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Engine 04 V6 Missing And Backfires

  • Thread starter Thread starter Smooth 04
  • Start date Start date Oct 1, 2017
S

Smooth 04

New Member
Oct 1, 2017
4
0
1
Oct 1, 2017
#1
  • Oct 1, 2017
  • #1
Looking for tips to solve this issue.
My 04 V6 has a severe miss and backfire, Has New plug wires, coil and plugs and also replaced the cam position sensor
Not seeing any codes as of now. Any help would be great!!
 

wmburns

SN Certified Technician
Aug 14, 2009
5,892
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Houston Texas
Oct 1, 2017
#2
  • Oct 1, 2017
  • #2
Without a doubt the FIRST test that should have been done is to check the alternator for excessive AC ripple (bad diode). Why? Because a bad alternator diode can "cause" a false bad cam sensor signal.

Here's some more information that may help.

Howto perform charging system voltage drop test
https://www.stangnet.com/mustang-fo...perform-charging-system-voltage-drop-test.56/

Then go back to trouble shooting the miss fire.
 
S

Smooth 04

New Member
Oct 1, 2017
4
0
1
Oct 1, 2017
#3
  • Oct 1, 2017
  • #3
Thanks, The alternator checks out fine, I double checked the firing by connecting a spare plug to each wire and its getting a good spark from each wire. # 5 plug is staying wet with fuel could I possibly be looking at an enjector problem?? Car ran perfectly then after sitting for an hour cranked it up to find the engine missing at all rpm ranges. Also disconnected MAS but no change. Compression checks are good and no vacuum leaks.
 

wmburns

SN Certified Technician
Aug 14, 2009
5,892
514
204
Houston Texas
Oct 1, 2017
#4
  • Oct 1, 2017
  • #4
Sooooooooooo. IF #5 is wet with fuel THEN there has to be no combustion in #5. What could cause this condition?:
  • There must be no spark or
  • There's no compression or
  • The spark is out of time.
I'm a big believer in Occam's razor.

https://en.wikipedia.org/wiki/Occam's_razor

If we follow Occam's Razor what is one simple possible solution to explain your symptoms? Something were the spark is good, Compression is good, there's fuel but in spite of all that there's still a misfire?

How about incorrect spark plug routing? Such that the spark plug wires are routed to the wrong cylinders. This will give a spark but at the wrong time.

V6 coil pack diagram
http://www.allfordmustangs.com/foru...king-rough-idling-injectors-next.html#2951811
 
S

Smooth 04

New Member
Oct 1, 2017
4
0
1
Oct 1, 2017
#5
  • Oct 1, 2017
  • #5
Wires are routed correctly, Being there is spark and good compression looks like I will be checking on the timing next
 

wmburns

SN Certified Technician
Aug 14, 2009
5,892
514
204
Houston Texas
Oct 1, 2017
#6
  • Oct 1, 2017
  • #6
Tell us HOW the cam sensor was installed and set up. I could see a case where IF the #1 were on TDC of the exhaust stroke instead of the compression stroke it could make the fuel injectors fire when the valves are closed.
 
S

Smooth 04

New Member
Oct 1, 2017
4
0
1
Oct 2, 2017
#7
  • Oct 2, 2017
  • #7
Update
Thanks for the tech tips but after digging in to it deeper we found that the timing chain had in fact jumped about 2 teeth causing the issue. After a long afternoon replaced gears and chain and it's now running like a champ..
 
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