Hey i have question i have an 85 iroc z and have a 400 smallblock with double hump heads and its goin to be carburated but my car currently has the stupid Tuned port injection and My chiltons says my ECM recieves information concerning engine rpm road speed transmission gear positoin power steering and air conditioning i need to get around this if any one has any hints tips or how to do the swap it would be greatly appriciated
Engine SWAP
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Pull the ECM out, carefully open it, dump acetone in it, light a match and stand back. Enjoy your carbureted car without the computer 
The ECM uses that feedback to calibrate the injection. It doesn't use them to control the tranny or the speedo, rather it uses the information to run the TPI.
Some of the gauges or idiot lights might not work after the swap since they got a signal from the ECM but someone else can help you with that. I don't know the finer points of which gauge gets controlled where.
Other things to consider... the distributor IS controlled by the ECM, so you'll need an older HEI with mechanical/vacuum advance. If you have electric fans they are controlled by the ECM so you might need an adjustable thermostat switch. The A/C signal to the ECM used to control the idle speed. When you turn the compressor on it draws down the idle so the ECM compensated. You'll just need to get a little idle solenoid from an earlier carb. It just taps into the A/C power and pushes the carb's throttle open a tiny bit. Super simple to attach. I'm sure I'm forgetting some finer points but others will fill in.
The ECM uses that feedback to calibrate the injection. It doesn't use them to control the tranny or the speedo, rather it uses the information to run the TPI.
Some of the gauges or idiot lights might not work after the swap since they got a signal from the ECM but someone else can help you with that. I don't know the finer points of which gauge gets controlled where.
Other things to consider... the distributor IS controlled by the ECM, so you'll need an older HEI with mechanical/vacuum advance. If you have electric fans they are controlled by the ECM so you might need an adjustable thermostat switch. The A/C signal to the ECM used to control the idle speed. When you turn the compressor on it draws down the idle so the ECM compensated. You'll just need to get a little idle solenoid from an earlier carb. It just taps into the A/C power and pushes the carb's throttle open a tiny bit. Super simple to attach. I'm sure I'm forgetting some finer points but others will fill in.
Get your self a pre computer Q-jet or Holley or BG carb, mount on decent intake. I installed a Speed Demon on an air Gap.
As stated above you´ll need a pre computer HEI as well.
I cut all the wires to do with the EGR and carb, you need a little black box to run the lockup torque convertor, several places do these, I got one from B/M.
I left the computer in the car and it still runs the fans, I installed dual fans.
The ECM usually only reports problems to do with engine management,
all those smog controls,what it´s got to say about power steering I could´nt guess.When I swapped in my 350 I had to get a new ECM chip calibrated for that engine, your problem probably is you´ve got that 400 in there and there won´t be a chip for that.
It´s great to be liberated from a more than 20 year old carb, from the electrical side and the general wear and tear they´ve been through.
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As stated above you´ll need a pre computer HEI as well.
I cut all the wires to do with the EGR and carb, you need a little black box to run the lockup torque convertor, several places do these, I got one from B/M.
I left the computer in the car and it still runs the fans, I installed dual fans.
The ECM usually only reports problems to do with engine management,
all those smog controls,what it´s got to say about power steering I could´nt guess.When I swapped in my 350 I had to get a new ECM chip calibrated for that engine, your problem probably is you´ve got that 400 in there and there won´t be a chip for that.
It´s great to be liberated from a more than 20 year old carb, from the electrical side and the general wear and tear they´ve been through.
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the TPI is a pretty desirable piece to some. so you might consider using it. I would think someone could tune or chip your computer to work with your 400 with cam specs & CR ect. but 1985 might be old enough of a computer that it could be hard to get that done, then again maybe you can upgrade your computer. personally I like a carb & a Good Ole HEI my self too. the TPI would be more efficient and precise in timing advance and fuel delivery and spark, than a carb setup would be. if a carb was the plan I would sell the TPI & computer and all the factory wiring I could salvage to recoup some of your 400s cost, complete factory setups sell best. I think there is company's that make the wiring for factory TPI setups for those who buy tpi or any fuel injection with out a wiring harness. just think down the road in time if you get rid of the TPI setup that emissions could bite you in the butt.
Good Luck
Mustangsaly
Good Luck
Mustangsaly
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