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Error code- lean condition

I posted this under another thread, but here it is again.

Vehicle: '96 Ford Windstar, 3.8l

I had a coolant leak on the lower intake gasket into cylinder #4 (rear bank). The starting problems have gone away since I changed gasket.

However, I'm getting error codes indicating a lean condition. Most often on bank 1, but often on both banks. These happen while it's warming. My handheld code reader shows the O2 sensor not ready when these codes are registering, so how can it know it's too lean?

With the way the gaskets are built, it's virtually impossible to create an intake problem. I've checked all the vacuum hoses & everything is hooked up. I'm about ready to replace the O2 sensors, since the van is close to 100k miles anyway.

I didn't get any error codes before replacing the gasket. Is it possible that the O2 sensor was gummed by the burning coolant? Maybe it was used to the coolant before, & has an issue now that it's not there? Grasping at straws.

-Jeff Deeney-

Reply to
Jeff Deeney
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A properly operating O2 sensor will vary between slightly rich and slightly lean as the mixture is being constantly corrected. A bad O2 sensor will read either always rich or always lean.

An O2 sensor can go bad because of excessive heat (from a clogged exhaust), antifreeze, continuous rich mixture, or by some accounts, gasket sealer, or just bad luck.

Reply to
Mike Walsh

slightly lean as the mixture is being constantly corrected. A bad O2 sensor will read either always rich or always lean.

This seems very intermittant. Like a glitch. By reading too lean, it would appear that it's trying maximum fuel to correct the situation, but is unsuccessful.

exhaust), antifreeze, continuous rich mixture, or by some accounts, gasket sealer, or just bad luck.

You left out pixies & demonic possession. :-)

I'm guessing antifreeze buggered the O2 sensors. I need to verify that I don't have a head gasket leak before I buy new sensors. I'll borrow a kit to measure the radiator gases to make this determination. I'd hate to drop $90 on new O2 sensors only to foul them again.

Thanks for the thoughts.

-Jeff Deeney-

Reply to
Jeff Deeney

Reply to
Mike Walsh

The O2 sensor diagnostic "Not Ready" on the scan tool probably just indicates that the diagnostic didn't pass.

At that mileage, new O2 sensors would not be a terrible idea, but it's uncertain if that's the cause - you'd think you'd get a code for O2 sensor slow response or something if that were the case, and I think that silica contamination usually causes a rich indication, not lean. Does your scan tool display the actual current fuel trim values?

Reply to
Robert Hancock

Doh! Just got to looking *real* close at things. I knew, but didn't thoroughly believe Murfy's law #62:

"99% of the time, new problems that occur after you work on something were due to you buggering something else in the process".

Looking at the o-rings between the upper & lower intake manifolds there appeared to be a gap. Sure enough, I can slip a feeler gage in there.

When I pulled the upper manifold, I had a number of the rubber-steel bolt spacers fall out when I turned it over. They looked the same, but now I know some of them are different lengths. I must have not put them back in the right spot. Should be a 30 minute fix.

Wouldn't you know, I just sunk $90 into new front & rear O2 sensors, only to find out I'm still getting the same error. The rear O2 was pretty green from the previous intake manifold coolant leak, so it probably needed replacing anyway. May as well replace in pairs. It will probably improve the mileage that has been steadily declining.

-Jeff Deeney-

Reply to
Jeff Deeney

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