New member swapping 4.3 for 5.7 tbi

Hello All! I've been a frequent reader of the forum (especially recently), but never registered. I have a 1994 K1500 5-spd that I'm trying to finish up a 4.3 to 5.7 tbi swap on. I'm new to working on SBCs and not finding a lot of useful help here in WV.

I found the Jasper 5.7 in a 1990 Cadillac Fleetwood with 89k documented miles. Engine started and ran great in the donor. I have the 5.7 in my truck and running. Trying to button up a few things to get it running great. I'm using the 4.3 wiring harness and ECM with 5.7 sensors.

I'm currently getting a code 43 (ecm/knock sensor) and low idle. I've talked to some other people who have completed a 4.3 to 5.7 swap and they claim that the 4.3 chip can be used for the 5.7. The truck is running "ok," but I think it could be better. I ordered a Jet 29404-S chip and realized it wouldn't fit my 16197427 ECM. Jet tech support told me that I needed a chip for the 5.7 that their performance chip could piggyback on.

I'm having trouble finding the correct chip for my ECM. I figured it was time to join the forum and ask for expertise from someone who knows. Any help would be greatly appreciated.

I've been thinking most, if not all, 94 K1500 with a 5.7 would have an automatic transmission. Maybe you can program your own chip with the modified attached .bin file? You have the option of using an adapter board to use a chip you program for yourself, see attached pictures. I think the Code 43 is because you will need a different knock sensor. Based on personal experience, I would use the knock sensor for a 1994 K1500 5.7 liter with AUTOMATIC Transmission with the 16197427 computer.

dave w

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Originally Posted by dave w

I've been thinking most, if not all, 94 K1500 with a 5.7 would have an automatic transmission. Maybe you can program your own chip with the modified attached .bin file? You have the option of using an adapter board to use a chip you program for yourself, see attached pictures. I think the Code 43 is because you will need a different knock sensor. Based on personal experience, I would use the knock sensor for a 1994 K1500 5.7 liter with AUTOMATIC Transmission with the 16197427 computer.

dave w

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I didn't have any intentions of programming a chip. I'm not certain how to get started. I'll have to look on the forum and figure it out.

The donor was an automatic that only used 1 knock sensor. The 4.3 had 2. I added a 2nd to the 5.7 that was for a manual shift. I'll try swapping that one out for a sensor for an automatic.

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The donor was an automatic that only used 1 knock sensor. The 4.3 had 2. I added a 2nd to the 5.7 that was for a manual shift. I'll try swapping that one out for a sensor for an automatic.

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Both sensors should be from the 4.3 / 7427 if you are using a 4.3 / 7427 chip. Because the 7427 was never used with a manual transmission and 5.7, and because you have dual knock sensors, no stock chip will be exactly correct for your truck. You should find someone who can, or you should learn how to, program custom chips. And since you can pull off this engine swap then I'm sure you can program chips.

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Originally Posted by 1project2many

Both sensors should be from the 4.3 / 7427 if you are using a 4.3 / 7427 chip. Because the 7427 was never used with a manual transmission and 5.7, and because you have dual knock sensors, no stock chip will be exactly correct for your truck. You should find someone who can, or you should learn how to, program custom chips. And since you can pull off this engine swap then I'm sure you can program chips.

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The knock sensors on the 4.3 didn't fit the 5.7. The auto trans donor came with one and I purchased one for a 5-spd (wasn't aware there was a difference) to go in the other side. I'll probably try Dave's suggestion and see if the KS for an auto trans will work.

This swap has been outside my budget for a while now. I'd like to find someone that can program and get me running as soon as possible. However, it would be nice to find someone that can both get me running and help me learn to program for future mods.

