Hello All,

2004 6MT Sedan with 113K miles, dropped a valve in cylinder #4 (large piece broke off) on July 4th.

Let it set a month (punishment for both of us), then tore the motor down and found this big hole in an exhaust valve on cylinder #4 (middle cylinder on driver's side).

 

Took the heads down to a local Hi-Perf machine shop and had them done ($475) - replaced two valves in the process.

Returned to me for re-assembly - notice the "scarring" on the head surface from the broken valve, as well as the "scarring" on the top of the piston (piston cleaned up with some emery cloth and Scotch-Brite).

 

Re-assembled engine, set all timing marks according to Factory Service Manual, then fired it up. Started instantly but runs rough with an obvious misfire, and won't rev.

Thought maybe we had not lined up the timing marks correctly (our first time tearing down a G motor), so spent a day disassembling, re-checked and everything still spot-on. Re-assembled engine. Checked compression (another way to determine if timing is correct) - 185+ lbs in every cylinder (excellent!).

Started it again - same result. Fires right up and idles at 1,000 RPM (cold), but runs rough with a misfire and won't rev at all. Frankly, it runs now exactly like it did when it had the hole in the valve - just no smoke out the exhaust)

Has set NO codes. Have heard theories from bad or clogged injector to clogged Cats to bent or bad coil pak(s) to bad MAF sensor to clogged PCV. Nothing is obvious.

Trying to avoid re-inventing the wheel here. Anybody have this problem before? If so, what was it? How did you cure?

Thanks for your help/comments ??

 

Umm, maybe follow this thread: https://g35driver.com/forums/g35-sed...ensor-bad.html

Try not to concentrate on what has been done to the car, use the service manual and focus on the symptoms as they present themselves currently.

Good Luck!

 

hey.. i know this guy... you posted these pics on 6mt as well, correct? =)