Spark plug change ?

[coldman]

I have a 06 trailblazer 4.2 with 75000 miles, should I change the plugs or let it go a bit longer. Not having any performance issues except that the gas milage has gone down from 16mpg city to 13mpg.

 

[Sparky]

They are supposed to be good until 100k. Pull one or two and check them if you want. Can't hurt.

Other things usually impact mpg more unless the plugs are way worn. For example, weather is getting colder, so it takes longer for it to warm up = more fuel burned. Winter fuel blend also hurts mpg. I've noticed a bit a drop recently from the colder temperatures.

Is your temp gauge reaching full 210 or hovering below that?

 

[coldman]

Temp gauge is 210 no problem there. Is it a waste of money to change them now?

 

[Sparky]

Probably not a waste per se. Wouldn't hurt anything. Just make sure to use AC Delco 41-103 only.

 

[dmanns67]

Temp gauge is 210 no problem there.

Do you have an ELM327 and torque app or some sort of scan tool to see the live data for your current coolant temp? My gauge read 210, but in reality my temps were right around 184* which was running too cool. It was not cool enough to through a CEL, but I replaced the t-stat before it got to that point. After replacement, I see 194* to 205*.

 

[coldman]

Do you have an ELM327 and torque app or some sort of scan tool to see the live data for your current coolant temp? My gauge read 210, but in reality my temps were right around 184* which was running too cool. It was not cool enough to through a CEL, but I replaced the t-stat before it got to that point. After replacement, I see 194* to 205*.

No scan tool, but the heater core was replaced about a year or so ago and a new thermostat was installed.

 

[808_LS_EXT]

I have a 06 trailblazer 4.2 with 75000 miles, should I change the plugs or let it go a bit longer. Not having any performance issues except that the gas milage has gone down from 16mpg city to 13mpg.

Pffffffft, save your money...
I'd be rejoicing if I got 16 on the hwy.

I replaced spark plugs (with Denso)...
Also,
Denso O2 Sensor,
Stant Thermostat,
AC Delco CTS, &
Dorman Exhaust Manifold...

Tried running it without an air filter(for zero restriction),
spare tire and rear seats removed (for less weight)...
I never throttle more than needed and try to drive on flat routes during non-peak hours.

All to no avail,,,
Still getting 11mpg on the freeking hwy... 10 city.

GOOD LUCK!

 

[coldman]

Pffffffft, save your money...
I'd be rejoicing if I got 16 on the hwy.

I replaced spark plugs (with Denso)...
Also,
Denso O2 Sensor,
Stant Thermostat,
AC Delco CTS, &
Dorman Exhaust Manifold...

Tried running it without an air filter(for zero restriction),
spare tire and rear seats removed (for less weight)...
I never throttle more than needed and try to drive on flat routes during non-peak hours.

All to no avail,,,
Still getting 11mpg on the freeking hwy... 10 city.

GOOD LUCK!

Sounds like an uphill battle.

 

[808_LS_EXT]

Sounds like an uphill battle.

I tried driving only downhill too... lol

On the flipside of all that,
Back in 2008 when the recession started and gas prices shot through the roof,
my wife was driving a 80,000 mile 2000 Accord with the V-Tec that averaged 24mpg....
it suddenly dropped to 12mpg

There was no rich smell, no misfire, no loss of power, and no SES code.
I pulled the plugs, and they appeared in great shape with proper gap.
After a few weeks of pulling my hair out, I bumped into a friend who worked as a Tech @ Honda.
He said the OEM plaitnum plugs get micro-deposits on them and confuse the ECM.
He advised I install copper plugs... I did.

The fuel economy shot back up to 24mpg for the next 20,000 miles till we sold the car.

So it's up to you whether you should install a $48 set of plugs...
(my Densos costed me $72 locally, I was in a hurry to improve my fuel economy.)

I may try a set of coppers in the TB... what do I have to lose?!

 

[coldman]

Seems like everyone recommends the oem plugs.

 

[808_LS_EXT]

Seems like everyone recommends the oem plugs.

I preferred AC Delco, but Denso was the only plug available locally...

I searched the other TrailVoy site (I wasn't a member here yet) and there was a lot of good feedback about Densos,
so I spent the $72 on them.

 

[Royalwapiti]

Let us know how they work. I get 13 mpg or so with mine as well.