P0301

[Kelsda]

Hi, all
Looking for information on the dreaded P0301 misfire cylinder 1 swapped out plugs and wires not new ones played the old shell game no change still P0301 new cap and rotor still same code 1996 yukon 5.7 vortec motor 115,000 miles friend came over with an expensive scan tool told me o2 sensors working but did not show misfire P0301 any suggestions would be greatly appreciated read something else about distributor gear possibly worn out how much play does a rotor have ? The more I read the worse it is to figure out May Day MayDay

 

[liquify33]

How does it run? Distributor gear at 115k miles seems highly unlikely to me. Have you done the spider injector swap yet?

I’ve had a 0305 lately and ran a can of Seafoam in a nearly empty tank and it went from better to gone in under 50 miles.


And don’t toss that distributor out.

 

[Kelsda]

How does it run? Distributor gear at 115k miles seems highly unlikely to me. Have you done the spider injector swap yet?

I’ve had a 0305 lately and ran a can of Seafoam in a nearly empty tank and it went from better to gone in under 50 miles.


And don’t toss that distributor out.

Low rpms stumbles, really rough highway speed seems fine worried about killing cats driving, did not do spider upgrade yet I don’t think its leaking fuel no black smoke from what i read different codes for a bad spider like P0300 random misfire i will see if the manifold is leaking next. I will try the sea foam maybe carbon build up

 

[exp500]

Check for vacuum leaks around intake, seafoam/ berryman in gas tank. Check fuel pressure, check fuel trims/ misfire on all 8, maybe even cam retard offset (timing at zero) Torque app works for that. Usually ignition module just fails, but maybe its close. Same with coil. Do you have bright white/blue spark? Lastly are you loosing coolant? Coolant Clean?

 

[OR VietVet]

Basics. Compression test. Vacuum leak inspection. Suspect the spider though, common problem.

 

[liquify33]

Do you hear a ticking sound?

 

[Kelsda]

Checked compression 165 no leaks around intake possible coolant leak reservoir empty once again no visible leak

 

[OR VietVet]

What is the compression at the next cylinder, #3? Pressure test the cooling system and inspect for a leak. Look at the bottom of the water pump at the weep hole.

 

[Kelsda]

I did see a wet area on the right side and rear of motor can’t really see where it is coming from I was looking around with a mirror I’ll do a Preasure test seems like oil but possibly antifreeze

 

[OR VietVet]

I did see a wet area on the right side and rear of motor can’t really see where it is coming from I was looking around with a mirror I’ll do a Preasure test seems like oil but possibly antifreeze

Heater hoses and this is in that area: https://www.rockauto.com/en/moreinfo.php?pk=84579&cc=1166431&jsn=2248

Make sure to clean off that wet area before pressure test and leave the pressure tester on there at pressure and watch for pressure drop. That weep hole at water pump can be tricky but if is leaking should leave a corrosive stain/trail.

 

[Kelsda]

Heater hoses and this is in that area: https://www.rockauto.com/en/moreinfo.php?pk=84579&cc=1166431&jsn=2248

Make sure to clean off that wet area before pressure test and leave the pressure tester on there at pressure and watch for pressure drop. That weep hole at water pump can be tricky but if is leaking should leave a corrosive stain/trail.

Pressure test shows leak from radiator drivers side can’t really see where must remove to confirm weird not leaking on the ground only under 15 psi on tester, popped out twice on me. Sending antifreeze everywhere cleaned off try again tomorrow when dry test kit comes with like 20 adaptors none fit mine had to use twist lock expansion one

 

[liquify33]

Pressure test shows leak from radiator drivers side can’t really see where must remove to confirm weird not leaking on the ground only under 15 psi on tester, popped out twice on me. Sending antifreeze everywhere cleaned off try again tomorrow when dry test kit comes with like 20 adaptors none fit mine had to use twist lock expansion one

The common external failure points of the intake manifold gasket are parallel to the dash in the front and back and the corners. If it’s internal your oil will look like chocolate milk

 

[exp500]

Wrap some toilet paper around the heater control valves/tees and the intake manifold Quick disconnent. If it gets wet it's easy to spot. Also bring the pressure up slow a little at a time to 15-16 max. it may start leaking at 2. I'm thinking you have a spider or lower manifold problem by your description. Is spark Bright white/blue?

 

[Kelsda]

Wrap some toilet paper around the heater control valves/tees and the intake manifold Quick disconnent. If it gets wet it's easy to spot. Also bring the pressure up slow a little at a time to 15-16 max. it may start leaking at 2. I'm thinking you have a spider or lower manifold problem by your description. Is spark Bright white/blue?

