Occasionally dies right after startup, then starts fine afterward?

[jwill]

Hi Guys,

I'm a new member, I've been reading this site since ordering my Camaro in Jan, thanks for making such a great resource available! I've searched and can't find this topic covered yet, but I hope one of y'all have seen this before:

First, it's a totally stock 2011 LS3 (I haven't done anything but wash it). About once/twice a week, I go to start the Camaro, it starts, runs for maybe 1 second, then dies. After that happens, I start it up again and the car runs fine. It's never done this twice in a row, always after the start/die, it starts up and runs fine. Some more details: Yes, clutch is to the floor. Car is in neutral. Engine temp doesn't seem to be a factor (happens hot or cold), and time since being driven doesn't seem to be a factor (It's happened first startup in the morning as well as after a long run and only being off for 5 mins). Also, no check engine light. This started after my first service @ 3300 miles (@ the dealership). Not like *right after/same day*, but still it never happened before that and started about a few days later. The car has maybe 4500 miles on it now.

Any ideas? Because of the intermittent occurrence, I really don't want to take it to the dealer w/o a thrown code, they'll most definitely have the thing forever and it'll never happen. Thanks for any help!

[PQ]

MAF Sensor maybe?

[jwill]

Good idea, but wouldn't a MAF throw a code? Have you seen lots of MAF issues w/o codes? I doubt they'd replace that w/o one, unless there's a way to independently test the MAF, do you know of a way to do this?

[Fuel Fire Desire]

My 99 V6 vert did this too. No codes, no CEL, fuel smell after it died, and an increased fuel consumption. I changed just about every electronic sensor on it, even the fuel injectors. I had 2 shops and the dealer itself stumped as to what to do. It ended up being the reason I sold it. I do miss that car. :(

[jwill]

Wow, future may look bleak! I wouldn't sell based on this, but it's annoying for sure.

I googled testing MAFs, I found this. Will do and report back once I know, but just for future DIYers, here 'tis:

MAF sensors can be tested either on or off the vehicle in a variety of ways. You can use a MAF Sensor Tester and tachometer to check the sensor’s response. If testing on the vehicle, unplug the wiring harness connector from the sensor and connect the tester and tachometer. Start the engine and watch the readings. They should change as the throttle is opened and closed. No change would indicate a bad sensor.

The same hookup can be used to test the MAF sensor off the vehicle. When you blow through the sensor, the readings should change if the sensor is detecting the change in air flow.

[PQ]

Originally Posted by jwill

Good idea, but wouldn't a MAF throw a code? Have you seen lots of MAF issues w/o codes? I doubt they'd replace that w/o one, unless there's a way to independently test the MAF, do you know of a way to do this?

If your car is newer, then it woudnt' have the same early issues. Those arent really the same as you are describing anyway.

You'd think it would throw a code, yes. But since it dies so quickly and then starts back up no problems, it's possible that the code is not sent.

If you think about it, your car dying like that should send a code anyway. So the fact that there is no code is already an oddity. You can start your car and let it idle with no MAF at all. Of course it won't run right. But I've done that and not got a code before. So it's possible.

I'd take it to the dealer and just have them perform a test. It most likely wont' show anything but if the car does it while they have it then they can fix it.

Could be anything. Fuel, Air, Electonic etc etc etc. Get some video. Does the car run for a full second? Two seconds maybe? Does it actually start? Or just turn over with fuel and never actually stay for a bit?

[jwill]

The car definitely starts, and a second is a good approx. It's not *more* than a second, if anything it's less. Will report back after MAF test, Thanks for the lead!

[PQ]

Originally Posted by jwill

The car definitely starts, and a second is a good approx. It's not *more* than a second, if anything it's less. Will report back after MAF test, Thanks for the lead!

There's some type of hiccup in it for sure. My suggestion was just based on the fact that it does it seldom and random. I think it would do it twice in a row on one start-up but just hasn't randomly happened that way. Like maybe the MAF or different sensor reads funky air flow and sends a ton of fuel or not enough fuel in a manner that cuts the engine. I'd say clean the maf but your car is so new it shoudn't need it.

My AIT wires are not connected to the MAF sensor anymore because I routed them into my blower. So I'm not sure if that could be a possibility.

The random problems really suck. If it happend every time then you could just borrow one and try it.

[brianko]

Originally Posted by jwill

Any ideas? Because of the intermittent occurrence, I really don't want to take it to the dealer w/o a thrown code, they'll most definitely have the thing forever and it'll never happen. Thanks for any help!

