Oh sh*t dude, how long have you been running costco gas??
Its really good stuff, I've got family that works there, but its got no additives.. after a few months on it we had two vics running rough, cant recall if one got a CEL. If you're gonna keep using it, pour some additive junk in there.. just to be safe.

 

It is top tier gas. Has signs about additives on the pump. Fuel economy seems better than other options here (Mobil or shell). You think not good quality tho?

I have used fuel system cleaner before if that is what you are talking about. Didn't notice any particular change after, but I still do it 1x/yr

 

One of my old roommates is from an oil family so he is effectively an industry insider. He said that the "majors" spent massive amounts of money on proprietary fuel system detergents. Higher octane fuels also have more detergents and additives. And the gas from the majors is consistent; likely cleaner and higher quality on average. You pay a lot for that.

His recommendations for good cars was:

1. Only buy fuel directly from the majors (e.g. ExxonMobil, Shell, etal.)

2. Don't buy unbranded fuel as the quality may vary tank by tank.

3. Use the high test at least on occasion as it provides those expensive detergents and additives (and may give somewhat better fuel mileage and power).

For sure, the majors & high-test are higher profit margin so buying 87 from the unbranded corner guy will be a lot less expensive.

We never talked about fuel from hypermarkets like Costco so I have no idea there. Higher test will require some additives regardless.

 

We're gonna have to start a new thread. Eventually.

Hearsay aside, gave two of my vics a rough idle after several months of use, which was resolved with some 91 chevron. It was.. dios mio, it may have been as much as seven years ago. maybe five, its all a blur.

This is the same advice I received from my automotive instructor in college, and he was 50 shades of smart despite having a fondness for ripped jeans.. i'll never forget the sound of the flawless 67 shelby mustang he brought in.. it was gurgley, with some bwahhing notes when revved. in all seriousness I've never heard anything so pretty.

I believe it whole-heartedly and would recommend seeing how she runs with some 91 chevron. Rockafeller created the game after all.

For those wishing to go down deep, stay down long, theres a way to know.
Fuel analysis is a thing, though I cant name any companies besides FOI. I havent done it and completely forgot about it. I wonder if its been used to test costco gas. Given pricing and personal experiences thats certainly where my interest lies.

 

I'm sure somebody's done it, I'll see if I can find any test results on the internet.

I agree with your instructor. My personal belief is Costco buys in large enough quantities they don't want the blow up if their suppliers cut corners. But I would not buy gas habitually from "Joe's trading post" (this is an actual place) as they are competing on price and the major brands with deeper pockets are getting more from their refinery. Still its easy enough to try shell for a few tanks starting next time.

Gas is unfortunately not that convenient around here despite my being in a crowded area. Costco is the only place I have a reason to go, Mobil if I happen to drive across town, but shell is a trip out and back just for that. I would only do that habitually if I see some benefit from it.

 

Heres a quick handy alternative! Costco, I think, sells bottles of techron. Any fuel cleaner run consistantly may do enough. My arguement is founded only on two vehicles that were otherwise healthy until. Then healthy again after.

I'll step up and test the costco out here too, it may be a little while though. The used oil analysis however is in the mail, hah!

 

Resurrecting this .. My problem is not completely gone.. Perhaps there is more than one problem. Car still feels down on power but i think it's more the very first thing i called out ...

""when I give the car a little gas, revs will rise briefly, then sink a little bit"""

What could cause THIS?? Car does respond in a linear way to throttle in neutral so throttle position sensor unlikely to be bad imo.

 

Did you ever check your 4th plug? The wiring that's blocking it is part of the O2 sensor harness. If you could see, you might be able to unclip them... but they're kinda hard. I have the Sprintex supercharger, that gave me a lot of room to work with (similarly, you can remove the cowl and the intake system up to the manifold)... and I still couldn't unclip that thing (maybe I could do it if I used pliers). But I was able to work around it.

To remove the coil, you'll need a very short socket or use an angled wrench (ratcheting wrench would work well). With a little twisting/turning the coil will come out after that. But good luck trying to do that while you can't see around the intake manifold.

