Engine Shaking - P0304 Misfire Code

[oldscsc]

There ya go! Glad to hear you got the problem at least diagnosed. May not be fun work, but it will be rewarding once its back together and running well.

 

Keep up the good work.

[Jsdirt]

SOAB! Sorry to hear that.

 

Any updates?

[DustyDee]

I finally got the cam shaft out last week. That is a bugger of a job right there. I had to drop down the steering assembly and front differential in order to get the oil pan off, so that I could remove the bolt from the oil pick-up tube on the bottom of the oil pump, so that I could remove the oil pump, so that I could get the timing chain off, so that I could get the cam shaft out.... did you follow all that?

 

I sent the cam shaft off to get re-done. The one lobe was damaged pretty good. I should be getting it back any day now. Then I get the fun job of putting it all back together! I'm hoping to have it done this week.

 

While I got it apart I'll be cleaning up the heads and re-seating the valves. What else should I do while I have it all apart?

[Jsdirt]

Oil pump has to come out now? WTF! Never worked on any LS - just old school 350's or 262's.

 

Valve seals wouldn't hurt, if you haven't already done those. Maybe springs too, but I don't think you've got enough miles on them to worry about that too much.

[DustyDee]

This isn't my picture, but it's pretty much the same. The oil pump is on the crank shaft.

 

 

 

 

 

Valve seals will be replaced. New gaskets for everything that came off.

Edited March 16, 2015 by Dusty Dee

[PJB1972]

Hell of a good job tracking that problem down, buddy!

Kudos, sir!

[Jsdirt]

Whiskey Tango Foxtrot ....... GM designers never sleep! AHH now I see why it had to come off!

 

Wasn't picturing that style at all - looks just like a larger version of what was on a '00 Focus 2.0 SPI that I rebuilt the top end of, after it ingested a valve seat ...

[007inblack]

My brother and I picked up a 2009 Silverado Hybrid with what was supposed to be a bad motor.

Put a rebuilt motor in along with a new AGM battery and the truck bucks violently after starting the engine and so now I'm trying to figure out what is going on. Going to hook the Tech II up to it again (unfortunately the Tech II card is a 2010 so it's not the latest).

VVT and AFM were deleted using the parts, but they are not programmed out of ecm yet as I was told that as long as I used all the hard parts for deleting those, the computer wouldn't be able to do anything to cam degree, or cause the engine to go into 4-cyl mode in any way (not even fueling).

 

New engine details:

 I picked up an identical 'core' that wasn't able to start from a local salvage yard (lucky to find a LFA core within 50 miles) and went to town collecting parts to rebuild it, but with some changes, utilizing factory parts and an aftermarket Melling 10295 oil pump.

Parts used for the rebuild (all new or rebuilt):

GM LS3 head gaskets (verified they are the same thickness as LFA gaskets)

GM LS7 lifters 

GM LS7 lifter trays

GM Ly6 valley cover

GM LS9 camshaft

ARP cam bolts

LS9 4x cam sprocket

rebuilt stock 243 heads

LS9 valve springs

LS2 timing chain

LS3 timing cover (no VVT)

LS2 timing chain dampener

Durabond coated cam bearings (original front cam bearing had a little scoring so I got the new bearings for peace of mind/cheap insurance).

Clevite 77 main and rod bearings (stock sizes as there was no crank/rod damage)

Piston-to-valve clearance was measured and stock pushrods from another engine were used as they were a perfect fit)

New oil pressure barbell

New timing/rear main cover/valve cover/valley cover gaskets

Block was cleaned and checked/honed prior to reassembly

Crank and cam were 'timed' prior to timing set being installed

 

Is there anything outside of the gas engine (aka in the hybrid system) that could be causing the truck to run so violently? Truck has 142,xxx miles.

 Thanks in advance for any help.

Edited May 16, 2018 by 007inblack

[Richard Clark]

I,m having same problem 4 cylinder misfire code moving parts doesn't move code always po304 misfire #4cyl timing light won't flash only on #4cyl can it be crank sensor

[Richard Clark]

I said that code 304 misfire #4cyl moved coils injectors to see if code moves to no still #4 cyl misfire code timing light flashes on all plug wires but no flash on#4 

[sefiroxx]

I said that code 304 misfire #4cyl moved coils injectors to see if code moves to no still #4 cyl misfire code timing light flashes on all plug wires but no flash on#4 

Likely a wiring problem to the #4 coil