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My 308 is too lean

Discussion in 'Technical Q&A' started by kdross, Dec 16, 2003.

  1. kdross

    kdross Formula Junior
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    Feb 10, 2002
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    Ken
    I have a 308QV that I think is running too lean. How do I verify this? Also, how do I increase the fuel mixture so that the engine is not running so lean?

    Thanks.
    Ken
     
  2. rexrcr

    rexrcr Formula 3

    Nov 27, 2002
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    Rob Schermerhorn
    Search the old and new archives, you'll come up with very detailed information. You're likely to get 30+ hits.

    Search parameters: 308 jetting Weber carburetor

    We recently discussed A/F ratio and data acquisition methods. Philip is installing an aftermarket wide-band oxygen sensor system in his 308 now.

    Best regards,

    Rob Schermerhorn
     
  3. f355spider

    f355spider F1 World Champ
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    May 29, 2001
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    Hugh G. Rection
    Ken,
    You have to take it to a shop with an exhaust analyzer, and they put the "sniffer" in the CO ports in the exhaust manifold (see all those tubes with the nuts capping them off?). This way you can read it before it hits the cat. Really not a DIYer procedure without the machine. There are a number of threads on this in the old F-chat site, and a couple recently here too. You might do a search...

    Dave
     
  4. snj5

    snj5 F1 World Champ

    Feb 22, 2003
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    Russ Turner
    kdross
    A stock US 308 qv has a k-jetronic injection, and mixture is set by an exhaust sniffer as Dave says. These are available at most shops, and the FI can be set by the CO number I believe, which sets the richness. Many Porsches, Volvos and VWs use Kjet as well and will use the similar settings if you need a start on where to look.
    good luck
    rt
     
  5. kdross

    kdross Formula Junior
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    Feb 10, 2002
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    Ken
    Thanks guys. My car has a hollowed out cat, so I am assuming that I can just read the exhaust coming out of the muffler. I will have the car in the shop after the holidays, but I was wondering if I could do this myself. I guess not.

    Dave: I got my new radiator cap, thermostat, and fan switch from Algar. I purchased a stock thermostat, but took your advice and got a lower temp fan switch. Thanks for the info.

    Ken
     
  6. Steve Magnusson

    Steve Magnusson F1 World Champ
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    Jan 11, 2001
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    Steve Magnusson
    Ken -- Since your '85QV is a K-Jetronic with Lambda Sensor, if you make a (warm-idling) DC voltage measurement of the Lambda (O2) Sensor output (which would be measuring the voltage between the single wire coming from the O2 sensor and the chassis ground) I think you could learn a great deal about the overall health or unhealth of your system (even if you wouldn't DIY the solution yourself).
    If it's quasi-working, the O2 sensor voltage output should be banging around between ~0.1V and ~0.9V (during warm idle) -- anything else and you know you've got a problem to investigate further. Just thought I'd suggest as a first look...

    edit after seeing your previous post -- Do you have an active O2 sensor in place?
     
  7. kdross

    kdross Formula Junior
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    Steve:

    Yes, my O2 sensor and thermocoupler are still in place and working. Only the cat is hollowed out. The rest of the system is stock as far as I know.

    Ken
     
  8. Steve Magnusson

    Steve Magnusson F1 World Champ
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    Steve Magnusson
    Then its output should still be meaningful as described below.
     
  9. parkerfe

    parkerfe F1 World Champ

    Sep 4, 2001
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    Franklin E. Parker
    A high protein diet and a workout program will bulk her up some.
     

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