Hey guys, i have searched the posts to try and find an answer to no avail. ive had a rough idle problem for a while. cyl 1 misfires every couple to few weeks. i have changed plugs , wires, cap , rotor, iac, tps, and rerouted the wires(twice). i started checking injectors by listening to them - they all work. my main focus has been cyl 1 since it is the only one to misfire. anyway, i also pulled the connectors while it was runnning to see what happened - all cyl's changed the idle when disconnected except cyl 1. ok - then i swapped injector 1 with injector 5. no change at all. i pulled the connectors at idle again to see if 5 was still firing and it was. cyl 1 was still not firing. ok - not a bad injector. well, now i have p0301 , 308, and 300 codes. i have been screwing with this truck for ever now - can some one please help me. oh, also, i checked the plugs - not bad - cyl 1 isolator had a slight browntint to it but thats it. i'll check the coil next

 

sounds like a burnt valve in the head our a broken vavle spring.

 

Sounds like you've done all of the easy stuff. I think I'd start looking at the mechanical stuff. Start with a compression check before any disassembly.

 

well, iv'e rulled out the injectors completely, i hope. i took them all , including rails, to work and ultrasonic bathed everything for about 45 min in D60 solvent. didnt fix the problem but did improve throttle response alot. replaced coil (mechanic i talked to said i should - so just to rule another thing out, i did)(didnt really make sense to me why it would only misfire on cyl #1 if it was the coil - but what the hell) started a compression test - frozzzzze my butt off so i just did the easy ones for now and will do them all over when it warms up to the mid 40's this weekend. so far i have
cyl 1) 135
cyl 3)138
cyl 2)170
cyl 4)152
(got the easy ones)
oh, also, i removed the valve cover and inspected valve springs - nothing broken, not a stuck valve.. i was really hoping thats what it was. something somewhat easy.
the compression numbers dont look to encouraging at this point.

 

finished the compression test.
1)150
2)172
3)165
4)155
5)135
6)148
7)140
8)170
this is not what i expected to see. cylinder #1 is the one that Always misfires. i also did a leakdown test to double check since sometimes a compression test doesnt always indicate a problem. anyway, with 100psi regulated pressure my leakdown was only 5psiwith the gauge read ing 95psi. as far as i can find the typical spec is 3-8%. i have 5%. i also checked the intake for oil pooling and found it just a little damp looking. what the heck is going on with this thing.i would thinkwith what test ect.. i have done i have ruled out mechanical problems. it has to be fuel or fire now. injector wiring? ecu?does anybody have any suggestions? anything would help

 

sounds to me like the head gasket has a small tear in it. just enough to mess with the firing order

 

Could be a plugged or restricted injector.
Pull the rail and swap the injector to another cylinder . See if the misfire moves to that cylinder. With the injector off check the inlet side and see if it's full of rusty crud

 

in my original question up top; Ive already swapped the injectors. they looked fine. i also ultra sonic bathed them and the rails jsut to be certain.does the cap and rotor manufacturer make any difference? or the wires? i bought them all at autozone. just to make sure i am getting chrysler wires, cap n rotor today and will install them tomorrow. please keep the ideas coming. i have my doubts the new new wires ect. will cure the problem.

 

are any of the wires touchin each other? i read that sometimes they can interfere with each other causin a misfire if they are too close. just a suggestion. im in the same boat as you right now, except its my #7 cylinder

 

iv'e done the tsb on the wires. ive tried to get them all kind of isolated. as much as possible anyway. i couldnt wait until tomorrow to so during lunch ireplaced the cap, rotor and wires Again but this timethey were from the chryslerdealer. no change at all.double checked for the gazzilionth time just to reverify and with it idling i diconnected the injector connectors and all make a change to the idle except cyl #1. which is my constant misfire.when unplugged, cyl 1 doesnt change the idle much if any at all.its negligible.i wouldthink injectorif i hadn't already swapped it with cyl 5 and cyl 1 was still the problem. i hate dumping money into it and crossing my fingers to see if it helps.