Checking For A Miss

[Dave0803]

I am almost certain I have a miss. It seems to be at low rpm's (below 2000). What is the best way to find out which cylinder has the miss? It's a 2000 GT.


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[Rusty67]

If the cylinder is missing consistently you should get a code. I would just pull the spark plugs one at a time and visually inspect them to see what they look like. If one of them looks way different (wet maybe) compaired to the others that might be your problem cylinder. It could be the plug or a weak COP unit.

 

[Dave0803]

Thanks man. I don't have any codes. The car just seems rough up to about 15000 RPM and then it clears up. I've replaced motor mounts, plugs, fuel filter, ect. and nothing has fixed it. I was down to the COP's but wasn't sure of a good way to check them.


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[Rusty67]

The other thing you can do is if you have a good code reader that also has a live data scanner you can look at the data for each coil and try to find the one that doesn't look like the others.

Once you have a suspect cylinder swap the COP unit from another cylinder you think is good and leave the plugs where they are. See if the symptom follows the COP unit.

 

[Dave0803]

I have the predator tuner that will data log but I don't see anyway to look at the cylinders. What tuners will allow that?


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[Rusty67]

Well, I'm not talking about a tuner but more of a generic ODBII code reader that has scanning capability. I'm not sure what tuners will let you do this. Maybe an SCT ?

 

[Dave0803]

Mine doesn't seems to do it. It might not be a miss I'm feeling though, what im feeling is a vibration that I can feel in the whole car at about 1000-1500 RPM's. I've replaced coils & plugs, fuel filter, motor & trany mount. Other than that it seems to run fine. It's driving me nuts.

 

[Rusty67]

Stick or auto ?

 

[Dave0803]

It's a stick. This morning when I drove it it seemed to be stumbling on acceleration a little. Never had a problem with it all last week. It sat this weekend and didn't get driven till this morning.

 

[Rusty67]

You are going to need something with scanner functionality to find the problem easily.

You might want to run a compression/leakdown test just to be sure. Also if you pull the spark plugs and check the color of the plugs you might find the problem cylinder.

 

[Dave0803]

Might have to take it to shop then cause I don't think I have what I need to check all that.