P0305 code on 2000 Sierra 4.3L...what next?

[markophonic]

Misfire on cyl #5

What exactly should I look for to "fix"?

Is it electrical or maybe a fuel injector problem?

 

[Molson02536]

Misfire on cyl #5

What exactly should I look for to "fix"?

Is it electrical or maybe a fuel injector problem?

Start with the simple and inspect the spark plug wires and rotor and cap. Common for the breather screen at the bottom of the distributor to get dirty and clog up which promote condensation in the distributor cap which will cause corrosion.

If there is any signs of damage to the wire, replace it. If it's the rotor and cap, replace it with a good one that has brass sleeves. The cheaper cap without the brass sleeves will cause multiply arching. At this point, you might as well give your Sierra and ignition tune up if on cylinder has issues. http://www.accel-ignition.com/Produ...jID=595&minID=5951&selection=9&minselection=0

Good luck and keep us posted.

 

[markophonic]

Thanks Molson!

I read where if you receive a Misfire code like this that it needs to be taken care of immediately because it could cause problems with the cat converter...is this true? How quickly could this mess up the converter??

 

[Molson02536]

Thanks Molson!

I read where if you receive a Misfire code like this that it needs to be taken care of immediately because it could cause problems with the cat converter...is this true? How quickly could this mess up the converter??

It's the backfire that causes issues with the Catalytic Converter, with just one of your cylinder's misfiring. I would not loose any sleep over it since you have not mentioned any backfires issues.

If you like, you can try adding half a can of http://www.seafoamsales.com/ in to your gas tank and the rest in through your vacuum tube. (PVC Line) Just to clean out your fuel line and upper intake. Also clean your MAF sensor with MAF sensor cleaner, just follow the instructions on the spray can.

Good luck and keep us posted and let me know what condition your #5 spark plug is. (Driver's side to the back of the engine.) Would help to know if the cylinder is lean or rich.

 

[markophonic]

It's the backfire that causes issues with the Catalytic Converter, with just one of your cylinder's misfiring. I would not loose any sleep over it since you have not mentioned any backfires issues.

If you like, you can try adding half a can of http://www.seafoamsales.com/ in to your gas tank and the rest in through your vacuum tube. (PVC Line) Just to clean out your fuel line and upper intake. Also clean your MAF sensor with MAF sensor cleaner, just follow the instructions on the spray can.

Good luck and keep us posted and let me know what condition your #5 spark plug is. (Driver's side to the back of the engine.) Would help to know if the cylinder is lean or rich.

I put some seafoam in the gas tank...I'm going to put the rest of it through the vacuum/pcv line. I cleaned the MAF sensor with the CRC MAF cleaner.

I purchased the accel distributor cap and rotor that you suggested and will be putting that on when the weather here clears up a bit (single digits and snow)

I had a shop near my house replace my fuel filter a week or so ago.

I went back to the same shop today and had them run their diagnostic tests etc...they of course detected the misfire cylinder #5. but nothing else.

They pulled the plug (it was a Bosch platinum) and said it was very wet. Also said those plugs don't seem to run well with this motor...seems I read that here too!

They replaced the plug and it seems to be running fine now (fingers crossed) I've only driven it a couple miles back home. no codes or anything yet (fingers still crossed).

I'm going to get some new plug wires and plugs before I put on the new cap and rotor. Any suggestions for what plugs to use?? how about wires??

One thing I noticed on the invoice, but wasn't mentioned to me was a line under what work was performed that says...intake manifold leaking coolant. Now i know this can be an issue with the vortec v6 and can't believe he didn't mention anything to me...I'll call them back in the morning to find out what is up.

I do know the coolant level is fine (I think its the dexcool stuff...its orange and looks fine and tests fine) I changed the oil a couple of weeks ago and it looked fine...not like any water or anything was in it.. I'll check the oil in the morning.

 

[markophonic]

It's the backfire that causes issues with the Catalytic Converter, with just one of your cylinder's misfiring. I would not loose any sleep over it since you have not mentioned any backfires issues.

If you like, you can try adding half a can of http://www.seafoamsales.com/ in to your gas tank and the rest in through your vacuum tube. (PVC Line) Just to clean out your fuel line and upper intake. Also clean your MAF sensor with MAF sensor cleaner, just follow the instructions on the spray can.

Good luck and keep us posted and let me know what condition your #5 spark plug is. (Driver's side to the back of the engine.) Would help to know if the cylinder is lean or rich.

