Mechanics

PREIGNITION KNOCK

2002 Ford 500 • 6 cylinder 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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Hopk6344
June 8, 2011.




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

Docfixit
Jun 8, 2011.
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.

Tiny
Hopk6344
Jun 8, 2011.
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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Tiny
Hopk6344
Jun 8, 2011.
That just means flow of vacuum not exhaust gas into intake

Docfixit
Jun 8, 2011.
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

Tiny
CJ MEDEVAC
Jun 8, 2011.
Could also be the knock sensor not retarding the timing when engine is detonating or engine is overheating and type of fuel use

Rasmataz
Jun 8, 2011.
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

Docfixit
Jun 8, 2011.
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?

Tiny
Hopk6344
Jun 13, 2011.
The timing chain/belt (whatever it uses) and the sprocket was replaced 30 thousand miles ago. (About 3 years ago).

Tiny
Hopk6344
Jun 13, 2011.
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?

Tiny
Hopk6344
Jun 13, 2011.

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