If there is carbon build up in the combustion chamber it retains heat and can cause pre ignition detonation preventing the full advance of the ignition timing by the engine management control.... There is another person on this forum that had the same problem with his automatic Fit, and by adding some fuel injector cleaner and driving at higher RPM than he normally did, is now saying that his car has never run better.... He had spent a great deal of money for a super charger prior to this and his car even ran poorly, until doing this... I believe that the hot weather is is a contributing factor in your loss of power, but low RPM driving. the higher gearing and torque converter weight of the automatic will cause carbon accumulation.... Get out on the road put the throttle down and blow it out..... You can't blow it up or hurt it by doing it and that is what car owners have been doing since they have been making cars.

 

^^^ the temperatures inside the cyls are so much hotter when actually running full compression (at wot), that's what oxidizes the carbon off so well. When cruising the dynamic compression is usually between 3:1 and 5:1.

That's why the Onan Deere needs the heads off every couple years to brush off the carbon. 6:1 comp never gets hot enough, even air cooled, unless the grass is a foot tall. Also that's why a farm tractor never really runs smooth until you've plowed a field with it, gotta get it to open the governor and keep it open for a while.

Honestly it's the first 5 minutes after you start driving that the worst deposits occur, when it's harmful to drive hard and to boot the surfaces are cool enough for the incomplete combustion that forms elementary carbon in the first place. It'll self-clean enough if you drive a half-hour or more every day, but if you're driving 3 miles like me, it would take a trip across state before it gets rid of that buildup so I go full throttle a couple times a week after getting the motor good and hot.

Usually doesn't form on the intake tract. More where the injector sprays onto the back side of the valve, and its higher-than-average temp can cause the fuel to break down if the fuel concentration is sufficient and the airspeed (read: vapor pressure) is not. The worst hotspots aren't usually on the piston face, it's the flat face of the valve, which are much hotter. They only transmit heat into the head via the really thin seating surface.

detonation = super accel of flame front due to combustion pressure and after the spark plug sets it off, puts too much stress on rod bearings- this is what hotspots can cause, or bad gas + high comp; usually happens near TDC

preignition = compression + hotspots causes ignition during compression stroke before TDC and before spark plug fires, if you get this dieseling your motor is gonna be messed up quick, few actually run into this

Weight slows it down too, today between the 4 of us I know we were a good 200# over the limit of the car . Felt like a Geo Metro.

 

The whole truth and nothing but.... Great post!!!!

 

One thing we warn customers about is dirty gas: we advise them to run a bottle of injector cleaner thru a tank of gas once a month to keep injectors clean and full flow. Weak flow = low power.
Plus we hear from our oil comrades that gas today has less energy per lb so that also means less power. They're doing it to get more gas output per barrel of oil. If your car picks up after running a bottle of non-alcohol injector cleaner (Available at low cost from WallyWorld) either can be true but on the third its probably less energy gas.
Or there is considerable carbon deposits on the valve stem that impede air-fuel flow and its hard to clean that off except by head teardown but you can try.
PS dirty gas refers to dirt etc not poor gasoline. Its the stuffmost easily clogs injectors.

 

Or an 850cc Austin Mini. Although the aero of the Fit is such that, given highway speeds and favorable terrain, the little guy doesn't do all that badly with a load on.

 

i'm gonna try driving my Fit a little harder on this gas tank. i usually shift around 2500-3000RPMs, i'll WOT coming to onramps or just merging into traffic. i've been consistently getting about 32-36mpg. the only time i hit over 40 was driving from the Bay Area, CA to Biloxi, MS., i took I10 the whole way pretty much.

this month is going to be fun.

 

I am happy to be old enough to have driven a whole lot of cars that make the Fit seem like a AA/fuel dragster in comparison.... One of them was a 1964 Lancia Flamina that sold for more than 2 XKE Jaguars at the time and was quite advanced engineering wise.... If you ever took a cross country trip in a VW Micro Bus going through the mountains in West (By God) Virginia you would have a completely different definition of slow.... I could go on and talk about some other really slow cars, but old people need a lot of rest and it is bedtime.

 

I went to the dealership with the acceleration issue. I explained to them about hitting something on the freeway. They inspected the car, and no damage was detected. He explained the whole heat and humidity thing to me. He also told me that since the computer hadn't picked up anything there wasn't much they could do. they did offer a fuel injector induction service. I did take that offer, and still no change. I'm getting frustrated. I got my 08 AT sport last year at this time with no problems. I trully can't control my cars acceleration anymore. It has been a month and a half with this issue. It especially sucks on inclines when the speed starts dropping.

 

This might sound stupid, but I had an old clunker with a similar issue. It got to the point where I had the car floored and could only go about 45-50 mph. It turns out the brake calipers were sticking. I'm not a certified mechanic or anything, but I'm just putting that out there. Good luck I hope you resolve this soon

 

Your dealer should have done this after verifying unusual power loss on hills. We find a 3 to 4 mph loss from climbing a 10% grade on cruise controlset at 60 mph is pretty normal in AT 5th.. Shouldn't be more than 5 mph anyway.
1. check for plugged air filter and air intake to the filter. That hit you mentioned...
2. Check exhaust piping for partially crushed pipe or impacted muffler that could dislodge baffles causing pluggage. Again that impact you mentioned...
3. Check fuel pump flow to specs. Problem can be due to fuel filter or fuel pump or crimped/plugged gas lines.

