> should the frequency valve buzz non-stop when the engine is running? That's a damn good question, and I'm still not sure of the answer. Mine would run all the time which made me wonder why they even had a Lambda relay which could shut it off. That could be done switched straight off the ignition. The first time I heard one cycling on/off was on Jim Reeve's car at the Memphis show. I have since seen many DeLoreans that do this. When the frequency valve "cycles" it is due to the Lambda ECU switching it off and not due to an intermittent electrical connection. Now that I bought a dwell meter and have used it on a few cars, I have come up with the following theory: DeLoreans are set up such that if the frequency valve is switched off or non-functional then the engine runs lean. The Lambda system monitors the exhaust to determine the optimum duty cycle for the frequency valve so that the engine isn't either too rich or too lean. The effect of a high duty cycle is to make the fuel mixture richer; and inversely, the effect of a low duty cycle is to make the fuel mixture leaner. If the Lambda ECU determines that the engine is running so rich that the frequency valve can't do enough to lean it properly, then it will just shut the valve off completely. The logic behind this is that if a low duty cycle won't lean out the fuel mixture then as a last ditch effort the Lambda ECU will try using no duty cycle at all which is technically an infinitely low duty cycle. Hence the frequency valve cycles off. On a properly running engine, the frequency valve should never have to cycle off. If it does cycle off then the engine is set to run too rich. To make matters more complicated, if you have a vacuum leak then it could be compensated for by mis-adjusting the air/fuel mixture. Now you have two problems that cancel each other out -- vacuum leaks and a dorked with fuel adjustment. This is just a theory guys. Do any of you concur? Am I full of shit? Well, we already know the answer to that last question. ;-) I'm an expert bullshitter. I keep a turd in each pocket. Walt Yahoo! Groups Sponsor ADVERTISEMENT <http://rd.yahoo.com/M=244522.3313099.4604523.1512248/D=egroupweb/S=170512 6215:HM/A=1595055/R=0/*http://ashnin.com/clk/muryutaitakenattogyo?YH=33130 99&yhad=1595055> Click Here! <http://us.adserver.yahoo.com/l?M=244522.3313099.4604523.1512248/D=egroupm ail/S=:HM/A=1595055/rand=649929858> To unsubscribe from this group, send an email to: DMCForum-unsubscribe@xxxxxxxxxxxxxxx Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service <http://docs.yahoo.com/info/terms/> .
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