6.0 LQ4 Rough idle cold start. ??? Bad Intake Gaskets ??

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Thinking its the typical common intake gaskets leaks ??
smirk2.gif


Valve cover gaskets were done last year with updated Fel pro blue gaskets


Application:

2001 Silverado HD LQ4 6.0 with 150K miles

Already New fuel pump, New WIX fuel filter, AC/DELCO tune up, LOTS of fuel cleaner, DEEP cleaned the intake with Gumout+PEA

No CEL, But my creade code reader got a codes P0171 P0174 ??

Very bad idle-sputtering in cold start, then after 2-3 minutes ECM compensates, warms up and runs great ??

Also i think i'm going nuts crazy, But looks like no EGR valve gasket also ?? Gonna get new one at AZ today and pull out EGR and see whats up ??

Dave
 
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Have you ever replaced the intake gasket? It is probably time. The EGR stovepipe has an O-ring where it goes into the intake. The EGR itself has a gasket.
 
Originally Posted by ls1mike
Have you ever replaced the intake gasket? It is probably time. The EGR stovepipe has an O-ring where it goes into the intake. The EGR itself has a gasket.



Nope i havent replaced it yet. A job I dont have time/skill to do and prefer to find someone VERY qualifed to do !!

And I was referring to the EGR valve near the fan assembly. I have had MANY of these trucks and done a few EGR gaskets in the past. To me it looks like there's NOTHING between the EGR valve ???
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[Linked Image]
 
Originally Posted by classic70
Check IAC and clean well, check for vacuum leaks. Check fuel pressure to see what it is at idle.



IAC i'll have to see. VAC leaks and fuel pressure have been checked before and nothing found ?? MAF sensor I haven't cleaned either ill do that tonight when I replace EGR valve gasket

Dave
 
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Here is the TSB number for the intake gasket problem.GM TSB #02-06-04-023A.

If you haver not done it at 150,000 it is time. The intake gasket on these takes about an hour and half. I have done about 10 of them. 5 on my own cars for various reasons. (2 on the WS6 for heads and cam and new LS6 intake, 1 on the Caprice for cam swap, 2 on my old 2500hd once to do knock sensors, once to do the actual gasket. 5 times on other people's stuff. Just about any Mechanic can do it. No oil or coolant touches the intake so it is simple.

My 02 2500HD did the same thing.

Those two codes with no check engine light are classic intake gasket. So it runs rough cold and smooths out with warm as the everything expands most likely partially sealing the gasket, but you still get unmetered air flow.

Have the Knock sensors ever been done?


How long have you owned it?
 
Is there a cut off year for intake gasket? Mine was a 02 build date in Express but had the new ones. 01 perhaps since Mike had a 02 (build date 01?) and this one is a 01? Pull one of the intake bolts and if it has blue loctite on it that might a good indicator?
 
Originally Posted by ls1mike
Here is the TSB number for the intake gasket problem.GM TSB #02-06-04-023A.

If you haver not done it at 150,000 it is time. The intake gasket on these takes about an hour and half. I have done about 10 of them. 5 on my own cars for various reasons. (2 on the WS6 for heads and cam and new LS6 intake, 1 on the Caprice for cam swap, 2 on my old 2500hd once to do knock sensors, once to do the actual gasket. 5 times on other people's stuff. Just about any Mechanic can do it. No oil or coolant touches the intake so it is simple.

My 02 2500HD did the same thing.

Those two codes with no check engine light are classic intake gasket. So it runs rough cold and smooths out with warm as the everything expands most likely partially sealing the gasket, but you still get unmetered air flow.

Have the Knock sensors ever been done?


How long have you owned it?



Ya Mike thinking the same thing on intake gaskets
thumbsup2.gif
I bought the truck last summer and just been using it around town carry parts/packages for my business, no towing or off roading.


And ya I know when the intake gaskets are done its best to replace the knock sensors, I know those are common failures also.


