linux2

This is my second problem with the suburban I recently bought, but I think this may be easier to solve or is just "normal".

Does anyone else have the issue of their engine and vehicle vibrating a little bit when idling?

Mine seems to do this and there are no error codes. The dealership took a look at this and said "everything was good". I've plugged into a scan tool myself and I noticed the spark advance changes a lot at idle. Every second it jumps about 3-5 degrees. If I give it a little throttle it holds the advance steady. Everything else looks alright from what I can tell. Any other ideas on what I may want to check/adjust/or replace?

SabrToothSqrl

doesn't sound normal to me.

linux2

What sensors would likely be responsible for this?

I've thought about changing the spark plugs but I would think the misfiring would likely happen at all rpms if that were the case. Does anyone by chance know what the values of the sensors on a 2011 Suburban should be?

I can check them against my scan tool and use that to help determine where the issue resides seeing as the dealership just wants to take my money. I'd bring it to another dealer, but the other one near me is significantly worse than the one I brought it to first.

Thanks again!

SabrToothSqrl

new plugs? clean air filter? I'd start with the basics... After driving a Model S, I notice all vibration in cars now...

linux2

The air filter is brand new, so can't be that. I'll try the plugs next. I remember doing the ones in my cobalt at 60K and one had a fairly burnt insulator cap, so who knows how well it was working.

I'd describe the vibration at idle exactly the same as a 1971 Oldmobile delta 88 I had. It just didn't feel like it fired quite right all the time at idle and vibrated a little bit. When throttle was applied it was completely smooth. Mind you this was a Olds rocket 350 with a 4 barrel carb with 2 of the jets blocked off (some weird factory thing... guess they ran out of 2 barrel carbs). Needless to say I would expect it to idle a bit crappy. 2011 Suburban, not so much.

linux2

I cleaned the mass airflow sensor as well as replaced all the spark plugs, which were drenched in gas/oil. They were also white deposits on the spark plugs. After doing this it is much better, but not perfect. I am going to replace the mass airflow sensor and see if that clears things up. My bet it is will.

I'll update this with my findings once I replace it. If that doesn't completely clear it up I will replace the crankshaft position sensor as well, but I'm guessing it's fine.

in2pro

might also want to see what the alcohol content reading is... its possible you have a bad gas or you could have a less than perfect injector...