Poor MPG
Laughing Gas
Joined: Oct 2017
Posts: 1,143
Likes: 13
From: ND
what kind of mix? i was seeing 7-8mpg driving around town today mix of 4x4 and just spinning due to crap roads and drivers. 15-25mph and lots of stop and go.
i still think you are down at least 1 cyl, possibly 2 and are just dumping fuel....is your engine actually getting up to full temp?
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Senior User
Joined: Jan 2019
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Holy cow! That's only 5.33 MPG! 
My bone stock 3.73 EX did better than that towing the old 9,500lb ToyHauler, something is just not right here.......... When are those new plugs going in?
Does your exhaust smell like exhaust or does it small like gasoline? I'm not suggesting getting your face up to the tailpipe, just a general smell test standing near the pipe at the rear of the EX. With mileage that low and what I'm betting is at least one cylinder with a miss it seems like there would be a lot of unburned gas in that exhaust stream. ANd over time that WILL kill your catalytic convertor.
My bone stock 3.73 EX did better than that towing the old 9,500lb ToyHauler, something is just not right here.......... When are those new plugs going in?Does your exhaust smell like exhaust or does it small like gasoline? I'm not suggesting getting your face up to the tailpipe, just a general smell test standing near the pipe at the rear of the EX. With mileage that low and what I'm betting is at least one cylinder with a miss it seems like there would be a lot of unburned gas in that exhaust stream. ANd over time that WILL kill your catalytic convertor.
New plugs are going in on Thursday now. Got everything including the o-rings for the coils.
Some trips are short enough the EX won't get up to temperature, like taking my wife to work in the morning (well, it's a 20 min round trip so it's probably just getting to temp by the time I'm done). Most trips do see it to temp though.
Cargo Master
Joined: Oct 2006
Posts: 2,097
Likes: 5
From: chicago northwest suburbs
At this point I would use a GPS and verify speed and mileage. my speedo is off by almost 2 mph. and after a 1000 mile trip Im off by 40 miles or so ( I forget the exact number) this is compared to my GPS. I would go that route at this point.
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Senior User
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10 new plugs. 10 new coils - all prepped with o-rings (I still have 90 left in that bag!)
Ended up paying $3 a plug and $17 a coil. Pretty good given the brands I thought.
So should I tell him to torque between 27-32 ft/lbs? Any reason not to go with either end of that scale?
Cargo Master
Joined: Oct 2006
Posts: 2,097
Likes: 5
From: chicago northwest suburbs
I don’t remember seeing it, but what year is your X. I don’t torque mine. I just tighten them with a hand ratchet. You don’t want them finger tight but you also don’t want to use a breaker bar on them. I go a little more than snug so I would guess around 25ftlbs? And I’m on my 2nd set of plugs. I do them every 50k I have 102k now. Never popped a plug, but I have the PI heads which have more threads per plug hole!
Laughing Gas
Joined: Oct 2017
Posts: 1,143
Likes: 13
From: ND
I don’t remember seeing it, but what year is your X. I don’t torque mine. I just tighten them with a hand ratchet. You don’t want them finger tight but you also don’t want to use a breaker bar on them. I go a little more than snug so I would guess around 25ftlbs? And I’m on my 2nd set of plugs. I do them every 50k I have 102k now. Never popped a plug, but I have the PI heads which have more threads per plug hole!
i torque to 28ft/lbs
Laughing Gas
Joined: Oct 2017
Posts: 1,143
Likes: 13
From: ND
On first start up it stinks of gas. For the first 5 minutes of driving it plumes white smoke (not vapor) out of the exhaust too. It's heavy when accelerating. I've always chalked this up to the harsh cold starts though, as it dies off.
New plugs are going in on Thursday now. Got everything including the o-rings for the coils.
Some trips are short enough the EX won't get up to temperature, like taking my wife to work in the morning (well, it's a 20 min round trip so it's probably just getting to temp by the time I'm done). Most trips do see it to temp though.
New plugs are going in on Thursday now. Got everything including the o-rings for the coils.
Some trips are short enough the EX won't get up to temperature, like taking my wife to work in the morning (well, it's a 20 min round trip so it's probably just getting to temp by the time I'm done). Most trips do see it to temp though.
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Senior User
Joined: Jan 2019
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Will report tomorrow with new plugs installed and photo of the old ones.
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Cargo Master
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From: chicago northwest suburbs
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From: Media PA
Nope, ALL 6.8 EXs came with the PI (Performance Improved) heads, they had only 4 plug threads in '00, '01 & '02, in '03 the PIs were upgraded to the more reliable 7 plug thread design. The 6.8s built prior to '00 were non-PI and had lower HP/TQ ratings due to the lower flow abilities of the intakes and heads.
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From: Media PA
Cargo Master
Joined: Oct 2006
Posts: 2,097
Likes: 5
From: chicago northwest suburbs
Nope, ALL 6.8 EXs came with the PI (Performance Improved) heads, they had only 4 plug threads in '00, '01 & '02, in '03 the PIs were upgraded to the more reliable 7 plug thread design. The 6.8s built prior to '00 were non-PI and had lower HP/TQ ratings due to the lower flow abilities of the intakes and heads.
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Joined: Jul 2010
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From: Media PA
Thread Starter
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Senior User
Joined: Jan 2019
Posts: 190
Likes: 1
Will do! Thanks Tom. Here's to hoping I'll see that MPG difference!