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Mixture range of stock Zetec?

B

bcubed

CEG'er
Joined
Dec 30, 2007
Messages
32
I can't help it...part of my inquisitive nature is to screw around with things that work just fine on their own.

To that end, I'm interested to see if my '98, Zetec-equipped Contour can be run on substantially more Ethanol than the 10% in the Owner's manual.

This comes down to two things: corrosion/deterioration resistance and mixture range in the stock engine control module. Since ethanol requires a 9:1 mixture ratio (gasoline is 14.7:1), the richer the car can run in open-loop mode, the greater the max ethanol %.

Anyone out there know 1. closed-loop starting mixture? 2. richest open-loop mixture? Failing this info, I'll just start with 1gal E85 with the first tank, and up it 0.5 gal/tank until I pop a code or notice drivability issues.
 
BoSoxBruin said:
And why would you want to do this, your MPG will go down :confused:
Click to expand...

Well, as I can get my hands on 200-proof for $2/gal, I can take a considerable mileage hit and still come out on top.

From the other post, the valve issue intrigues me. The lead issue was due to lead salts acting as a type of lubricant for the valves. For ethanol, either there's some sort of heavy HC in gasoline acting as a lubricant, or cylinder head temps are higher on ethanol, or perhaps soot is protecting the exhaust valves in the same way that lead used to (ethanol might burn "too clean.")

Since my '98 was built at a time in which auto companies knew a mandated increase in ethanol was a real possibility, there has to be SOME leeway engineered in. I'm guessing up to E30 is fairly safe, though I'll stick a second fuel filter in-line in the eng. compt. and tear it open after 1K mi or so and look for rubber detrius.
 
Is your 98 return style or returnless?

If it's return style, then you could just keep bumping up the fuel pressure as it leans out.

The problem that I think you will run into is a lean situation. Because you need more E-85 and normal gas, the stock PCM can only richen it up to a certain point. You may be able to run up to E50 on a stock system just by bumping your stock pressure from 40psi to the 60-65 range. You will need an aftermarket pump to pull that one off though.

Smart money would also be to put an EGT on cyl4. That way you can monitor the temps on the cylinder that is likely to show problems first. That and watch your plugs like a hawk. Our hyper pistons don't like deto.

IIRC, I think you will throw a CEL if your LTFT is over/under 15%. (Long Term Fuel Trim) You should also get a decent OBD-2 scanner to monitor things. The Scangauge is pretty slick.

HTH,
BP
 
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To do this properly and not half-a$$ed, you really need bigger injectors...

Otherwise you're just asking to pop your engine from lean detonation.
 
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