A Used 5.7 Liter Memcal / Chip is a low cost option? According to the information I have available to me, the Memcal / Chip (code BPSA) for sale in the ebay link below is for a 1995 Van 5.7 liter with Manual Trans using the 16156930 computer (electrically identical / interchangeable for a 16197427 PCM).

http://www.ebay.com/itm/CHIP-BPSA-35...xWBJim&vxp=mtr

More information on the 16156930 Computer http://www.gearhead-efi.com/Fuel-Inj...Information-31

dave w

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Originally Posted by dave w

A Used 5.7 Liter Memcal / Chip is a low cost option? According to the information I have available to me, the Memcal / Chip (code BPSA) for sale in the ebay link below is for a 1995 Van 5.7 liter with Manual Trans using the 16156930 computer (electrically identical / interchangeable for a 16197427 PCM).

http://www.ebay.com/itm/CHIP-BPSA-35...xWBJim&vxp=mtr

More information on the 16156930 Computer http://www.gearhead-efi.com/Fuel-Inj...Information-31

dave w

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The ebay listing says "4L60E." Am I missing something? I'm assuming you are saying this is a good chip to program for my truck? I've read quite a few of your posts on the forum on various topics. If you say this is the chip I need, I'll order it.

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Originally Posted by gar925

The ebay listing says "4L60E." Am I missing something? I'm assuming you are saying this is a good chip to program for my truck? I've read quite a few of your posts on the forum on various topics. If you say this is the chip I need, I'll order it.

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Order the chip.:thumbsup: I used two different sources to confirm that chip code BPSA is from a 95 Van 5.7 liter / Manual trans.

dave w

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Originally Posted by dave w

Order the chip.:thumbsup: I used two different sources to confirm that chip code BPSA is from a 95 Van 5.7 liter / Manual trans.

dave w

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Ordered. Should arrive Friday.

Do you think this will be a direct replacement or will I still need to do some initial programming?

The chip might need some re-programming, depending on how "Stock" your 5.7 is or is not? If you have removed emissions, changed injectors, modified the exhaust system, or have an aftermarket performance intake the chip will very likely need re-programming. I would expect a factory 5.7 liter / manual trans chip would be a HUGE improvement from a factory 4.3 liter / manual trans chip for your engine swap.

dave w

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Originally Posted by dave w

Order the chip.:thumbsup: I used two different sources to confirm that chip code BPSA is from a 95 Van 5.7 liter / Manual trans.

dave w

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It may be too late to question, but neither my 4.3 or 5.7 had an ESC mounted next to the throttle body. Do you foresee this being a problem? I did a quick search on AutoZone for an ESC for the van and nothing showed up. Hopefully, that's a good sign.

Thanks for all your help Dave!

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Originally Posted by dave w

The chip might need some re-programming, depending on how "Stock" your 5.7 is or is not? If you have removed emissions, changed injectors, modified the exhaust system, or have an aftermarket performance intake the chip will very likely need re-programming. I would expect a factory 5.7 liter / manual trans chip would be a HUGE improvement from a factory 4.3 liter / manual trans chip for your engine swap.

dave w

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The only thing that has been changed is the exhaust. The PO deleted the cat and installed a 2.5" y-pipe to 3" single with a glasspack. I'm able to use the current exhaust temporarily, but it's rusted out. I intend to go with 2.5" to an x-pipe and then... I haven't decided on mufflers yet. The PO also installed 33s, which I think made the 4.3 even more sluggish.

It won't be long before I'll want to make some changes. I've already got my eyes on a Lunati .468/.468 cam.

I guess now I need to figure out everything I need to get started datalogging and possibly try my hand at tuning.

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Originally Posted by gar925

It may be too late to question, but neither my 4.3 or 5.7 had an ESC mounted next to the throttle body. Do you foresee this being a problem? I did a quick search on AutoZone for an ESC for the van and nothing showed up. Hopefully, that's a good sign.

Thanks for all your help Dave!

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The ESC is in the Memcal / Chip on a 16197427.

dave w

Update:

I picked up two knock sensors for a '94 k1500 5.7 w/auto trans and swapped out the ones for 5-spd. The check engine light is gone, but there doesn't seem to be much, if any, change while driving.