So checking spark old screwdriver or plug ground out and look ? heater control was changed not to long ago I’m going to take out radiator leaking out of same location as yesterday lower left corner no mayo on oil cap or foam on dipstick,no fuel or antifreeze smell in oil or out of tailpipe maybe just upgrade spider and change upper and lower manifold gaskets valve covers,and thermostat all original cost maybe 700.00 in parts a few nights to do so what do you think?

 

[liquify33]

So checking spark old screwdriver or plug ground out and look ? heater control was changed not to long ago I’m going to take out radiator leaking out of same location as yesterday lower left corner no mayo on oil cap or foam on dipstick,no fuel or antifreeze smell in oil or out of tailpipe maybe just upgrade spider and change upper and lower manifold gaskets valve covers,and thermostat all original cost maybe 700.00 in parts a few nights to do so what do you think?

Seems the right ballpark when you factor in spider cost, the heater hose quick disconnect, a tap to repair it when it crumbles and gasket makers. 1/2” NPT, go ahead and get one now or PM me and I’ll mail you mine for $15.
The Summit/FelPro kit comes with all you need besides extra Permatex. We added orange all around the lower intake gasket where it meets the heads and manifold around the coolant passages as well as the black along the flat surfaces. Bought 1 tube each.
Spider swap is super easy with manifold off the truck.
The lower intake/spider swap is a rite of passage on these rigs
A small 1/4” torque wrench and a good metric set will get you there.
Extensions, socket wobble joints, a pad for the hood latch (you’ll spend a lot of time sitting on it), good lighting, beers for friends or some audiobooks if you’re solo.
If you find yourself wondering which fuel pressure regulator, the answer is either. The one with the vacuum line is for multiple vehicles, the one without a tube will also work. Make sure that’s replaced also (should come w/spider) fuel filter is also recommended.
Protect your harnesses and electronic bits from coolant and debris (don’t ask how I know).

outside of troubleshooting my own dumb mistakes, surface prep took the longest and was the least pleasant.

 

[Kelsda]

Seems the right ballpark when you factor in spider cost, the heater hose quick disconnect, a tap to repair it when it crumbles and gasket makers. 1/2” NPT, go ahead and get one now or PM me and I’ll mail you mine for $15.
The Summit/FelPro kit comes with all you need besides extra Permatex. We added orange all around the lower intake gasket where it meets the heads and manifold around the coolant passages as well as the black along the flat surfaces. Bought 1 tube each.
Spider swap is super easy with manifold off the truck.
The lower intake/spider swap is a rite of passage on these rigs
A small 1/4” torque wrench and a good metric set will get you there.
Extensions, socket wobble joints, a pad for the hood latch (you’ll spend a lot of time sitting on it), good lighting, beers for friends or some audiobooks if you’re solo.
If you find yourself wondering which fuel pressure regulator, the answer is either. The one with the vacuum line is for multiple vehicles, the one without a tube will also work. Make sure that’s replaced also (should come w/spider) fuel filter is also recommended.
Protect your harnesses and electronic bits from coolant and debris (don’t ask how I know

Liquify33 my apologies some how I was blocking you and someone else I reversed it took a while to figure out my i-pad screen jumps around a bit sometimes it’s frozen it’s 8 years old

 

[liquify33]

@Kelsda
I probably had it comin’!

 

[east302]

I’m going to take out radiator leaking out of same location as yesterday

If you’re going to replace the radiator, here is a “heads up” on what not to get...

A lot of aftermarket radiators have a spare port below the radiator fill that is not used on the vortec 350. They put a rubber cap and clamp on it. It will crack and leak (100% guaranteed) which you may not notice until it’s too late. Here’s a random one from rockauto:

The Delco version matches what came from the factory and does not include the spare port. I’d recommend going with that and saving yourself the aggravation. Here’s what I used on my 98 with oil and transmission cooler connections.

 

[OR VietVet]

If you do go with the aftermarket with the port, you can get clear silicone straight tubing and cut to fit with 2 clamps and use a brass plug that has serrations at the clamp area so the second clamp has some grip for the tube when plug is inserted.

east302 is correct, that rubber cap from the aftermarket supplier will leak, absolutely 100% for certain it will.

 

[Kelsda]

Thanks for information gents, going outside to start tearing down intake it’s a little cold out (30) so I’ll give it a few hours had to order the delphi FJ10566 from a friend going to take a few days for me to receive