Help diagnosing misfire on cyl 2. This is what I know

[Pegasus]

Need some help diagnosing the misfire on cylinder no 2. Vehicle is a 1997 Tahoe 5.7 with 160,000 miles. Service engine soon light is flashing and truck has a miss throughout rpm range. Code is a misfire on cylinder 2. Replaced all plugs (no. 2 was fouled and had oil on it all others were clean). all new wires and cap and rotor. Checked new plug on #2 and had fresh oil on it. Checked the cylinder for compression and had 180 psi. Not sure what compression should be but 180 seemed high. I figured it is high due to the oil. I also checked spark and it is strong and steady. I assume the oil is causing the miss I'm guessing the cause could be a valve stem seal leaking. Do you guys have any thoughts or opinions. Could the issue be something besides the valve stem seals. Thanks in advance

 

[SunlitComet]

i go worn valve seal/valve guide. you have good pressure so it would not be a ring issue normally.

 

[Pegasus]

Thanks for the welcome! How would you approach this? Would your first step be to replace the seal and see if that works before removing the head to replace the valve guide. I replaced valve seals on a different engine years ago are valve guides something that i would have to take the head to a shop?

 

[SunlitComet]

do the seal first. the guide would have to be done buy a machine shop.

 

[gpracer1]

When at wide open throttle an engine will smoke if the rings are bad, and at deceleration (held in gear) it will smoke if the valve stem seals are bad and at idle also.
That is the common scenario. Look out back for white/blueish smoke during those times.

 

[SunlitComet]

but don't inhale

 

[Pegasus]

Did the seals today. No change still a miss on #2. Any way to be sure I'm getting fuel to that cylinder? Very frustrating help please

 

[SunlitComet]

Have a fuel injector balance test done it will determine if too much or little fuel is getting thru and will include all eight of them.

 

[Pegasus]

Thanks. Do most mechanics have the equipment to perform that test. Do you know more or less what that would cost?

 

[retorq]

If you had the equipment to do a compression test then you should have been able to determine the seals weren't leaking, you would have heard or seen air escaping around the valve stem.

 

[SunlitComet]

Thanks. Do most mechanics have the equipment to perform that test. Do you know more or less what that would cost?

Yeah they use a high end snapon, otc or Gm scanner and fuel pressure gauge to test the pressure drop of each injector firing giving a basic idea of flow comparison. Should be about an hour job.

---------- Post added at 03:19 PM ---------- Previous post was at 03:17 PM ----------

When you did the seals did you have many binding in that valve?

 

[Pegasus]

Thanks SunLitComet. Ammco says they will do the test for $ 40. No binding but seals were definitely worn glad I changed them anyway. Ended up driving about a 100 miles today still missing of course but pulled plug #2 when I got home and no oil on it. I could only imagine its a fuel issue going to have the test done Monday.
To the other poster on this thread if you don't have a helpful comment why post it. I believe this forum should be to help each other with their issues not give useless comments.