2008 Mega cab sluggish until 3,000 rpms

HemipoweredMega · Feb 22, 2017

I have a 2008 1500 Mega cab 4x4, all stock except for a flowmaster 50 series muffler. Lately the truck seems really sluggish on acceleration until it hits 3000 rpms then it feels like it has all the power in the world. I did a plug change, oil change, new air filter, cleaned the tb, did a seafoam treatment, tried some fuel injector cleaner and didn't notice much of a change. Truck has 145,000 miles on it. Seems to have regular maintenance done but the truck was from Canada so the records are in French lol. Anybody have suggestions on what to try next? Truck has no issues starting or running. Tires are a little oversize, 285/70/R17, but that didnt seem to bother it when I first bought it. Could it be a plugged cat? That was my next thought... Thanks guys

SilverStreak88 · Feb 22, 2017

Check out my thread... http://www.ramforum.com/f50/throttle_body_help-81936/ Clean the AIT while your at it, cured most of my throttle issues.

HemipoweredMega · Feb 22, 2017

What did you use to clean the AIT? Just electronics parts cleaner or is there something special I need to use? Thanks!

usaf2006 · Feb 22, 2017

Remember. Hemis produce most of their power at higher rpms. Plus you're in a huge truck lol. The trans also drives according to your style. Do a pcm reset by unhooking the battery for 10-15 minutes. Should restore quite a bit of power.

HemipoweredMega · Feb 22, 2017

I have had the truck for a year now and it just started acting up recently. Doesn't feel like its missing, almost feels like its not getting enough air or fuel, or can't get rid of the exhaust. Ill try cleaning the tb again, I have done it twice in the last 12,000 miles, both times it was pretty clean to start.

usaf2006 · Feb 22, 2017

I wouldn't bother then. I'm telling ya, try the pcm reset.

blackbeautyhemi · Feb 22, 2017

Clogged cat maybe?

HemipoweredMega · Feb 22, 2017

blackbeautyhemi said:
Clogged cat maybe?

That's what I was thinking of checking next. Any recommendations on a brand of replacement cat thats decent quality but not super expensive?

07MegaCabRam · Feb 22, 2017

Could be a bad cat. What about the plugs?

The mpg go to hell ? Could be both.

My 2007 Megacab and a SuperChip tuner with a shift schedule made the truck feel like it had 100 more horsepower. I would highly recommend that. It wakes the truck up BIG time.

Marciel · Feb 22, 2017

I agree, big truck and the hemi makes all its power on top. What gears do you have?

Sent from my SM-N910V using Tapatalk

usaf2006 · Feb 22, 2017

My truck gets 13-14mpg whether I'm doing highway or city... 4wd RCSB... maybe my cats are clogged lol.. Just did my plugs about 6k miles ago. 3.55 gears with 265/70/17s. I've never been able to explain my mpg..

Although she does have some good power when I need it.

Gut the cats and go with spark plug nonfoulers on the rear o2 sensors to keep from getting the CEL. That'll free up some flow.

blackbeautyhemi · Feb 22, 2017

HemipoweredMega said:
That's what I was thinking of checking next. Any recommendations on a brand of replacement cat thats decent quality but not super expensive?

Doesn't walker make a cheaper cat than oem? Mine are just little high flow cats, not sure if that's something you'd want or not.

blackbeautyhemi · Feb 22, 2017

usaf2006 said:
My truck gets 13-14mpg whether I'm doing highway or city... 4wd RCSB... maybe my cats are clogged lol.. Just did my plugs about 6k miles ago. 3.55 gears with 265/70/17s. I've never been able to explain my mpg..

Although she does have some good power when I need it.

Gut the cats and go with spark plug nonfoulers on the rear o2 sensors to keep from getting the CEL. That'll free up some flow.

I get the same mpg as you around town lol. And I tried those nonfoulers on mine with my high flow cats and they didn't work. Created another CEL. Hemifever tune took care of that.

usaf2006 · Feb 22, 2017

blackbeautyhemi said:
I get the same mpg as you around town lol. And I tried those nonfoulers on mine with my high flow cats and they didn't work. Created another CEL. Hemifever tune took care of that.

Can I get away with using hitemp painted headers vs ceramic coated? Can't afford real stainless or ceramic coated... Just curious if hi heat temp painted headers were a waste.

blackbeautyhemi · Feb 22, 2017

usaf2006 said:
Can I get away with using hitemp painted headers vs ceramic coated? Can't afford real stainless or ceramic coated... Just curious if hi heat temp painted headers were a waste.

Not sure, I don't have any experience with the hi temp headers. Someone else will have to chime in on that one.

usaf2006 · Feb 22, 2017

I'll stop Jacking this thread and make one lol

SilverStreak88 · Feb 22, 2017

HemipoweredMega said:
What did you use to clean the AIT? Just electronics parts cleaner or is there something special I need to use? Thanks!

Used CRC MAF sensor cleaner, don't spray it the electronics (black housing).

2008 Mega cab sluggish until 3,000 rpms

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