The chip I ordered should arrive by Friday. Hopefully that will take care of the low idle, rev limiter, and remaining issues. I'll post an update when I get the chip installed.

The wiring schematics I have access to show the V8 uses One Knock Sensor, and the V6 uses Two Knock Sensors. When you install the V8 Memcal / Chip, you might need to unplug one of the knock sensors.

dave w

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Originally Posted by dave w

The wiring schematics I have access to show the V8 uses One Knock Sensor, and the V6 uses Two Knock Sensors. When you install the V8 Memcal / Chip, you might need to unplug one of the knock sensors.

dave w

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Will it be ok to just tape up the plug or will I need to put in a resistor?

The truck seems to be running better since getting rid of the code 43. I should have the chip installed this evening.

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Originally Posted by gar925

Will it be ok to just tape up the plug or will I need to put in a resistor?

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Good question, lets see what happens with the new chip. Maybe the new chip will be OK with two knock sensors? I would think with two knock sensors, the new chip will set a code 43? I would think if you get a code 43 with the new chip, unplugging one of the two knock sensors would clear the 43? My thinking is the more "Original Factory Parts / Original Factory Wiring" you have, it's less likely there will be an error code or other issues.

dave w

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Originally Posted by dave w

Good question, lets see what happens with the new chip. Maybe the new chip will be OK with two knock sensors? I would think with two knock sensors, the new chip will set a code 43? I would think if you get a code 43 with the new chip, unplugging one of the two knock sensors would clear the 43? My thinking is the more "Original Factory Parts / Original Factory Wiring" you have, it's less likely there will be an error code or other issues.

dave w

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I installed the new chip as soon as I got home from work today. The truck starts strong, but searches for idle speed and stalls within a minute. No codes.

Allow me to add the sources for the information I posted, see link and attached pics. Seemingly all good sources, Moates website, Moates BCC Lookup Excel Spreadsheet, and TunerCats CAL Data.:thumbsup:

Moates website copy / paste: "These ECMs are largely interchangeable – as a rule of thumb, any of the 4 hardware boxes ( 16197427, 16196395, 16156930, 16168625 ) can run any of the 4 main masks ( $0D, $0E, $31 or $E6 ) BUT you will have issues using a V6 memcal for a V8 application or vise versa. Your memcal MUST be from a vehicle that has the same number of cylinders as the engine you are trying to run."


dave w

http://support.moates.net/92-95-4l60e-4l80e-tbi-trucks/

Thanks for the info. I wonder if the wiring harness would be different from the '94 4.3 to the '95 5.7?

My understanding was that on the 4.3L with dual knock sensors, the sensors were 8k ohms each while the single sensors on the 5.7L were 4k ohms. The dual sensors were just wired in parallel. So in theory, the 2 x 8k sensors or 1 x 4k sensor should interchange without throwing a code for being the wrong resistance.

The manual transmission knock sensor was likely 100k ohms which would explain why it didn't work. You likely could have added a resistor to it to make it work.

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Originally Posted by lionelhutz

My understanding was that on the 4.3L with dual knock sensors, the sensors were 8k ohms each while the single sensors on the 5.7L were 4k ohms. The dual sensors were just wired in parallel. So in theory, the 2 x 8k sensors or 1 x 4k sensor should interchange without throwing a code for being the wrong resistance.

The manual transmission knock sensor was likely 100k ohms which would explain why it didn't work. You likely could have added a resistor to it to make it work.

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Hopefully, the knock sensors will work out with the BPSA memcal I ordered.

It should, the resistance required would only change with a different PCM.

When I installed the BPSA memcal from a '95 5.7 tbi van, the truck started fine but surged. I reset the IAC with no changes. I didn't get a light. Not sure if it's the chip, wiring harness, or if it just needs to relearn. The truck seams to run fine other than low idle with the original memcal (BJFD).

I think we'll have this figured out and completed soon.

