How to: reduce the rich condition of a cold start.

[C3H8]

Originally Posted by ShadeTreeMech

I suppose it depends on the engine design. Some cars will do well with diesel added, especially the older, more rudimentary engines. I had a 96 spectrum with a 1.5 that could run diesel when mixed with a bit of gas---mind you I didn't log the fuel consumption with the tenacity of my esteemed collegue mwebb has so intricately done, it was a matter of being able to get cheap off-road diesel for free in a time of financial hardship.

I honestly don't think diesel is a good additive for the modern gas engine, but it helps a bit on the older ones.

he wasn't testing diesel FUEL.

by his own admission he was testing a diesel fuel additive.

[ShadeTreeMech]

C3H8, that is an interesting screen name. Isn't that the molecular formula for propane?

I would suspect adding the propane changes things up a bit. And changing things up a bit changes the known rules concerning modifications, and considering your astounding fuel economy, who can deny your knowledge? Of course, I must ask, since others will, do you add the gallons of propane used into the amount of gas used? Otherwise, your mpg figure would be off quite a bit.

[ShadeTreeMech]

Originally Posted by C3H8

he wasn't testing diesel FUEL.

by his own admission he was testing a diesel fuel additive.

Ah, didn't catch that first go around.

[euromodder]

Originally Posted by ShadeTreeMech

C3H8, that is an interesting screen name. Isn't that the molecular formula for propane?

It is.

I would suspect adding the propane changes things up a bit.

Propane is a gas, so one can't just "add" propane to petrol or diesel, though it can be injected simultaneously.

Injecting liquid propane in diesel engines has proven to have excellent effects on FE !

Diesel LPG conversions

[C3H8]

yes i factor in propane.

propane is a tricky thing to measure. if you look at it by a purely miles per gallon basis, it does get less mpg's then gas. by a good amount too. the thing is, propane is significantly cheaper then gasoline. so although the mpg drops a bit, the actual cost per mile also drops (because its reduced cost more then makes up for its reduced mpg's). so i try to adjust the mpg i tell people to accurately reflect the "true" mpg when taking into account its cost. that's where i get 40mpg from.

[ShadeTreeMech]

I assumed he meant simultaneous injection; I've also heard of adding propane, or for the more adventurous and those with better lined pockets, compressed natural gas, to a diesel engine for better performance.

You'd be interested in this link I bet: H-Line Conversions - Hummer H1 & H2 Diesel and Green Fuel Conversions - Wichita, Kansas

He does a lot of bigger cars, but how hard is it to downsize a bit?

[cfg83]

C3H8 -

Interesting mod. With my previously unheated 02 sensor my car takes about a minute to go into closed loop :

http://www.youtube.com/watch?v=CZ9G_h5o2Yc

My cold start water temperature (FWT) didn't have far to go. It started at 69 degrees F in the video and the ECU/PCM went to closed-loop at about 82 degrees F.

I have since switched to a heated 02 sensor, but that's mostly for engine-off at stoplights + already-hot water temperature conditions.

CarloSW2

[Arragonis]

Sorry but I don't get the point of this thread. I have my fireproof boxers on on please feel free to flame me all you like.

To my simple and addled mind the original post explains how to trick your car's fuel injection system into thinking the engine temp is higher than it is. In that condition it will stop being in 'rich' (aka 'lets warm this sucker up asap') mode quicker than otherwise and so it won't inject more fuel than is needed.

After this mod your car also won't overheat because, er, the thermostat kind of dictates that and keeps everything cool from that point on. And thats a mechanical thing not really computer controlled because, well, why would a car maker do that when a thermostat is such a cheap, reliable and if not working it is a failsafe device ?

Most car makers (Daewoo and their plastic manifolds excepted) are not that stupid.

Then a couple of people noted that well actually not doing this mod and actually driving your car will also make it warm up quicker, and (gasp) it will detect a warm engine and therefore not be in 'rich' (aka 'lets warm this sucker up asap') mode for very long. Which saves some fuel.

They will probably be OK. Their oil light goes out and they go for it which is probably fine, as long as they have a non-return oil filter (so the oil is not coming all from the sump which takes time, even if the system is pressurised). for most modern engines or where you don't buy a 1 quid oil filter that will be fine.

So why mess with your car's FI system ? Why mess with additives of any form, gas or liquid ?

Petrol doesn't burn. Honest. Its the evaporate of petrol that burns. You have to get it to evaporate to explode it. Compressing works as that heats it up lots and very quickly, which is what an engine does in the 'squeeze' bit. Atomising it into a fine spray also works as it increases the surface area to evaporate which is what the FI system does, or indeed is also what an old carb does. But a big help is warmth. Like a warm engine. Which is why your engine has a 'lets warm this sucker up asap' mode in the first place.

Mind you of course running lean in a petrol engine doesn't have any bad effects at all does it ?

So why do this ? If you mess up your car no longer runs and you end up having to repair or replace an ECU - mega spendy.

If you buy some decent oil and a quality filter (not much spendy each time) you can drive straight away on startup and warm up quicker. Block your grill in winter then you warm up even quicker as well and still don't overheat thanks to that thermostat magic.

AFAIK adding Diesel to a petrol engine makes it cough and smoke a bit until it is gone but no damage. Doing the opposite is bad as petrol of course disolves oil, so it wrecks the diesel pump for a start and costs a fortune to pump it out when your GF uses the wrong pump. Guess how I know

[RobertSmalls]

Carmakers set up the car to do lots of things I don't care for during warmup. My Subaru idled very high and ran very rich (I could smell the HC emissions plainly) to guarantee a warmup without ever stalling or stumbling. The Subaru's programming went overboard with its warmup programming, and an adjustable pot on the dash would be just about perfect for toning it down a little. Or maybe just a resistor on a toggle switch in parallel with the CTS.

The Insight has a different problem. It considers initial coolant temperature and ambient air temperature when deciding whether it's okay to lean burn and auto stop. Well, I want lean burn sooner, so I'll see if I can fool it into allowing that.

[ShadeTreeMech]

As much as I am for modifying a car to take advantage of better fuel economy, I also respect the skill involved in engineering an engine to be as efficient as possible (except Chrysler, which seems to always be 10 years behind. I work on a 1990 Dodge van that has a *gasp* smog pump fitted as stock. WTF!!!)

What is the cost of 1 minute of excessive fuel usage compared to the value of a properly tuned engine? If you're OCD about such things, get a diesel. The gas engine is years behind in sophistication, hence why diesels give better economy. But causing an over lean condition will burn a hole in pistons, and afterwards, your pocketbook. Ask me how I know if you doubt this.