pcmhacking.net

My car has a Gas Research gas "carburettor" where gas gets fed into an idling circuit, and the IAC stepper is attached to a billet aluminium block that has a small gas hose going into the side. So there is two completely separate but parallel idling circuits. This car is always a bit pesky to start unless you prime the gas first, even if it has only been sitting for 5 minutes. Then it fires immediately. None of this just-turn-the-key-and-it-starts business.

What I want to try is close the throttle a bit more and open the IAC further during cranking because the air speed through the IAC must be fairly high when cranking so it would stand a better chance of sucking gas in perhaps than what the carburettor would. I'm running a $5D xdf What IAC setting should I change? - see pic.

The IAC assembly showing air in and out and small idle gas inlet.

is the car duel fuel if so just fit a pet start, if the car is straight gas i would fit an auto prime between the secondry circuit in the convertor and the direct manifold vac with a soiliniod hooked up to the starter motor, closing the tb so the iac opens up more will afect the idle tune so the idle circuit will need to be leaned off and you will be back were you started

Yeah I was going to say the same apart from dual fuel as I'm 99% gas research don't really support dual fuel.

So yeah I would be hooking the primer you already have fitted to a timed circuit with the starter solenoid.

gas reasurche dose suport duel fuel efi, ive done quite a few over the years, but gas injection is the best for efi cars these days

could also use the fuel pump prime circuit on the ecm to control the gas primer. ie. when you key on the car normally the fuel pump runs for 2 seconds.

gotta be careful doing that... if you jsut hook it up to the fuel pump circuit, it will be priming all the time while the engine is running .. I dont know much about gas systems or how they prime, would that be bad?

If you moved from 5D to 12P and if 12P supports keying flex tables off a flag (not sure?) then you could use a flex out, based on the cranking flag.

if you use a soliniod between manifold vac and the secondry circuit in the convertor hooked up to the starter it will only prime when starting, the gra carby would prob be using the secondry circuit of the convertor for the iac so you could t into that right at the convertor and run the soliniod off that, dont do it in the line to the iac as that should have a jet in the line some where,

I'd like to try a wider opening of the IAC first. If that's a flop then I'll see about some of these suggestions here.
So... what do I change?