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Discussion Starter #1
Hello everyone and thank you for all the good information over the years,


I need to diagnose a vibration that only occurs at a mid range ICE RPM. I can not mimic the right RPM just using the gas pedal in park with the hood open. Is it possible for the dealer or even better my self to somehow slowly increase the engine RPM until said vibration and noise occurs for proper diagnosis?

It would have to be much more precise than using the gas pedal with the hood open as that doesn't seem to be able to allow the operator to feather through the full range of the engines RPM.


Many thanks!
 

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Hello everyone and thank you for all the good information over the years,


I need to diagnose a vibration that only occurs at a mid range ICE RPM. I can not mimic the right RPM just using the gas pedal in park with the hood open. Is it possible for the dealer or even better my self to somehow slowly increase the engine RPM until said vibration and noise occurs for proper diagnosis?

It would have to be much more precise than using the gas pedal with the hood open as that doesn't seem to be able to allow the operator to feather through the full range of the engines RPM.


Many thanks!
What does the vibration sound like? I find the Volt engine rather buzzy at various RPMs, but that's just the way it is. Is the vibration in another part of the car? It could be a tire that is out of balance, or out of round.
 

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Discussion Starter #3
What does the vibration sound like? I find the Volt engine rather buzzy at various RPMs, but that's just the way it is. Is the vibration in another part of the car? It could be a tire that is out of balance, or out of round.
Thanks for the reply...

It is a buzzing / humming that has plagued me since the car was purchased, only happens a specific mid range RPM level. I do not think it is in/on the engine but might be a n AC line that sits against the firewall but it is impossible to tell when the car is moving which is the only time it is possible to hear it. It is load and obvious. FYI I have already combed through all the forums over the past two years and had the muffler tab shaved off, heat shield replaced etc. but it has not effected it in the least :|
 

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Thanks for the reply...

It is a buzzing / humming that has plagued me since the car was purchased, only happens a specific mid range RPM level. I do not think it is in/on the engine but might be a n AC line that sits against the firewall but it is impossible to tell when the car is moving which is the only time it is possible to hear it. It is load and obvious. FYI I have already combed through all the forums over the past two years and had the muffler tab shaved off, heat shield replaced etc. but it has not effected it in the least :|
Well, compared to your Audi, the Volt engine buzzes a lot, particularly when under any load -- such as climbing a grade. This is still entirely possible. Because when the engine load (or at least the perceived load on the propulsion system) gets higher, the battery will kick in to help out. You can see that happen on your dash. The power from the engine will rise, and then fall slightly as the power from the battery increases to help out.
 

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I have never tried mountain mode with the hood open ? Try that.
 

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I had an ICE "BUZZ" in my '13 that ONLY occurred at 35 MPH while going up a certain grade on my way home. It was hitting the speed/rpm "just right" to make that sound. I once thought about going down the rabbit hole of trying to "fix" it but realized it's a lot of effort for minimal gain since it was an intermittent issue that only occurred under certain circumstances.

You should invest in a legit OBD2 scanner and an app which will tell you the engine RPM and note it when you hear the sound. Gen 1 Volt operates only at so many fixed RPMs.
 

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Discussion Starter #7
I had an ICE "BUZZ" in my '13 that ONLY occurred at 35 MPH while going up a certain grade on my way home. It was hitting the speed/rpm "just right" to make that sound. I once thought about going down the rabbit hole of trying to "fix" it but realized it's a lot of effort for minimal gain since it was an intermittent issue that only occurred under certain circumstances.

You should invest in a legit OBD2 scanner and an app which will tell you the engine RPM and note it when you hear the sound. Gen 1 Volt operates only at so many fixed RPMs.

That is a good point I have been thinking about getting one for a while. Once I have the RPM band though could the dealer be able to replicate the specific RPM? I was told once it is not possible but highly doubt it as it seems asinine to not be able to listen to an engine through it's entire RPM range.
 

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The engine doesn't go through the entire RPM range, at least not in the sense of a normal ICE. RPM is determined by the computer (and only coincidentally by the throttle position). They would have to instruct the computer to set RPM in maintenance mode. Does the Volt even have a throttle cable or is it all done by ECU?
 

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I've never looked, but if you take the plastic cover off of the engine, can you access the throttle body and manually adjust rev it? Obviously it's electronically controlled, but usually it's done by a cable or servo and you can still twist it by hand.
 

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Why can you not just have the dealer where you bought the car have his ace mechanic test-drive the car, if you have a local stretch of road that exhibits the problem? If it's a warranty claim you may not have to pay a dime.
It is my understanding that Volt engines lack counterbalancers, probably to save cost, and instead, rely on engine mounts to quell vibration points. I never noticed any vibration peaks on my '13. The Gen 2 engine, after a long break-in, seem to be pretty smooth, mostly silent at cruising speeds on level ground and less frenetic when climbing steep hills.
 

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Discussion Starter #11
i will heed your advice and take it to the only good dealer near me. To be clear it is more e of a buzzing sound very similar to what others have described when they found an AC line up against the firewall or strut tower. I thought it was the heat shield for the longest time but after adjusting and replacing it...it was still there. Had the muffler tab bulletin performed but that didn't change it either.

I am eating toward the firewall strut tower AC line problem. If anyone has any more advice I really appreciate it !!
 

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Discussion Starter #12
i will heed your advice and take it to the only good dealer near me. To be clear it is more e of a buzzing sound very similar to what others have described when they found an AC line up against the firewall or strut tower. I thought it was the heat shield for the longest time but after adjusting and replacing it...it was still there. Had the muffler tab bulletin performed but that didn't change it either.

I am eating toward the firewall strut tower AC line problem. If anyone has any more advice I really appreciate it !!
 
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