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Discussion Starter · #1 ·
I've noticed there are a lot of MPG discussions lately, even a few about how accurate our gas needles are, tank capacity and how much running the A/C can impact your MPGs. I took a trip to visit a friend just south of Birmingham, AL in a small town called Chelsea, AL...I was traveling from near Huntsville, AL. From the Chevron I always fill up at, down there, and back was 224.2 miles. Of that 224, 202 miles were on I-65 and I-565.

With the cruise set on 75 mph, the A/C off, recirculation mode on (no outside air allowed in), and tires at 40 psi I achieved 36.08 MPG for the round trip. I used 6.213 gallons and filled up at the same pump I always use on the same pump setting, running regular grade gas, and pumping in an additional 0.8 gallons after the first click (just a habit of mine). The attached pics show the numbers.

Only "mods" to the car are the RV6 PCDs, which I believe 100% are allowing me to achieve slightly higher MPGs than before when running the restrictive OEM pre-cats. Just wanted to share as it is truly amazing what kind of MPGs these "older" cars can achieve when they're allowed to breathe a little easier and you stay on top of routine maintenance...even when it's a V6 5AT.

Who knows what kind of MPGs I could achieve if I actually tried to hyper-mile again like when I was able to produce 36.6 MPGs back some 70k miles ago vs. just running cruise control. :thmsup:

First pic is fuel gauge in Chelsea, AL at destination, second is fuel gauge back at Chevron before filling up, third is amount of fueled placed into tank at fill-up, and fourth is fuel gauge after filling back up and resetting the trip meter.
 

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Old Bird...sometimes wise
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Exceptional! Please explain what this means "Only "mods" to the car are the RV6 PCDs".
I still miss living in Hartselle, Al.
 

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Discussion Starter · #3 ·
Exceptional! Please explain what this means "Only "mods" to the car are the RV6 PCDs".
I still miss living in Hartselle, Al.
Hey man, yeah North AL is always great this time of year. What I meant by only "mods" or modifications to the car are the RV6 Performance brand PCDs (pre-cat deletes) is that is the only non-OEM part on the car that could have an impact on the MPGs. I simply decided to replace the OEM pre-cats with the RV6 PCDs because 1) the OEM units are way more expensive and 2) I could help the engine breathe a little easier and pick up some fuel economy. Plus Richie at RV6 Performance is a pleasure to deal with and I spoke with him several times on how they would positively or negatively impact my car before purchasing.

Everything else on her as far as the power-train is stock :thmsup:
 

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Wow, this is "4 cylinder, 9th Gen with a Continuous Variable Transmission (CVT) territory."

Proof that maintenance is the key to performance. These V6s amaze me- power when you need it, AND high highway mpg when you need it.

Mike, can you explain a little more about the pre-cat deletes? Do they affect emissions? Does Alabama test?
 

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Discussion Starter · #5 ·
Wow, this is "4 cylinder, 9th Gen with a Continuous Variable Transmission (CVT) territory."

Proof that maintenance is the key to performance. These V6s amaze me- power when you need it, AND high highway mpg when you need it.

Mike, can you explain a little more about the pre-cat deletes? Do they affect emissions? Does Alabama test?
Thank you for the kind words Rick!

The PCDs are basically a free flowing pipe that you bolt in place of the OEM pre-cats. I opted to spend the additional money to get mine ceramic coated (which look amazing) and it was still a few hundred dollars cheaper than going back with OEM pre-cats. I replaced all 4 O2 sensors at the same time I installed the PCDs, all for cheaper than 2 OEM pre-cats.

As for emissions: Yes, it is my understanding that these will cause you to fail emissions testing, both if the tests are visual inspections or the actual "old-school" testing of measuring tail-pipe contaminants. But it is my understanding that the later test is rarely performed these days. You can definitely smell a stronger exhaust smell from not having the OEM cats in there and there is a slight growl at idle until it warms up and the idle RPMs drop.

Alabama does not do any sort of emissions testing or inspections, so that is the only reason I chose to install them. If your emissions testing only consists of them hooking to the OBD port to check for codes, then you will still pass because Richie includes the O2 sensor "foolers" to keep the sensors farther out of the stream of exhaust, therefore not triggering any CEL codes. And I have put a few thousand miles on mine with no codes thrown at all. I know some people might bash me for "hurting the environment", but even without the cats this car is expelling less emissions that those old 350 or 351 powered Chevys and Fords that are still pounding the roads.

