Tahoe started to run weird!

[hertahoe]

2005 Tahoe LT with 136k 5.3l. It has never done this and has always ran smoothly! So last night I took her truck to the store about 10 minutes away. All was going well until I got into parking lot. Was stopping at stop sign and it started a slight surging effect. Put it in neutral and could still feel something isn't right. Put it back into D and hit a spot. Put it in and out of D a couple of times and same thing. Went and got a few items and looked underneath and no fluid leaking. Runs fairly smooth and no other sounds than it running a bit rough. **** it, lets go. Took off slowly and way down on power and seemed like it was missing, but no loud sounds, like backfiring. Get to first light, put it in neutral and looked at gauges and all seemed good expect the gas mileage readout. When I stated it said range was about 167milles. Now it stated 75 and started to go back above 100. I noticed a small bit of steam/smoke coming from front right of hood. But very small. Took off slowly and was surging, but not like a bucking bronco. Got it back the 3 miles to driveway. Opened up hood and no leaks visible (nor this morning) and idling decently and no signs of smoke or steam. This is baffling to me.

Edit: The check engine (yellow) would flash on and off. Not constantly flashing. I will admit, I don't have a OBD reader. So which one should I get?

 

[corvette744]

Maybe start by going to autozone for a free code reading-see what cha got.

 

[Cbncanada]

A little water in the fuel perhaps.

 

[SnowDrifter]

If you start it up now, after everything is cool, how's it run?

 

[hertahoe]

A little water in the fuel perhaps.

Could be, but it's garaged and use Costco gas. Had gone on a trip to her mother's that is 125 each way and drove like it always has. I could put some seafoam in.

 

[hertahoe]

If you start it up now, after everything is cool, how's it run?

A little off. Just ran to Autozone and picked up a reader. It has P0301 code. Could be plugs, wires, coil pack, injectors or vacuum leak. So the chase begins.

 

[hertahoe]

Maybe start by going to autozone for a free code reading-see what cha got.

Just went to Autozone and picked up a reader. Code P0301

 

[gooffeyguy]

That code is cylinder 1 misfire.

A vacuum leak would generate random cylinder misfires

I'd clear the code and see if it comes back the same after driving it. If it does, check and make sure spark plug and wire is tight, and maybe swap coil with another cylinder and clear code again and see if same one comes back of if it changed to the other cylinder you put the coil on.

 

[Fless]

If your scan tool can count or graph the misfires by cylinder number, that would give you more insight into which one might be misfiring. Don't lend too much credence to the cylinder number by just the code.

 

[Scottydoggs]

flashing cel generally means one of two things. you need a tune up real bad, or one or both cats are clogged up solid.

 

[corvette744]

Cylinder 1 -spark plug if your gonna pull it replace it-plug wire switch number 1 with next closest cylinder-if still shows code p0301 then switch coil to next cylinder as stated earlier.If code moves you know what it is.If after all those and still shows p0301 pull injector connector if it doesnt run rough it in the injector or harness.Noid light or as stated in another previous post 194 bulb watch for flashing.

 

[SnowDrifter]

Pop the plug put of cylinder 1 and see how it looks!

It's the driver's side front most. Right. Behind the alternator

Could be as simple as plugs and wires. To a piece of sediment or something got lodged in an injector. To rodent damage.

Also check your plug wired and make sure those aren't melted or cracked

Little unusual that a plug would go from nothing to presenting itself so strongly, but that's first step to check.

Don't go running out and buying parts just yet though. We're just doing a quick visual inspection.

 

[iamdub]

Put gas in it? Maybe the gauge isn't reading accurately and you're actually on fumes. That slight bit of "smoke/steam" could've been steam off the brakes. You said you noticed it when you had just come to a stop. Your location says Washington- was it wet out?

 

[hertahoe]

Pop the plug put of cylinder 1 and see how it looks!

It's the driver's side front most. Right. Behind the alternator

Could be as simple as plugs and wires. To a piece of sediment or something got lodged in an injector. To rodent damage.

Also check your plug wired and make sure those aren't melted or cracked

Little unusual that a plug would go from nothing to presenting itself so strongly, but that's first step to check.

Don't go running out and buying parts just yet though. We're just doing a quick visual inspection.

So I popped out #2 first because I wanted an easier test. It looked pretty worn. IIRC they have approx 40-50k on them and are the NGK V-power. I also smelt fuel, so something isn't burning properly. Probably best to get some plugs at the least. Then once I start to replace them, I can see if other plugs are bad or are fouled. I will go out now and look at #1. Didn't want to ask for advice and not follow it. Much appreciate all the responses! This community rocks! I need this thing to last since I will be taking it over in a few months. Have been looking at getting wife the 3.8 Duramax diesel Tahoe.

 

[hertahoe]

Put gas in it? Maybe the gauge isn't reading accurately and you're actually on fumes. That slight bit of "smoke/steam" could've been steam off the brakes. You said you noticed it when you had just come to a stop. Your location says Washington- was it wet out?

No. Had it idling a bit ago with no smoke. I don't hear any other abnormal sounds either.

 

[hertahoe]

What plugs would be best?

 

[iamdub]

What plugs would be best?

OEM or equivalent! Just be sure they are genuine. Plugs are a hot item to have been counterfeited. Basically, if they're really cheap, they're likely knock-offs. Best case, they just wear out quickly. Worst case, they fall apart and cause major engine damage.

I'm not totally sure, but I think Gen 3 and Gen 4 engines take the same plugs. I put NGK Iridiums (TR5IX) in mine when I refreshed/upgraded the engine in mid-2020. Should be good for 100K miles at least.

 

[Donal]

NGK Laser Platinum Plug Number PTR5D-10 Spark Plug is my choice. They cost more but last the longest. Save the invoice and document the mileage. they have milage warrenty. Cost around 14.oo each.​

Fill the gas tank. If you have the tools check fuel pump. Fuel pressure should go to around 48-50 psi and hold, go down 10-12 psi and hold.

 

[swathdiver]

Tech-2 time. Use OE Plugs and wires.

I paid about $6 and change each for brand new OE plugs at RockAuto recently and got a $24 rebate check from GM.

https://parts-catalog.acdelco.com/acesCat.php?

 

[corvette744]

I would follow the procedure i outlined and others first.Yes if you pull number 1 i would replace it just to see if the miss is gone.But before replacing anything else do as outlined to narrow down the failure.Switching the plug wire and or coil to the next cylinder will tell you what the problem is if its ignition.If no change pulling injector connector and seeing if it pulses is the other area.po301 is specific to number 1 cylinder find the problem in that cylinder.Is the tahoe missing at all times-warm and cold.