carb to tbi conversion

[anwat]

Is there anybody on this Forum in the Houston, Texas area that can tweak the PPOM from my 1227747 ECM.

Since you haven't had a reply in a week on this one, there are many people out there who can write a chip for you. Don't know of anyone near you, but I have used Harris Tuning in West Virginia, (Harristuning.com) there is also a ton of very useful info on his site for free. I have also used Sinister Performance in Indiana, very knowledgeable and do a lot of diesel stuff also. I have heard good things about Howell, who I know you are already familiar with. My advice would be to steer clear of people off ebay and similar places, find someone who specializes in these engines that can help you troubleshoot your issues...its nice if they will offer to rewrite your chip if something isn't right instead of charging you for a new one. Hope all is going well with your build!

 

[dyeager535]

I'd steer clear of tbichips.com if he is still out there, I started hearing less and less good things about that operation as time went on.

Doubt you'd go wrong with howell.

 

[Dan Brown]

Thx a lot, guys. May just bite the bullet and use Howell @ 200 bucks, or will call Harris Tuning and Sinister Performance and see what they'd charge.

 

[Bigb55]

If you are going to use a stock 88-94 ECM. Replace it with a dynamic EFI setup. You can then use one of the base tunes or tune it yourself. Take out sensors, trans, etc.

Its on par with Edelbrock, holley, FITech but uses stock FI parts

 

[anwat]

I've got give you a warning here, from personal experience. This is where the money will start to leave your pocket quickly. From what I'm understanding about your build, you are just trying to get a TBI injection system that works reliably on your previously carbed engine. If you want to upgrade the stock GM TBI system, it gets expensive and you have to take a systemic approach. You can do a ton of mods to the intake to get more air and fuel in, but if you're running stock exhaust manifolds, it won't do much good. The ECM you have is a 20+ year old unit with matching technology. By todays standards, it's a stone wheel. You only need a chip to ...well, actually, I don't really know why you need a chip. You have the VSS installed correctly, which is one of the reasons you would need one, your trans isn't going to be a factor since it's a manual. You have the ESC wired up correctly to the ECM and the knock sensor, the distributor is working with the system you have. What are you attempting to get with the aftermarket chip? Is there a specific issue you're trying to write out or in?
If not, I'd get that thing running, run some diagnostic logs, and see if there's a need for anything to be changed. Changing the chip should be the last thing you need to do after you have everything running. I reread you posts up to this point, and don't see a need for a chip yet...unless I missed something.

 

[Dan Brown]

I'm not sure what you mean by "chip". Do you mean the PROM? If so, I thought the PPOM is what made the electronic fuel injection work so it needed it. I do have headers. I, too, am not wanting to put an aftermarket 'chip' on it, as I'm really not looking for super performance, I just want to make it run with what I have now. I realize the ECM I have now, 1227747, is OBD1. It's replacing the one I originally started with, 16197427, which I was told was an OBD2 ECM by Larry's Electric.. I, too, realize that OOD1 technology is at least 30 years old. I'm not worried about that as I want to keep it simple and OBD1 seemed to work okay when it first came out. I used to have a 1987 GMC Safari with OBD1, and it worked just fine. As for the VSS, it is now installed and wired like I was told it needed to be and the ESC is not yet installed, but will be soon.

Don't know if you're familiar with Harris Tuning (harristuning.com). I've been Emailing with Brian Harris, the Harris in Harris Tuning. He's telling that he'll tweak my chip or PROM, which ever, for 230 bucks, and I really don't want to do that if I don't have too. I'd just like to finish up all the wiring and get the truck running and see what happens, then worry about any tweaking I may or may not need.

Thx Anwat

 

[bp71k5]

I'm not sure what you mean by "chip". Do you mean the PROM? If so, I thought the PPOM is what made the electronic fuel injection work so it needed it. I do have headers. I, too, am not wanting to put an aftermarket 'chip' on it, as I'm really not looking for super performance, I just want to make it run with what I have now. I realize the ECM I have now, 1227747, is OBD1. It's replacing the one I originally started with, 16197427, which I was told was an OBD2 ECM by Larry's Electric.. I, too, realize that OOD1 technology is at least 30 years old. I'm not worried about that as I want to keep it simple and OBD1 seemed to work okay when it first came out. I used to have a 1987 GMC Safari with OBD1, and it worked just fine. As for the VSS, it is now installed and wired like I was told it needed to be and the ESC is not yet installed, but will be soon.

