2006 Avalanche Engine Issues

[Daniel MacElfrish]

Hello!

 

Our 2006 Avalanche has been having some issues the last couple of days: it loses power and the engine light flashes when under load before going back to normal at lower power. Got the codes checked; the most likely issue was the mass airflow sensor. That got replaced this morning, but it still acts up.

 

The other codes pulled were:

 

P0300 engine misfire detected; it's supposed to have 100,000 mile spark plugs in it, and it hasn't reached that point yet. Coils, then, perhaps?

 

P0449 EVAP Vent Solenoid Valve Control Circuit, though I'm not sure that would have this effect.

 

It also threw up a C0110 Pump Motor Circuit Malfunction for the ABS system, though I'm not sure that would have an effect this that either.

 

Any help you could give would be much appreciated!

[richard wysong]

The flashing CEL indicates a misfire. A good scan tool will tell you which cylinder(s) are misfiring then you can start diagnosing the cause. I would start  by changing the plugs and checking the compression on the affected cylinders. If the misfire still exists after that try swapping the coils around and see if the mis follows the coil. Welcome to the forum! The EVAP and ABS problems will NOT cause a misfire

Edited March 9, 2024 by richard wysong

[Daniel MacElfrish]

Richard,

 

Thanks! We'll get those checked out!

[Douglas Nathan]

13 hours ago, richard wysong said:

The flashing CEL indicates a misfire. A good scan tool will tell you which cylinder(s) are misfiring then you can start diagnosing the cause. I would start  by changing the plugs and checking the compression on the affected cylinders. If the misfire still exists after that try swapping the coils around and see if the mis follows the coil. Welcome to the forum! The EVAP and ABS problems will NOT cause a misfire

 

[Douglas Nathan]

Thanks Richard, this is my son helping his Mom. She iwns my former Avalanche now, she bought it a little while back. Any assistance you can offer him is greatly appreciated!

[newdude]

22 hours ago, Daniel MacElfrish said:

Hello!

 

Our 2006 Avalanche has been having some issues the last couple of days: it loses power and the engine light flashes when under load before going back to normal at lower power. Got the codes checked; the most likely issue was the mass airflow sensor. That got replaced this morning, but it still acts up.

 

The other codes pulled were:

 

P0300 engine misfire detected; it's supposed to have 100,000 mile spark plugs in it, and it hasn't reached that point yet. Coils, then, perhaps?

 

P0449 EVAP Vent Solenoid Valve Control Circuit, though I'm not sure that would have this effect.

 

It also threw up a C0110 Pump Motor Circuit Malfunction for the ABS system, though I'm not sure that would have an effect this that either.

 

Any help you could give would be much appreciated!

 

 

Any ticking or tapping or knocking?  

 

Just because the plugs "say" they are 100k mile plugs doesn't mean they will last 100k mi.  Pull them and check them.  Replace with OE ACDelco plugs only as well.  Aftermarket ignition components and O2 sensors on GM vehicles do not agree.    

 

The other two codes won't lead to a misfire.  

[dna9656]

1 hour ago, newdude said:

 

 

Any ticking or tapping or knocking?  

 

Just because the plugs "say" they are 100k mile plugs doesn't mean they will last 100k mi.  Pull them and check them.  Replace with OE ACDelco plugs only as well.  Aftermarket ignition components and O2 sensors on GM vehicles do not agree.    

 

The other two codes won't lead to a misfire.  

The plugs are AC Delco (the sexy, expensive ones, iridium or some such) I believe. We are agreed Non-GM ignition, emission, and fuel parts don't agree with GM products. The truck was once mine, my son is taking charge of the maintenance and I'm getting him prepared to use this forum (and others) for solid advice on issues. I changed the "O" ring , oil pick up tube, timing chain and sprockets 3 years ago (maybe) and the ticking (rocker arms) went away and while I was in there I replaced all the rocker arms with quality units in case any needle bearings had come out of the arms; I think I read someplace that was sometimes happening. At the same time the oil pump was replaced with a Mellings Hi Volume oil pump, the  engine now produces a wonderful 40 PSI at idle, fully warmed up.  The fuel computer in the dash was informing me that while on the freeway, at 60 MPH, we were getting 20 MPG; I good increase over the 14 to 16 previously.  I also replaced a coil or 2 and may still have a 3rd on hand. It has slotted and drilled rotors all the way around, a new cat back, shocks, tires and the front suspension rebuilt. I installed a new fuel pump, a oil pressure sending unit (it's on it's 2nd one, it's GM too. I changed out the axle lubes, the outer rear axle bearings, added new shocks too,plus a new set of tires at Costco. There is a very good and reasonable upholstery shop in Texas that made a a bottom seat cover for it that matched perfectly. the original had "been the route" and I replaced it. THAT took a lot of strength! It has a new water pump and power steering pump, A POS after-market radio that was poorly installed. The A/C needs work, it has a leak somewhere. I have a set of seals I hope to install this summer, then take it to a shop to get charged. I have a new driver's seat belt to install, it is safe but returns very slowly.

[dna9656]

Firestone says it's a coil.

[Daniel MacElfrish]

Everyone,

 

Thank you for your replies! Indeed, replacing the #6 coil has cleared the code from the computer.

 

Thank you for your time and assistance!