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Discussion Starter #1 (Edited)
car idles really rough and bucks when idling because one of the cylinders isnt firing we checked the coil and spark plug and they dont seem to be the problem i looked into it a little and some people point to the DME. i tried swaping the DME but the car wouldnt run with the swapped one, if it is the DME does anyone know to to proporly replace or fix it? also this might be unrelated but eml light comes on sometimes, goes away temporarily if i turn the car off and start it back up.
 

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we dont have a scanner atm waiting to borrow one from a friend thought id try here in the mean time
 

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sorry i think i acccidentally replied to myself? im new here but we dont have a scanner yet but im getting one soon
 

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sorry i think i acccidentally replied to myself? im new here but we dont have a scanner yet but im getting one soon
Nope, you responded right.

A scanner will prevent a lot of speculation, by narrowing it down dramatically.
See this link on direction for where and what to purchase. OBDFusion and a Veepak scanner are less than $20 for Android and less than $40 for Apple smartphones. You will find it invaluable, it's a must have if you're going to work on your own car. It will cut way down on the stress levels as well, even if you don't do your own work. there are more in-depth software solutions, but starting with this is the way to go.

Here's the link with more information :
https://forum.e46fanatics.com/showthread.php?t=897616
 

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ROLL TIDE!
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A bad DME causing ONE cylinder to misfire is not common, in 15 years I've never dealt with one. Once you get the codes scanned, it will shed a lot of light on your problem. Just curious, how did you determine the coil and spark plug weren't the problem? Without a scanner, how did you know which cylinder was dead? Did you do a compression test on that cylinder?
 

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Discussion Starter #7
we unplugged each coil while running till we found the one that didnt change when unplugged then we switched out the coil and sparkplug on that cylander with new ones and the problem was still there
 

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ROLL TIDE!
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we unplugged each coil while running till we found the one that didnt change when unplugged then we switched out the coil and sparkplug on that cylander with new ones and the problem was still there
Ok, good, that's the "old school" way of doing it. I'd do a compression test on that cylinder. If you have compression, the only other culprit would be the injector or wiring/DME which again, is rare. A mechanic stethoscope or even long screwdriver placed on the injector and then to your ear will allow you to hear the clicking of the injector as it pulses. Doesn***8217;t 100% mean the injector is GOOD, but at least you***8217;ll know if it is getting the signal to open.

Did you use the right plug? Single prong plugs don't tend to work very well in these cars.
 

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There were a few people that had similar symptoms and they put a cleaner in to clean the rings and that fixed their problem, what is a leak down test?
 

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Cogito Ergo Zoom
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There were a few people that had similar symptoms and they put a cleaner in to clean the rings and that fixed their problem, what is a leak down test?
My car had similar symptoms. One cylinder had close to 0 compression. Turns two valves on cylinder 5 were stuck open and that was all she wrote. There was no way to clean without overhauling the head which I'm not capable of. Believe it or not, if that is your problem then the best, most cost affective way to save your car if you want to is to install a new to you motor. All in with new seals, gaskets, CCV, hoses, motor and trans mounts, etc... was just under $2000. Took me and a fellow fester 9 days and if you like wrenching a very doable and fun project. Not for the faint of heart though.

A leak down test will tell you whether you have a bad head gasket or a bad valve.

I may not be the sharpest tool in the shed, but I don't see how "cleaning the rings" could bring back compression.
 
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