LLT Major MPG loss

[sycraft]

you need spark plugs...... get these and then check

[DandDC09]

Originally Posted by sycraft

you need spark plugs...... get these and then check

Any ideas on a good performance plug and part number? Or would you recommend stock replacement?

I've heard this cars plug change is pain? True? I've done plenty of changes in the past. Just curious if I should do the DIY...

[sycraft]

easy on the 6, get the OE plugs....

[rtcat600man]

Originally Posted by sycraft

easy on the 6, get the OE plugs....

easy and for sure go with stock plugs.

[DandDC09]

Spark plugs changed. Still avg 27 on the highway @ 70mph.

Here's a pic that I want to see what you guys think of this. This was the middle plug port dri vers side, but there were a few like this.

[sycraft]

not bad, but seals from cover to plug tubes could be replaced. wont cause your loss of mpg

[Ventmaster]

Anyone else ever pulled those plugs? Or are you using any oil to speak of?

Some old school guys will use a little motor oil on the threads if the anti-seize isn't handy,,,

[DandDC09]

Wasn't associating with the mpg loss. Just curious about it, since I've seen it before. I'm not really familiar with the LLT design motor, but have plenty of hands on automotive work before. Call me old school I guess. After all I did say plugs and wires earlier.

This is the first the plugs have been replaced, but there has been some service work on it for a head leak. The mechanic at that dealership had even left 3 bolts loose and one fell out!

Did a fuse pull anyways and the power seems to have come back a little too, so says my butt dyno! I'm sure the motor will do a relearn and go back to what was with the 87oct.

I will see where the next few days takes me.

Thanks again for the ideas and tips!

[mycamaro2011]

I had the same oil in my spark plug holes.

i would dump the rx can. do you have the rx oil breather also? or drilled dirty side barb?

iam also guessing to that if you take your air intake off you prob have oil in the throttle body and air intake.

Originally Posted by DandDC09

Spark plugs changed. Still avg 27 on the highway @ 70mph.

Here's a pic that I want to see what you guys think of this. This was the middle plug port dri vers side, but there were a few like this.

[TJ91]

This is exactly what happened to my v6 and I've pretty much given up
Sat in a buddies SS who drives more aggressive and his MPG was a bit better then mine
I did the sea foam
Did not do the plugs because I was advised that it was a waste and I see it didn't help your mpg either

Driving my car like a prius and still getting 14mpg and we have summer blend gas now. Really don't know what to do. The o2 sensor replacement looks promising

[camarozzzz]

Originally Posted by TJ91

This is exactly what happened to my v6 and I've pretty much given up
Sat in a buddies SS who drives more aggressive and his MPG was a bit better then mine
I did the sea foam
Did not do the plugs because I was advised that it was a waste and I see it didn't help your mpg either

Driving my car like a prius and still getting 14mpg and we have summer blend gas now. Really don't know what to do. The o2 sensor replacement looks promising

I am in a similar situation as well! I get about 19 to 23 MPG on my V6 when I baby it. Basically never get more than 24...
Checked tonight...currently rocking 19.1 litres/ 100km....just roughly south of 13MPG...this is a blend of 90% city and 10% highway. I do not drive that aggressively...so I am really not sure how it is always this low.

[Trentin24]

Originally Posted by camarozzzz

I am in a similar situation as well! I get about 19 to 23 MPG on my V6 when I baby it. Basically never get more than 24...
Checked tonight...currently rocking 19.1 litres/ 100km....just roughly south of 13MPG...this is a blend of 90% city and 10% highway. I do not drive that aggressively...so I am really not sure how it is always this low.

In my V6 I drove aggressive and mostly city and saw 17-19 MPG. I also ran BMW full synthetic oil. Their oil meets higher specifications due to their european cars. Anyways, I also changed the spark plugs at 45,000 miles because I checked two and they seemed to be carbon fouled. (I work at a parts store so I get a discount). After I changed the plugs to an NGK Iridium, I noticed better throttle response by a bit and also my MPG started to get a bit better. Not sure why. That is just my personal experience. I was also on stock 18s.

[TooCool5]

Originally Posted by CreativeDawn

Fuse Pull may be SOLELY for the V8s but I have PERSONALLY noticed a difference after pulling the 5 and 20 leaving it overnight. The next morning I turn it on, the sound is slightly different, the vehicle pulls harder as well. All goes back to normal after about a week worth of driving. Sometimes I'll clear the TCM Adaptives if I want to have quicker shift points.

I know it goes back to learning mode, but whatever. Everyone has their own viewpoint on this and you can do as you want with your own car.


PS - I too was having issues with MPG at one point, but I did a reset and drove on the highway and went up as far as 26.9 on average with a highpoint of about 39+.

When I HYPER DRIVE (keep it neutral while going downhill) it goes up to almost 100 mpg.....Try it yourself........I live in California and 280 is the perfect area to hyperdrive because it's wide and vast.

X2 on the fuse pull.
I have done a high of 34 hwy and a low of 28 hwy depending on the hills or flat road.
I also run fuel injector cleaner every 3 months or so.

[sycraft]

IMHO injector cleaner does nothing for the Di motor