2019 Cold Startup Rough Idle/Shaking
Thread Starter
Intermediate
Joined: Jul 2018
Posts: 33
Likes: 6
2019 Cold Startup Rough Idle/Shaking
I have a 2019 Stingray, and on cold startup, there is a rough idle, and or slight shaking for about 1-2 minutes. Is this normal for this engine. Do others experience this?
Thanks for the input.
Thanks for the input.
Drifting
Joined: May 2007
Posts: 1,547
Likes: 210
From: Huntersville, NC
Still, check for loose plug wires. They fit tight on the plug and snap into the coils. I think you will need a TORX to get the coil pack covers off. Mine had a loose plug wire that caused other issues as well, and when that plug and plug wire were replaced, My startup idle improved.
You would be amazed at the problems a loose plug wire can cause. I got a service rear axle and service stabilitrak message on the DIC that was cured by fixing the plug wire issue. At first seemed to me like an ingrown toenail causing a cardiac arrest, but in this world of interconnected systems and nannies, I guess....
You would be amazed at the problems a loose plug wire can cause. I got a service rear axle and service stabilitrak message on the DIC that was cured by fixing the plug wire issue. At first seemed to me like an ingrown toenail causing a cardiac arrest, but in this world of interconnected systems and nannies, I guess....
Melting Slicks
Joined: Aug 2016
Posts: 2,762
Likes: 1,017
From: MOUNTAIN HOME Arkansas
You would get a DIC notification (CEL) if there was a misfire going on. Without a video/sound clip impossible to absolutely say it's normal. Have you been to dealer? I would make sure this is normal. I suppose it's possible (not likely) a code could have been thrown & would show up when a reader is plugged into OBD port, again, new car-go to dealer.
Drifting
Joined: May 2007
Posts: 1,547
Likes: 210
From: Huntersville, NC
Misfire code.
A misfire only shows on the dic if it occurs on two successive ignition cycles. You can see it as h history thru the obd. My situation was a loose wire, and the misfire was random. The cold starts were unusually rough but smoothed out.
Le Mans Master
Joined: Oct 2014
Posts: 8,673
Likes: 2,728
From: Atlanta GA
I chased a random misfire for 6 months in my C6 , every once in a while I would feel a shake or a pull against the brakes . Ended up being a spark plug wire to close to the alternator that was inducing RF into the ECM , never set a code or CEL
Back to the OP's question. Depends on what you call rough , unlike the others my car cold starts and runs fine with no shaking ...
Dave
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Racer
Joined: May 2017
Posts: 418
Likes: 60
From: Reading PA
A misfire will not go away after it's warmed up though, so the fact that is it is only happening for a couple of minutes tell you it's not a misfire. I suppose it's possible if it's barely loose for it to heat up and get a tighter connection, but I doubt this is the case. On start up it's going to idle higher (1500-2000) rpm for 20 seconds or so, and then gradually smooth out as the car warms up. This is because the car dumps more fuel into the car to warm up the 02 sensors. A video would be warranted to say if it's normal or if something else is going on.
Le Mans Master
Joined: Oct 2014
Posts: 8,673
Likes: 2,728
From: Atlanta GA
it is idling high to warm up the cats faster......
When operating in closed loop , which is everything except WOT , the o2 sensors work by varying the voltage signal that they send to the ECM which in turn riches or leans out the mixture
they have their own heating circuit and a reference temperature and voltage output that represents the proper air to fuel ratio
to cold and a higher voltage from the O2 sensor the ecm will lean out the mixture , to hot and a lower voltage signal, the ECM will richen the mixture .
This system leads to some over shoot both ways and you can see this in the short term fuel trims as they tend to bounce around
When the engine is cold it is set to run at a higher RPM and a slightly richer mixture for faster warmup of the cats because they need to be hot to work at optimum effeciancy . This is why you get that "raw" gas smell at startup as the cats are cold .....
the engine can run slightly rough during this period but it should not be real bad ..
Dave
Last edited by Dcasole; Sep 12, 2018 at 11:37 AM.
Racer
Joined: May 2017
Posts: 418
Likes: 60
From: Reading PA
No it does not DUMP more fuel to warm up the sensors...not sure where u heard that from? I am sure it was just a misunderstanding
it is idling high to warm up the cats faster......
When operating in closed loop , which is everything except WOT , the o2 sensors work by varying the voltage signal that they send to the ECM which in turn riches or leans out the mixture
they have their own heating circuit and a reference temperature and voltage output that represents the proper air to fuel ratio
to cold and a higher voltage from the O2 sensor the ecm will lean out the mixture , to hot and a lower voltage signal, the ECM will richen the mixture .
This system leads to some over shoot both ways and you can see this in the short term fuel trims as they tend to bounce around
When the engine is cold it is set to run at a higher RPM and a slightly richer mixture for faster warmup of the cats because they need to be hot to work at optimum effeciancy . This is why you get that "raw" gas smell at startup as the cats are cold .....
the engine can run slightly rough during this period but it should not be real bad ..
