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Reduced Engine Power and Check Engine Light

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Old Jul 29, 2009 | 10:29 PM
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Default Reduced Engine Power and Check Engine Light

As you may know, up here in the Great Northwest (I'm a lumberjack and I'm okay, I sleep all night....) We're experiencing a bit of a heat wave.

So, I'm driving my C6 in traffic and the ambient temperature in the instrument panel reads 110. The car runs fine and the air conditioning is working well, the coolant guage reads slightly below 220 and so I decide to stop to top off the fuel tank. It took about a 1/4 tank of Techron and as I got back in the car and started the engine, it ran very rough. Then a message appeared in the DIC indicating "reduced engine power" or some such. I beleive the engine check light came on as well. A steady light, not flashing. I drove the car a few miles under reduced power to my destination and shut it off.

After letting it sit for 30 minutes or so, I restarted it and it ran fine. The check engine light remained on however. I checked the gas gap and removed it and replaced it, making sure to turn it a few clicks, but the engine light remained on.

I went out again later to go home and it started right up, ran fine, but the engine light remains on. The owner's manual suggests if it's a gas cap issue when replacing it after fueling, the light should go out after a few trips. I don't know how many a few is.

I'll take it to the local Suburban, Tahoe, Malibu and Silverado dealer tomorrow to have them check it out. Anyone every experience anything like this before? I'm convinced it has to do with the 100+ temperatures, but maybe not.
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Old Jul 29, 2009 | 10:42 PM
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Someone recently posted about the gas cap issue and it was reported that it takes 5-6 start/stop cycles to get everything to reset.

The thing that has surprised me the most about driving in this heat and the car running at 220 degrees of coolant temp. was how much the performance is reduced.

To quote a poignant love song, I don't jack my lumber baby, since my chain saw you......

It must be the weather.
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Old Jul 29, 2009 | 11:00 PM
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Need to know what code is stored
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Old Jul 30, 2009 | 12:06 AM
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need to plug in a scanner and read those codes to know whats going on.
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Old Aug 10, 2009 | 07:46 PM
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Okay, just to close this out, I took the car to the local dealer and according to the OBDIII the check-engine light signal turned out to be what the tech called a "history" message. Apprently it appears with the high temperatures we experienced, plus my in-traffic stop and go driving, the ECU underwent some sort of a heat soak and temporarily sent the wrong message to the systems.

The car runs fine, the light was reset and so I guess that's it.

Anything sound odd here? I'm just wondering why, if the computer sent the message, nothing was replaced, only reset.
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Old Aug 10, 2009 | 07:55 PM
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Originally Posted by last901
Okay, just to close this out, I took the car to the local dealer and according to the OBDIII the check-engine light signal turned out to be what the tech called a "history" message. Apprently it appears with the high temperatures we experienced, plus my in-traffic stop and go driving, the ECU underwent some sort of a heat soak and temporarily sent the wrong message to the systems.

The car runs fine, the light was reset and so I guess that's it.

Anything sound odd here? I'm just wondering why, if the computer sent the message, nothing was replaced, only reset.
Not that the tech found an actual problem...just never heard of a ECU heat soak problem on the current Corvette (yes, I know it can happen)

But, these things are in the SW deserts and muggy conditions of the Gulf states...so you may want to keep an eye on it.

Another possiblity could be a coolant heat soak or an air bubble in the system...did the cooling fan stay on during the fill up? The temp gauge only works (correctly) if coolant surrounds it.

After a proper cool down check the coolant levels.

Just my 2¢

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Old Aug 11, 2009 | 02:47 PM
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Same thing happened the other day started to drive car steped on gas engine lite came on car crawled at 5 mph.
Drove over to dealer shut car off waited for rep mean while started car again no engine lite started to leave got to driveway lite came on same problem.(By the way one of those smart reps also thought it was the gas cap.) Left car turned out the problem was trottle body assembly had to be replaced.
END OF PROBLEM.
JY
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Old Aug 11, 2009 | 03:08 PM
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If it were the gas cap, you should not have had reduced power, only the check engine light on. It will reset, but only after numerous start ups...took mine 3 days. It has happened to me twice. The last time I just unhooked the negative battery terminal and left it off several minutes. When I hooked it back up, no check engine light, but the car never did lose power of any kind.
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Old Aug 11, 2009 | 03:25 PM
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(Thread Hijack) Love the Duc in your avatar, I just got a Monster 1100S(Hijack over)
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Old Aug 11, 2009 | 03:59 PM
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Originally Posted by **** Jockey
I don't jack my lumber baby, since my chain saw you......
good ole' Jackyl
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Old Aug 12, 2009 | 06:28 PM
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Originally Posted by MAJ Z06
(Thread Hijack) Love the Duc in your avatar, I just got a Monster 1100S(Hijack over)
A fabulous bike. Best monster ever - save, perhaps, for my S4.
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Old Aug 12, 2009 | 06:54 PM
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Originally Posted by markabc6
Not that the tech found an actual problem...just never heard of a ECU heat soak problem on the current Corvette (yes, I know it can happen)

But, these things are in the SW deserts and muggy conditions of the Gulf states...so you may want to keep an eye on it.

Another possiblity could be a coolant heat soak or an air bubble in the system...did the cooling fan stay on during the fill up? The temp gauge only works (correctly) if coolant surrounds it.

After a proper cool down check the coolant levels.

