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Old 05-04-2008, 12:26 PM
UT_Tech UT_Tech is offline
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Join Date: Dec 2007
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Possible Bad WUR

This car does not have a computer for the fuel injection and there is no temp sensor on your car which could cause this problem. There is a controller box which uses the O2 sensor to control the "lambda valve". This valve looks like an injector with two hoses on it. The lambda controller is a very dumb bit of analog circuits. The job of the labmda valve is to tweak the air mixture slightly richer or leaner for emissions control. The lambda vave can only move the air/fuel mixture a few percent and a failure in the O2 sensor/lambda system can NOT this cannot cause the engine to run rich enough to get 11MPG.

DO NOT drive the car running this rich. The engine block in your car uses a silicon/aluminum allow which wears out very quickly (a few hundred miles) if the mixture is rich enough to wash down the oil film from the cylinder walls. That happens at about an AFR of 11:1. A mixture that rich would explain 10MPG.

You have to check your control pressure. This is very easy to do with a simple tool. Email me at the office (support@unwiredtools.com) and I would be happy to lend you one at no charge. It takes less than 5 minutes to check control pressure. If the control pressure is less than about 3.2bar when the car is warmed up then your Warmup-Regulator is bad. A bad WUR is very easy to fix, if you fix it before it destroys your engine.

A bad fuel accumulator can cause a WUR to go bad by allowing pressure pulses to propagate through the fuel system. These pressure pulses cause calibrations shifts and metal fatigue failures in the little brass parts inside the WUR. That's generally why rebuilt WURs are not a good option.

The control pressure test I mentioned will also diagnose a bad accumulator.
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Steve S
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UnwiredTools, LLC
www.unwiredtools.com

1982 380SLC
1994 E320TE
1998 E300DT
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