Violent Ping and P0300 code

jpgoodnu · 08-13-2007, 01:03 AM

I have a 2002 Z71 Silverado with 5.3liter(not Flex fuel) and automatic with 70K on it. About 2 weeks ago I started getting sudden and Violent knock and ping(sounds like machine gun fire), it would only occur above 3000 rpm and NOT at light throttle(drove fine if not pushed), and it NEVER gave a Service Engine light or any codes. I suspected bad gas,changed the fuel filter,but after 3 more tanks of fuel(last 2 with Techron added) it has only gotten worse. I hooked up a SnapOn scan tool and even though there was still no codes to retrieve I got a "intermittent misfire, cylinder 2" when it would occur AND also the service engine light was now flashing, but still no codes. I swapped the coil and wire from cylinder 2 to 4 hoping the problem would move and I'd then swap the wire only and replace whichever was bad, but the problem stayed at cylinder 2, I then changed that plug, but still not fixed. Yesterday it changed again, now it idles rough and is sluggish with a odd exhaust tone(suspect running on 7 cylinders), it also started intermittently pinging at idle or just above and now the Service Engine light is on steady with a P0300 code from a cheapy actron scan tool(haven't had access to the SnapOn again yet). I am not going to run it anymore for fear of burning a valve or piston. Any ideas? My gut says it is a lean condition,but at $96 I don't want to just "Try" a new injector.

03chevy · 08-13-2007, 11:45 AM

code p0300 is random/multiple cyclinder misfire detected. that's what my scanner says your code is hope that helps

NCroadracer · 08-13-2007, 04:34 PM

Check your fuel pressure, if it's good your injectors and fuel rails are possibly clogged (and can be cleaned out).

jpgoodnu · 08-13-2007, 10:24 PM

How would I clean the injectors? Can they be disassembled to be hand cleaned or is there a pressurized cleaning system I can use?

nnunez · 08-14-2007, 11:36 AM

I dont think that you could tell a lot of difference if only 1 cyl is not running correctly. You may have more than one.

As far as cleaning the FIs, they have an injector tool that cleans them out with pressure. I dont think you can do it by hand since there are electrical connectors as well. Just take it to your local mechanic and get them to do the top carbon purge (I think thats the name).......cost about $80.

jpgoodnu · 08-15-2007, 01:42 AM

Well Folks, I got my answer today! AS this has been a deteriorating condition, today it was at the shop and running like absolut **** and seemed to be throwing a excessive amount of heat from under the hood(coolant temp normal). On a hunch we checked the exhaust with a "heat gun" and found both cats were way too hot(one worse than the other). We pulled the two O2 sensors out before the cats and BINGO-no more Ping and loads of pep. The bad news is that the engine pipe with the 2 cats is $800, BUT luckily for me that I am just under the wire for the emmisions warranty and the local dealer is going to take care of it. Weird how this initially caused a intermittent misfire only on cylinder 2(must have been the first to trigger the fault, before I backed off the pedal) and progressed to random cylinders as it got worse. Now my question is WHY did the cats melt/plugup? Delaer says they'll give it a thorough "once over" so it doesn't happen again.

jpgoodnu · 08-15-2007, 10:44 PM

Final update- Apparently my "Gut" was right after all, the dealer replaced the engine pipe/cats(under warranty) and then discovered the misfire still existed. They made a educated guess and performed the GM fuel injection service(apparently ther is a TSB about just this problem) and problem is gone and WHAT A DIFFERENCE. "She runs like a puppy again", smooth idle and acceleration(and plenty of it). I hope my ordeal and it's resolution helps others out there. Best Wishes, Jay

crabtruck · 08-16-2007, 02:16 AM

Quote:

Originally Posted by jpgoodnu

Final update- .....They ..... performed the GM fuel injection service...... and problem is gone .......