Just my 2¢

And your 2 cents is appreciated. I've checked the coolant level and it's right where it should be. The tech didn't say anything about having to add any nor did he mention about that being the source of the problem

Further, I may have used the wrong nomenclature when I referred to the ECU. The tch told me it was the "computer" so I assumed that meant the ECU. Either way, what the tech explained to me was that the "message" and check engine light display was - how did he put this? - a "history" message, by which I presumed meant that the OBDII diagnostics recorded the incident, but now shows everything to be working normally. Does that make sense?

Sad to say, After reading so many posts on this forum relating to poor service, bad diagnoses and general incompetence of some dealers and their technicians, I have developed a fundamental distrust of Chevrolet service departments, though I've had no real issues with my local dealer in Issaquah.

I will continue to watch this and will let you all know if it reoccurs.

Thanks everyone for the great advice. This forum is great.
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Old Aug 12, 2009 | 08:57 PM
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Originally Posted by last901
And your 2 cents is appreciated. I've checked the coolant level and it's right where it should be. The tech didn't say anything about having to add any nor did he mention about that being the source of the problem

Further, I may have used the wrong nomenclature when I referred to the ECU. The tch told me it was the "computer" so I assumed that meant the ECU. Either way, what the tech explained to me was that the "message" and check engine light display was - how did he put this? - a "history" message, by which I presumed meant that the OBDII diagnostics recorded the incident, but now shows everything to be working normally. Does that make sense?

Sad to say, After reading so many posts on this forum relating to poor service, bad diagnoses and general incompetence of some dealers and their technicians, I have developed a fundamental distrust of Chevrolet service departments, though I've had no real issues with my local dealer in Issaquah.

I will continue to watch this and will let you all know if it reoccurs.

Thanks everyone for the great advice. This forum is great.
Good...just keep an eye on the coolant temp during your heat wave...and to be on the safe side get some sort of ref to coolant vs oil temp...just in case you have 'stat getting flaky on you or on its way out...listen for cooling fans coming off and on...etc

I know a lot of ...but you did have a concern, and was never verified.

g/l

FWIW...I have a co-worker that lives somewhere around you and I make it up that way every year or two...and to have that kind of heat wave I can only imagine the trauma the locals are having.

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Old Feb 18, 2018 | 02:10 PM
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what
Originally Posted by last901
As you may know, up here in the Great Northwest (I'm a lumberjack and I'm okay, I sleep all night....) We're experiencing a bit of a heSo, I'm driving my C6 in traffic and the ambient temperature in the instrument panel reads 110. The car runs fine and the air conditioning is working well, the coolant guage reads slightly below 220 and so I decide to stop to top off the fuel tank. It took about a 1/4 tank of Techron and as I got back in the car and started the engine, it ran very rough. Then a message appeared in the DIC indicating "reduced engine power" or some such. I beleive the engine check light came on as well. A steady light, not flashing. I drove the car a few miles under reduced power to my destination and shut it off.
After letting it sit for 30 minutes or so, I restarted it and it ran fine. The check engine light remained on however. I checked the gas gap and removed it and replaced it, making sure to turn it a few clicks, but the engine light remained on.

I went out again later to go home and it started right up, ran fine, but the engine light remains on. The owner's manual suggests if it's a gas cap issue when replacing it after fueling, the light should go out after a few trips. I don't know how many a few is.

I'll take it to the local Suburban, Tahoe, Malibu and Silverado dealer tomorrow to have them check it out. Anyone every experience anything like this before? I'm convinced it has to do with the 100+ temperatures, but maybe not.
. What was the result when you took it to the dealership? Were there any problems they discovered? Is it something major I should be concerned about or any damage to the car. This just happened to me today and worried I will have to replace something.
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Old Feb 18, 2018 | 03:47 PM
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This post is several years old. However, starter heat soak can cause the car to stumble and go into Reduced Power Mode after driving it for a while when hot. If the car sits and cools, it will start normally. First, I would test the battery to make sure the starter isn’t draining the battery and then check the solenoid on the starter for burnt connections.
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Old Jul 24, 2018 | 05:20 AM
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Originally Posted by last901
And your 2 cents is appreciated. I've checked the coolant level and it's right where it should be. The tech didn't say anything about having to add any nor did he mention about that being the source of the problem

Further, I may have used the wrong nomenclature when I referred to the ECU. The tch told me it was the "computer" so I assumed that meant the ECU. Either way, what the tech explained to me was that the "message" and check engine light display was - how did he put this? - a "history" message, by which I presumed meant that the OBDII diagnostics recorded the incident, but now shows everything to be working normally. Does that make sense?

Sad to say, After reading so many posts on this forum relating to poor service, bad diagnoses and general incompetence of some dealers and their technicians, I have developed a fundamental distrust of Chevrolet service departments, though I've had no real issues with my local dealer in Issaquah.

I will continue to watch this and will let you all know if it reoccurs.

Thanks everyone for the great advice. This forum is great.
Wow, to bad. I live in OR Salem to be exact. We have a Chevy dealer here in town and another about 10-15 miles away. I take my 08' C6 and my previous car 97' C5 to the Salem dealer Capitol Chevrolet. I guess I should be thankful the tech that works on mine is one of the top techs in the NW and he loves Vettes and Camaros. And he does know his shi*t. Love talking with him. It costs a fortune but always gets done right. He's easy to talk to and answers ALL questions, my service writer is awesome too a good team. Mine has been doing the reduced power crap too, hopefully I can get it fixed under service contract. Good luck. Love this car though, better then my C5 but I would still drive it with no problem. People ask me why put up with such a fussy piece of equipment, it's the fever I tell them once you drive one a few times you get the fever. I equate it to having a killer hot girlfriend, you put up with the occasional drama and headaches because everything else is so friggen awesome. If I had to pick between them, not even a contest the C6 comes home with me.
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