Propane Fumigation on gas EFI cars

[Crazyrabbit]

I am driving a 2009 Toyota Matrix but believe this thread could benefit just about anyone driving a closed loop EFI gasoline burner. I have more 16 ounce cans of propane than I can count and get them for free or at next to no cost. I think I could fumigate the propane into the intake and improve my mileage. I think I could establish the maximum flow by getting the car warmed up, adding Propane until the idle speed began to drop. Anyone done this? Any thoughts on the matter? Obviously, more propane could be used once there was a load, but I'd like to start really simple. If I had infinite MPG at a stop light instead of zero, I'd call that a good starting place. A calliape manifold of solenoid valves or some proportional valve and control could go much further but I'm no going there anytime soon.

[cRiPpLe_rOoStEr]

You would waste a good amount of fuel through the valve overlap at the intake stroke, not to mention the intake manifold may freeze like it used to happen in a Canadian Corolla fitted with the 7A-FE engine which an uncle of mine used to own and had it fitted with a CNG fumigation setup. As LPG is stored in liquid phase, unlike CNG which is stored in vapour phase, the temperature drop while it switches from liquid to vapour tends to be more intense. I'd rather try some of those multi-port sequential injection kits often used for both CNG and LPG conversions instead of fumigation in any vehicle originally fitted with sequential MPFI.

[Isaac Zachary]

You could try it. I'd reset the ECU and add very small amounts of propane. If there's some way to have it come on gradually as you step on the throttle would be the best. If done in small amounts the ECU may just correct for it and inject a little less fuel. The problem is as soon as you run out or your propane system ices up then your ECU may throw a code thinking you suddenly got an intake leak or something.

[Stubby79]

If it uses a mass airt flow sensor, and you inject it after said sensor, you might be OK, assuming the ECU compensates for it running rich from what the O2 sensors are telling it.

If you add it before said sensor, or if it uses an absolute pressure sensor, the engine will see the gaseous propane as more air and try to add more fuel. O2 sensors/ECU might not be able to compensate enough.

And something to consider...pure propane setups are known to burn exhaust valves...reading up on it, it appears to only be an issue when running rich on propane. You'd be running on the rich side with your setup. Might cause long term issues, if the ecu isn't compensating enough.

Doubt you'd have to worry about things icing up if you were only putting out a low volume (not running on just propane).

You'll want some kind of propane regulator. Like off of a portable BBQ. Or maybe use a plumbing torch head...as a volume restriction rather than pressure restriction. If you were looking to just idle off of it, with an injector kill switch, I might suggest the cheap dual-fuel carbs meant for generators and other such small engines to do the mixing.

Conclusion...start slow, expect to find a limit to the benefit and back off when you hit it. Oh and make sure you have a way of reading and resetting ECU codes.

[Vwbeamer]

I acually built some test equipment for a company that converted gas engines to run on propane. these were small engines, mainly used on lawn mowers. The company I worked for went broke, when the price of propane went up. This was 2012-2013 IIRC.

Same guy was building a kit to fog the intake on taxi cabs with propane, this was the 5.0 liter ford motors found in old crown Vics. The controller was a simple ardunio. It simply read the TPS and PWM a single propane fuel injector, which wasn't a proper injector at all, just a 12v air valve (https://www.amazon.com/Yukon-Gear-YZ.../dp/B0078UA1F4). You can get them cheaper, that's just first one I found. I bought them off ebay for around 10 bucks. They have other uses also.

I don't have access to the programing, but I'm sure it was a simple table. The car still used gas as the primary fuel. at the time gas was over 3.50 and propane was 1.90. Economics changed, gas came down, propane went up some reason, I can't recall. Whole deal went went under.

I still have about 5 K of circuit boards and parts in my garage for the test equipment I was building. it was a wide band 02 sensor, pressure gauge for the propane( it was regulated down to 4 PSI) all wrapped up in a package and controlled by an ardunio pro. It was designed for engines converted to run entirley on propane. The device I built allowed an idiot to tune the conversion kit. you just turned the regulator screw until the lights on the tester turned green.

I'm not sure how the hybrid gas-propane engines were tuned. I'm guess he monitored the exhaust with a wide band and kept upping the propane until it ran rich. We never thought about raw propane going out the exhaust. Sometimes it pays to be stupid because you don't over think these things.

[Vwbeamer]

here's same valve cheaper. https://www.amazon.com/s?k=Solenoid+...A-ACA-DDAA-1BA

[cRiPpLe_rOoStEr]

I'm aware of some direct-injection engines being fitted with 5th-generation CNG kits, yet it requires a small amount of the original fuel through the stock injectors in order to prevent them from getting damaged, while the CNG goes through sequential port-injection. Maybe it's not so much of rocket-science to try a similar approach if you're really willing to try the LPG fumigation enrichment in a port-injection engine, considering the LPG replaces some of the oxygen flow through the intake while it expands.

[67-ls1]

How long would a 16 oz bottle of propane last before it needed to be changed?

[cRiPpLe_rOoStEr]

Originally Posted by 67-ls1

How long would a 16 oz bottle of propane last before it needed to be changed?

It will depend on the amount of LPG fumigated, and its expansion ratio which may also vary according to many other factors such as outside temperature and humidity of the air. Assuming the LPG won't go through a vaporizer as in most bi-fuel conversions.

[Isaac Zachary]

One of the downsides to attempting to add small amounts of propane to a gasoline EFI engine is that propane, as a gas, easily displaces the air entering. So not only does it burn up with some of the oxygen it also displaces more oxygen, unlike a liquid fuel that wouldn't diplace as much.

Of course if you can also get your hands on some cheap bottles of oxygen... Ummm... Never mind... Bad idea... Abort mission!