Don't know what happened to my last post...so I'll try again

Molson...per your suggestion I put some Seafoam in the gas tank...I'll run some through the PCV vacuum line tomorrow. I also shot some of the spray into the throttle body, let it sit for 10 minutes and ran it out...I also used some CRC MAF cleaner on the MAF sensor.

I purchased the Accel cap and rotor you directed me to but haven't installed them yet.

I took the truck to a shop near my home and had them take a look at it. They ran their diagnostic tests etc. and got the "misfire cyl #5" as expected but no other codes. They pulled the #5 spark plug and said it was "really wet". also said it was a Bosch platinum and that they don't work so well in this motor (seems I read that on this forum or somewhere also). They replaced the plug with I believe an AC and this seems to have cleared everything up...so far. I only drove home a few miles and it ran great!

I wish they would have replaced all of the plugs but I think they want to be sure this takes care of the problem?

I'm going to replace the rest of the plugs and a new set of spark plug wires...any suggestions for wires or plugs??

Something they didn't mention to me but made a note on the invoice was a possible intake manifold coolant leak??? I've read this can be common and bad...so I wonder why it wasn't mentioned to me at all???

 

[markophonic]

Don't know what happened to my last post...so I'll try again

Molson...per your suggestion I put some Seafoam in the gas tank...I'll run some through the PCV vacuum line tomorrow. I also shot some of the spray into the throttle body, let it sit for 10 minutes and ran it out...I also used some CRC MAF cleaner on the MAF sensor.

I purchased the Accel cap and rotor you directed me to but haven't installed them yet.

I took the truck to a shop near my home and had them take a look at it. They ran their diagnostic tests etc. and got the "misfire cyl #5" as expected but no other codes. They pulled the #5 spark plug and said it was "really wet". also said it was a Bosch platinum and that they don't work so well in this motor (seems I read that on this forum or somewhere also). They replaced the plug with I believe an AC and this seems to have cleared everything up...so far. I only drove home a few miles and it ran great!

I wish they would have replaced all of the plugs but I think they want to be sure this takes care of the problem?

I'm going to replace the rest of the plugs and a new set of spark plug wires...any suggestions for wires or plugs??

Something they didn't mention to me but made a note on the invoice was a possible intake manifold coolant leak??? I've read this can be common and bad...so I wonder why it wasn't mentioned to me at all???

 

[markophonic]

Took it to a local indy shop near my home and they ran diagnostics and came up with the P0305 code as expected but no other codes.

They pulled the #5 spark plug and said it was "really wet"...It was a Bosch platinum and he said those don't work to well in these motors...replaced it with an AC Delco and it is running fine right now...I only drove a few miles home but it ran well.

I purchased the Accel cap and rotor that molson suggeted and I will be putting it on...I want to replace the rest of the plugs and the wires too.

Which wires should I buy...the prices are all over the place.

last weekend I put some Seafoam in the fuel tank and will run some through the PCV vacuum line tomorrow...I'll probably replace the PCV valve for the hell of it.

last weekend I also cleaned the MAF sensor with some CRC MAF cleaner.

 

[markophonic]

UPDATE:

I ended up letting a local shop near my home take a look at my truck and they ran their diagnostic computer checks...the P0305 misfire code was the only code. They pulled the #5 plug and it was "really wet". they replaced the plug and it runs great...I need to replace the other 5 plugs. The plugs that are/were in it were Bosch platinum and the mechanic said those don't work so well with this motor. Replaced with an AC Delco.

I also ran some seafoam through the PCV vacuum hose and put some in the gas tank. Also sprayed some in the throttle body. I used some CEC MAF cleaner and cleaned the MAF sensor.

I have an Accel cap and rotor that I'm going to put on along with new spark plug wires.

 

[Molson02536]

UPDATE:

I ended up letting a local shop near my home take a look at my truck and they ran their diagnostic computer checks...the P0305 misfire code was the only code. They pulled the #5 plug and it was "really wet". they replaced the plug and it runs great...I need to replace the other 5 plugs. The plugs that are/were in it were Bosch platinum and the mechanic said those don't work so well with this motor. Replaced with an AC Delco.

I also ran some seafoam through the PCV vacuum hose and put some in the gas tank. Also sprayed some in the throttle body. I used some CEC MAF cleaner and cleaned the MAF sensor.

I have an Accel cap and rotor that I'm going to put on along with new spark plug wires.

Good job, and keep us posted. If #5 plug goes bad again and is wet, that good chance that the #5 poppet valve is bad and will need to be replaced. But before you go and replace that, try having your injection system cleaned which is the cheaper out of the two.

http://members.shaw.ca/betterthanyoutoo/Sticking Poppet.htm