• From: Wadsworth, OH
  • Registered: 2010-07-29
  • Posts: 85

Topic: Chevy 4.3L ECM question

We are dropping a '90 or '91 (not really sure which year) Chevy 4.3 down in our 924.  The original plan was to pull the TBI and carb it so we dont have to deal with the computer crap anymore.  However, it was mentioned to me that a replacement ECM is built for that motor which bypasses all of the sensors and crap and basically just runs your fuel and spark.  In searching for it I have come up with squat.  I was told it is used by hotrodders who drop that motor into old cars and it is basically a plug and go system.  Has anyone heard of this and happen to know who makes them and where I can get one.  I went all through summits page and googled everything I could think of, but nothing seemed to come up right.  Any help would be appreciated.  We have the motor complete with wiring harness and the old computer.  It would just be nice not to have to deal with that rats nest.  Or, in your opinion should we just toss it and carb the damn thing.

2 Reply by Scotty (edited by Scotty 2012-04-01 08:32 PM)

  • From: Northern Mexico
  • Registered: 2012-02-14
  • Posts: 728

Re: Chevy 4.3L ECM question

You can get a chip that eliminates all the sensor (Non vital) and smog codes. Talk to Brian

at Harris Performance.  336-471-2827

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#3 IROC MAIDEN
  • From: WPB Fl.
  • Registered: 2010-10-27
  • Posts: 783

Re: Chevy 4.3L ECM question

Eliminate the sensors?
Coolant temp, knock, throttle position are all good ideas and should not be trivialized nor eliminated, nor are they a big deal to keep, just transfer the engine/harness complete, there are only a few power wires to hookup inside the car.

What you want is a aftermarket PROM chip in the stock computer to ignore things like EGR, smog pump and such.

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  • Registered: 2009-05-27
  • Posts: 111

Re: Chevy 4.3L ECM question

That TBI system is a bulletproof setup and not so many wiring challenges, If you have a doner car just grag the ecm and harness. Power and ground and keep all the sensors. we wired up all the power to a main shut off. Your biggest challenge is the high pressure fuel system. But it is only about 16 psi on a TBI.

  • From: Van Nuys, CA
  • Registered: 2011-02-11
  • Posts: 2,609

Re: Chevy 4.3L ECM question

http://www.painlesswiring.com/webcatalo … ield=60101

This may do it, but it still lacks the computer

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  • Registered: 2012-01-02
  • Posts: 55

Re: Chevy 4.3L ECM question

91 305 Camaro - TBI/ECM killed us @ Sears PointLess... We spend almost all weekend switching sensors, replacing ignition, distributor, even the ECU.. in the end, we advanced the distributor manually and ran the ECU it in diagnostic mode.. 

Before the next race, we are ripping the TBI, ECU, all the electronic stuff out and going old school (HEI, Carb, no ECM).  Now, after slamming it, don't suppose you want to buy it :-)

it's all coming out.

  • From: Wadsworth, OH
  • Registered: 2010-07-29
  • Posts: 85

Re: Chevy 4.3L ECM question

Thanks for the offer, but I think we have just about had it with the computer crap.  We were interested in the idea because the TBI system is fairly reliable (and is already on the engine).  I just hate digging through the rats nest that is a wiring harness.  I think we may just keep it as simple as possible even if it isnt as efficient or powerful as the TBI.  The engine is goin in this week so we will lay the harness out completely and decide then if we want to screw with it or just slap a carb and new dizzy on.  Hell, maybe well try the TBI first and have the carb set up as a back up incase it fails.  There's no better time to switch a fuel and electrical system like at the track.

  • Registered: 2011-07-12
  • Posts: 133

Re: Chevy 4.3L ECM question

Throw away the fuel injection?

Your just swapping one problem for a whole bunch of different ones.

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  • Registered: 2012-01-02
  • Posts: 55

Re: Chevy 4.3L ECM question

gearhead455 wrote:

Throw away the fuel injection?

Your just swapping one problem for a whole bunch of different ones.

yea, but i can fix the different ones in minutes.   Not trying to debug sensors that we don't even need.

  • From: Wadsworth, OH
  • Registered: 2010-07-29
  • Posts: 85

Re: Chevy 4.3L ECM question

My thoughts exactly.  I can do mechanical.  It's electrical that gives me fits.

  • FJ40Jim
  • FJ40Jim
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  • From: Lancaster OH
  • Registered: 2009-05-02
  • Posts: 1,118

Re: Chevy 4.3L ECM question

I rebuild carbs for a living, and i would still rather have the TBI on that engine.

Try http://howellefi.com/ for a universal, off-road ECM.

Jim C.
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  • Registered: 2011-07-12
  • Posts: 133

Re: Chevy 4.3L ECM question

Carburetors do not have to be "broken" for you to have lot's of problems. Carburetors and fixed timing curves just inherently aren't very good at dealing with changing conditions on the track.

Not trying to be a dick, but the reaction of "I don't understand it therefore it's crap" is a bit silly. FI is superior once it's set up, you don't have to worry about fuel boiling in the float bowls or the engine spark knocking once the intake air temps go up. TBI really is the simplest of all fuel injection, it's not that hard and it definitely beats checking the color of your spark plugs every hour trying to track down that intermittent random misfire.