Good luck. Yes, and check your gas supplier by trying another supplier or two. its not often but sometimes dirty gas will load the intake valves with enough deposits that act as plugged intake air manifold that limit air flow just as well. That however, ain't a simple solution nor Honda's fault.

Good luck.

 

I add Lucas Fuel Additive twice a month and I always try to stick with 1 gas station to avoid bad gas. You be amazed how many cars a year we get with poor performance issues and its due to wattered down gas.

 

Well how about this? How do you control the VTEC to kick in?? Sometimes I can feel the extra power at 2500-3000 rpm and sometimes it just rev smoothly up......

 

btw, i just tested it tonite on a long stretch of road. I tried to accelerate from 60mph to 70mph and it took forever. With only 5 gears, it seemed like I can only top it at 75mph as well......

Won't try to pass a tanker in this thing.......

Not encouraging it but anyone has ever tried achieving a top speed for the Fit?

 

Actually time the difference. A stopwatch or stopwatch wrist watch is needed to actually determine how 'slow' is 'forever'. An automatic in drive or auto? In 5th gear will take a good while because its geared for top speed of 180 mph. 60-70 is only 2000 to 2300 rpm or so where there is little power.
Using auto in 3rd see how long it takes. BTW, third gear is good to 90 mph so 60 to 70 is a breeze.
If you are new to small displacement engines rpm is the key; it has to wound up to get power.

 

I have no experience with the automatic fit, but my manual model doesn't start accelerating strongly until the tachometer has reached the 3200 RPM mark which is about where it is in 5th. gear at 70MPH. 3Rd. will go to 80 but the limiter kicks in before it reaches 81..... It seems to me that with the automatic a person would have to get the revs up a little over 3200 RPM to be able to optimize their acceleration..... There is a post by one guy here that claims that a police officer clocked him at 114 MPH in 4TH gear but gave him a ticket for going 90 something, and his car has an automatic transmission.

 

It may be your ECU conflicting as well. If you drive your car like a grandma, it will stay a grandma meaning its going to stay fuel efficient and when you step on it, it wont go that fast. To keep power going on these cars, you got to step on it once in a while and I mean step on it. Push it like you are trying to race it lol. I know it may sound silly but the ECU learns your driving habits. If you drive fast all the time, it will be fast all the time, if you drive slow all the time, it will be slow. So if you drive slow, and punch it, it will still feel slow, you got to beat her around a little to get it back to normal. Hope this makes any sense.

Another maintenance check, check your valve gaps, they may be suffocating your air flow. Over time the exhaust side likes to tighten up and the intake side likes to loosen.

 

My last car (prelude) felt like what your describing. What's funny is that I drove it slower then it should have been driven and ended up with having to clean out the EGR ports a couple times. I got a lot of carbon buildup and it's probably from constantly revving at lower RPMs. I told my cousin who's a mechanic now, that it seemed slow and I never beat on it. He said that's the problem right there, I don't know open it up enough. Now with my Fit, I make sure to rip it up at least once a week. It's a Honda motor that likes to rev high. They are built that way, no harm done. As long as your not one of those kids that just beats on it until the engine breaks you'll be fine.

 

Had almost the same problem with my dad's 03 Sunfire... Power dropped considerably and it hesitated. When i went to the dealer, the Service Advisor just said ''Put one bottle of Red Line Injector cleaner into a full tank of premium and ride it like you stole it!'' As my father didn't felt confortable enough with the idea of giving his car a beating, me and my brother got that job... Ran like a champ after that but it really needed his weekly beating...!! :P Maybe the Fit is no different... I don't know because there are a lot on good inclines around here where i always floor the car!!

-Injector cleaner...
-Plugged air filter...
-Bent or crimped exhaust or fuel line as allready stated...
-Brakes calipers problems (Wheels would be hot!!)
-Poor gas, try gas from a better brand like Chevron...

Marko!!

 

With a manual you need 4th gear in order to pull decent 60 to 70 time which should be in the 8 to 10 sec bracket on level ground, no headwind, etc. The autos' 3rd is about same as manuals 4th. In any case 114 mph is entirely possible on level ground and especially little downhill or with tailwind. We've clocked several manuals at about 108 to 110 mph tops and autos at 103 to 106, measured by radar gun. Ours, not cops.
See 'you tubes' "Fit leading a lap at VIR" to see how we test.
The Fit does not offer sterling acceleration; just excellent driving manners and gas mileage. And I suspect long life in around town and country service.

 

The fastest I've gotten my fit to was around 90 MPH. I believe the tach was hovering between 3500K and 4K RPM. Only did it once so I don't remember too well. I don't get why Honda made a Tach that goes to 140?