My simple low-cost first step: Disconnect the negative battery cable first. Let it sit for a few minutes, then reconnect. Restart.

If that doesn't work, start looking elsewhere.

[Fuel Fire Desire]

Originally Posted by jwill

The car definitely starts, and a second is a good approx. It's not *more* than a second, if anything it's less. Will report back after MAF test, Thanks for the lead!

I dont know how the GM transponder keys work, but this sounds a lot like what my 08 jeep would do if I tried to start it with my cut key instead of the factory transponder key. It would start like normal, but then shut off exactly one second after.

IDK if the receiver could be not detecting the key on the first try, but its an idea to bring up to the dealer.

[BostonU93]

Any resolution on this? My 2014 Camaro started doing this at 5600 miles?

[cajun1le]

Has anybody hooked up a fuel rail pressure gauge to see what the static rail pressure is before start up, during and after?

[dirtyharry]

I bought my ZL1 new two years ago and it now has 20,000 miles. Here's what I found:

Mine started this at 800 miles. It was very intermittent. I started noticing that it happened warm, cold, or during an intermittent stop. It would fire immediately and then die (run for about half a second). The subsequent starts and drives were uneventful.

I finally had my dealer look at it when it went in for a bad Onstar sensor in the mirror (3000 miles). He said they found no codes, but ran an ethanol test on the gasoline and it came in at 9%. He stated that they had seen this on a couple of other LS engines (camaros and corvettes) He suggested switching gasoline.

I was using Chevron and Shell exclusively, but the service manager (been a customer of his for 20 years) said try Exxon. Apparently, they use the least amount of ethanol in their fuel. All summer blends have ethanol, but they supposedly have the least and some research claims that they have minimal to none in their winter blends.

I went 8 months before having another episode. Since then, I have only had a handful and two were on the same tank from a Shell station I filled up at when I was low on fuel. Since the switch (over a year ago) when running Exxon, I have only had it happen once when filling up at an unfamiliar gas station.

To further validate the theory, I filled up with Valero last week and my car died today for the first time in months... It seems that it dies (on all brands) in the summer more - which validates the ethanol theory.

In 20,000 miles I had the Onstar button, and a rear license plate light bulb go out. Other than that, the car has been flawless. It has seen rain, snow (not intentional), and never given me a problem. It is 100% stock except for a K&N filter and the upsized Michelin PSS tires. Mobil 1 and filter ever 5k, Cabin air filter every 10k, and Rear diff fluid change every 10k.

I drive the piss out of it, but only when the tires are warmed up and the oil is above 150 degrees.

Hope this helps.

[cajun1le]

Originally Posted by dirtyharry

I bought my ZL1 new two years ago and it now has 20,000 miles. Here's what I found:

Mine started this at 800 miles. It was very intermittent. I started noticing that it happened warm, cold, or during an intermittent stop. It would fire immediately and then die (run for about half a second). The subsequent starts and drives were uneventful.

I finally had my dealer look at it when it went in for a bad Onstar sensor in the mirror (3000 miles). He said they found no codes, but ran an ethanol test on the gasoline and it came in at 9%. He stated that they had seen this on a couple of other LS engines (camaros and corvettes) He suggested switching gasoline.

I was using Chevron and Shell exclusively, but the service manager (been a customer of his for 20 years) said try Exxon. Apparently, they use the least amount of ethanol in their fuel. All summer blends have ethanol, but they supposedly have the least and some research claims that they have minimal to none in their winter blends.

I went 8 months before having another episode. Since then, I have only had a handful and two were on the same tank from a Shell station I filled up at when I was low on fuel. Since the switch (over a year ago) when running Exxon, I have only had it happen once when filling up at an unfamiliar gas station.

To further validate the theory, I filled up with Valero last week and my car died today for the first time in months... It seems that it dies (on all brands) in the summer more - which validates the ethanol theory.

In 20,000 miles I had the Onstar button, and a rear license plate light bulb go out. Other than that, the car has been flawless. It has seen rain, snow (not intentional), and never given me a problem. It is 100% stock except for a K&N filter and the upsized Michelin PSS tires. Mobil 1 and filter ever 5k, Cabin air filter every 10k, and Rear diff fluid change every 10k.

I drive the piss out of it, but only when the tires are warmed up and the oil is above 150 degrees.

Hope this helps.

Other than inferential observations, did you ever extract fuel from the tank to see what the ethanol percentages were?