I recently got the Hemi tuneup at 30k miles on my 2010 Dodge 1500. Now the gas mileage is greatly reduced, it idles roughly, and it seems underpowered (downshifts much more frequently and higher RPMs just to maintain 70mph). Feels like there's constant resistance almost like it did when towing a trailer (prior to this tuneup in tow mode). Seems to also hold lower gears longer before up shifting.

Taking it back in but expect this to be the start of a long saga given initial explanations of "reflash of settings means truck is relearning my driving pattern". When new it didn't drive like this so this explanation doesn't make sense to me.

Anyone experience this or have any ideas? Thanks in advance.

 

Wrong plugs or plug gap. Coil issue but ought to set check engine light. If gap is to big it affects timing somewhat. If wrong plugs t9hey affect a lot. What I mean by wrong plugs is like the E3s . A pulse duration plug. Otherwise many plugs like Denso,Autolite,Bosch etc. if correct number work just fine. There is no real 'tune up' Its a plug change.

 

You replaced the plugs at 30,000...??? Why...??? Because the manual says so..???
These trucks will easily go to 60,000 on the original plugs. (i wish i could find the part number to those new hemi police plugs that will go 100,000 miles, i would buy them in a heartbeat and never change the plugs again. By the time it would need plugs again, i`d already be driveing a brand new truck and not replace them...hehehehe)

But anyways.....
I`ve seen a few different scenerios make this very same thing happen.....
the monkey that installed your plugs probably installed the wrong plugs
or the monkey broke the insulator on a couple plugs installing them
or the monkey didnt gap them properly, or maybe didnt install the rear plugs at all
or maybe the monkey screwed up a coil pack putting it back on, or might not be plugged back in
This is exactly why i do my own work. I feel sorry for some of you that dont have that option.

 

I don't work on my own cause I don't have to and can afford to pay someone. I've been getting my vehicles worked on for years and really never one issue with the work thats been done. The hemi plugs that go 100k are listed with a part number. same plug used in the hemi Hy-bred and one other. NGK double platinum. Yep the manual says every 30k. But some monkeys always know more then the engineers. I used Autolite Iridiums.

 

Yup. Lifetime powertrain and I don't want any issues with it by not following the mfg schedule regardless of how silly it seems. Yes, my plugs looked fine at 30K and I'm guessing that the new ones will look just as fine at 60K. Luckily I change them myself so I'm just out the $60 or so for the new factory plugs and an hour or 2 of my life.

 

Will have them check the plugs. And yeah I replaced them by schedule to maintain warranty coverage.