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Fuel economy display readings WAY UP!?!?

Sierraface

By Sierraface
in Ask A GM Technician

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Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

That doesn't seem that far off - maybe 2" or so. If you're at a high elevation, then that's perfectly normal.

 

Also, if your air filter is plugged up, that will skew the BARO reading, since airflow is restricted.

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

No problem, man. Hope you get her straightened out.  :cheers:

Sierraface Enthusiast

Sierraface

Posted
  • Author
Posted

So now I'm thinking I have a small vacuum leak in my brake booster somewhere thats causing that small leak into to the engine which would also explain why I had to top up on brake fluid awhile ago. I also had seen a stain just below and blamed it on a little engine oil i spilled haha.

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

Fluid won't get into the booster, unless the master cylinder is leaking. Some times though, a leaky booster is the result of a leaking master - the brake fluid wrinkles & dries out the rubber diaphragm over time.

  • 1 month later...
Sierraface Enthusiast

Sierraface

Posted
  • Author
Posted

Haha maybe that was just an oil stain afterall then. Brake fluid refill remains a mystery to me. So its been awhile since i had time to look at this issue more but here it is...after connecting the code reader again i noticed the EVAP symbol is red opposed to all the others are green. Just doing some research and the EVAP system works off a vacuum from the manifold. Found my EVAP purge valve and decided to test a couple things. I removed it and blew into it, no air passage. I connected the wire connector, turned the key on to send current through it and tried sending air through it, still no air passage. Shouldn't that have opened for purge mode? I tested the wires with the meter, signal to engine ground strap was 12.2v but wire to wire was 9v. Seems as though the purge valve isnt getting enough voltage to trigger it open. Im also wondering if or how this relates to my small vacuum leak issue. Or how these signals talk to each other and convince my long term oxygen trims make it seem like there is a vacuum leak which in turn tells the computer to spit out more fuel to consume. Anyone? I also found a coolant leak from a hose crimp connection while looking around. Frig!

tbarn Senior Enthusiast

tbarn

Posted
Posted

The purge solenoid is pulse width modulated. Not " on or off".

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