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.