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94 S420 RIP 2/8/13 02 ML55AMG, 06 CLS55AMG, 89 Mas. 228, 84 Por. 911 Carrera, 93 Toyota t.t. Supra
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1,582 Posts
Discussion Starter #1
I have been beating my head against the wall for 2 months with the ignition system in my S420. I was on the highway coming home at about 2200 rpm. It was running perfectly and suddenly lost power. Got it home ran the check and it threw one code 7 ignition system failure. So I changed everything wires, plugs, coils, rotors, caps and still does he same thing and and after clearing it throws the same code. I have already changed the wiring harness. I'm at a loss here and I noticed an inconsistency. The rotor on the driver side distributor is tight, no play. The rotor on the passenger side has play in it and is moving from side to side approximately 5 degrees (approx. 1/4 inch). Could this be the source of the problem? Please help guys I'm in the backwoods of Pennsylvania and this is killing me. I love driving this car and suffering withdrawal.
 

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1995 S500 coupe, 1990 Mazda Miata
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694 Posts
Sounds like the rotor mount on that side is loose? When you take the rotor off, there is a 6mm allen head bolt holding the mount on. Here is a good thread with pictures about it. Hopefully that's all it is and not that the cam pulley (the piece the rotor mount bolts to) is loose as that would be a lot more involved.
 

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Premium Member
1997 S600 (sold)
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4,660 Posts
I have been beating my head against the wall for 2 months with the ignition system in my S420. I was on the highway coming home at about 2200 rpm. It was running perfectly and suddenly lost power. Got it home ran the check and it threw one code 7 ignition system failure. So I changed everything wires, plugs, coils, rotors, caps and still does he same thing and and after clearing it throws the same code. I have already changed the wiring harness. I'm at a loss here and I noticed an inconsistency. The rotor on the driver side distributor is tight, no play. The rotor on the passenger side has play in it and is moving from side to side approximately 5 degrees (approx. 1/4 inch). Could this be the source of the problem? Please help guys I'm in the backwoods of Pennsylvania and this is killing me. I love driving this car and suffering withdrawal.
Tighten up the rotor and see what happens. Does the car start and run at all now?

Brett
 

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Registered
94 S420 RIP 2/8/13 02 ML55AMG, 06 CLS55AMG, 89 Mas. 228, 84 Por. 911 Carrera, 93 Toyota t.t. Supra
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1,582 Posts
Discussion Starter #4
Yes it does start and runs but sounds like one side is out of timing. The rotor is going to be removed again and then I will check for the lose rotor mount. Thanks for the info. I was almost ready to roll back it to the dealer 55 miles away (it is the closest one). Will keep you posted.
 

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94 S420 RIP 2/8/13 02 ML55AMG, 06 CLS55AMG, 89 Mas. 228, 84 Por. 911 Carrera, 93 Toyota t.t. Supra
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1,582 Posts
Discussion Starter #5
95Scoupe you were correct! I gave up trying to remove the rotor and cracked it out with a screwdriver. The rotor mount was loose enough that I removed it with my fingers. Fortunately I purchased another rotor mount because the old rotor mount was actually ovalled out from being loose. Problem is the cam pin that locates the rotor mount is bent which is why it's oval led out. Any ideas on repair? Ideally removing the old pin and replacing it with new would be the correct way to effect the repairs. Any suggestions would be helpful.
 
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