Don't know if you're familiar with Harris Tuning (harristuning.com). I've been Emailing with Brian Harris, the Harris in Harris Tuning. He's telling that he'll tweak my chip or PROM, which ever, for 230 bucks, and I really don't want to do that if I don't have too. I'd just like to finish up all the wiring and get the truck running and see what happens, then worry about any tweaking I may or may not need.

Thx Anwat

He just meant that you shouldn’t be spending money on a prom/chip right now until the truck is actually running. You’ve just got a long way to go before needing that. It’ll run ok with the current chip, you’ll just get a check engine light for the missing smog equipment. Will need a chip burned to get rid of the error codes and probably tune it.

If you hadn’t got this far already, I would have advised to go with an aftermarket throttle body injection system. It tends to easier in the end unless you are keeping everything stock or already have all the parts.

 

[Dan Brown]

Thx for the advise bp71k5, that's exactly what I'm going to do, get it running then worry about the details. You mentioned "smog equipment". What equipment are you referring to? I am using the EGR valve, which is the only smog stuff it has, as the truck is 47 years old and doesn't really need anything else in Texas. What is that might trigger the MIL to come on?

As for using an aftermarket injection system, it probably would have been easier. When I started this project several years ago I told myself that I didn't want to spend the money to go that route so I now have all the parts to do it and am bound and determined to git-r-done.

 

[bp71k5]

Thx for the advise bp71k5, that's exactly what I'm going to do, get it running then worry about the details. You mentioned "smog equipment". What equipment are you referring to? I am using the EGR valve, which is the only smog stuff it has, as the truck is 47 years old and doesn't really need anything else in Texas. What is that might trigger the MIL to come on?

As for using an aftermarket injection system, it probably would have been easier. When I started this project several years ago I told myself that I didn't want to spend the money to go that route so I now have all the parts to do it and am bound and determined to git-r-done.

the AIR valve you mentioned earlier would be part of it. Not sure if that’ll throw a code though. I removed my EGR so not sure how any of that stuff works. I just removed the EGR feature in the PROM.

 

[Dan Brown]

The AIR came off the truck not long after I bought it in 1974 and put headers on it. This of course was long before computer controlled fuel injection came along. We'll see.

 

[anwat]

Sorry, I was tied up with a crack in my brand new exhaust manifold and wasn't checking in. But BP71k5 is exactly right.
As far as Brian Harris goes, he was very patient with me, and he knows his stuff. He rewrote my chip 5 or six times trying to get the fuel trim right and I was very happy with the amount of time he put in to help me out. But I was trying to upgrade the GM TBI system by changing the cam, getting more airflow through the engine and changing the fueling tables. After spending a couple of years dialing it in and seeing the resulting gains in performance, I completely agree that an aftermarket system is the way to go. The next truck I got had an FI tech on it, which is way easier to tune, troubleshoot and work with, with miles less wiring, and gives much better gains in HP and TQ. But I get that you're knee deep in this already, and are stubborn just like me and want to finish it. But the PROM/chip in your computer now should do fine to get it running and driving. Some of the ECMs will work fine without smog equip, others may not, you'll just have to see if it throws a code and deal with it then. My 90 came from the factory with no AIR system, so if yours did too, you'll be fine. The chip is probably the last thing you should do....and I can say, from experience, you truck will run without a chip. Not for long, and not too well, but it will start and move from one side of the street to the other with no chip.

I would suggest that since you have the wiring diagrams, try to hook up an ALDL port on this truck to help you with troubleshooting. It shouldn't be too difficult if you're running all the sensors, which it sounds like you are. An ALDL port is GM's first version of OBD diagnostics, your ECM will do all the work, you just need a way to see what's its doing. With a laptop, you can see what the computer is seeing, you just can't change it. Your Safari would have had it, don't know if you ever used it, but it's very helpful in my opinion.