S-10 Forum banner

1 - 16 of 16 Posts

·
Registered
1994 Oldsmobile Bravada
Joined
·
16 Posts
Discussion Starter · #1 ·
So I'm gonna swap my CPI to TBI and had a crazy thought, just wondered if it would even be possible to use the same computer in it. I have a 4.3 TBI throttle from a 91' S10 so I'd have to hook the injectors up in parallel. I just want an opinion, whether or not you think it would work. Either way, I'm gonna put a mega squirt on it.

Here's some back story:
The orginal CPI failed and didn't see any practicality in fixing it as is. Even though it would be easier, I just didn't want to have to spend upwards of three to four hundred dollars on something that will probably fail in not too much time. Anyways I had a quadrajet lying around and picked up a manifold for $100 and installed it. I didn't do anything else except install a fuel pressure regulator. I went into that with the idea of installing TBI later, and now I'm at the point where I think I want to upgrade. I just thought it would be funny if I could go complete minimal effort for all this and literally just slap a TBI on using the OG computer. I honestly doubt it, but it'll be an interesting experiment.
 

·
Been there Done it
Joined
·
11,264 Posts
What year truck? Computer location and number?
If it's a 95 don't waste my time or yours.
 
  • Like
Reactions: ala_frosty

·
Registered
1994 Oldsmobile Bravada
Joined
·
16 Posts
Discussion Starter · #3 ·
What year truck? Computer location and number?
If it's a 95 don't waste my time or yours.
I didn't realize I forgot to put it in there. It's a 1994 Oldsmobile Bravada, I havent had it apart yet so I dont know the number but the service manual says the computer is behind the glove box
 

·
Been there Done it
Joined
·
11,264 Posts
You'll need to swap the ROM chip in the ECM to one out of a 4.3 TBI S10 or Blazer. That should be easy to find in a junkyard. Just 2 screws on the little door and it pops out. I assume you can handle the wiring changes.
 

·
Registered
1994 Oldsmobile Bravada
Joined
·
16 Posts
Discussion Starter · #5 ·
You'll need to swap the ROM chip in the ECM to one out of a 4.3 TBI S10 or Blazer. That should be easy to find in a junkyard. Just 2 screws on the little door and it pops out. I assume you can handle the wiring changes.
Would it really be that easy? What wiring changes would I have to do? I know could handle it, but I dont know what I'd have to do from there.
 

·
Been there Done it
Joined
·
11,264 Posts
You'll need to find a 94 factory service manual which will have the wiring diagrams for both engines and see what is different and make the changes. Not one of those useless CD's. The wiring is the part those leave out because it takes a lot of space. I tried a couple and returned them.
I looked thru the manuals I have and apparently some TBI's in 94 came with a VCM mounted under the hood. You don't want that one. 94's also came with an ECM under the dash which is what you do want to duplicate. IIRC running the wires thru the firewall on those is a PITA because it used a big gooey plug below the heater/AC housing.
You can probably get an engine harness off a 94 TBI full size pickup with a 4.3 or either SBC and use that. It should be the same and easier to find one still intact. When I swapped a 5.7 TBI into my 94 4.3 TBI S10 the wiring just plugged in. All I did was change the ROM chip. Some guys claim you don't even need to do that. But GM did have different part numbers for the different engine's chips. You'll never find any of that info today. I did that swap 22 years ago.
 

·
Registered
1994 Oldsmobile Bravada
Joined
·
16 Posts
Discussion Starter · #7 ·
You'll need to find a 94 factory service manual which will have the wiring diagrams for both engines and see what is different and make the changes. Not one of those useless CD's. The wiring is the part those leave out because it takes a lot of space. I tried a couple and returned them.
I looked thru the manuals I have and apparently some TBI's in 94 came with a VCM mounted under the hood. You don't want that one. 94's also came with an ECM under the dash which is what you do want to duplicate. IIRC running the wires thru the firewall on those is a PITA because it used a big gooey plug below the heater/AC housing.
You can probably get an engine harness off a 94 TBI full size pickup with a 4.3 or either SBC and use that. It should be the same and easier to find one still intact. When I swapped a 5.7 TBI into my 94 4.3 TBI S10 the wiring just plugged in. All I did was change the ROM chip. Some guys claim you don't even need to do that. But GM did have different part numbers for the different engine's chips. You'll never find any of that info today. I did that swap 22 years ago.
Well if there are really a whole lot of wiring differences, then I might as well go straight to the megasquirt since I want to do that anyways. I know I could handle it, but if its going to be that involved why not go straight to the megasquirt.
 

