Sputtering, stalling, low power..

[harryhoudini]

Occasionally the truck will stall. RPMs drop really low, it sputters a bit and stalls. Can't say it is at any particular time. Truck could just be driven, I turn it off, run in a store and when I start driving away it will stall. Only when on the brake or at low speeds when the RPM's drop down around the 1k range is when they sometimes drop to the 200 range and then it stalls.

I can't decide if it is eletrical causing not enough juice (alternator, battery) or if the engine isn't getting enough air/fuel/spark to make the power.

90k service just done (fluids, etc) but spark plugs were not replaced. Battery could be original, not sure.

What do I look at first? Battery? Alternator? Spark? Air?

Intake air filter is clean/new.



On another side note... brakes are squeeling. New pads and rotors (OEM) and it generally is not pad accidentally touching the rotor, it is under semi-hard braking. So I am guessing it needs some anti-squeel to stop the pads from vibrating against the calipers when friction is present. Sound right?

 

[KathmanduCruiser]

My two guesses are either the throttle body needs cleaning or that the vaccum hoses need replacement.

 

[harryhoudini]

Ahh.. good stuff. Any tips on cleaning the TB?

Would I know if the hoses need replacement from a visual (cracked, dry hoses) or does that require a pressure/smoke test?

 

[jp213a]

Occasionally the truck will stall. RPMs drop really low, it sputters a bit and stalls. When on the brake or at low speeds when the RPM's drop down around the 1k range is when they sometimes drop to the 200 range and then it stalls.

90k service just done (fluids, etc) but spark plugs were not replaced. Battery could be original, not sure.

Take it to one of the chain autopart stores and have them pull the diagnostic codes with their scanner. This is usually a free service. They can also test your battery. jp

 

[harryhoudini]

Thanks.. no engine light, would I still have codes?

Had a light before, it was the o2 sensor pre cat pass side.. it was replaced, code cleared and no more light.

Could it be that sensor bad or another one? I'll take it to my standard place as I really don't have the time to do much more than post the question

 

[Wellcraft19]

Unlikely a bad O2 sensor would wreak that much havoc.
As said before, I'd check the throttle body and hoses for vaccum leaks.
You can easily lift the aircleaner out of the way (note a few hoses) and then get good access to the throttle body. Clean it out with a rag. Or, if more thorough, remove it (still "connected") so you can clean it easier on both sides of the throttle plate.

 

[Jim_Chow]

I followed lexusben's tips on cleaning the TB (left it on the car). I sprayed carb cleaner on a rag and rubbed around the TB flap. For stubborn carbon buildup, I used a stainless brush (like a toothbrush) to scrape loose the deposits. You can gently push the flap in as long as the key isn't in the ignition. Don't spray car cleaner directly into the TB, as the sensor is at 12 o'clock and it can be damaged by the cleaner. I had buildup at 58K mi, not a whole lot, but some. Better than waiting for the TB flap to stick to the carbon and have it throw a code. Otherwise, the dealer will diagnose it as a bad TB, replace the entire TB (like $1500). I've added TB cleaning every 30K mi to my PM list although it's not spec'd in the manual.

 

[Cruiser4UGA]

Sounds like a mass air flow sensor to me.