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1984 380se
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12 Posts
Discussion Starter #1 (Edited)
Hello, The cars frequency valve is inop. but the valve is ok, I tested it with an injector tester and it buzzes, there is power on one side but nothing on the other, I suspect it gets a freqency modulated ground signal from the ecm, I had an extra ecm and tried it to no effect, I jumped the overload relay pins 87 and 30 no effect. I disconnected the 02 sensor no effect. I played around with the co adjustment no help.
Any ideas? Pat:crybaby2:
 

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Registered
1984 380se
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12 Posts
Discussion Starter #2 (Edited)
I forgot to mention control fuel pressure is good, warm up regulator functions, and rest pressure is good. Car starts fine, just runs to rich, no freq. valve operation.
 

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Registered
'84 500 SEC Euro 040 black Lorinser 2005 sl500
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2,516 Posts
Is it a euro 380 with an aftermarket frequency valve and lambda computer or is it a US (NAM) model with hard fuel lines to the frequency valve and everything stock from the factory?

If it is a euro import it is probable that there is a direct ground to the battery or passenger fender well from the added on lambda brain in the foot well. The ground wire is often thought to be some added on phone system wiring or audio add on and gets mistakenly removed from either the battery ground or fender well ground point.

If it is a US 380 I am not that familiar with the stock lamda system.
 

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Registered
1984 380se
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12 Posts
Discussion Starter #4 (Edited)
It's a US model everything is stock. I read somewhere that the oil temp. sensor somehow controls the frequency valve, not sure how to test it, where it is, or if it really has anything to do with this? I also thought the frequency valve should be buzzing key on engine off or running.
Need some help. Pat
 

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Registered
1984 380se
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12 Posts
Discussion Starter #5 (Edited)
I know this is an oldie, I'm just not sure if the freq. valve should run, key on engine off and engine running. That would really help. Anyone out there remember how this system works? I have read all the post's about this and still don't know. I am a Master tech. and have all equipment to test this, just not factory stuff.
BTW, I looked at the online service manual, and it still doesn't mention anything about the operation of the freq. valve other than the 50%duty cycle. I have this disk set but my system is 64bit windows and the disks don't work. Nice to see it online WOW!
Any help would be greatfull, Pat
 

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Moderator
1991 500SEC 55K mi. 1987 560SEC Now 153K mi. 2020
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4,532 Posts
Hi there PGM,

RE " freq. valve should run, key on engine off and engine running " I have never heard a frequency valve run engine OFF Key ON... I would only expect it to operate with engine running, maintaining the fuel pressure.. dumping excess back to the tank according to oxygen sensor readings and other conditions.. I know my answer simplistic... Its been a long time since I really worked on those things daily.

Cheers good luck man,

MBL

I PMed earlier as well..
 

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