Active Fuel Management Issues.

hd2500407 · May 10, 2009

Does anyone know if there is a fix to my problems with my 08 Chevy Silverado 6.0lt Max with Active Fuel Management. When my truck is in drive it seems to have a miss or hesitation. Feels like the engine is chugging and just not running smooth. I have had it back to the dealership and they stated Chevy is aware of this issue but no fixes at the present time. I am getting ready to put a new computer upgrade from Westers Garage soon and they said they can fix the problem.

Any help would be appreciated.

66nova · May 10, 2009

Does anyone know if there is a fix to my problems with my 08 Chevy Silverado 6.0lt Max with Active Fuel Management. When my truck is in drive it seems to have a miss or hesitation. Feels like the engine is chugging and just not running smooth. I have had it back to the dealership and they stated Chevy is aware of this issue but no fixes at the present time. I am getting ready to put a new computer upgrade from Westers Garage soon and they said they can fix the problem.

Any help would be appreciated.

When it's in drive or when it's in 4 cylinder mode? If it is all the time when it's in drive, then its not an AFM issue. Have you changed gears after you went with bigger tires?

What kind of info are you looking for if Wester is going to fix it?

cerbomark · May 10, 2009

a ecm aftermarket tune fixed that feeling on my 07 v max when I had it.

hd2500407 · May 11, 2009

Truck has done this from the day I picked it up with 141miles on it from the dealership. I notice it more when its in drive opposed to 3rd. My gears are 4.10 and that should be fine with the larger tires I hope. Westers stated they could fix this hesitation/miss and make it run better. Another one posted that an aftermarket pcm worked to take that hesitation out.

Brian

Does anyone know if there is a fix to my problems with my 08 Chevy Silverado 6.0lt Max with Active Fuel Management. When my truck is in drive it seems to have a miss or hesitation. Feels like the engine is chugging and just not running smooth. I have had it back to the dealership and they stated Chevy is aware of this issue but no fixes at the present time. I am getting ready to put a new computer upgrade from Westers Garage soon and they said they can fix the problem.

Any help would be appreciated.

When it's in drive or when it's in 4 cylinder mode? If it is all the time when it's in drive, then its not an AFM issue. Have you changed gears after you went with bigger tires?

What kind of info are you looking for if Wester is going to fix it?

hd2500407 · May 11, 2009

cerbomark,

what type of ecm did you use. Can you tell me what your truck was acting like prior to the fix.

Brian

a ecm aftermarket tune fixed that feeling on my 07 v max when I had it.

hd2500407 · May 11, 2009

cerbomark,

what ecm aftermarket did you go with and what type of feelings did your 07 present to you.

Brian

a ecm aftermarket tune fixed that feeling on my 07 v max when I had it.

66nova · May 11, 2009

Truck has done this from the day I picked it up with 141miles on it from the dealership. I notice it more when its in drive opposed to 3rd. My gears are 4.10 and that should be fine with the larger tires I hope. Westers stated they could fix this hesitation/miss and make it run better. Another one posted that an aftermarket pcm worked to take that hesitation out.

Brian

Does anyone know if there is a fix to my problems with my 08 Chevy Silverado 6.0lt Max with Active Fuel Management. When my truck is in drive it seems to have a miss or hesitation. Feels like the engine is chugging and just not running smooth. I have had it back to the dealership and they stated Chevy is aware of this issue but no fixes at the present time. I am getting ready to put a new computer upgrade from Westers Garage soon and they said they can fix the problem.

Any help would be appreciated.

When it's in drive or when it's in 4 cylinder mode? If it is all the time when it's in drive, then its not an AFM issue. Have you changed gears after you went with bigger tires?

What kind of info are you looking for if Wester is going to fix it?

I had a few issues with my 07 Vmax before my tune. I felt it going in and out of 4 cylinder mode a lot and it was a rough transition. Only issue I had with AFM.

Idle was not smooth and the truck would shake ans surge at really low speeds.

It also had an awful hesitation/stall when you would hit WOT (damn GM nannies). GM programmed a 4 second delay for WOT runs.

I went with a Black Bear tune and I could not be happier.

cerbomark · May 17, 2009

I had wait4me tune and then another local efi live tune. It had a rough idle, which the dealer said was NORMAL on these trucks. That meant they could fix it Also if you were driving at speed,light on the gas, 4 mode, and just put a little more pedal into very lightly, it would feel like it was fighting to stay in 4 mode and lugging. My tunes smoothed out the idle and I had the AFM shut off. I now have an 09 5.3 AFM and I can hardly feel the 4 to 8 mode change.

Irv · May 31, 2009

I now have an 09 5.3 AFM and I can hardly feel the 4 to 8 mode change.

