V8 Just Died at a Stoplight...

[cice]

Hi folks,
I have a 2007 V8 with 238k miles. It still runs like new... except today, while sitting in traffic at a stoplight I looked down and the engine had just stopped. The CEL, battery, and oil lights were all on. I put it in park, turned the key and it fired right back up. No CEL and no pending codes. I've driven it around tonight and it hasn't had any issues. No hesitation, sputtering, or randomly shutting off. Just rock solid like usual. I filled up the tank and added a can of Sea Foam. Any other ideas on what could have caused the random engine stop? :shrug:

Thanks!

 

[rdruss]

No solid ideas, but when last do plugs, timing belt, battery? Check your battery terminals for one being loose.

 

[cice]

Excellent suggestions, thank you! Plugs are due at 240k (already have them in the garage). Battery terminals are solid and connected well (had that happen before where they were loose) Timing belt was done about 30k miles ago. Battery is 2-3 years old.. but the engine cranks really hard so I think the battery is fine...

 

[cice]

It seems... and now I'm biased... to idle lower than it used to. It ideas around 500 - 480 RPM when the A/C compressor isn't running. Could that be the issue? The RPMs dropped too low and the ECU shut off the engine?

 

[MrSeth]

No solid ideas, but when last do plugs, timing belt, battery? Check your battery terminals for one being loose.

I am going to second that you check your serpentine belt AND battery terminals. Sometimes they can wiggle off or just be loose enough to kill it.

 

[cice]

What do you mean by check the timing belt? It is buried in the engine... Do you mean the serpentine belt?

 

[MrSeth]

It seems... and now I'm biased... to idle lower than it used to. It ideas around 500 - 480 RPM when the A/C compressor isn't running. Could that be the issue? The RPMs dropped too low and the ECU shut off the engine?

FSM states 650 to 750 rpm at idle is normal (for reference)

I once had a DIRTY air filter on my V8 and it low idled too. Lost power on acceleration, sputtered etc.. I wonder if its that?

 

[MrSeth]

What do you mean by check the timing belt? It is buried in the engine... Do you mean the serpentine belt?

sorry friend, yes, serpentine belt. If they are hard and worn, they can slip a lot leading to your alternator not charging your battery or powering your vehicle as well as it could be.

 

[rdruss]

Ever cleaned your mass air sensor and throttle body?

 

[cice]

Thanks guys, changed the air filter two weeks ago and also cleaned the MAF. Serpentine belt is a good idea though, and the A/C was cycling so maybe it slipped...

 

[Zero0575]

Any chance you have a secondary air pump bypass kit? I had the same issue, eventually giving me rich codes after dying a couple times. Ended up being my secondary air pump bypass went bad. Lifetime warranty replaced for free, and no issues since replacing.

 

[cice]

It did it again today. What bypass kit did you have installed? The slyfox one?

 

[gaber6]

Maybe a small vacuum leak?
Perhaps a dying battery also. I had many electronic gremlins when my battery was going.

 

[xtremewlr]

It did it again today. What bypass kit did you have installed? The slyfox one?

Clean the throttle body as rdruss suggested.

Change the spark plugs that you said you have sitting in the garage.

Disconnect the battery for about 30 minutes, while you clean the TB and change the plugs to reset the ECU.

I'd also take the battery into an Autozone and have it checked. Even though it cranks fine, it might be end of life at 3 years old and causing weird things to happen.

 

[Zero0575]

It did it again today. What bypass kit did you have installed? The slyfox one?

Hewitt.