2006 5.3 2WD Tahoe missing going up hill sometimes

[2006Tahoe2WD]

My 5.3 only has 171k miles. I got it at 100k miles and have been keeping up on the maintenance. The plug and plug wires are about 65k old.
In the last year or so it feels like I'm getting a definite miss going up hill at freeway speeds at medium to heavy throttle but not enough for it to kick down. This doesn't seem to happen all the time in the same conditions. No money lights are coming on. At all other times it runs smooth as butter.
I'm pretty sure I have the original fuel pump and filter. I don't recall where the filter is or if I've seen it.
What do you recommend to start digging in to this issue? Some things mentioned..
- clean mass air flow sensor
- replace air filter (I just did this)
- run Lucas fuel system cleaner
- fuel pressure might be low
- fuel filter might be "full"
- buy a scanner (what type?) and watch while I recreate the symptom, what ? fuel trim, miss-fires, fuel pressure, ? , ?

If there is already a thread on this please link.

Thanks.

 

[2006Tahoe2WD]

Geees, is it something I said?

 

[Fless]

Yes, clean the MAF. Consider replacing it with an OE MAF.

Pick up a scanner that will read individual cylinder misfires, and check those out, especially while the issue is happening.

I don't think your 2006 has an inline fuel filter, just the filter on the fuel pump pickup sock in the tank. If there is one inline, it would be on the driver's side frame rail underneath the back of the front driver's seat.

"Rent" a fuel pressure gauge from your local auto parts store -- they usually will rent them for a deposit, which is returned when the tool is returned -- and see if they can provide an extended hose so you can watch the fuel pressure (tape it to the windshield) while the issue is happening. Also do a standard KOEO (key on, engine off) fuel pressure test.

At night, pop the hood and fire up the truck, and use a spray bottle to mist around the coils and plug wires. Look for arcing.

 

[rockola1971]

Geees, is it something I said?

You arent getting a flashing check engine light but you believe you are getting misses? Have you verified miss counts and what cylinders are doing it on a scanner? Are you sure you arent experiencing torque converter unlock shudder? The TC will unlock around 45 MPH or under heavy engine load going up a hill depending on throttle load and speed.

 

[2006Tahoe2WD]

okay, thanks guys... I'll start working on it. I don't think it is translock shudder it is happening at about 60MPH or so. Like driving over the Sunol Grade near Fremont CA.

 

[rockola1971]

okay, thanks guys... I'll start working on it. I don't think it is translock shudder it is happening at about 60MPH or so. Like driving over the Sunol Grade near Fremont CA.

Whats the history on your transmission? 171k is well past the typical number before tranny rebuild usually needs to happen. At 60MPH you could be experiencing 2-4 band slip in 4th gear which can be similar to what a misfire feels like when the engine and vehicle jerks. Does your RPM's jump up when this "misfire" symptom happens?

 

[2006Tahoe2WD]

Whats the history on your transmission? 171k is well past the typical number before tranny rebuild usually needs to happen. At 60MPH you could be experiencing 2-4 band slip in 4th gear which can be similar to what a misfire feels like when the engine and vehicle jerks. Does your RPM's jump up when this "misfire" symptom happens?

I don't hear the rpm jump - it just feels a bit jerky. I'm very easy on the tranny the fluid has been changed at 100k when I got it and at about 160k. Color and smell was good per the transmission technician. My thought at this point is to try a fuel pressure test and see if I can use a long hose and read the gauge when driving and see how the pump keeps up at high power levels.

 

[swathdiver]

- buy a scanner (what type?) and watch while I recreate the symptom, what ? fuel trim, miss-fires, fuel pressure, ? , ?

Tech-2

 

[Fless]

My '04 doesn't have a fuel pressure PID, and I think being able to read that didn't come until the NNBS. Count on using a mechanical fuel gauge.

 

[swathdiver]

My '04 doesn't have a fuel pressure PID, and I think being able to read that didn't come until the NNBS. Count on using a mechanical fuel gauge.

Yep, even the 2007s can't see fuel pressure in the computer, mechanical gauge only.

My initial thought on this post was cats, but Rockola's recommendations seem spot on.

 

[2006Tahoe2WD]

Thanks guys for the info./tips. Here is my getting-started list:
1 - clean mass air flow sensor
2 - Autozone borrow fuel pressure tester and test with key on and running.
3 - run Lucas fuel system cleaner
4 - attempt to find fuel filter under the vehicle
5 - take out one spark plug and see what it looks like (now about 60k on iridium aftermarket plugs) - I could be talked into new wires and plugs. What is the current best make/model of iridium plugs for 2006 5.3?
6 - drive to the place where I get the "missing" and see if I can recreate the miss.

 

[2006Tahoe2WD]

For a Denso Iridium I'm coming up with PN 5090 Iridium Long Life. The other number it is under is ZTJ16R10.

 

[2006Tahoe2WD]

The cross reference is a ACDelco 41-993 Professional Iridium Spark Plug
Added info. I think this plug has a 0.060" gap - I don't think that is right for my engine.

 

[2006Tahoe2WD]

I just ran into this new plug type.
NGK 94567 Specifications
Ruthenium HX High Ignitability
Supposed to last longer than iridium.
Anyone tried these?

 

[petethepug]

2nd on the fuel pump. Just x posted on another Tahoe with a similar stutter/ stumble. At least you can search for an OEM pump on R/A or Amazon now and not have to pay the GM premium price for having their part # and logo printed on the pump.

If you’re on your original fuel pump you’ve done good.

Congrats on getting that much life out of an OEM pump. The OEM units are made by VDO / Continental and Bosch. Add the GM logo on those same parts raises the price another $1 - $200.

I suspect with that chopper pic on your avatar your truck has benefited from military spec maintenance schedule. The only other thing you’ll want to swap out while the tank is down is the charcoal evap canister. It’s filled with thousands of activated carbon pellets held in place by a mesh (aquarium filter) media.

When that goes, it’s like letting thousands of minions into your fuel system that clog every orifice in their path. Order and replace the carbon canister while your doing the pump or you’ll end up doing it 2x to pull and clean the tank and all the lines again.

 

[rockola1971]

My '04 doesn't have a fuel pressure PID, and I think being able to read that didn't come until the NNBS. Count on using a mechanical fuel gauge.

That would be sweet to be able to see fuel pressure with a factory installed pressure transmitter. Would also make troubleshooting a dead fuel pump quicker too.

 

[2006Tahoe2WD]

This is so exciting....
I got the "loaner" fuel pressure test kit from Autozone.
Key on - goes right to 59-60 pounds.
Then bleed off and it doesn't go back up.
Then key on and start and it snaps to 59-60psi... if I bleed it goes down a bit and then snaps back to 59-60psi.
I think the pump is okay. Right?

 

[rockola1971]

This is so exciting....
I got the "loaner" fuel pressure test kit from Autozone.
Key on - goes right to 59-60 pounds.
Then bleed off and it doesn't go back up.
Then key on and start and it snaps to 59-60psi... if I bleed it goes down a bit and then snaps back to 59-60psi.
I think the pump is okay. Right?

If yours has the check valve in the fuel pump module then it shouldnt bleed off. How much is the pressure dropping?

 

[2006Tahoe2WD]

If yours has the check valve in the fuel pump module then it shouldnt bleed off. How much is the pressure dropping?

I don't think it bled off much maybe down to 30psi. I'll retry today and report back.

 

[Fless]

I don't think it bled off much maybe down to 30psi. I'll retry today and report back.

Document it over time. For example, 60 lbs initially, 45 lbs at 1 min, etc. Or use seconds if it's faster than that!