99 yukon 5.7 vortec misfire HELP

[lifted_yukon22]

No i haven't done a compression test it's got new acdelco plugs wres cap and rotor. When it threw the p0305 on the cheap scanner I had I replaced the #5 injector and same thing

---------- Post added at 07:23 AM ---------- Previous post was at 07:08 AM ----------

I wouldn't tell you to shut up anyway I'm thankful for each and every person trying to help me out. I appreciate that you all would take the time out of your day to help someone you done even know

 

[SunlitComet]

"read" plug number five for any signs of goofiness and as mentioned run a compression test. what ever you did to try to fix it did not solve the problem. Do the test of the whole engine see we can get the overall health of engine as well as comparison to nearby cylinders.

 

[ccapehartusarmyINF.(ret)]

dude i think were back to floating valve

 

[lifted_yukon22]

Ok I'll get a compression checker and check number 5 it will be a couple of days before I get it

---------- Post added at 03:48 PM ---------- Previous post was at 03:21 PM ----------

Until then I'm going to play with mt250 to see what all going on.

 

[SunlitComet]

Double check the plug and wire while waiting.

 

[lifted_yukon22]

Ok I will in the morning before leaving work

---------- Post added at 04:51 PM ---------- Previous post was at 04:51 PM ----------

I'm just wondering why would the snap on read p0300 and the actron scanner read p0305

---------- Post added at 04:54 PM ---------- Previous post was at 04:51 PM ----------

I'm also going to check the valve springs and adjustment on the valve also. I should've already done it but haven't had time

---------- Post added at 05:02 PM ---------- Previous post was at 04:54 PM ----------

I'm also going to check the valve springs and adjustment on the valve also. I should've already done it but haven't had time

---------- Post added at 05:18 PM ---------- Previous post was at 05:02 PM ----------

Misfire again in the way work #4 went to 34, #5 went to 883, #7 went to 11. So is the misfiring mutal between those cylinders?

 

[ccapehartusarmyINF.(ret)]

is that the firing order for those cylinders 4,5,7,

---------- Post added at 02:27 PM ---------- Previous post was at 02:23 PM ----------

i looked up the firing order for that motor
1,8,4,3,6,5,7,2

---------- Post added at 02:44 PM ---------- Previous post was at 02:27 PM ----------

okay yer not going to do a compression test on just cylinder 5 your gonna wanna do all 8 cylinders
okay after a little research
im guessing whats gonna happen is when you do the compression test cylinder 5 will have a really low pressure reading and cylinder 4 and 7 wont be that low but theyll be lower then the good cylinders
so its possible cylinder 5 is kaputt and cylinder 4 and 7 are on there way

 

[OR VietVet]

Cylinder 4 is in the opposite head. 3 and 7 are on either side of 5.

 

[ccapehartusarmyINF.(ret)]

No i haven't done a compression test it's got new acdelco plugs wres cap and rotor. When it threw the p0305 on the cheap scanner I had I replaced the #5 injector and same thing

---------- Post added at 07:23 AM ---------- Previous post was at 07:08 AM ----------

I wouldn't tell you to shut up anyway I'm thankful for each and every person trying to help me out. I appreciate that you all would take the time out of your day to help someone you done even know

Dude more then happy to help i have alot of automotive experience and schooling between the Army UTI but do to the worsening of my service connected conditions i wasnt able to really get a job workin in the automotive field so i got lots of knowledge and no place to really use it other then on this forum and workin on my car
i was able to

 

[SunlitComet]

It is not uncommon to get some stray misfire reading when some bad cylinders are about. giving the history you post concern your self primarily with #5. when that is fixed rung the misfire history again.