misfire on #3

[ricky68]

So I have been getting this message -p0303- misfire on cylinder 3. So I changed out the plugs, plug wires,distributor,and button. It returned a few days later. Funny thing is it only shows up going uphill at about 50 70 mph and on a long grade. It doesn't seem to be the angle so much as the length because I live on a steep short hill and have no problem going home. When it comes on (check engine light) it skips some and then goes away after I level out at the top of the grade .Light stays on a few days and eventually goes off.
Thanks for any help.

 

[chevync]

Compression test, had a 4.3 do the same thing, found out it was a cracked head.

 

[SunlitComet]

mixtures that are off or sticking valves can cause those issues.

 

[ricky68]

In the course of tuning up my truck I pulled out what appeared to be the original distributor. When I replaced it the problem finally revealed it's source. It appears to have been a bad valve spring or valve. The result was not pretty. So rather than redo the heads and stick them on top of a block with over 200,000 miles on it , and my son starting to drive next year , I decided to just put a new motor in it.I got a new crate motor from gm and changed it out. I should be good for another quarter million miles now.

 

[SunlitComet]

with proper maintenance.

 

[ricky68]

She had over 180 on her when I got her , and I am pretty meticulous on my maintenance. Plus , I just don't like the idea of parting with her , lol