L99 Vibration in car

[PlymouthBarracuda]

Some updates... Maybe this weill be interesting for you.

1) I went to our local GM officials, but they rejected testing my car because they accept stock vehicles only. I deleted both catalytic converters and disabled AFT O2 sensors in ECU firmware. But they said one interesting thing about cause of misfiring: the empty pipe (without cat.) can't make counterpressure as assumed, so this could be a reason of little misfiring. Also they suggested me to replace timing chain.

2) My mileage is 99.500. I found 2 videos regarding this theme's topic.

https://youtu.be/4vX8cNWb7Ow?t=129s

(from 2m 09 sec till 2m 31 sec).

So, it's a normal that DOD/AFM cause stuttering and vibration of the engine. Maybe I and GenesisCoupe just need to replace Engine Mounts ?

https://youtu.be/mkly7XmMsOs?t=140s

(from 2m 20 sec)

This is an official video explaning how AFM works and what failures could be.

Reasons are low oil pressure, VLOM internal leak (anyway it is a good idea to replace valley cover with solenoids), Sludge inside the engine.

He says that good engine must have 25 psi on hot idle, or if low -> inspect VLOM. I have no fault codes and no metal ticking sounds, only vibrations, like something engaging/disengaging constantly, then calms down.

My oil pressure is good, I think so. I attach pictures of cold idle, cruising and hot idle. Oil is 5W30 (Wolf with Dexos 2).

Any comments are highly appreciated

[gtstorey]

Originally Posted by GenesisCoupe

If engine is opening its good to replace everything for not to open it second time, for me )

Did I found right solenoids you are talking about ? (Engine Cylinder Deactivation Solenoid For 05-2014 Chevy GM GMC 12571609 12580901)

That is the valley cover with the solenoids. I thought the solenoids were available separately, but I could be wrong.

[gtstorey]

Originally Posted by PlymouthBarracuda

Some updates... Maybe this weill be interesting for you.

1) I went to our local GM officials, but they rejected testing my car because they accept stock vehicles only. I deleted both catalytic converters and disabled AFT O2 sensors in ECU firmware. But they said one interesting thing about cause of misfiring: the empty pipe (without cat.) can't make counterpressure as assumed, so this could be a reason of little misfiring. Also they suggested me to replace timing chain.

2) My mileage is 99.500. I found 2 videos regarding this theme's topic.

https://youtu.be/4vX8cNWb7Ow?t=129s

(from 2m 09 sec till 2m 31 sec).

So, it's a normal that DOD/AFM cause stuttering and vibration of the engine. Maybe I and GenesisCoupe just need to replace Engine Mounts ?

https://youtu.be/mkly7XmMsOs?t=140s

(from 2m 20 sec)

This is an official video explaning how AFM works and what failures could be.

Reasons are low oil pressure, VLOM internal leak (anyway it is a good idea to replace valley cover with solenoids), Sludge inside the engine.

He says that good engine must have 25 psi on hot idle, or if low -> inspect VLOM. I have no fault codes and no metal ticking sounds, only vibrations, like something engaging/disengaging constantly, then calms down.

My oil pressure is good, I think so. I attach pictures of cold idle, cruising and hot idle. Oil is 5W30 (Wolf with Dexos 2).

Any comments are highly appreciated

Is the ECM registering misfires? Misfiring is something totally different from vibration to me. Has the car been tuned for modifications? The "lack of counterpressure" being a problem is crap, but the car does need to be tuned.

[PlymouthBarracuda]

Originally Posted by gtstorey

Is the ECM registering misfires? Misfiring is something totally different from vibration to me. Has the car been tuned for modifications? The "lack of counterpressure" being a problem is crap, but the car does need to be tuned.

Car is fully stock. In ECU just disabled both AFT O2 sensors to eliminate check engine light, how it was in old cars.

Misfires could see my diagnostics master by reviewing real time engine data, but no fault codes were registered.

I found 2 videos already, owners complains that all we described are normal symptoms for AFM engine...

[GenesisCoupe]

Originally Posted by PlymouthBarracuda

Car is fully stock. In ECU just disabled both AFT O2 sensors to eliminate check engine light, how it was in old cars.

Misfires could see my diagnostics master by reviewing real time engine data, but no fault codes were registered.

I found 2 videos already, owners complains that all we described are normal symptoms for AFM engine...

