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-   -   Cylinder 4 misfire (https://www.miataturbo.net/engine-performance-56/cylinder-4-misfire-82588/)

cowboys647 Jan 12, 2015 11:38 AM

Cylinder 4 misfire
 
Hey guys. I just recently had my engine out to fix a stuck oil pressure relief valve and now that I got everything back in my engine has a miss in the 4th cylinder. I'm getting spark and fuel and the compression for all the cylinders are similar. The only thing I can think of is maybe my timing is a tooth off. I'm going to try and get a picture of my cams here soon but they seem lined up right. Would the timing being a tooth off only cause a miss in the last cylinder?

guttedmiata Jan 13, 2015 07:42 AM

No, cam timing being off isn't going to cause a single cylinder to change. What did you do to verify spark? How did you determine it's #4?

cowboys647 Jan 13, 2015 11:11 AM


Originally Posted by guttedmiata (Post 1196050)
No, cam timing being off isn't going to cause a single cylinder to change. What did you do to verify spark? How did you determine it's #4?

I took the cop out and put a spark plug in it to check for spark. I figured maybe my cop was bad so I swapped front to back but still had the miss. Also changed out spark plugs with no luck. As to how I know it's the back, I took turns unplugging my cops and the car ran the same with #4 plugged in as plugged out. For some reason, it's not firing and the car was running perfect prior to pulling the engine so I doubt that my #4 injector could have become clogged during that time. Compression was still good in the cylinder and I only ran it a second without oil pressure so it shouldn't be my rings. I'm running out of things to check..

aidandj Jan 13, 2015 01:54 PM

Assuming your injector isn't clogged isn't the best idea. Try to swap injectors around and see if the misfire changes?


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