·
time to get cereal
Joined
·
5,098 Posts
Which Megasquirt are you using?
 

·
Registered
1994 Oldsmobile Bravada
Joined
·
16 Posts
Discussion Starter · #9 ·
Which Megasquirt are you using?
I haven't purchased it yet, but I'm going to go with the megasquirt 2. I haven't decided if I want to completely eliminate the original ecm by getting the microsquirt as a trans controller, but I definitely want to get the megasquirt 2.
 

·
time to get cereal
Joined
·
5,098 Posts
Cool, you should post your progress in the Member Projects section.
 

·
Been there Done it
Joined
·
11,264 Posts
I'm not real familiar with Megssquirt, but from looking online it appears to just be the controller and some wiring to control batch fired fuel injection. That's 25-30 year old tech and you still need a throttle body of some kind. Seems kind of expensive at over $500. I noticed it said the wiring would need "some customization". So you still end up doing some wiring.
I feel it would make sense on a older vehicle that originally had a carb, but don't see the cost/benefit ratio on a truck that already has batch fire injection. Why not just snag a CPI off a 94 Blazer and stick it on there for about $100 or less. I've thrown out a couple working ones to swap in V8's. Think I still have one laying around in the barn.
Enlighten me if I'm way off base here.
 

·
time to get cereal
Joined
·
5,098 Posts
Well, you can do other things with Megasquirt as well, like run SFI, coil on plug, drive by wire, MAF or speed density, different crank triggers, VVT... it's really made for the computer/electronics nerds.
 

·
Registered
1994 Oldsmobile Bravada
Joined
·
16 Posts
Discussion Starter · #13 ·
I'm not real familiar with Megssquirt, but from looking online it appears to just be the controller and some wiring to control batch fired fuel injection. That's 25-30 year old tech and you still need a throttle body of some kind. Seems kind of expensive at over $500. I noticed it said the wiring would need "some customization". So you still end up doing some wiring.
I feel it would make sense on a older vehicle that originally had a carb, but don't see the cost/benefit ratio on a truck that already has batch fire injection. Why not just snag a CPI off a 94 Blazer and stick it on there for about $100 or less. I've thrown out a couple working ones to swap in V8's. Think I still have one laying around in the barn.
Enlighten me if I'm way off base here.
Even though the CPI can bring more power, I'm not interested in the reliability of it. I have enough bad experience of it myself and heard too many other stories. I'd rather go with the TBI and I'm also looking for the ability to change my tune to what I want. The Bravada originally came with the CPI, and I still have it all, but its just too much money to invest into something thats just going to fail.

Just an edit to this, the TBI throttle body will work just fine with the mega squirt. I can keep everything else stock and can control anything I want to.
 

·
Registered
1994 Oldsmobile Bravada
Joined
·
16 Posts
Discussion Starter · #14 ·
Cool, you should post your progress in the Member Projects section.
I think I will, I am a ways out from actually doing the swap though. I drive this car in the winter and my other car is under a cover.
 

·
time to get cereal
Joined
·
5,098 Posts
Yea, I drive my S10 in the winter, my new(er) car is under a cover. The car I should be putting back together is hard to keep interest in, lol. I'm planning on putting my 2.2L on the 'squirt eventually. I want to go all out with better crank trigger, coil on plug ignition, maybe drive by wire, etc.
 

·
Registered
1994 Oldsmobile Bravada
Joined
·
16 Posts
Discussion Starter · #16 ·
Yea, I drive my S10 in the winter, my new(er) car is under a cover. The car I should be putting back together is hard to keep interest in, lol. I'm planning on putting my 2.2L on the 'squirt eventually. I want to go all out with better crank trigger, coil on plug ignition, maybe drive by wire, etc.
It's funny my other car is the same age, and in much worse condition it just does awful in snow. I really shouldn't be driving this Bravada in winter, its got no rust on it. I am washing it everytime I get gas to help out with the salt.

I don't know a whole lot about all the upgrades I can do with the squirt, I just know there is a lot. Like the crank trigger, I really dont know how I could upgrade but know its possible. My plan for this thing is to, piece by piece, upgrade it. I may eventually go all out and do a 5.3 LS swap someday(probably just a truck motor) but that would be more than 5-6 years down the road.
 
1 - 16 of 16 Posts
Top