That said... the issue you're presenting does kinda of feel like the issue I had at one point during my spark plug saga (which technically is still going, since I didn't re-thread cylinder #4 which gave a DTC with the cylinder I did rethread, #2). Basically, it feels like it loses timing... which it did, since one or more spark plugs weren't firing (I think that's when the dealer found spark plugs with broken ground tips).

If nothing else, check that 4th spark plug and double check the rest just to be sure. Possibly even the coils... though that's a little beyond me to figure out how to check them.

 

Yeah, my plan is to do a full cowl remove one day soon .. But there's no reason to do it rushed since the car runs ok. I want to buy plugs so I can replace them all, plus clean throttle body and check timing. But it's becoming such a huge project .. I might break it up into plugs/body and then button it up and get to valves another time.

The fourth valve does worry me a tiny bit. I'm kinda crossing off easy stuff first. Cleaned EGR valve this weekend, but it was pretty spotless. Wondering to check pcv soon too, that's another easy one, and possibly adding a few thimbles of ATF, wondering if the car might be uber sensitive to the level.

Its like the old tale: ask a drunkard why he's looking for his lost change under a steep lamp, and he says, "because it's easier to see here!"

 

Did you clean your throttlebody? Those get dirty quickly with modern cars thanks to EGR exhaust gas recirculation. After 25k miles my cars have plenty of junk in the throttlebodies but frankly this is too frequent. Maybe cleaning every 40k miles makes sense for top performance depending on car; at 100k I would expect all throttlebodies to be a mess.

One problem is that the edges of the butterfly (and/or the "tube" they rest on at idle) get hard deposits built up from engine pollution. So the butterfly never closes properly. More air leaks into engine at idle so idle is always a bit off and computer is never able to properly map engine. Cleaning the TB and allowing engine time to remap can significantly improve idle, acceleration, drivability, noise, fuel mileage. Or you might notice no difference.

This is easy, fast and cheap for DIYer. I never take TB off cars for cleaning but some people do for dirty/problematic throttlebodies. There are some special tips here for FIT throttlebody clean which state you should not soak the butterfly hinges or the moly grease will be diluted. Also don't use carb cleaner as it will kill TB coatings. MAF sensor cleaner is really not strong enough. I use throttlebody cleaner for throttlebodies. Be careful not to lose fingers in strong springs/motors of throttlebody. Also don't press on the butterfly with your fingers to move it as you can knock off calibration. I always disconnect battery and work with a buddy on the accelerator pedal but don't know steps for FIT. Do a quick search here for detailed FIT steps and factory recommendations.

 

Calibration of the throttle plate's positioning thingy never occurred to me. Food for thought to be sure.

All good stuff, but I wonder about the actual theory that the revs increase and drop before motion is achieved. It strikes me as communication between the engine and transmission, or just something happening after the engine.. something involving the drivetrain.. even brakes could cause an issue like that, no? The engine doing its thing but theres excess resistance that it has to overcome.
Nothing else is coming to mind at the moment.

Why not, on a slow day, crack a beer and remove the front wheels.. if nothing seems odd, then maybe the rears? Does your parking brake operate properly?

Think I hear my factory recalling me

 

By far, the largest volumes of Gasoline, Heating Oil, Jet Fuel, Natural Gas, Natural Gas Liquids (Propane / Butane) are transported in pipelines from production areas / refineries to refined product storage / distribution points. Each pipeline operates like a common carrier for that product and any producer can put their gallons / cubic ft as long as it meets an minimum standard (concept of fungible commodity). From that point on, it's just accounting $. For example, natural gas has a minimum of 850-900 BTU / cubic ft and it all gets blended together. Same thing with electricity. Unless you have a dedicated wire, those electrons can and are from any supplier (within the laws of physics so to speak).

For gasoline, the generic product (summer / winter blends) ends up at a tank farm to serve the local market and tanker trucks arrive there to fill up (as example - it's uneconomical for an Exxon/Mobil dedicated tanker truck to fill up in Louisiana and drive to Rhode Island to deliver a load). Depending on the retailer ultimately getting the fuel (Exxon/Mobil, Shell, etc), their additive package is already in the tanker for regular / better / best / ethanol blends. As noted above, Exxon/Mobil's additives will be unique to their brand, Shell has their additives, etc, and CostCo / Sam's Club / other hyper-price sensitive retail operators will get the generic additives packages for reg / better / best.

