? Maybe, I can pay the extra $500 for the adapter. Which brings up another question - How much does it generally cost to add a tail housing to a 4wd tranny to convert for 2wd use??

[extd56]

The transmission will have to be disassembled to change it over to a 2WD. It can get real spendy to have it done because it is taken down like you are going to rebuild it. The 4L80 is a good trans but there is a big price difference in parts between a 4l60 and a 4L80 kind of like betwen a small block Chevy and a Big block Chevy. Just my .02 because I asked my tranny shop about doing this and they said go find the correct trans.

[Tx Firefighter]

Fellows, I remember 93 being the first year for electronic trans. Before 93 it was simply a 4L80 if I remember right. I started in the dealership in 94, so I may be fuzzy here. Anyway, the tranny guys at the dealership used the swap 4L80E's into early stuff using a 6.5 diesel pickup computer. That computer was a stand alone unit that didn't have any engine functions like the gas engine trucks used. The diesel had no electronics to talk to the tranny.

[53burb]

All the wiring harnesses I see listed start from '91....Is there something easy I could ask him to look at to see if it is an electronic tranny?? I assume there is a bundle of wires coming from/to the tranny. Is there such a thing as a 4L80 as opposed to a 4L80E???

[extd56]

I believe that all of the 4L80E transmissions are electronic as 1991 was the first year for them in a 3/4 ton but I am not a trasnmission guy. Also to run this trans you will need an electronic speedo which is not too big a problemunless you wnat tostay with a stock dash.

[53burb]

I have emailed Brian from TBIchips.com a couple of times. He said that a carb'd 350 will work, but the tranny needs a throttle position input, & the brackets for a carb would need to be fabbed. All the other inputs can be disabled. He also mentioned of putting the throttle body injection back in place on the 350 as this would work. I think I will mention this to the guy who has the engine. Can anybody tell me more about the diesel computer?? This might be an option as well. Will the 4l80E have the same inputs into a 454 computer as it does into a diesel computer??
Thanks,
Chris

[53burb]

anybody????

[mnunn454]

This thread is real interesting to me. I'm not anywhere near ready to buy any hardware, but it'll be great info if/when I do.

If I'm hearing you correctly:

4L80E needs only a TPS input (and maybe a fused 12V source) to act normally.

Computers that are set up for diesel power and 4L80E do this but the OEM computer will still require a custom chip and/or a burn setup specifically for that.

4L80Es are available in 2WD and 4WD versions. 4's are probably more common, but converting one from 4 to 2 is cost prohibitive.

TPS input can be obtained by fabbing a TPS to a carb, (Gotta scratch my head on how to do this with a 4-barrel), or by using a throttle body.

If using the throttle body, then EFI and it's computer are assumed.

Hope I haven't missed anything here.

Now, lets assume I find a miraculous way of getting a TPS mounted onto my 4-barrel. Don't I need some kind of gizmo to take that TPS resistance signal and "convert" it to an input the tranny needs to see? Or, is it just an analog 12 volt resistance (Ohms) signal? (sorry, electronics is a black box to me).

Wouldn't it be nice if things were this simple?

Thx for clearing the fog.

[53burb]

I think you got it right except for the diesel computer part. IIRC, he stated that the diesel computer controls the tranny only, but it still needs a TPS input. The email is on my work email address. I will copy/paste or link or forward it tomorrow.

[53burb]

Here is a copy of the email. TCI makes aTPS input for carbs. It is over $250.







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From: Peganyee, ChrisX C [mailto:chrisx.c.peganyee@intel.com]
Sent: Saturday, April 14, 2007 12:58 PM
To: Brian - TBICHIPS
Subject: RE: '91 3/4 4x4 Suburban


Brian,

Thanks for ALL the help!!! If he decides to take my advice, I will definitely direct him to you for a new chip.



Thanks again,

Chris




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From: Brian - TBICHIPS [mailto:sales@tbichips.com]
Sent: Friday, April 13, 2007 7:23 PM
To: Peganyee, ChrisX C
Subject: RE: '91 3/4 4x4 Suburban



yes the computer is fine but he will need a special chip for the computer as the 454 injectors are larger than the 350 injectors. On the diesel computers, the wiring harness is completely different and they too used a TPS sensor.