Dave
it is idling high to warm up the cats faster......
When operating in closed loop , which is everything except WOT , the o2 sensors work by varying the voltage signal that they send to the ECM which in turn riches or leans out the mixture
they have their own heating circuit and a reference temperature and voltage output that represents the proper air to fuel ratio
to cold and a higher voltage from the O2 sensor the ecm will lean out the mixture , to hot and a lower voltage signal, the ECM will richen the mixture .
This system leads to some over shoot both ways and you can see this in the short term fuel trims as they tend to bounce around
When the engine is cold it is set to run at a higher RPM and a slightly richer mixture for faster warmup of the cats because they need to be hot to work at optimum effeciancy . This is why you get that "raw" gas smell at startup as the cats are cold .....
the engine can run slightly rough during this period but it should not be real bad ..
Dave
Le Mans Master
Joined: Oct 2014
Posts: 8,673
Likes: 2,728
From: Atlanta GA
At a higher RPM, there needs to be more FUEL, hence my statement of the ECM commanding extra fuel during the process. And in order for the car to go into closed loop, the heater element in the 02 sensors needs to reach a certain temperature. More fuel, more air, more heat, this happens quicker. This all happens during the start up period. You stated exactly what I stated in different words basically. This is why I love the forums. People comment just for the sake of getting their comment in.
As many people here on this forum know I don't make statements just to make statements , my posts are always backed up by data or my 40 years in the Automotive industry , and I am here to help people , which can be proven by the amount of THANKS that I have received by helping others
But since you just opened the door lets take a look at this article on how a O2 sensor really works since you obviously have no idea and made a snarky comment directly at me ..
yes An O2 sensor needs heat to generate the necessary signal but in no way does this heat come from " MORE FUEL " as you state and NO, I did not state what you stated just in different terms .....
http://www.autotap.com/techlibrary/u...en_sensors.asp
The oxygen sensor must be hot (about 600 degrees or higher) before it will start to generate a voltage signal, so many oxygen sensors have a small heating element inside to help them reach operating temperature more quickly. The heating element can also prevent the sensor from cooling off too much during prolonged idle, which would cause the system to revert to open loop.
Dave
Racer
Joined: May 2017
Posts: 418
Likes: 60
From: Reading PA
Tennis Pro , No need to get your feathers in a ruffle and insult me
As many people here on this forum know I don't make statements just to make statements , my posts are always backed up by data or my 40 years in the Automotive industry , and I am here to help people , which can be proven by the amount of THANKS that I have received by helping others
But since you just opened the door lets take a look at this article on how a O2 sensor really works since you obviously have no idea and made a snarky comment directly at me ..
yes An O2 sensor needs heat to generate the necessary signal but in no way does this heat come from " MORE FUEL " as you state and NO, I did not state what you stated just in different terms .....
http://www.autotap.com/techlibrary/u...en_sensors.asp
This element is what heats the O2 sensor up during the OPEN LOOP cold start and also during prolonged idle periods , not dumping more fuel
Dave
As many people here on this forum know I don't make statements just to make statements , my posts are always backed up by data or my 40 years in the Automotive industry , and I am here to help people , which can be proven by the amount of THANKS that I have received by helping others
But since you just opened the door lets take a look at this article on how a O2 sensor really works since you obviously have no idea and made a snarky comment directly at me ..
yes An O2 sensor needs heat to generate the necessary signal but in no way does this heat come from " MORE FUEL " as you state and NO, I did not state what you stated just in different terms .....
http://www.autotap.com/techlibrary/u...en_sensors.asp
This element is what heats the O2 sensor up during the OPEN LOOP cold start and also during prolonged idle periods , not dumping more fuel
Dave
In the end, upon cold start up, the car DOES use more fuel until closed loop is achieved.
Last edited by 1c8vette64; Sep 12, 2018 at 04:21 PM.
Le Mans Master
Joined: Oct 2014
Posts: 8,673
Likes: 2,728
From: Atlanta GA
Upon cold start, the air is going to be cooler, yes? Cooler air is more dense, yes? More dense air means it needs more fuel for complete combustion, yes? Is the car going to able to monitor that the car is runing lean becasuse the aur is more dense in open loop? No. So the ECM adds more fuel to compensate for this. Why do cars idle higher when its colder outside? Because the air is more dense and in open loop, the car doesn't have the feedback information to make the mixture correctly, so upon cold start the ECM is going to command for more fuel. This is for both driveability during open loop (so the car isn't misfiring and shaking like crazy) and to ensure the car isn't running too lean. It controls fuel in open loop by overcompensating with more fuel until the car reaches closed loop. Anytime the car is on open loop status, it is going to run richer.
In the end, upon cold start up, the car DOES use more fuel until closed loop is achieved.
In the end, upon cold start up, the car DOES use more fuel until closed loop is achieved.
at first you said
This is because the car dumps more fuel into the car to warm up the 02 sensors
You win ... I am done ... now time to get back to the OP's problems which was answered ....
Dave
