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Re: Is cleaning injectors easy, or worth it? (archive)
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Posted by Clyde on October 28, 2001 at 22:44:01:

In Reply to: Is cleaning injectors easy, or worth it? posted by Stew on October 28, 2001 at 20:10:34:


My 87 535 is having problems with NOx emissions and appears to run slightly lean. All rubber induction and vacuum hoses have been replaced as well as the fuel pressure regulator. I replaced the catalytic converter and oxygen sensor and am still high on NOx. I've run about 4 bottles of TechRon through in the last year. About the only items left to inspect and/or repair are the injectors and injector O-rings.

Are these easy to remove after 170,000 miles? If I can remove them, is there a preferred method or fluid for cleaning them? For varnished carburetors, I've always soaked them in Chem-Dip (gallon can with strainer included) with good results. Is this fluid OK or will it damage them?

I can get new injectors for $50 each at BavAuto. Is it worth trying to clean them or should I just get new ones?

Any thoughts or past experience?

Thanks.


Your NOx issue is troubling, because the catalytic converter is the one and only NOx control element on this car. Replacing it should reduce your NOx to very low levels. The converter should be a "three-way" catalyst element, capable of reducing nitrogen oxides to nitrogen. The DEC and OEM units are of this type,

As for injector cleaning, that's a matter of choice and budget. 170,000 miles is a lot of service. If you have them reconditioned, you're still left with the original case, pintles, and coils.

As for the oxygen sensor, have you checked for voltage swinging briskly between roughly 0.2 and 0.8 V? Pull back the boot on the spade connector near the rear of the engine, and connect the positive side of a DVM to it; the negative goes to chassis or the negative battery terminal. Car should be fully warmed up, and run it at 1500 to 2000 rpm. You want to see the voltage cycling 1 to 2 times a second. If your car is really running lean, the sensor will be "stuck" below 0.3V.

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