TP355Z

Hey guys - a buddy of mine has a 1991ish TBI truck that he transplanted a 400 sbc into. He has the holley 670 tbi (with 85 lb/hr injectors I think) and thats about it. He ran a larger cam than me, I think his duration is like 214/220 with .450/.455 lift (or something like that) but he can't get the truck 2 run right. I think its a combination of big cam / big motor that's pushing the system too far. But have any of you guys programmed truck computers? He's desperate and I want 2 help him out. If possible - throw me some ECM numbers that he can try, like - would he be able to put an 8746 into his truck? B/c if that'd work, I could give him a chip to try. I dunno.

Ty

HaulnA$$

More information is needed. What ECM are you using now. It should be a 7747 that was originally in that truck. Either way you will have to do some chip re-programming no matter which ECM is in there. At the very minimun, the injector constants and the engine displacement constant will have to be changed just to get you in the ballpark. To get it to run right you will have to have some more programming done to the fuel/spark tables, etc. You will not find an OEM chip/ECM combination that will fix all your problems. With more information, I'm sure that there are many around the boards that would be willing and able to help you out.

c4boom

would starting with a 454 ss truck chip be a good start for him this way he is less likely to go lean

Low C1500

That motor is gonna need more fuel, the 85# injectors are only 85# @ 22psi, at stock pressure (like 10-13 psi) the holley injectors flow about the same as stock 350 injectors. The ecm will easially be able to handle the engine setup. With a engine swap like that you need to make sure all the sensors are working right (scanner), also a vaccum leak can cause a rough condition. But like was already said, you need to supply more info about the problem.

HaulnA$$

Quote:

would starting with a 454 ss truck chip be a good start for him this way he is less likely to go lean

This is a step in the right direction but goes too far. Going to a 454SS chip would cause the engine displacement constant to be off in the wrong direction but the injector constant would be very close assuming that the Holley TBI has 85# injectors (many of them have 65# ones identified by the yellow plastic under the caps, 85# ones have red plastic under the caps) as the early 454SS has 80#injectors and the later oneds had 90#. The problem is not going lean but going rich. With a smaler ECM engine displacement constant (i.e. a 350 constant but running a 400) and a smaller injector constant (i.e. 55# for a 350 but running 85# injectors) the engine is going to run REALLY rich. However with a 454SS chip you will have the same problem because now the ECM injector constant is close but the displacement constant is too high which will cause the ECM to dump in too much fuel to satisfy 454 cu. in. It may not be as bad as the first scenario but it will still be rich. There are 2 things you could do that come to mind without burning a chip. 1) Use the stock 350 TB but raise the fuel pressure as high as it will go (the stock injectors can easily handle upwards of 25 psi but the stock fuel pump won't) and see how it does. 2) The Holley TBI's usually come with the fuel pressure set on the high side (around 13 psi) so you may be able to lower the fuel pressure to around 9 psi and see how it does. It must be noted that these suggestions are not the way to properly address the problem. The right way to do it is to re-program the ECM. You might try www.tbichips.com or some of the other chip programmers out there.

TP355Z

here are the numbers he gave me off the computer:

Service Number: 1614629986AWLD K312890957
Chip Num: AWLD 7714 EB4(F?)Z101AZ4ZGAH14

This might be of some use...

The big question is which truck ecm's can be programmed easily. Thats the first step he needs to conquer because everything else *so he says* is already all set (new tbi, new sensors, ect)

Tyler

HaulnA$$

O.K. the 16146299 ECM shows to be for a 92-93 Truck, 5.7L V-8 TBI with a $99 prom mask and your AWLD bin file. This ECM is easily programmable for someone with the proper equipment and software. Armed with this info, you should be able to get it done.

91rs4life

See man...this is why I stick to carbs. I understand nothing here. If someone cares to educate me feel free. all I know is what chips are in your ECM (RAM ROM PROM EEPROM KAM) and basically what they do...don't know numbers.

TP355Z

takes a little diligence and effort, s'all

Ty