So if you're in a state like Alabama, they are definitely worth it to gain economy and eliminate yet another piece of the puzzle that could possibly fail again in the future (the OEM pre-cats).
 

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Old Bird...sometimes wise
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Amazing how well they perform when you unclog the exhaust system isn't it? I can only imagine how well my 3.5l RAV4 would run without precats. No can do in TX though.

If you want fabulous BBQ in Hartselle go to Holy Smoke BBQ across the street from Dairy Queen. A friend of mine owns it and is a Pitmaster Supreme. The restaurant is new.....they moved from an area near Culman.
 

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Discussion Starter · #7 ·
Amazing how well they perform when you unclog the exhaust system isn't it? I can only imagine how well my 3.5l RAV4 would run without precats. No can do in TX though.

If you want fabulous BBQ in Hartselle go to Holy Smoke BBQ across the street from Dairy Queen. A friend of mine owns it and is a Pitmaster Supreme. The restaurant is new.....they moved from an area near Culman.
I think I saw an ad for that place...will definitely stop in and check it out on my next trip! Thanks for the info :thmsup:
 

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How does the 5AT final drive compare to the 6spd? What direction was the wind blowing? Head, side, tail?

In my 6spd I've gotten 36.48 driving closer to 67-70, against the wind, pure freeway fill with no stops between. It can help or hurt depending on wind direction.

Was there a need to replace the precats, or did you just choose to? I've been debating on them.
 

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Discussion Starter · #9 ·
How does the 5AT final drive compare to the 6spd? What direction was the wind blowing? Head, side, tail?

In my 6spd I've gotten 36.48 driving closer to 67-70, against the wind, pure freeway fill with no stops between. It can help or hurt depending on wind direction.

Was there a need to replace the precats, or did you just choose to? I've been debating on them.
I'm not sure how the final drive compares to the 6MT, but would also love to find out. As for wind, there was a 3-5 mph tail/quartering wind (from the NE while I was traveling S) on the trip down, and a 4-6 mph head wind (N wind while I was traveling N) today on the trip back. So yes, a tail wind was present, but it wasn't a full on tail wind and I faced a slightly stronger head wind heading back this morning. I agree though, some days when cold fronts head through and it's blowing 15-20 it feels like you lost 40 horsepower and the gas gauge drops fast haha.

The reason I replaced the pre-cats was because I started getting pending trouble codes showing up on my UltraGauge, P0420 to be exact. Then finally one day the CEL came on because of that code. From my research many people who had this code come up spent plenty of money and time trying to pinpoint the problem - was it O2 sensors, which one, was it the cat, etc.

So since I never "half-ass" a job, I decided to replace everything that could cause that code to appear, which would be the pre-cat and 4 O2 sensors. Once they were removed, I could see a few areas of the honeycomb starting to clog when I shined a flashlight through it, so they needed to come out.

So if you're getting on up there in miles (150k+) and your state doesn't do inspections or emissions testing, they are a proven way to let your engine breathe a little easier. And I would bet you would really find a nice difference on a 6-6 Accord with them installed vs. a V6 5AT like mine.
 

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Freelance Gynecologist
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Consistently impressed with Honda's V6, really a good mix between performance and fuel economy.
 

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Old Bird...sometimes wise
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I think I saw an ad for that place...will definitely stop in and check it out on my next trip! Thanks for the info :thmsup:
Having had his ribs before I moved back to TX I can attest that nothing comes close......wear a huge bib cause supper will be all over your clothes.
 

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subtract 261000 miles to get engine mileage
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The reason I replaced the pre-cats was because I started getting pending trouble codes showing up on my UltraGauge, P0420 to be exact. Then finally one day the CEL came on because of that code. From my research many people who had this code come up spent plenty of money and time trying to pinpoint the problem - was it O2 sensors, which one, was it the cat, etc.
this is the current problem that i'm having on my car: the infamous P0420 code. i have noticed that if i redline it, the CEL will come on for a few days, then turn off again.

solution: new redline is 5k RPMs for the time being.... :lmao: :naughty: :banana: :wave:
 

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Discussion Starter · #13 ·
this is the current problem that i'm having on my car: the infamous P0420 code. i have noticed that if i redline it, the CEL will come on for a few days, then turn off again.

solution: new redline is 5k RPMs for the time being.... :lmao: :naughty: :banana: :wave:
I too would notice that redlining would trigger the pending code (showing on the UltraGauge but no CEL yet). The pending would come and go for about 4-5 months before the CEL came on. Even then it still drove fine and I didn't notice any drastic decrease in performance. You might consider going the same route since you're also in Alabama, but I'm not fond of the cats on the I4. I thought about just trying to solve the problem piece by piece with replacing O2 sensors first, but I wanted the peace of mind that it was good to go for another 150k+ miles.
 

