Impala Forums banner

1 - 20 of 31 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter · #1 ·
I have shudder and vibration when driving car at level speed in high drive
gear, almost like engine lug, but completely disapears when speed is
increased and tranny gears down to standard drive, versus 3 cylinder eco
drive. Tried running premium gas and using injector cleaner for two fills
with no change in function. I am afraid of a developing transmission
problem...any suggestions or answers?
 

·
8th Gen Antagonist
Joined
·
13,660 Posts
Could you be a little more specific? Are you saying it only does this in 3cyl mode?
 

·
Registered
Joined
·
126 Posts
I get vibration in 3 cyl. mode around 40-50 MPH in my 08. I have ignored it since owning the car as 3 cyl. is not going to be as smooth.
 

·
Registered
Joined
·
158 Posts
I tend to get a bit of surging going on in that speed range when lightly loaded and almost coasting. Cleaning the MAF and mostly the throttle body seems to help quite a bit. Just be sure to use the right cleaner for the MAF!

Other than that, don't really note any vibrations - although the 3-cyl mode helicopter-sounding exhaust drone is a bit annoying, as is the slight bump when going between the modes. At least the lights don't dim when switching into 3-cyl mode, as they did on my '07 LT3. :)
 

·
Registered
Joined
·
222 Posts
The MAF uses a heated wire sensor. Very easy to destroy the MAF using the wrong cleaner. CRC and others offer the correct MAF cleaner
 

·
Registered
Joined
·
437 Posts
My '09 LTZ does not have this problem. That's because GM discontinued the AFM system on this engine. Probably for a good reason.
 

·
Premium Member
Joined
·
10,732 Posts
I personally liked the AFM on my 09 5.3. I think they finally got it right, and then ended production. The 5.3 AFM in the 2010 Suburban I have for the winter works fairly well too.
 

·
Registered
Joined
·
158 Posts
IMO, the AFM seems to do what was intended - noticing a 1-2mpg bump whenever it can stay in 3-cyl for longer periods.

Going up and down a relatively flat Interstate - at 60-65, it stays in 3-cyl mode a lot. The sweet spot seems to be around 70mph (the speed limit in MO) where it's constantly acting like a woman - can't make up its mind what it wants to do. At 75 and up, pretty much in 6-cyl all the time.

Heard tell that GM discontinued the AFM because of customer complaints about the little blip when switching between modes. Haven't been able to verify this, though.

Suggest AFM is a good concept, and to date has been reliable - just a better choice for the larger displacement motors that have the surplus torque and more extra cylinders to spare.

One thing I noticed was the statement seen somewhere that I can't currently recall about the importance of using the correct viscosity oil for proper AFM functioning. I do notice that the vehicle stays in 6-cyl mode longer in cold weather until things are really warmed up - not sure if this is an intentional emissions thing, or a cold, thick oil thing.

On another note - can't wait for summer gas to return. Fuel economy is tanking on this winter blend.
 

·
Registered
Joined
·
222 Posts
If its oil try a synthetic 5W-30. GM used to recommend a synthetic 0W-30 if temps <-22 F. Ok just checked my owner manual they still do, but should be a Dexos for my car as well. So far have not found a Dexos rated 0W-30.

The made in Germany Castrol Syntec 0W-30 is a damn good oil, should be good enough to meet Dexos

I too get a kick out of winter "emissions" blend gas. How does getting lower fuel economy help our environment??
 

·
Registered
Joined
·
158 Posts
I too get a kick out of winter "emissions" blend gas. How does getting lower fuel economy help our environment??
Eh, IIRC, winter blend was originally intended to help with cold starts - the fuel being more volatile than its summer counterpart. Towards the emissions side, I suppose the extra fuel consumed per mile going on down the road is more than offset by not puking out so many unburned hydrocarbons out of the gate?
 

·
Registered
Joined
·
222 Posts
The winter blend was originaly designed for cold start ease, especially with carb engines. Fuel injected engines have much less cold start issue.

The EPA mandated reason, per this article from the EPA

http://epa.gov/otaq/regs/fuels/sai.pdf

is to lower CO in areas that have higher onroad vehicle CO emissions. What they don't seem to address is the increase in PM10 emissions
 

·
OEM LOL
Joined
·
3,804 Posts
You should be sorry cause if it saves one child... :wink:

At least i got back a 1/10th of what they took from me.

Took 20k gave me back 2k:yahoo:

And they taxed my tax return from last year because thats taxable income :dizzy::dunno:
 

·
8th Gen Antagonist
Joined
·
13,660 Posts
Like hell it is, somebody done fucked up!
 

·
Registered
Joined
·
2,092 Posts
I don't declare tax returns as taxable income...
 

·
Registered
Joined
·
222 Posts
Tax refund is taxable for the next year in Canada as well.

Yeah, don't get me started. I will have no choice but to hit the bottle and giggle at this little skit


It may not be 60%, but it's still enough to piss me off
 
1 - 20 of 31 Posts
Top