cis issues/clicking relays
 

Hello all,
I posted about a week ago about my rough idle issues ('81 911SC). I replaced the fuel pump relay, fuel pump fuse, and the interior light fuse. The car fired up fine but now have a very slight rough idle and clicking O2 sensor relay only at idle. The relay does not click under acceleration.
I replacd the O2 sensor relay and the car fired up fine and warmed up w/ no idle issues. Went for a spin and I noticed that the O2 relay and the fuel pump relay are clicking only at idle and not while I'm accelerating. Now after that quick spin I notice a rough idle and clicking relays.
Also the new thing that I noticed is when I turned on the headlights, I noticed that the engine seemed to bogg and the rough idle became worse. I stepped on the accelarator and the issues were gone (relay clicks and rough idle).
Any suggestions? I am planning on checking the battery connections. But I thought I'd ask for any other things to check for as well. I read some other posts about the rev-limiter relay and proper grounding straps, and possibly a faulty CDI. Thanks for any help and suggestions. :)

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what are the voltage measurements at the battery at idle and at higher rpm with the lights and heater blower on ?

Unfortunately I haven't gotten that far as to checking. These observations were from last night. Any ideas you might have without the voltage values? Thanks.

well.. I was just suspecting a voltage issue. The first place to start would be the battery. If ok then I would tap into the relay hot trigger wire and see what's happening. Then the relay ground.

Ok RoninLB bear w/me because I'm new to this. Where is the relay hot trigger located and where is the relay ground. Thanks.

check a wiring diagram for relay operation. Also some relays don't operate like the routine. If you don't have one, get one. Actually buy every auto elec repair and explain book you can. Stop at a local speed shop for their elec books. Maybe $20ea will get you started.

http://forums.pelicanparts.com/uploa...1109280886.jpg

Bumping this thread because i have the exact same issue.

Was this ever resolved? From my searches it doesn't seem like many others have this problem.


Cortney

The fuel pump relay ‘chattering’ at idle can be caused by the air metering plate not being adjusted properly or the air box is cracked.

Johnny thanks for the reply. Following up here for posterity - I ended up re-setting my ignition timing advance and that took care of it. Not sure why improper ignition advance would cause relays to click on & off but resetting it solved the problem for me.

I also likely have air/vacuum leaks somewhere, but I’m planning to do a CIS teardown and rebuild next weekend so we’ll see.