WTF...at start cold idle jumps to 4K and holds itself!
02-13-2015, 07:24 PM
#1
Melting Slicks
Thread Starter
WTF...at start cold idle jumps to 4K and holds itself!
I started my car today for a few people at work that were dying to hear the beast. I hit the start button and everything fired up fine, idles ~900 RPM. I tapped the throttle to "gently" rev the motor to ~1500 to 1800 RPM's with no issue, idle came right back down to ~900 (remember, the car is cold!). I tap the throttle a second time expecting the same results and all of a sudden the idle rocketed to ~4000 RPM (as if I mashed the pedal halfway) and just hung there for about 3 seconds.....I tried tapping the throttle again thinking that maybe it was physically rubbing and got stuck but this made no change in RPM.....it was as if the pedal was suddenly unresponsive. Then without warning the idle just dropped back to normal. Anyone else experience something like this?
02-13-2015, 07:28 PM
#2
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St. Jude Donor '09
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"World Class Performance for your Corvette"
Intake Design and Engineering since 1999
Halltech Systems, LLC
262-510-7600
For service email:
orders@halltechsystems.com
www.halltechsystems.com
02-13-2015, 08:52 PM
#6
Pro
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Welcome to driving computers. My current 14 Z51 will do that sometimes. Imagine my surprise the first time when after starting it cold and backing out of the shop immediately. I probably gave a slight blip as I was putting it in reverse and did again as I was letting the clutch out. The rpms took off just as the clutch was grabbing lurching the car out of the shop through the door opening. By the time I reacted to the surprise, pushed the clutch in, and hit the brakes, it moved quite a bit.
It has done the same thing several times and seems to be a function of controlling emissions. I was one of the few who complained that the throttle response in the C7 was horrible. There were a number of threads with this complaint since introduction. It was greatly improved when a number of software updates were done. Updated throttle mapping was included with one of them. Apparently some cars had incorrect programming. Mine was a fairly early build, #5933 and as I understand it changes were made after ~6500, if my memory is correct. I did not experience it after the update but it was late in the driving season and I hardly drove it. Every time I move it cold I am prepared for a surprise.
Perhaps there is an issue but more than likely it is the computer telling your engine what to do instead of your foot. I also don't like the way it will hold throttle for a few moments after lifting in certain situations.
It has done the same thing several times and seems to be a function of controlling emissions. I was one of the few who complained that the throttle response in the C7 was horrible. There were a number of threads with this complaint since introduction. It was greatly improved when a number of software updates were done. Updated throttle mapping was included with one of them. Apparently some cars had incorrect programming. Mine was a fairly early build, #5933 and as I understand it changes were made after ~6500, if my memory is correct. I did not experience it after the update but it was late in the driving season and I hardly drove it. Every time I move it cold I am prepared for a surprise.
Perhaps there is an issue but more than likely it is the computer telling your engine what to do instead of your foot. I also don't like the way it will hold throttle for a few moments after lifting in certain situations.
02-14-2015, 03:58 PM
#7
Melting Slicks
Thats not cool...Anybody else experience this?
02-14-2015, 04:21 PM
#8
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Neg. I picked my Z up in November and have have driven to work nightly through the winter. Some mornings I get off work as low as 5degrees F. No problems whatsoever.
02-14-2015, 05:32 PM
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I started my car today for a few people at work that were dying to hear the beast. I hit the start button and everything fired up fine, idles ~900 RPM. I tapped the throttle to "gently" rev the motor to ~1500 to 1800 RPM's with no issue, idle came right back down to ~900 (remember, the car is cold!). I tap the throttle a second time expecting the same results and all of a sudden the idle rocketed to ~4000 RPM (as if I mashed the pedal halfway) and just hung there for about 3 seconds.....I tried tapping the throttle again thinking that maybe it was physically rubbing and got stuck but this made no change in RPM.....it was as if the pedal was suddenly unresponsive. Then without warning the idle just dropped back to normal. Anyone else experience something like this?