I was curious if I would be able to feel it in my new truck (first truck with this feature) and the answer is, no I can't. I

I put the DIC on and can actually watch it go from 4 to 8 and back again, but I can't feel it, works super smooth imo.

wlvrn1215 · May 31, 2009

seems like some do it and some don't

brims · May 31, 2009

And it seems that some that don't feel it and get a tune start feeling it.

VMax2007 · May 31, 2009

And it seems that some that don't feel it and get a tune start feeling it.

Yep, I am in that category. So I just had it shut off. That was in March and I have noticed exactly ZERO change in MPGs since.

AFM is worthless in these 5000 lb bricks....period!

brims · May 31, 2009

And it seems that some that don't feel it and get a tune start feeling it.

Yep, I am in that category. So I just had it shut off. That was in March and I have noticed exactly ZERO change in MPGs since.

AFM is worthless in these 5000 lb bricks....period!

My ECM is on it's way to Virginia for Justin to shut it off for me. That constant feel of shifting was very annoying and I don't know how good that would be, may not be a lot but it's like chipping away at a stone wall with a screw driver.

elcamino · May 31, 2009

My 2008 is completely stock and its been doing this for the last year. When in V4 mode the engine vibrates or shudders till it goes into V8 mode. I can keep a steady speed and pressure on pedal and got this to go for almost a mile before it kicks into V8. I think it getting worst but the dealer has no answer. They say of the hundreds of trucks they sold I am the only one to complain of this. I am considering a 2010 Duramax. Don't need it but want to get rid of AFM.

One thing about tunes it that your powertrain warranty is gone.

Read this in recent tech literature. I am just passing on info, not criticizing those who do this.

Identifying Aftermarket Non-GM Calibrations
By Blog Admin on February 1, 2009 7:17 PM | No Comments

For more details, refer to bulletins 08-06-04-033 (Gasoline Engines) and 08-06-04-006A (Diesel Engines).

General Motors is identifying an increasing number of engine, transmission and catalytic converter part failures that are the result of non GM - aftermarket engine and transmission control calibrations being used.

When alteration to the GM released engine or transmission control calibrations occurs, it subjects powertrain and driveline components (engine, transmission, transfer case, driveshaft and rear axle) to stresses that were not tested by General Motors. It is because of these unknown stresses, and the potential to alter reliability, durability and emissions performance, that GM has adopted a policy to cancel any remaining warranty coverage to the powertrain and driveline components, whenever the presence of a non-GM / aftermarket calibration is confirmed -- even if the non-GM control module calibration is subsequently removed.

Warranty coverage is based on the equipment and calibrations that were released on the vehicle at time of sale, or subsequently updated by GM. That's because GM testing and validation matches the calibration to a host of criteria that are essential to assure reliability, durability and emissions performance over the life of the warranty coverage and beyond. Stresses resulting from calibrations different than those tested and released by GM can damage or weaken components, leading to poor performance and or shortened life.

Additionally; non-GM-issued aftermarket engine control modifications often do not meet the same emissions performance standards as GM-issued calibrations. Depending on state statutes, individuals who install engine control module calibrations that put the vehicle outside the parameters of emissions certification standards may be subject to fines and / or penalties.

GM service bulletins 08-06-04-033 and 08-06-04-006 outline procedures to identify the presence of non-GM / aftermarket calibrations. GM recommends performing this check whenever a hard part failure is seen on internal engine or transmission components, or before an engine assembly or transmission assembly is being replaced under warranty. It is also recommended that the engine calibration verification procedure be performed whenever diagnostics indicate that catalytic converter replacement is indicated.

In February 2009, PQC will begin piloting a process to confirm the ECM calibration is GM-issued. Beginning in February, PQC will require a picture of the engine calibration verification screen, as outlined in the bulletin, before authorizing any V8 engine replacement (both Gas and Diesel). (fig. 19)

If a non-GM calibration is detected by the dealership, follow the procedures outlined in the bulletin. Once documentation of the non-GM calibration has been received, and verification has taken place through GM, the remaining powertrain and driveline warranty will be cancelled and noted in VISS, and the dealership will receive the following notification:

Based on information that has been received, please inform the customer that the Powertrain portion of the New Vehicle Warranty is no longer in effect for the engine, transmission, driveline and rear axle on VIN XXXXXXXXXXXXXXXXX, due to the presence of non-GM calibrations and / or equipment. The stresses resulting from the non-GM calibrations and / or equipment were not validated by GM and therefore cannot be warranted on any components that are subject to those stresses. Repairs to powertrain or driveline components that may currently require repair should not be covered under the terms of the new vehicle warranty. The warranty group has been advised of this information and VISS will be updated accordingly.