Wierd cylinder miss issue
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Newbie
Joined: Apr 2010
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1990 300e
Wierd cylinder miss issue
Hey guys (and girls), been referred here several times on other issues so thought I would register and get some help from you guru's.
I just bought a 1990 300e. The engine had a miss when I bought it. I immediately changed the oil, spark plugs (platinum 4+, gapless) and spark plug wires. I have also ran 2 cans of 'sea foam' through the injectors.
Problem. The car is hard to start 'cold'. If you depress the accelerator it will fire up and run 'chunky' till warm. The 6th cylinder (farthest from the distributor cap) still misses, even after new plugs and wires. If you take the wire and pull it off the spark plug and then just touch it to the top of the spark plug the miss goes away. It will continue to run perfect until you shut off motor or hit a bump.
I removed the new spark plug and it has oil residue (or burn).
Anyone ever have this problem? And if so, how do I fix this miss?
Because of the miss, the A/C compressor will not stay on. I am positive this is because of the speed sensor when engine bears down when a/c is turned on. The a/c runs perfect if you hold the rpms at 1000.
Anyway, I am interested in any help you can give. Thanks!
FW
PS I have checked the OVP and the fuse is in good condition and no rattling noises. The engine does not stall, just hard to start and miss. I don't want to have to open the hood and fidget with a spark plug wire every time I drive the car!
I just bought a 1990 300e. The engine had a miss when I bought it. I immediately changed the oil, spark plugs (platinum 4+, gapless) and spark plug wires. I have also ran 2 cans of 'sea foam' through the injectors.
Problem. The car is hard to start 'cold'. If you depress the accelerator it will fire up and run 'chunky' till warm. The 6th cylinder (farthest from the distributor cap) still misses, even after new plugs and wires. If you take the wire and pull it off the spark plug and then just touch it to the top of the spark plug the miss goes away. It will continue to run perfect until you shut off motor or hit a bump.
I removed the new spark plug and it has oil residue (or burn).
Anyone ever have this problem? And if so, how do I fix this miss?
Because of the miss, the A/C compressor will not stay on. I am positive this is because of the speed sensor when engine bears down when a/c is turned on. The a/c runs perfect if you hold the rpms at 1000.
Anyway, I am interested in any help you can give. Thanks!
FW
PS I have checked the OVP and the fuse is in good condition and no rattling noises. The engine does not stall, just hard to start and miss. I don't want to have to open the hood and fidget with a spark plug wire every time I drive the car!
Last edited by f.wittman; Apr 23, 2010 at 01:53 PM.
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Joined: Apr 2007
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E
If there is oil on the plug then your valve stem seals are toast. A very common problem. If you are handy, the job can be done with a valve spring compressor in a couple hours without removing the head. Do all of them.
Also those spark plugs are incorrect for this engine. You want non-resistor type.
Welcome to the forums!
Also those spark plugs are incorrect for this engine. You want non-resistor type.
Welcome to the forums!
Thread Starter
Newbie
Joined: Apr 2010
Posts: 2
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1990 300e
Hey ps2cho, thanks for the reply.
When I took out the spark plug and looked at the fouling material, it wasn't oil. I also had to add transmission fluid after about 2 weeks after a fluid change.
Further investigation led me to the Transmission Modulator.
The transmission modulator has a vacuum attachment that is located, DIRECTLY across from the cylinder that was missing.
Long story short, the modulator was bad ($49 from a local parts store) and was allowing the vacuum to suck transmission fluid into the manifold. Changed modulator, drove it for a day and cylinder now hits.
When I took out the spark plug and looked at the fouling material, it wasn't oil. I also had to add transmission fluid after about 2 weeks after a fluid change.
Further investigation led me to the Transmission Modulator.
The transmission modulator has a vacuum attachment that is located, DIRECTLY across from the cylinder that was missing.
Long story short, the modulator was bad ($49 from a local parts store) and was allowing the vacuum to suck transmission fluid into the manifold. Changed modulator, drove it for a day and cylinder now hits.
