PREIGNITION KNOCK

  • Tiny
  • hopk6344
  • 2002 Ford 500
  • 6 CYL
  • 2WD
  • automatic
  • 11,000,000 miles

I have 2002 ford windstar with the large v6 (vulcan) and I noticed that it has recently started pinging or knocking under acceleration. It does it when the engine is hot, not when it is cold. The problem occurs under light to moderate acceleration or just after the automatic transmission shifts. I've taken it to a diagnostic center and they have checked the EGR valve and associated systems, polled the computer for error codes (none found). I have no check engine lights or other warning lights.

Their best guesse was bad gas. I've changed brand/gas station and have run a half tank of premium through it and while the knock has diminished, it is still there. What could be causing this problem?

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Wednesday, June 8th, 2011 AT 3:24 PM

14 Replies

  • Tiny
  • Docfixit
  • Expert
  • 18,991 posts

Suspect EGR the operation system may have checked out but passage ways maybe blocked with carbon. Need to remove EGR inspect and clean. EGR must operate or knock will occur

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Wednesday, June 8th, 2011 AT 4:00 PM
  • Tiny
  • hopk6344
  • Member

I will double-check, but I think they took the egr valve off and checked the passage ways to make sure they were unobstructed. I remember the tech saying that could be a problem when I dropped the van off for diagnostics.

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Wednesday, June 8th, 2011 AT 4:03 PM
  • Tiny
  • hopk6344
  • Member

I just checked with the tech - they did NOT do a physical inspection of the passages. They pulled the sensor data and the flow sensor showed full flow - indicates no obstruction.

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Wednesday, June 8th, 2011 AT 4:08 PM
  • Tiny
  • Docfixit
  • Expert
  • 18,991 posts

That just means flow of vacuum not exhaust gas into intake

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Wednesday, June 8th, 2011 AT 4:40 PM
  • Tiny
  • CJ MEDEVAC
  • Expert
  • 9,225 posts

DOC,

COULD TIMING, OR SLOP IN THE TIMING HAVE THE SAME AFFECT?

I FEEL SURE ON THIS RIG, "ADVANCE" IS ELECTRICALLY CONTROLLED, NOT VACUUM---PRONE TO NON-WORKING MECHANICAL PARTS, LIKE IN OLDER VEHICLES.

THE MEDIC

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Wednesday, June 8th, 2011 AT 5:34 PM
  • Tiny
  • rasmataz
  • Member

Could also be the knock sensor not retarding the timing when engine is detonating or engine is overheating and type of fuel use

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Wednesday, June 8th, 2011 AT 5:45 PM
  • Tiny
  • Docfixit
  • Expert
  • 18,991 posts

Found Technical Service Bullitin REF> 04-19-2 that is a reflash for PCM to adjust Octane to control knock. Bummer is dealer would have to do

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Wednesday, June 8th, 2011 AT 5:45 PM
  • Tiny
  • hopk6344
  • Member

Well, my mechanic flushed the fuel injectors and the combustion chamber to remove carbon, still getting the preignition. Next on the list is to do a physical inspection of the EGR ventilation passageways. Also, found out that this year of ford does not have a knock sensor. If this doesn't work, what would you recommend?

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Monday, June 13th, 2011 AT 5:51 PM
  • Tiny
  • hopk6344
  • Member

The timing chain/belt (whatever it uses) and the sprocket was replaced 30 thousand miles ago. (About 3 years ago).

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Monday, June 13th, 2011 AT 5:53 PM
  • Tiny
  • hopk6344
  • Member

Mechanic said the ventilation passages were clear, but found a problem with the EGR control solenoid. Could this be causing the problem? Also, wouldn't that cause an error code on the computer?

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Monday, June 13th, 2011 AT 9:45 PM

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