Is that the same as NCroadracer told you ?

jpgoodnu · 08-16-2007, 02:32 AM

Yes in fact it is.

crabtruck · 08-16-2007, 02:38 AM

Amazing how many problems come back to fuel or wiring.
Thinking about throwing away all my wrenches and buying a new dvm and a gas can

08-13-2007, 01:03 AM	#1
jpgoodnu Full Member Join Date: May 2006 Posts: 19	Violent Ping and P0300 code I have a 2002 Z71 Silverado with 5.3liter(not Flex fuel) and automatic with 70K on it. About 2 weeks ago I started getting sudden and Violent knock and ping(sounds like machine gun fire), it would only occur above 3000 rpm and NOT at light throttle(drove fine if not pushed), and it NEVER gave a Service Engine light or any codes. I suspected bad gas,changed the fuel filter,but after 3 more tanks of fuel(last 2 with Techron added) it has only gotten worse. I hooked up a SnapOn scan tool and even though there was still no codes to retrieve I got a "intermittent misfire, cylinder 2" when it would occur AND also the service engine light was now flashing, but still no codes. I swapped the coil and wire from cylinder 2 to 4 hoping the problem would move and I'd then swap the wire only and replace whichever was bad, but the problem stayed at cylinder 2, I then changed that plug, but still not fixed. Yesterday it changed again, now it idles rough and is sluggish with a odd exhaust tone(suspect running on 7 cylinders), it also started intermittently pinging at idle or just above and now the Service Engine light is on steady with a P0300 code from a cheapy actron scan tool(haven't had access to the SnapOn again yet). I am not going to run it anymore for fear of burning a valve or piston. Any ideas? My gut says it is a lean condition,but at $96 I don't want to just "Try" a new injector.

08-13-2007, 11:45 AM	#2
03chevy Senior Member Join Date: Dec 2006 Location: jax,fl Posts: 1,186	code p0300 is random/multiple cyclinder misfire detected. that's what my scanner says your code is hope that helps __________________ A dirty mind is a terrible thing to waste!

08-15-2007, 01:42 AM	#6
jpgoodnu Full Member Join Date: May 2006 Posts: 19	Violent Ping Well Folks, I got my answer today! AS this has been a deteriorating condition, today it was at the shop and running like absolut **** and seemed to be throwing a excessive amount of heat from under the hood(coolant temp normal). On a hunch we checked the exhaust with a "heat gun" and found both cats were way too hot(one worse than the other). We pulled the two O2 sensors out before the cats and BINGO-no more Ping and loads of pep. The bad news is that the engine pipe with the 2 cats is $800, BUT luckily for me that I am just under the wire for the emmisions warranty and the local dealer is going to take care of it. Weird how this initially caused a intermittent misfire only on cylinder 2(must have been the first to trigger the fault, before I backed off the pedal) and progressed to random cylinders as it got worse. Now my question is WHY did the cats melt/plugup? Delaer says they'll give it a thorough "once over" so it doesn't happen again.

08-15-2007, 10:44 PM	#7
jpgoodnu Full Member Join Date: May 2006 Posts: 19	Violent Ping Final update- Apparently my "Gut" was right after all, the dealer replaced the engine pipe/cats(under warranty) and then discovered the misfire still existed. They made a educated guess and performed the GM fuel injection service(apparently ther is a TSB about just this problem) and problem is gone and WHAT A DIFFERENCE. "She runs like a puppy again", smooth idle and acceleration(and plenty of it). I hope my ordeal and it's resolution helps others out there. Best Wishes, Jay

08-16-2007, 02:32 AM	#9
jpgoodnu Full Member Join Date: May 2006 Posts: 19	Violent Pinging Yes in fact it is.

08-13-2007, 04:34 PM	#3
NCroadracer Senior Member Join Date: Apr 2007 Posts: 295	Check your fuel pressure, if it's good your injectors and fuel rails are possibly clogged (and can be cleaned out).

08-13-2007, 10:24 PM	#4
jpgoodnu Full Member Join Date: May 2006 Posts: 19	How would I clean the injectors? Can they be disassembled to be hand cleaned or is there a pressurized cleaning system I can use?

08-14-2007, 11:36 AM	#5
nnunez Senior Member Join Date: Dec 2005 Posts: 307	I dont think that you could tell a lot of difference if only 1 cyl is not running correctly. You may have more than one. As far as cleaning the FIs, they have an injector tool that cleans them out with pressure. I dont think you can do it by hand since there are electrical connectors as well. Just take it to your local mechanic and get them to do the top carbon purge (I think thats the name).......cost about $80.

08-16-2007, 02:38 AM	#10
crabtruck Senior Member Join Date: Jul 2007 Location: on your 9 Posts: 3,366	Amazing how many problems come back to fuel or wiring. Thinking about throwing away all my wrenches and buying a new dvm and a gas can

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