1996 tahoe lt with trouble code p0304. CA Smog issue

[kevdogedog]

1996 tahoe lt with trouble code p0304. CA Smog issue. `i got it for a song and now i know why, slightly rough idle, but runs well overall. 1996 tahoe, changed the oil and plugs, air filter and took it to a ca smog check and missed on the 'hc' by by about 36 and failed. max 100, average 26 my score 139. it passed at 2500 rpm test, but the fail was at idle. have since replaced the wires, cap, rotor. i have had it sniffed since at idle and the numbers seam even higher. I have got a check engine code 2 -3 times it goes off and on, i used a reader and found it to be code p0301, cylinder 4 misfire. had it 2 months and still havent passed smog to put it in my name. very frrustrated here. help a brother out. any ideas or tips?http://www.tahoeforum.com/images/smilies/happy160.gift?

 

[tahoe nick]

I have same issue with my 97. Please post any help you get. Have also replaced plugs,wires,cap,rotor and no change. May be fuel poppet valve clogged on the injecinjecand not spraying fuel properly

 

[kevdogedog]

i know these are tough to diagnose

i know these are tough to diagnose. i still havent smogged yet. it runns well, no smoke or anything, just has a slight misfire at idle still.

 

[bladenbullet]

have you tried swapping the #4 injector with another cylinder to see if the misfire moves with it?....

 

[kevdogedog]

i have the 'spider type injectors i think they are located under the intake manifold. I am taking it in for diagnostic this week. i will post the results asap. thanks guys!