eratic timing,runs rough,does not excellerate properly,noise from plenum/intake on 2004 Mercury Mountaineer

2004 merc. mountaneer 4.0 v6 93,000miles it was making a rattling noise when accelerating for some time but it went away after getting up to normal speed.didnt alarm me much. 2weeks ago it just started sounding like a diesel(noise is def. coming from or echoing through the plenum)its been using a lot ofgas also i though t sounded out of tme so i checked it and it is bout 19degrees advanced but the timing jumps around does not stay at 1 point put it on the obd2 scanner obd code p0340 ,&p1336 came up whenchecked. i change the cam sensor and chec engine light still cam on but only the p0340 code was present now.so i changed the crankshaft sensor. same code coms up.p0340 i took the plenum and valve covers off to do a visual nspection of timing chains n guide. everything looked fine.put it aall back together and still having same problem. i was told t my need a varition relearn done or pcm updated is this true for my truck? i evn changed the plugs wires oil and filters thnking it may be causing the roughness but nope i am very handy and an usually fix cars but i am at my wits end with my mountaineer..i also esed a volt meter to check th wires going into the cam sensor and it read correctly what could cause th timing to be off? and o jump around so much?

by in Vineland, NJ on January 26, 2011
1 answer 2 comments
ANSWER by on January 26, 2011
replace the dpfe. it is a sensor in the egr side of the system. it is a common issue that fors had issues with in the early years. the dpfe will throw a 340 code before the 401 code it usually sends. i would try this before spending any more money. Roy
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COMMENT by on January 26, 2011
would that cause the timing to be off like that ?? thanks i st looked into the dpfe and my truck doesnt have one seperate from th egr valve . seems to be all in one unit i am assuming nd the parts store as well.. anything else??? egr valve is too exspensive to not know for sure
COMMENT by on January 26, 2011
the timing will vary according to the load of the motor. it will change and move around. it is controleed by the computer. there is no provision for adjustments in todays cars. if the dpfe is not doing its job. the egr will not function correctly and could cause pinging. this would be in a extreme condition. another reson for the pinging is carbon build up around the valves. when you have your car serviced, ask about a 3 step cleaner for the top of the motor. we do it all the time with tune ups and it works very well. Roy