Brian

Harris Performance
PO BOX 1447
Randleman, NC 27317
336-471-2827
www.tbichips.com and www.tpichips.com







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From: Peganyee, ChrisX C [mailto:chrisx.c.peganyee@intel.com]
Sent: Friday, April 13, 2007 9:56 AM
To: Brian - TBICHIPS
Subject: RE: '91 3/4 4x4 Suburban

Brian,

Thanks for the info. Can he still use his existing computer?? Or would he need a computer for a 350?? Would he also need a reprogrammed chip to accept the 350 mapping as opposed to a 454 if he uses the 454 computer. Also, what about the older diesel computers?? I understand their function was only the transmission. Do you think this would work if he removed the entire engine & fuel injection??



Thanks,

Chris




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From: Brian - TBICHIPS [mailto:sales@tbichips.com]
Sent: Thursday, April 12, 2007 6:04 PM
To: Peganyee, ChrisX C
Subject: RE: '91 3/4 4x4 Suburban



He can just mount the 454 throttle body on the 350 intake as its the same bolt pattern. you will have to take the intake to the machine shop and have the bores in the intake bored to match the throttle body as the 454 bores are larger which is a good thing. All the 454 sensors will fit the 350 block as well. You just need to be careful what cam you use in the 350 as fuel injection is pretty picky about that. I have several cams listed on www.tbichips.com/truckmods.htm but on a 4x4 something mild like a edelbrock 2102 would be what I would recommend for good torque as that is going to be a pretty big torque drop from the 454.



Brian

Harris Performance
PO BOX 1447
Randleman, NC 27317
336-471-2827
www.tbichips.com and www.tpichips.com







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From: Peganyee, ChrisX C [mailto:chrisx.c.peganyee@intel.com]
Sent: Thursday, April 12, 2007 5:49 PM
To: Brian - TBICHIPS
Subject: RE: '91 3/4 4x4 Suburban

Brian,

Well, then, in this case, would the throttle body fit on a SBC TBI intake manifold along with the sensors?? What he wants to do is remove the 454 & install a 350. He currently has the Edelbrock conversion for the TBI to convert it to a multiport injection setup.



Chris




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From: Brian - TBICHIPS [mailto:sales@tbichips.com]
Sent: Thursday, April 12, 2007 2:34 PM
To: Peganyee, ChrisX C
Subject: RE: '91 3/4 4x4 Suburban

While I don't recommend going that route it is possible. Putting the fuel injection back on the 350 is the better decision but its not me. the computer is going to need a throttle position input which will be the hardest thing to accomplish with a carburetor. All shifting is based on speed sensor and that throttle position.



Brian

Harris Performance
PO BOX 1447
Randleman, NC 27317
336-471-2827
www.tbichips.com and www.tpichips.com







--------------------------------------------------------------------------------

From: Peganyee, ChrisX C [mailto:chrisx.c.peganyee@intel.com]
Sent: Thursday, April 12, 2007 2:49 PM
To: sales@tbichips.com
Subject: '91 3/4 4x4 Suburban

Hi,

I just spoke to you concerning a gentleman who wants to pull his existing 454 TBI engine from his Suburban & install a carb’d 350 small block Chevy in its place. He is running a 4L80E transmission. According to your info, a chip can be reprogrammed to delete all of the engine inputs. Is this correct?? Can the engine harness then be removed, leaving the transmission harness & computer??



Thanks,

Chris

[mnunn454]

Thanks Chris. Brian sounds very knowledgeable and so seems your line of reasoning.

Sounds like a diesel style computer hooked to a throttle position sensor on the engine end, and to the 4L80E tranny on the other end would work. I'm assuming TBIChips or someone would have to burn a special chip for it.

If a person has to find, buy and install the diesel computer, pay for a custom chip and buy a custom $250 TPS sensor, then the price starts approaching the store-bought 4L80E controller. However, if a person already has most of this stuff, then it'd be a little more reasonable.

Still though, it's good to know it's technically feasible.

I've heard the 4L80Es are as tough as the TH400's. I sure wish the demand for those $650 4L80E controllers were greater because it'd bring the cost down, making this a very reasonable install for hot rod and HD use.

By contrast, if you put the extra $650 into stronger TH700 internal components, you can probably get better than stock TH400/4L80 strength. If I were starting out from scratch and not going to use fuel injection/ computer, that's the way I'd likely go. However, if I were going to use fuel injection with it's TPS and computer, then the 4L80's the only way to go.

Thanks for the info.

[53burb]

Check out my other thread on a '91 454 & 4L80E. Basically I am getting this combo. The wire harness for the engine & tranny is going to cost $575, not to mention the computer, chip, & fuel pump....