Cylinder 5 Misfire

[philosofy1]

OK, first I would like to start off by saying thanks to all those that have helped me with answers when I posted up questions.

Now, on my 98 Chevy C1500 (350) I am getting a misfire code for cylinder 5. I am nearing the end of the work that I have done on this truck, I feel this is the only thing that is holding me back.

The parts that I have replaced since I have inherited this truck:

spark plugs
cap
rotor
wires
ignition coil
ignition module
fuel pump
fuel pressure regulator
coolant temp sensor
oil pump
egr valve
pcv valve
O2 sensor (2x) (before cat)
belt
belt tensioner
battery
starter

I highly doubt any of these can cause a misfire, but who knows? Also, what is the idle suppose to be set at? The idle jumps, but i'm pretty sure it's cause of the misfire, would adjusting the idle help?
Please, please, please, if anyone have any good ideas or suggestion please share it, I"ve been waiting a long time to drive this truck.

Thanks

[Z71_guy]

you may have a bad plug or wire try swapping the plug to another cylinder and see if the code follows if it does then you found your problem if it stays swap a wire and see what happens

[Jimmiee]

Looks like you have changed everything but the injector. ;)

[philosofy1]

I'm crossing my fingers that I don't have to replace them. I've ran out of money for this project so if it is, then it's going to have to wait.

[Z07]

Pay close attention to the routing for #5 and #7 plug wires. If they run parallel it is possible for #5 to induce a spark into #7 and that would be very early on its compression stroke. These wires should cross at 90 degree angles when needed and be seperated a bit when they have to run close to each other. For a test try taking wire #5 out of the looms and run it way away from the others.

[nightmanx1]

I have the same thing but #1 and the last time it was the intake gasket was blown out. I am going to start digging into mine tomorrow.

[grimreapersshadow]

get yourself some starting fluid and spray the area where the intake meets the heads and if your rpm's go up like you just pressed on the pedal then you got an intake leak and need to do them lower gaskets

[philosofy1]

Thanks guys, I'm try this stuff out today!!!

[philosofy1]

I was short on time yesterday, so I only had time to do the wire situation, yeah that didn't work. So, I'm left trying to find a vaccum leak.

[jt_5.7]

OK, first I would like to start off by saying thanks to all those that have helped me with answers when I posted up questions.

Now, on my 98 Chevy C1500 (350) I am getting a misfire code for cylinder 5. I am nearing the end of the work that I have done on this truck, I feel this is the only thing that is holding me back.

The parts that I have replaced since I have inherited this truck:

spark plugs
cap
rotor
wires
ignition coil
ignition module
fuel pump
fuel pressure regulator
coolant temp sensor
oil pump
egr valve
pcv valve
O2 sensor (2x) (before cat)
belt
belt tensioner
battery
starter

I highly doubt any of these can cause a misfire, but who knows? Also, what is the idle suppose to be set at? The idle jumps, but i'm pretty sure it's cause of the misfire, would adjusting the idle help?
Please, please, please, if anyone have any good ideas or suggestion please share it, I"ve been waiting a long time to drive this truck.

Thanks

i have a question is the miss consistent or is it random

[thaxboyd]

1999 Suburban K1500 5.7 Vortec 130K miles.
Below is my problem.....................

Started misfiring, scan said misfire #5, Misfire is felt through the whole RPM range. Changed the following:
Plugs, Wires, Cap, Rotor Air Filter. (Fuel filter was changed 6 months ago along with a check of the fuel pressure, new factory pump 3 years ago)

Still #5 misfiring, changed the following
Upper int. manifold gasket
Lower int. manifold gaskets
Cleaned all grime
Cleaned injectors
Replaced injector #5

Still runs like crap have not scanned but exh. manifold port for #5 does not get as hot as the rest. I changed out the throttle position sensor as the cleaning made the old one not work and transmission shift was messed up….. Fixed that problem but not #5

I checked the compression of #5 and it is about 130psi. I also verified there is spark going to the plug. Tomorrow I am going to switch plugs putting a known good one into #5 and then #5 plug into a hole I know is working.

Any other ideas???????

[rotaryenginepete]

maybe a plastic spacer to keep the plug wires from crossing. a lot of times they will jump spark even thru the insulation. get something to keep that plug wire away from the block, and all the other wires around it. hopefully this might work...