Like at the supply end, any retailer's product has to meet some sort of minimum standard that won't harm engines. So, I wouldn't expect to see an engine run better / worse on one retailer's regular blend of fuel versus another's unless that particular service station has a damaged underground storage tank and/or piping / pump system that has allowed water to get in or that sediments inside the storage tank aren't being filtered out and now your car's fuel filter is clogged.

Maybe the unique additive packages offered by Exxon/Mobil, Shell, etc will make a difference over many years. I agree that you could see a difference between reg / better / best in higher compression engines. I have 3 motorcycles and each 'likes' a different grade but they don't care about the brand. I could also see an engine having a harder time burning a low-volatile summer blend of gasoline in Canada during the dead of winter.

 

Good points. Maybe the fuel quality really doesn't matter for automobiles. But with the very high quality injection and EGR schemes of modern engines, maybe it does. For sure gasoline sells wholesale with several grades and a wide variety of specs we don't see as retail customers.

 

I'm going to plead 'no contest'. For 12 yrs, I was a natural gas / heating oil trader / hedger for a Fortune 500 manufacturer / user, and also managed their electricity for North America. So, that colored everything. For another 12 yrs, I was an energy consultant for industrial / commercial buyers. The energy biz is 'wide' and 'deep', so plenty of room for everyone and allows for a lot of 'musical chairs' if you get bored.

 

@spike55_bmw Your deep energy market experience trumps my short-lived clerk job and roommate chats! Regardless, thank you for taking the time to summarise the markets and your interesting experience.

My experience may just be atypical or maybe the markets have "evolved"!

 

Thanks for the pointers guys on fuel trading. Very interesting if perhaps not super relevant. I've tried two brands of gas across four tanks, makes no difference. Shell premium most recently and hard to get any better.

Looks like my next step will be clean the throttle body, since I've got cleaner (just did EGR) and looks easy to remove airbox.
Then it's onto plugs - I read this type of issue can potentially be caused by compression issue (unclear to me how) which could be a thing from a leaking plug/coil on #4.
It almost feels like the car is giving it gas, then retarding the timing for some reason. But, I can't come up with an explanation for that and I don't have a scangauge.
This problem is only apparent at low throttle: tiny bit of power, then falls off as RPMs fall. Get the car enough throttle and RPMs will rise for sure, even if it does feel a little weak.

Think I am going to become an expert on cowl removal Looks like I will have to do it at least 2-3x (one to check plugs, two to replace, three to adjust valves).

Wondering if I should add a little ATF fluid; I've read some reports Honda torque converters do this kind of thing and I know from experience sometimes it's very sensitive to the level. But, my level does look OK. Was changed @25K miles, could do again if needed but honestly shouldn't be necessary. Certainly, I really hope I do not have a torque converter issue.

 

My Honda mower is running great with just an oil change every two years and an occasional hose down and new spark plug. Just saying.

 

I suppose you could clean the EGR passages also, which is a different job. I don't know what the correlation is between EGR valve cleanliness and EGR passage cleanliness on the Fit.

Because the spark plugs are a pain, you should check and change the plugs at the same time. Also saves you money as you don't have to waste new clips.

For PCV valve you can clean it. Or get new OEM for like $5 at the dealer.

 

+1 for pcv valve. Vacuum biz is low rpm. Besides that, thinkin post engine. Lots of information in here by the way, thank you all for that.

 

Good news! Uh, partly. I was able to loosen the #4 bolt by sticking an Allen wrench into a socket. I could not tighten the fourth plug any more, although it was difficult to get the right leverage, but it sure doesn't seem like it will immediately back out. The bad news is, with an Allen wrench I can't truly tighten the bolt. So I just need to recheck it every so often.


I checked the #2 coil and while the plug was still tight since I tightened it up, the coil itself smells like chemical and exhaust. I think it could be good to change the plugs. I'll work on getting some.


I think my next step is to clean the throttle body, not because I think a sticky plate has anything to do with this, but because it's easy. Do you spray the cleaner on the body walls or just on a towel to wipe? I can't figure out where the PCV valve is so that's moved down the priority list. I looked at several diagram but amusingly on the actual engine I can't find it 😂