# Slight Miss!



## GTO4ART (Jan 7, 2005)

I have a slight miss in my LS1 engine, it has 46,000 miles, and runs great still. However there is an unusual shake in the drivetrain that is mostly felt during idle. The sparkplug wires and plugs appear to be in good condition...as they are the originals and have never been taken off, until now. All the spark plug electrodes look good too. I ran a compression check and notice a bit of a problem, all but one cylinder read about 150psi, the one that's low shows about 120psi. Does anyone know if this is enough to cause the miss I am encountering? Or do you believe it my be something different all together? An old-timer I spoke to said anything less than 40 pounds difference should not make a difference...I'm not too sure. I also ran trouble codes and came up with a lean mixture in both banks 1 and 2...any suggestions? Is this somehow related to the miss I am encountering? 

Thanks in advance for any advice!


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## 6QTS11OZ (Mar 27, 2005)

Even if the wires look okay that doesn't necessarily mean that they are okay. The only way to know for sure is to do a resistance check on each wire. I'm not sure what the reading should be for our wires but if a wire is showing a big difference in resistance than the other ones I would replace the wires. A conventional plug wire has a resistance of 10,000 to 15,000 ohms per foot of length. If it's measurably higher, the wire is probably bad. I would start there first. Normally when I notice a miss, I just replace the plugs and wires anyway, depending on the miles I have on the current set, and be done with it.


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## Rukee (Feb 8, 2007)

6QTS11OZ said:


> Even if the wires look okay that doesn't necessarily mean that they are okay. The only way to know for sure is to do a resistance check on each wire. I'm not sure what the reading should be but if a wire is showing a big difference in resistance than the other ones I would replace the wires. A conventional plug wire has a resistance of 10,000 to 15,000 ohms per foot of length. If it's measurably higher, the wire probably is bad. I would start there first.* Normally when I notice a miss, I just replace the plugs and wires anyway, depending on the miles I have on the current set, and be done with it.*


:agree
Can't overlook the obvious.


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## GTO4ART (Jan 7, 2005)

*Thanks...keep the advice coming!*

I will start there! New wires and new plugs. Any thoughts on the compression difference?


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## MrBaz (Mar 17, 2010)

GTO4ART said:


> I will start there! New wires and new plugs. Any thoughts on the compression difference?


20psi off is not something to just wave off. You need to find out what is causing that compression loss. Whatever is causing the compression loss could also explain what is causing the missing.
It could very well be a shot plug that is no longer sealing.


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## svede1212 (Nov 1, 2005)

Rats. I thought "Slight Miss" would have a picture of a skinny girl. . . 
Do you have an aftermarket air intake or have you ever had the old one off? If it's sucking air in anywhere past the MAF it will run poorly and cause a lean condition as you're pulling in unmetered air.


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## GTO4ART (Jan 7, 2005)

*more ideas?*

I have a K&N, it's cleaned regularly, and I checked the whole intake for leaks,...it was sealed all around. Any idea where I might find a set of MSD wires and AC Delco plugs at a good price? AutoZone wanted $65 for the wires and $6.99(each) for the plugs.


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