A question for the electronic gurus

Submitted: Friday, Mar 18, 2005 at 16:03
ThreadID: 21322 Views:1778 Replies:5 FollowUps:0
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Hi all
I am wanting to check some vital engine components with my multimeter (o2 sensor, air flow etc). The manual states what the expected resistance should be. How can I verify the accuracy of my multimeter, short of buying a resistor or something from DSE to check? Or perhaps this is the solution?! I have asked a workmate to borrow his Fluke multimeter as a reference, but then how do you check the accuracy of his?
I've reason to believe my second vehicle (RB30e engined Skyline) has some engine issues, and am sure that due to its very high mileage that it is a critical sensor as opposed to my pretty good servicing record.
Thanks in advance
Chris
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Reply By: hl - Friday, Mar 18, 2005 at 17:44

Friday, Mar 18, 2005 at 17:44
Hi,

You can't check the oxygen sensor with a multimeter properly. You can get some idea by putting a high impedance analog meter on it while the engine is running, the voltage will be quite low, but the important thing is it should vary between zero and whatever it is about 6 to 10 times in ten seconds.
A stuffed oxygen sensor actually has not a great effect on engine performance. It might idle a bit rough, but that is all.
As for the airflow meter, if it is the bosch as used in the VL commodore, you can see the wire in it glow briefly when you turn the ignition on or off. If it does that, it is probably ok.

Cheers

AnswerID: 102948

Reply By: Mike Harding - Friday, Mar 18, 2005 at 17:46

Friday, Mar 18, 2005 at 17:46
If you have a Fluke meter then for your application I wouldn't worry about it's accuracy providing it reads less than 0.5R when you short the probes and open circuit when they are open circuit it will be well good enough for your requirements.

The oxygen sensor is a consumable item - I cannot remember their expected life but it _should_ be replaced at some point, a Google search will indicate when. I'd be a bit doubtful of the value of a simple resistance reading to tell me the health of an O2 sensor - they are a pretty complex bit of engineering.

Mike Harding
AnswerID: 102951

Reply By: Member - Bradley- Friday, Mar 18, 2005 at 18:11

Friday, Mar 18, 2005 at 18:11
running rich is it? using more fuel than it should be ? Very common for the air flow meter on the rb30 skyline / vl to go bad, get an exchange unit from an injection supplier. They also suffer badly from water in the electronic connectors etc.
AnswerID: 102956

Reply By: lazylcd - Sunday, Mar 20, 2005 at 01:15

Sunday, Mar 20, 2005 at 01:15
hi chris
ask the hairy 1 with the 75 series :oD.

hows the disco going eddy??

Leighton
AnswerID: 103136

Reply By: Sand Man (SA) - Monday, Mar 21, 2005 at 11:06

Monday, Mar 21, 2005 at 11:06
With the multimeter on the resistance setting, short the probes together. The meter should read zero. Any resistance you then measure will be accurate enough for your needs.
Most analogue multimeters have an adjustable wheel to zero the scale when shorted out, but a digital multimeter doesn't (shouldn't) require it.

Bill


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AnswerID: 103266

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