Engine dies - but why?

[Jobi-Wan Kenobi]

Researching this myself but figured I'd see what the brain trust had to say. Has anyone had an issue where the engine just randomly dies? I've had this twice now this week. Monday I was driving through a parking lot at idle and the engine just died for no reason that I could tell. It started back up fin right away. The vehicle didn't lose electrical power. No fault codes to indicate anything related. But happened again tonight when I was sitting parked idling. My first was fuel pump but the reading I've done so far seems to say otherwise.

 

[iamdub]

Researching this myself but figured I'd see what the brain trust had to say. Has anyone had an issue where the engine just randomly dies? I've had this twice now this week. Monday I was driving through a parking lot at idle and the engine just died for no reason that I could tell. It started back up fin right away. The vehicle didn't lose electrical power. No fault codes to indicate anything related. But happened again tonight when I was sitting parked idling. My first was fuel pump but the reading I've done so far seems to say otherwise.

I wouldn't wanna drag your chunky ass around in this heat, either.














... Check your battery charge, positive and ground cables. Loose ignition switch? Does your keychain look like this?

 

[Jobi-Wan Kenobi]

@iamdub right, the thing can barely seemingly move its own ass sometimes

Anyway, battery is only a few months old but I can check the voltage in the morning. Alternator was actually just replaced a few weeks ago. I did read some stuff about failed ignition switches and pass-lock issues. Keys are pretty minimal though.

 

[swathdiver]

First thought it fuel pump, second is cats.

 

[nonickatall]

I would check, as already said by @iamdub the the engine mass points.

Good idea would be ne to use a scan tool, show live data of ignition and injection, and look i case of engine failure, what you see. If it's a problem with engine control, ignition switch oder something else, you should see that they are both switched off.

I would also check the other relevant values/sensors like MAF, O2 sensor, fuel pressure.

I had once a car which had a similar problem and I looked a long time for the problem. In my case it was a combination of a clogged fuel filter, a weak O2 Sensor and a fuel pressure which was slightly out of range, due to a wear our fuel pressure regulator.

I had another car which had the same problem, there it was the engine control unit...

 

[Jobi-Wan Kenobi]

I checked battery voltage this morning. From sitting over night it was reading 12.3v and then 13.9v when running. The positive connection was actually a bit loose bit ground was tight. Suppose monitor for now and see if it happens again and then dive in deeper.

 

[nonickatall]

A bad positive connection is as worse as a bad mass (negative connection)

 

[Jobi-Wan Kenobi]

Well the loose positive connection was a good find this morning but it didn't fix the issue. The engine died on me twice tonight while I was in town. When this happens again though I need to pay attention to whether or not I need to cycle the ignition off for it to start again. The first time it happened tonight I had to try starting it a few times before it actually started, but it didn't start until after I cycled the ignition (maybe was just coincidence). I also didn't notice whether or not the pass-lock light was on.

 

[mwilson62000]

It always happen at idle?

 

[CBIII]

Do you have solid fuel pressure?

 

[Jobi-Wan Kenobi]

@mwilson62000 it's not limited to just idle. The second time it happened last night I was driving through town at roughly 30 mph.

@CBIII right now I don't have anything to monitor fuel pressure. I only have a phone app and it does appear to be one of the parameters it looks at.

 

[mwilson62000]

@mwilson62000 it's not limited to just idle. The second time it happened last night I was driving through town at roughly 30 mph.

@CBIII right now I don't have anything to monitor fuel pressure. I only have a phone app and it does appear to be one of the parameters it looks at.

Ok. Just wondering. Years ago, my Tahoe almost died on me several times when stopping and it was simply the throttle body needed a good cleaning.

 

[Marky Dissod]

Years ago, my Tahoe almost died on me several times when stopping and it was simply the throttle body needed a good cleaning.

Had this EXACT same problem a month ago. Cleaned the throttle body, problem GONE.

 

[Jobi-Wan Kenobi]

@mwilson62000 and @Marky Dissod when you experienced this did the engine stumble at all? Mine runs fine and it just instantly shuts off. I've had the intake tube off a couple times but haven't noticed anything in the throttle body.

 

[Marky Dissod]

Technically it 'stumbled' as I'd approach a red light or stop sign. If I didn't use my left foot to brake and my right foot to gas the idle over 700RpM, the stumble would land on its face and the engine would shut off every time I failed to intervene.
Thought it was a battery / alternator issue. Turned out to be a gunked up throttle body.
Removed it, cleaned it, put it back on, problem was gone without a trace.

 

[wjburken]

@mwilson62000 it's not limited to just idle. The second time it happened last night I was driving through town at roughly 30 mph.

@CBIII right now I don't have anything to monitor fuel pressure. I only have a phone app and it does appear to be one of the parameters it looks at.

Go to AutoZone and “rent” a fuel pressure gauge kit. Hook it up so you can tape the gauge to your windshield and see what it shows.

 

[Fless]

@CBIII right now I don't have anything to monitor fuel pressure. I only have a phone app and it does appear to be one of the parameters it looks at.

There's no fuel pressure sensor on an NBS; to monitor it you'll need to rent or buy a fuel pressure test kit like @wjburken suggested.

 

[mwilson62000]

Ok. Just wondering. Years ago, my Tahoe almost died on me several times when stopping and it was simply the throttle body needed a good cleaning.

Had this EXACT same problem a month ago. Cleaned the throttle body, problem GONE.

Mine was just like @Marky Dissod Stumbled bad, but didn’t cut off. Be worth taking the intake tube off and cleaning up the throttle plate with some throttle body cleaner.

 

[Jobi-Wan Kenobi]

Alright, well I can definitely get the intake tube pulled off anyway and clean out the throttle body. I'll see about picking up a fuel pressure gauge tomorrow.

 

[CBIII]

Any luck?