First Post!

[Awake79]

Hey everybody, new here. Have an '05 2500HD, and have been doing some things to try and improve my MPG. Joined up here mostly for opinions on part brands and what not. Hopefully there may be something I'm smart enough to help you guys out with one day. lol! Take care all.

[j cAT]

Originally Posted by Awake79

Hey everybody, new here. Have an '05 2500HD, and have been doing some things to try and improve my MPG. Joined up here mostly for opinions on part brands and what not. Hopefully there may be something I'm smart enough to help you guys out with one day. lol! Take care all.

only use synthetic tranny fluid and engine oil.
clean the MAF every year with CRC MAF cleaner. at this time clean the IAC so the engine idle is correct at all times.

tire pressures need be check especially when the cold temps move in. air pressure drops...use nitrogen instead of air, as this does not change as much.

do not increase vehicle height. the higher you go more drag.


If you use paper air filter replace every 10,ooo mi. more if on off pavement dust zones.

replace the upstream O2 sensors at 100,ooomi. use ac irridium plugs, replace every 50,ooomi.measure plug wire resistance for proper ohms if too high replace.

I use techron injector cleaner every few thousand miles with marvel mystery oil . the keeps the injectors/fuel system clean .alcohol is damaging to these fuel system components especially with condensation in the fuel tank.

[Awake79]

Thanks for the info! Never thought minor preventitive maintenance things could help so much. Thanks again!

[Awake79]

Originally Posted by j cAT

only use synthetic tranny fluid and engine oil.
clean the MAF every year with CRC MAF cleaner. at this time clean the IAC so the engine idle is correct at all times.

tire pressures need be check especially when the cold temps move in. air pressure drops...use nitrogen instead of air, as this does not change as much.

do not increase vehicle height. the higher you go more drag.


If you use paper air filter replace every 10,ooo mi. more if on off pavement dust zones.

replace the upstream O2 sensors at 100,ooomi. use ac irridium plugs, replace every 50,ooomi.measure plug wire resistance for proper ohms if too high replace.

I use techron injector cleaner every few thousand miles with marvel mystery oil . the keeps the injectors/fuel system clean .alcohol is damaging to these fuel system components especially with condensation in the fuel tank.

Any reason why you prefer the AC plugs? I was looking into the E3 Diamond Fire, but I saw some pretty bad reviews about them and had second thoughts about them.

[j cAT]

Originally Posted by Awake79

Any reason why you prefer the AC plugs? I was looking into the E3 Diamond Fire, but I saw some pretty bad reviews about them and had second thoughts about them.

these engines are very picky on plug types. the OEM plugs used in this engine have changed from when these engines first come out.

though in the past I used bosch +2 plugs with no issues , after installing the new style irridium ac delco plugs I found better all around performance, most members recommend the use of these.

these E3 plugs are better used in smaller engines ..the computer on these vehicles is programed for the correct plug.

[Awake79]

Is that pretty much the same for most parts, if its not an OEM part, it confuses the computer?

[j cAT]

Originally Posted by Awake79

Is that pretty much the same for most parts, if its not an OEM part, it confuses the computer?

the use of non OEM parts is OK if the manufacturer makes them with the proper spec's. also some OEM parts have had defects. one item would be the intake gaskets. felpro makes excellant gaskets with design to coorrect GM gasket failure.

I have seen /installed aftermarket parts that had the same markings on the part surface. I purchased a transmission filter 4l60 deep pan paid 18.oo for it at NAPA. this filter had the same markings and I could not see any thing different from the OEM factory filter that was in the vehicle when built. dealership wanted 55.oo for the same exact filter.

the plugs with this engines fuel management is precise. E3 is not compatible. many have had bad issues using these with these engines.

with the oem iridium ac delco plugs you must not mess with the gap . doing so will damage the small wire at the tip. some damage good plugs by doing this and then say these plugs are not good.

IF THE GAP IS OFF THE PLUG IS DEFECTIVE!

[Awake79]

Really showing my lack of knowledge here but; do you mean the gap setting straight out of the box, or the GM gap setting from the owners manual?

[j cAT]

Originally Posted by Awake79

Really showing my lack of knowledge here but; do you mean the gap setting straight out of the box, or the GM gap setting from the owners manual?

the gap of the new plug is the correct gap. if you change this the plug will get damaged/return to the supplier for replacement.

GM changed the plug and the gap with my 2000 5.3L engine. when this was changed exactly I don't know. ac delco 41-110 is the plug last listed as the correct part. the gap in the manual may not be correct.

you will find the gap on used plugs of this type do not change as the material can handle the high combustion temps . what does happen is the plug tip with over 50,ooo mi can get distorted and the small wire can fall of the plug tip.