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  • SN95 4.6L Mustang Tech

Cam Change now Bizarre Noise

  • Thread starter Thread starter rcilurso
  • Start date Start date Feb 9, 2004
R

rcilurso

New Member
Jan 2, 2004
19
0
0
Feb 9, 2004
#1
  • Feb 9, 2004
  • #1
Put Comp Cams and springs in my 04 GT before the blower install. Broke them in and a strange "diesel like" noise was coming from the motor after about 15 minutes almost as if it was the valves themselves. I know, I know it's tough to get any trouble shooting done on line but bare with me Looked in the cylinders for contact... none. Inspected plugs, very lean. Took timing cover off, car still in time, redid timing anyway. Put the car back together and started it up... no noise. Great! Ran it for 4 minutes tops. Went on 2 week trip. Started car warmed it up and noise is there again only not as loud. If I disconnect the battery it is not there for a good few minutes then comes on and gets louder. Noise is in both the intake runners and the exhaust manifolds primarily. Sounds just like a diesel motor. Car idles fine then gets pretty rough, shaking on the motor mounts then smooths out again. Hardly ever stalls. Noise is present at idle all the way up to around 2000 when it almost completely goes away or my x pipe is so damn loud I just can't hear any more. I'm pretty sure it goes away. On the street the car is just plain flat all the way to 4000 then it takes off. Shift and it goes flat again. Cams are not too wild, blower grinds, no big deal. Can not find a mechanical fault.

My thought is that the computer my be trying to compensate for the cams. It is leaning it out and pulling timing perhaps causing a detonation type issue which may explain the dieseling. Car runs pretty smooth off idle and I checked timing 3 times... not the problem. It will get a custom tune with the blower but I'm worried I'll have to take the whole thing apart again to fix something before I can add boost. But, having said that, I can't imagaine what it could be if it's not fuel/timing.

Cams are something like 238/242 .550 .550
Comp recommended behive springs

Any thoughts?
 
M

matsm21

New Member
Sep 5, 2003
241
0
0
Long Island
Feb 9, 2004
#2
  • Feb 9, 2004
  • #2
might be the computor. other then that.....?? try calling a good shop and asking them.
 

lopey4.6

20+ Year Stangneter
Jan 4, 2004
309
0
16
Westlake,OH
Feb 9, 2004
#3
  • Feb 9, 2004
  • #3
Well I hope that diesel like noise is not detonation. I would get to a tuner and see what they say.
 

Sam98

Founding Member
Mar 15, 2002
1,625
1
0
Albuquerque, NM
Feb 9, 2004
#4
  • Feb 9, 2004
  • #4
You may just need to get it tuned now that you have the new cams. I had to retune mine quite a bit when I installed the PI cams. You have made a much more radical change, and you will probably have to compensate for it in the PCM.
 
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