Any progress? I have an 89 S10 I did basically the same swap and am watching this thread closely.

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Originally Posted by 89S10_Project

Any progress? I have an 89 S10 I did basically the same swap and am watching this thread closely.

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It turns out the BPSA memcal was programmed for an auto tranny and 5.7 injectors. I sent the chip off to have it checked out and reprogrammed since I have a 5-spd and was using the 4.3 injectors. The chip was cleared and programmed for 61 lb/hr injectors and everything fixed for the 5-spd.

I received the memcal back this week, but haven't had a chance to try it out or install the correct injectors. I was unexpectedly sent out of town on a business trip this week and with the holiday, I probably won't get a chance to work on it until next week. I should have the correct injectors this weekend. I'll keep you all posted.

I am not an EFI engineer, buuut:

The engineer in me says that the 4.3 injectors, while they may be made to work with a longer "ON" time, are going to be overworked and thus have their functional life shortened. Seems like it would be much smarter to go with the proper 5.7 injectors, especially given that they exist, are the same form factor, and will bolt right in place of the 4.3 units. (In fact, this is exactly what I did on my build, and why).

This may not be borne out by folks with much more experience in this area than myself, in which case I'll just file it away for future reference.

Pardon if this has already been covered - my head is awash with GMEFI stuff and it's all running together- is your truck's configuration somehow rare? If not, what's wrong with picking up a factory ECM for your engine/transmission off of Ebay, car-parts.com or a local salvage yard? I've never paid more than $50 for an ECM, and that was shipped to my door. Just seems like a really easy, cheap and simple solution, especially if you're resorting to having folks burn PROMs.

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Originally Posted by 89S10_Project

I am not an EFI engineer, buuut:
The engineer in me says that the 4.3 injectors, while they may be made to work with a longer "ON" time, are going to be overworked and thus have their functional life shortened. Seems like it would be much smarter to go with the proper 5.7 injectors, especially given that they exist, are the same form factor, and will bolt right in place of the 4.3 units. (In fact, this is exactly what I did on my build, and why).

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The 61 lb/hr injectors that I'm getting are for a 5.7.

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Originally Posted by 89S10_Project

Pardon if this has already been covered - my head is awash with GMEFI stuff and it's all running together- is your truck's configuration somehow rare? If not, what's wrong with picking up a factory ECM for your engine/transmission off of Ebay, car-parts.com or a local salvage yard?

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My K1500 5-spd came with a 4.3 and I swapped in a 5.7 reusing my original wiring harness, ECM, , TBI, and everything on the front of the engine. I thought all I needed was a memcal for my 16197427 ECM to finish it up and fix the low idle and low rev-limit issue I was having. Apparently, there was not a 5-spd 5.7 k1500 made with my ECM. Changing to the stock ECM for my truck and engine would likely not work with my harness and sensors.

The BPSA memcal from a 5.7 van was available for cheap on ebay and was compatible with my ECM. When I tried it, the truck surged at idle. Everyone (before I joined this forum) told me that the 4.3 injectors would work fine. This was probably the cause for my surging issue. Because I bought it used from ebay, I thought it would be a good idea for someone who knows what they're doing to make sure the memcal was in working order and to make sure it would work in my application.

That's when I found out that the BPSA would not work with my 4.3 injectors and that the tranny needed to be changed from auto to manual in the program. I'm not an EFI engineer either and just getting started learning the terminology on here. Maybe soon I can figure out how to make my own changes.

Gotcha, and now I recall all of this. Sorry for making you repeat yourself.

Yeah, I'm right there with you, and totally agree on your approach. I hope it works out soon!

i also been looking at this to BPSA and getting conflicting answer about the what Tranny it is a Manual or 4l60E ???
when I use Scotts BCC look up PDF I get 1995 34734 6930 G2 LO5 5.7 Man GU6 3.42 gears
and need a manual >bin for my 4speed M-20 5.7 350 with 3.73 gears .and though this bin BPSA be a good start.Thanks