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  • From: Northern Mexico
  • Registered: 2012-02-14
  • Posts: 728

Re: Chevy 4.3L ECM question

On IROC Maiden we got the TPI to work awesome with the old school heads and block. The entire ECM chip and everything is bone stock or Auto Zone parts. No need to worry about flooding in the turns, we get 14.1-12.9 air fuel through the entire RPM band. In fact at idle we are getting 18.6:1 That means the stupid rediculous V-8 we run is getting max MPG.  No vapor locks... Plus we can go from sea level to the rockies and won't have to touch crap. When we fill at the pumps at the track it don't matter if we dump in 91 or 116.... Sweet and simple.  It's worth every second to get EFI to work. We had plent of other problems at Sears pointless to deal with like the track kicking us off twice for being 12db too loud. LOL

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#3 IROC MAIDEN
  • From: Wadsworth, OH
  • Registered: 2010-07-29
  • Posts: 85

Re: Chevy 4.3L ECM question

I dont mind being a dick as long as its constructive dickishness.  I understand the electrics.  At least on a basic level.  However, from my experiences, the ECM doesn't have to be "broken" to give you all sorts of problems either.  And when you are running the shit out of old beaters those little sensors tend to lose their freaking minds.  And spending hours in the pits upside down under the dash sorting through the rats nest trying to figure out how to bypass said freak out is not my idea of fun.  Obviously kiwiracer has run into the same issues we have, and like us, is fed up with them.  I'm perfectly willing to say TBI is better than carb.  Except when you are trying to cram one POS into another POS the carb just seems like a simpler way to go.  The engine is in good shape, the harness is in good shape, the ECM is in good shape, for a '91 S10 with all the mounts, plugs, gauges and wire channels.  But for a '77 924, things tend not to fall into place so well.  Seems like in Lemons you'll find your carb fans and you'll find your FI fans, each having had problems with the other.  When it comes down to it, I'm sure we will be in the pits bitching about which ever choice we make.  But hey, if you are at Autobahn, feel free stop by and watch us rip our hair out.  Oh, but you might wanna keep your dick comments to yourself then, we probably won't be in the mood.

  • From: Northern Mexico
  • Registered: 2012-02-14
  • Posts: 728

Re: Chevy 4.3L ECM question

The coolest thing about a 4.3 is the amount of totally bas ass parts you can get on e-bay CHEAP. i've built 3 of these all well over 300hp. All of the crazy SBC parts fit. Forinstance when you have a set of 8 or 16 pcs and you toast one part on your V8 basically the whole set is worthless. Forinstance you can get 7 JE pistons for the $50 dollar range. One engine I scored a set of 6" Oliver Ti rods for 90 bucks.  Roller lifters, Rockers, push rods... all the same super deals.

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#3 IROC MAIDEN
  • From: Wadsworth, OH
  • Registered: 2010-07-29
  • Posts: 85

Re: Chevy 4.3L ECM question

Cheap and "reliable" is why we decided to go with the 4.3.  Size was another reason.  We wanted to keep at least some of the handling of the 924.  Otherwise, we would have crammed one of the 350's we have laying around down in.  So I guess by my own reasoning, CHEAP, I should just suck it up and run it the way we got it.  But just so you know, if we have all of those "computer crap" problems, I blame every one of you TBI fans...

17 Reply by Scotty (edited by Scotty 2012-04-03 12:28 AM)

  • From: Northern Mexico
  • Registered: 2012-02-14
  • Posts: 728

Re: Chevy 4.3L ECM question

The factory harness will make you want to give up in an instant. Everything from the dash to doors wants to make you throw some Prego Mushroom Sauce on it and eat it.  An aftermarket harness is really the way to go... No doubt. There are many guys that make the harness much cheaper than Painless. Howell is one of them. Brian can also hook you up with some home built harness builders that know their shit better and will answer the phone personally.

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#3 IROC MAIDEN
  • Registered: 2011-07-12
  • Posts: 133

Re: Chevy 4.3L ECM question

Which Autobahn race? I'll be there in October.

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  • FJ40Jim
  • FJ40Jim
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  • From: Lancaster OH
  • Registered: 2009-05-02
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Re: Chevy 4.3L ECM question

IDK if Scotty is talking about the Porsche or the GMC harness.  They both suck, but the Porch sucks morely.  Best bet, IMO, is gut the car, install the basic EFI engine harnes, then add just enough wires and switches to get engine, fuel pump, wipers, brakelights operable.

Jim C.
Muttonheads!, nee Focke-eWe190 81-85-86-87-95-97 GTI
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  • From: Northern Mexico
  • Registered: 2012-02-14
  • Posts: 728

Re: Chevy 4.3L ECM question

I've used these guys in the past....Good stuff.  http://ls1wiringharness.com/gmefi_002.htm

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#3 IROC MAIDEN
  • From: central ohio
  • Registered: 2009-09-19
  • Posts: 308

Re: Chevy 4.3L ECM question

PUT A CARB ON IT

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  • From: New Alexandria PA
  • Registered: 2010-06-14
  • Posts: 480

Re: Chevy 4.3L ECM question

TBI is not that hard really.  You need wires for an O2 sensor, coolant temp sensor, throttle position sensor, map sensor, distributor, coil, and injectors.

I am pretty sure that is it.  It is like a total of 25 wires.  Take your stock harness and strip off everything you don't need.  Go grab an ECU out of a manual transmissioned car.

It will work.  It will be reliable.  It is tuneable.

We run an older 350 with a TBI setup out of a 94 K1500.  We got a chip from Brian Harris.

This is WAY better that the carb we had!  The carb was tuned with a tuning kit and a wideband AFR guage.  It still wasn't as good as just starting the car and driving it.

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