Sucks have to find a GOOD mechanic for that job. Back when I was in your neck of the woods few years ago, There was a guy who worked at a GM dealer in Tacoma who did stuff on the side in Olympia. His prices were VERY good for the skill and work he did.


Trying to find someone like that here in Dallas


Dave
 
Originally Posted by GMguy84
Originally Posted by ls1mike
Here is the TSB number for the intake gasket problem.GM TSB #02-06-04-023A.

If you haver not done it at 150,000 it is time. The intake gasket on these takes about an hour and half. I have done about 10 of them. 5 on my own cars for various reasons. (2 on the WS6 for heads and cam and new LS6 intake, 1 on the Caprice for cam swap, 2 on my old 2500hd once to do knock sensors, once to do the actual gasket. 5 times on other people's stuff. Just about any Mechanic can do it. No oil or coolant touches the intake so it is simple.

My 02 2500HD did the same thing.

Those two codes with no check engine light are classic intake gasket. So it runs rough cold and smooths out with warm as the everything expands most likely partially sealing the gasket, but you still get unmetered air flow.

Have the Knock sensors ever been done?


How long have you owned it?



Ya Mike thinking the same thing on intake gaskets
thumbsup2.gif
I bought the truck last summer and just been using it around town carry parts/packages for my business, no towing or off roading.


And ya I know when the intake gaskets are done its best to replace the knock sensors, I know those are common failures also.


Sucks have to find a GOOD mechanic for that job. Back when I was in your neck of the woods few years ago, There was a guy who worked at a GM dealer in Tacoma who did stuff on the side in Olympia. His prices were VERY good for the skill and work he did.


Trying to find someone like that here in Dallas


Dave


I am in the DFW area and can probably work your job into my schedule in a few weeks because I am backlogged at the moment. I work full time for the GM plant working 7 days a week plus running my shop. I've done a few including my own 6.0 in my Sierra Denali. It really is not a difficult job.
 
Last edited:
Originally Posted by GMBoy
Originally Posted by GMguy84
Originally Posted by ls1mike
Here is the TSB number for the intake gasket problem.GM TSB #02-06-04-023A.

If you haver not done it at 150,000 it is time. The intake gasket on these takes about an hour and half. I have done about 10 of them. 5 on my own cars for various reasons. (2 on the WS6 for heads and cam and new LS6 intake, 1 on the Caprice for cam swap, 2 on my old 2500hd once to do knock sensors, once to do the actual gasket. 5 times on other people's stuff. Just about any Mechanic can do it. No oil or coolant touches the intake so it is simple.

My 02 2500HD did the same thing.

Those two codes with no check engine light are classic intake gasket. So it runs rough cold and smooths out with warm as the everything expands most likely partially sealing the gasket, but you still get unmetered air flow.

Have the Knock sensors ever been done?


How long have you owned it?



Ya Mike thinking the same thing on intake gaskets
thumbsup2.gif
I bought the truck last summer and just been using it around town carry parts/packages for my business, no towing or off roading.


And ya I know when the intake gaskets are done its best to replace the knock sensors, I know those are common failures also.


Sucks have to find a GOOD mechanic for that job. Back when I was in your neck of the woods few years ago, There was a guy who worked at a GM dealer in Tacoma who did stuff on the side in Olympia. His prices were VERY good for the skill and work he did.


Trying to find someone like that here in Dallas


Dave


I am in the DFW area and can probably work your job into my schedule in a few weeks because I am backlogged at the moment. I work full time for the GM plant working 7 days a week plus running my shop. I've done a few including my own 6.0 in my Sierra Denali. It really is not a difficult job.



Awesome !!! thanks for the offer
thumbsup2.gif
So you work at the SUV plant in Arlington ?? Man you must be VERT BUSY at that place getting ready for new models coming out soon.


I guess PM me your info and we'll get in touch when your ready ???


I'll order the intake gaskets and knock sensors so i'm ready when you are
thumbsup2.gif




Dave
 
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