Subject: several possibilities... Author: johnhstein as johnhstein, 85-M6CSi, 85 745i & 84 633CSi (moderator) : member since July, 2004 : 693 posts Posted on: 2004-08-09 09:52:24

And the easiest way to tell is to patch a DVOM to the O2 sensor wire...

If it is pinging and the DVOM reads above +0.5vdc, then you eithor have very poor gas, (somebody is putting the wrong grade in the station tank and charging for the good stuff ...

or...

You have glowing carbon tips causing the pre-ignition...

If the DVOM reads below +0.4 then you are running lean and need to find out why...

Possibilities are:

- Cracks in the intake path alowing unmetered air to the engine (rubber boots cracked, leaky oil filler cap, leaky oil dip stick, broken vac lines... etc..)

- Degraded injector seals allowing air into the intake manifild

- Dirty occluded injectors that need to be removed and professionally flushed / cleaned / calibrated..

Start w/ the DVOM and tell us what you find... The DVOM should flux between +0.4 to +0.6 vdc when fully warmed at cruise. Under full throttle it should jump above +0.5 to about +0.7 to +0.8vdc. (this is ofcourse assuming a new or fresh o2 sensor. If the sensor has more than 50k miles... start this investigation by replacing it. js

Regards

John Stein

• Pinging under load - rogerh 2004-08-08 10:23:38 (2982 views)
  • What model year is your car and what is the mileage? (nt) - DavidC 2004-08-08 21:23:35 (1093 views)
    • Re: What model year is your car and what is the mileage? - rogerh 2004-08-08 22:11:06 (1194 views)
      • several possibilities... - johnhstein, 85-M6CSi, 85 745i & 84 633CSi 2004-08-09 09:52:24 (1301 views)
        • Re: several possibilities... - rogerh 2004-08-23 15:11:56 (1184 views)
          • Next step is to patch in the DVOM and... - johnhstein, 85-M6CSi, 85 745i & 84 633CSi 2004-08-26 07:36:01 (1125 views)