Hello all...

I have a 2008 Fit Sport, been running like crap for several weeks now. Hesitation when accelerating, rough idle....just seems like it's 'missing"

I have 95000 miles give or take, (long commute to work) and since it was close to time for new plugs, I went ahead and replaced them. Still running rough, and with new plugs, MIL finally came on (P0301 (cyl 1 misfire), P0302 (cyl 2 misfire), and P0300 (random misfire)). Up to the point of new plugs, there was no MIL.

I replaced all 4 coil packs and reset the MIL. It was running better, but still giving me a little hesitation and rough idle. Compression Test was good. MIL came back on after about 30 miles.

I'm at a loss on what could be the cause...Perhaps clogged PCV valve? But I understand that to get to that entails removing the intake, is that correct?

Any advice for me? I have tools, and I'm not afraid to use them.

thanks in advance!

 

now that I think about it though...wouldn't a stuck PCV give me a different error code on the MIL???

 

valve job maybe

 

My suggestion is to swap out your new Pulstar plugs and install either of the Honda recommended plugs. Adding non-stock, weird design after-market plugs will make accurate ignition problem diagnosis unreliable/impossible. IIRC, the gap suggested by the plug maker was different than stock specs. too, but I may be misremembering over more than four years. If you do install stock plugs, gap them on the short side of the Honda-recommended specs.

As it is, your new plugs are throwing another variable into an already mixed bag of known problems.

 

My vote's for valve adjustment (assuming it hasn't been done)

I've never had spark plugs cause issues (unless they were missing an electrode...

 

+1 Tight exhaust valves

 

Or just simply gapped too far open

 

Adjust valves

 

aside from all that's already been mentioned by others, a bad injector would give the symptoms you've listed. Its doubtful since the car is relatively new but if nothing else pans out its worth looking into. If you have one of those stethoscopes you can hear if they are clicking.

 

Try doing a compression test. It will reveal if you got leaky valves.

 

Like everybody is telling you your symptoms are exactly like others have fixed with a valve adjustment and with your mileage if they never have been done it NEEDS one.

 

I know it's been a while since i started this thread, but needed to come back to it since I'm having the issue again.

So...i took the advice of this thread, and took it in for a valve adjustment, and it ran like a top for a few months, then back to missing, lurching on me at high speeds during acceleration, etc.

So I took it back to Honda, and had them look at it. They couldn't find anything wrong, and so I picked it up again. It ran fine for a while, then started again. CEL would flash, but never really lock in.

On my way home from work one day, it was acting up like crazy, so I took it back in, took the tech for a ride, and he saw what I was seeing.

They had it for 3 days, compression testing, etc...finally pulled the fuel rail, and they are telling me that all 4 of my injectors are bad, which I find VERY hard to believe. Does anyone have any ideas for this? When it started to act up, I ran a bottle of seafoam through the gas to no avail.

 

I was hoping someone else would respond

My guess is that there was more than one problem. Your valves needed adjusting and the fuel injectors were getting deposits.

I'm not sure how they all would go bad other than deposits. When did you do the seafoam: I understand it was after they diagnosed it as injectors?

Reading about seafoam it seems it's oil, naptha, and alcohol. It shouldn't hurt anything and might help clean them. Shrug. I'd try another fuel injector cleaner. Maybe run through a couple tanks with it. I can't recommend any but I've used "lucas" products (without noticing a difference, but I felt better afterward).

I think you'll end up following your mechanic's advice...

 

Redline si1 wil give you most bang for your buck as a fuel injector cleaner. The fit tank is small enough to run 1 bottle over 2 tanks and be fully effective. As far as usuage long soaks help; burning through the tank in 1 continous trip doesn't make cleaning go faster.
Read reviews and buy on amazon.
If your root problem is something else though, or your injectors are already clean, your answer wont be in a can.

Others are amsoil pi, gumout, chevron techron, bg 44k. But dont let bottle sizes fool you. the redline is reliably the cheapest per effectiveness

 

Dont be using a bunch of chemicals and crap to fix this issue.

If the valves were adjusted and it made a big difference, you can rule those out.

If the plugs and coils are still good, you can rule them out.


It is time for you to find a friend with a scanner, or your local autozone, and read the MAF and MAP sensors to see if they are functioning.

Either or will cause hard warm starts, random misfires, and in general cruddy performance and gas mileage.



The easy way is to undo the connector for the MAF and MAP sensors. you will of course get a check engine light for these sensors. Then go for a drive. The car does NOT require any sensors other then the crankshaft sensor to run. All other sensors are there to get optimum gas mileage and engine performance.

If your car does not hesitate nearly as much with those two sensors disconnected (do it with engine off and key out) then you can rest assured it is one of those two. a bad MAP sensor makes the computer think its seeing large amounts of engine load, which will effect ignition timing and increase fuel use. a bad MAF can cause all sorts of symptoms, especially if the sensor sometimes works. the computer gets a good reading, adjusts fuel trims, then goes WHHHAAAAAAaTTT when the sensor starts going nuts, then it craps the bed again when the sensor reads fine again.

 

If you wish to resort again to chemicals, I highly recommend Chemtool B12. get your fuel tank to half full, pour in the entire bottle. Turn engine on, idle for 20 minutes or so, shut it down. let it get cool, then run car like normal, aka work, grocery store, etc...

When it gets to a quarter tank, top it off with your normal fuel, and go from their

This should get you at least 20-80 miles depending on traffic, route, etc.. of cleaning power.

 

I am surprised no one mentioned the battery. It would cause all the problems described including malfunctioning sensors, coils and injectors. Carbon would also build up on the valves leaning the A/F. Adjusting the valves is normal maintenance and should be done every few years at least. There could also be vacuum leaks.

 

bad battery would not be serious if alternator is still good. even at idle its pushing plenty of voltage and amps.

 

+1 on sensors. Being intermittent doesn't suggest fuel injectors.

Did you by chance use an aftermarket oiled air filter?

 

That oil they use on filters will not harm anything.

Its too fine of an oil to clog anything up