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subtract 261000 miles to get engine mileage
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my car is still registered in PA attm. i would still like to keep PA registration in case i move back north.
 

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Mike I remembered when you did this (was it over the summer or did you just post about it over the summer?)

I don't have any issues with my 4 cylinder but Illinois emissions testing is:

1) Plug in the OBD II scanner
2) They stick the probe in your tailpipe.

My readings are almost all zeros....so I thought/wondered what if I put in a "test pipe"- which is what manufacturers used to call the pipe that was the exact shape/length as the catalytic converter on the Mitsubishi 3000GT VR-4.....I wonder if my Accord will still pass? I recall reading that some Civic owners did this and still passed with flying colors. They do NOT do visuals here.

That was good research on your part.

Illinois Emission Test Facility True Story: I flunked my emissions test two years ago....I pull into the bay, and a very obese gent that was beet red (it was 95 degrees outside) told me to leave the car running and step into the waiting booth. He did not look well at all. About three minutes later, they give me my report with FAIL written on it! The guy could not plug in the OBD II reader- so it said "faulty and/or tampered computer". I nearly hit the roof! The manager comes out, tells me to pull around and wait in line again, and ten minutes later I passed because he himself plugged it in.

6 months ago, I noticed on Autocheck (but not Carfax) that I have a big WARNING now because my car failed emissions. Unreal. These emission places were needed up until the year 2000. I swear they must hire graduates of Jiffy Lube Academy, 9:00am class.
 

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Discussion Starter · #16 ·
Mike I remembered when you did this (was it over the summer or did you just post about it over the summer?)

I don't have any issues with my 4 cylinder but Illinois emissions testing is:

1) Plug in the OBD II scanner
2) They stick the probe in your tailpipe.

My readings are almost all zeros....so I thought/wondered what if I put in a "test pipe"- which is what manufacturers used to call the pipe that was the exact shape/length as the catalytic converter on the Mitsubishi 3000GT VR-4.....I wonder if my Accord will still pass? I recall reading that some Civic owners did this and still passed with flying colors. They do NOT do visuals here.

That was good research on your part.

Illinois Emission Test Facility True Story: I flunked my emissions test two years ago....I pull into the bay, and a very obese gent that was beet red (it was 95 degrees outside) told me to leave the car running and step into the waiting booth. He did not look well at all. About three minutes later, they give me my report with FAIL written on it! The guy could not plug in the OBD II reader- so it said "faulty and/or tampered computer". I nearly hit the roof! The manager comes out, tells me to pull around and wait in line again, and ten minutes later I passed because he himself plugged it in.

6 months ago, I noticed on Autocheck (but not Carfax) that I have a big WARNING now because my car failed emissions. Unreal. These emission places were needed up until the year 2000. I swear they must hire graduates of Jiffy Lube Academy, 9:00am class.
Yes, it was back in June when the P0420 code appeared and the start of July when I installed them. And I too have read several people posting how they were still able to pass emissions testing with only the one main downstream cat...kind of makes you wonder if it would pass or not. Probably only way to tell would be to get a test pipe built and know somebody that runs an emissions shop that would let you do a "late night test" for a case of beer and not have it put on the car's record.

And that's some BS about it now showing up on your car's record because of the incompetent "technician". You're right, so many of these guys now days don't have a clue
 

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Nice results. But tire pressure at 40 PSI? Wow. I would be worried if I hit a big pothole and flatten my tire.
 

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Discussion Starter · #18 ·
Nice results. But tire pressure at 40 PSI? Wow. I would be worried if I hit a big pothole and flatten my tire.
Thanks man. And why would you be worried? :dunno: Max cold pressure is 44 psi and tires can go far above that due to the factor of safety that is used in designing them. If you know anything about traveling through Birmingham on I-65 and/or I-20/59, those potholes seem to take up more lanes than good asphalt haha :lmao:
 

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Running a comfortable 33-34psi, and speeds between 80-85, not afraid to get on it for a pass or three (HA) and about 20 miles of in town driving on the fill, I got 28.28mpg over 407 miles on Tuesday in ~35 degree weather. I can handle that.
 
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