Looks like this is a normal operation of afm

[1JEWLDSSRS]

I'm gonna chime in on this one. All that "vibration" you are feeling when the engine goes into "AFM/DOD mode IS a normal operation of the crappy "AFM/DOD" system!! That is why I had mine "tuned out" when we installed headers and did a dyno tune. Before, and the car was stock, when I would drive the car with the stock exhaust and that BIGASS resonator in the middle of the exhaust system and it activated, it sounded like a bunch of mad hornets stuck in a large coffee can and you could ALSO feel the vibration from that in the engine and the seat of your pants!! Then I found a way to bypass the AFM from some folks on this forum and started driving my Camaro in "manual mode"!! With the shifter pulled all the way back on the console is has an "M". And when in THAT position you can use the "tapshift" buttons on the backside of the steering wheel. Because when the engine is in a light load, states in the manual, the AFM/DOD will activate and run on only 4 cylinders, sound like crap and vibrate like hell, when you press the gas pedal, it will de-activate and give you back the other 4, then you are running on all 8!! To bypass the AFM/DOD you do like I stated above, move the shifter all the way back from "D" to the "M" position and while cruising around you hit the left."downshift" button on the back of the steering wheel, then tap the "upshift" button on the right/backside of the steering wheel and you will notice the AFM/DOD become disabled and you have all 8 cylinders!! And it will stay deactivated until you put the shifter back into "D", or press and hold the upshift button on the back/right side of the steering wheel for 3-4 seconds, and you will see on your dash that it is now back in "S" mode, which is sport mode, which it where you can use the tapshift whenever you want, up and down. When the shifter is in "D", shows that on the dash as well, you can use the downshift if you want, but then after about 10-15 seconds, it will return to "D", which is normal drive mode. So hope all this helps. You dn't need to replace anything, it is just the nature of this crappy AFM/DOD system... Enjoy the car and have fun..

[PlymouthBarracuda]

Originally Posted by 1JEWLDSSRS

I'm gonna chime in on this one. All that "vibration" you are feeling when the engine goes into "AFM/DOD mode IS a normal operation of the crappy "AFM/DOD" system!! That is why I had mine "tuned out" when we installed headers and did a dyno tune. Before, and the car was stock, when I would drive the car with the stock exhaust and that BIGASS resonator in the middle of the exhaust system and it activated, it sounded like a bunch of mad hornets stuck in a large coffee can and you could ALSO feel the vibration from that in the engine and the seat of your pants!! Then I found a way to bypass the AFM from some folks on this forum and started driving my Camaro in "manual mode"!! With the shifter pulled all the way back on the console is has an "M". And when in THAT position you can use the "tapshift" buttons on the backside of the steering wheel. Because when the engine is in a light load, states in the manual, the AFM/DOD will activate and run on only 4 cylinders, sound like crap and vibrate like hell, when you press the gas pedal, it will de-activate and give you back the other 4, then you are running on all 8!! To bypass the AFM/DOD you do like I stated above, move the shifter all the way back from "D" to the "M" position and while cruising around you hit the left."downshift" button on the back of the steering wheel, then tap the "upshift" button on the right/backside of the steering wheel and you will notice the AFM/DOD become disabled and you have all 8 cylinders!! And it will stay deactivated until you put the shifter back into "D", or press and hold the upshift button on the back/right side of the steering wheel for 3-4 seconds, and you will see on your dash that it is now back in "S" mode, which is sport mode, which it where you can use the tapshift whenever you want, up and down. When the shifter is in "D", shows that on the dash as well, you can use the downshift if you want, but then after about 10-15 seconds, it will return to "D", which is normal drive mode. So hope all this helps. You dn't need to replace anything, it is just the nature of this crappy AFM/DOD system... Enjoy the car and have fun..

Thank you very much

I tried M mode of transmission but this didn't affect. Only helps is Range Technology OBD device. I will use it instead swap to LS3.

[1JEWLDSSRS]

Originally Posted by PlymouthBarracuda

Thank you very much

I tried M mode of transmission but this didn't affect. Only helps is Range Technology OBD device. I will use it instead swap to LS3.

You are welcome sir, but driving in manual mode should have deactivated the AFM and allow all 8 cylinders to fire as normal AND stop the vibration. Mine always did. But if the range device works, use it.