'17 LS struggling on mountain roads

[GranPrix]

So I’m currently in the Blue Ridge GA area where many of the roads have an incline/decline of up to 9deg. My LS Tahoe seems to struggle going up these roads whether I manually shift it or let the truck shift on its own. Does anyone else have this issue? Only mods it has is a magnaflow muffler.

 

[OR VietVet]

9 degrees is a pretty steep incline. Might/maybe/could do better with a higher octane fuel but it is just likely the steepness of the incline on a stock engine. No cel's I assume and no felt misfires?

 

[swathdiver]

It's got 3.08s or 3.23s right? Might hold it in 3rd or 4th to keep the RPMs up.

 

[GranPrix]

9 degrees is a pretty steep incline. Might/maybe/could do better with a higher octane fuel but it is just likely the steepness of the incline on a stock engine. No cel's I assume and no felt misfires?

It had a misfire at one point when I went to manual and it automatically threw it into 4th gear. It was brief and no issues since

 

[Sparksalot]

So I’m currently in the Blue Ridge GA area where many of the roads have an incline/decline of up to 9deg. My LS Tahoe seems to struggle going up these roads whether I manually shift it or let the truck shift on its own. Does anyone else have this issue? Only mods it has is a magnaflow muffler.

9 degress or 9 %, there's a significant difference. Either is steep, and I wouldn't expect a lot of giddy up and git.

 

[OR VietVet]

9 degress or 9 %, there's a significant difference. Either is steep, and I wouldn't expect a lot of giddy up and git.

Yea, I didn't catch that. Good one.

 

[GranPrix]

9 degress or 9 %, there's a significant difference. Either is steep, and I wouldn't expect a lot of giddy up and git.

Degrees but not many, mostly in the 3-5 range.

 

[Doubeleive]

It had a misfire at one point when I went to manual and it automatically threw it into 4th gear. It was brief and no issues since

misfire for any reason is a sign something is wrong, maybe it's time for some maintenance

 

[GranPrix]

misfire for any reason is a sign something is wrong, maybe it's time for some maintenance

It has new plugs and wires, tranny flush, fresh oil every 5k

 

[Doubeleive]

It has new plugs and wires, tranny flush, fresh oil every 5k

where did you source the plugs and wires? how many miles? how old is the maf? has it been cleaned?
if the plugs and wires are new that leaves coil packs being a possible source of a misfire.
maybe try and do a drive record and see what the data says is going on, see what the fuel trims are, etc.
any change in mpg? how old are the cats?

 

[GranPrix]

107k OEM plugs and wires. MAF was cleaned about a year ago and was checked before the trip. Coils are still originals. Had to hold off on those… $$$ Original cats… I should get new cat sensors now that you mention it. MPGs haven’t changed, getting an avg of 18

 

[BlaineBug]

Clean the MAF sensor with appropriate MAF sensor cleaner for starters.

Nevermind, saw your page 2 reply.

 

[BlaineBug]

107k OEM plugs and wires. MAF was cleaned about a year ago and was checked before the trip. Coils are still originals. Had to hold off on those… $$$ Original cats… I should get new cat sensors now that you mention it. MPGs haven’t changed, getting an avg of 18

Was it legitimate mass airflow sensor cleaner? Brake cleaner can cause issues. CRC MAF sensor cleaner leaves NO residues on the sensor wires unlike other solvents.

 

[Doubeleive]

I hate to say it but if the engine is running good then you have to start poking an eyeball at the transmission
but you shouldn't have a misfire, how did that occur? check engine light?

 

[GranPrix]

Was it legitimate mass airflow sensor cleaner? Brake cleaner can cause issues. CRC MAF sensor cleaner leaves NO residues on the sensor wires unlike other solvents.

Yea legit MAF cleaner

 

[GranPrix]

I hate to say it but if the engine is running good then you have to start poking an eyeball at the transmission
but you shouldn't have a misfire, how did that occur? check engine light?

I thought about that.

The check engine light came on briefly. I was driving in automatic and switched it to manual so I could downshift it myself. When I did that it for some reason it threw it into 4th gear and rpms shot up to 4k and I up shifted to 5th immediately and everything went back to normal. Check engine flashed for like 3 sec.

 

[Doubeleive]

any history codes saved? if the cel came on and you haven't disconnected the battery since then, then there should be a historical code saved

 

[GranPrix]

any history codes saved? if the cel came on and you haven't disconnected the battery since then, then there should be a historical code saved

P0113
P0300
P2227
P2228

 

[Doubeleive]

P0113
P0300
P2227
P2228

aside from the random misfire those all appear to me to be intake related problems, which I bet could be causing the misfire.
I am no expert but if it were me I would maybe check for a intake leak by spraying some starting fluid around the edges of the intake and see if the idle changes and inspect the whole intake and make sure everything is on nice and tight, nothing incorrectly installed, cracked or broken, if nothing happens then aside from paying for a shop to check it I might just replace the maf sensor and map sensor and possibly even the throttle body, yes that's a shotgun approach and not the right way but if there is no unmetered air getting in then it has to be something
@swathdiver may have a more diagnostic approach, but you need a tool like a tech2 to help

 

[houstontaylor]

My 2003 Tahoe has no problem with the mountains of Colorado. I did replace the engine at 290,000 miles (now has 331,000 miles) due to sudden increase in oil use and that did help with hills and acceleration but it wasn't bad before that either.