Ok so far I've had this car for six months and I've been stuck fixing all these quirks on this car. First I experienced multiple misfires which I then changed the spark plugs and coil packs. That turned off the codes. Then I had code p420 probably from the misfires. So I went to a mechanic and they had a handmade converter made for the car. Ok light went off. Now 1000 dollars later.

The p301 code is on AGAIN! I'm literally so frustrated and could cry because I literally don't have the funds to keep troubleshooting.
I replaced the coil just to make sure but no luck. I'm bringing it back to mechanic tomorrow but I really could use some advice because the last thing I want to do is do any harm to this new converter.

I will mention that I have not yet gotten a valve adjustment ,but there's no tick sound. I also have not changed the plug that the coil goes into or the O2 sensors. Like I said coil packs and spark plugs (ngk) are new.

Please help me out.

 

first off, I'm no mechanic, I've read recently changing the spark plug gap from 55 to 35, I'm going to do this tomorrow, you do need a special tool for the sparks, for they are deep in the block of engine. like to know your progress as I well tell you if I made any progress.

 

Using Hitachi or Denso coils and OEM type iridium plugs? With quality parts, there are usually few problems.

Aftermarket, or eBay junk coils/plug often lead people to thinking there are problems that don't exist. Non-iridium plugs can also cause problems.

How many miles since last valve adjustment? Dealers and most mechanics mistakenly think no ticking noise means no adjustment necessary, but they fail to realize that "tight" valves are silent, but just as problematic as "loose" valves.

 

Assuming that coils are genuine part (Hitachi - Honda) and not a copy from Alibaba, compression test is the next step.

 

Your exhaust valves **WILL** tighten over time. They will remain silent if too tight. A tight valve will not close all the way eventually, and so could result in poor compression.

Get the valves adjusted now, then do the compression test.

 

I have an 07 Honda Fit and I have experienced the same thing since about 125,000 miles. I now have 148,000. At first, my mechanic looked but found nothing. Then the engine light started coming on and stayed on so he replaced the fuel sensor 6 mo. ago. Still happening -- this time with distinct misfire. He replaced spark plugs last week. This morning started up again -- especially when going up a steep incline.
Next Tuesday I have an appointment for valve adjustment -- hope it works. I have about $650.00 in so far. Valve adjustment quote $249.00. BTW, I also have no tick sound but as others have said values could be too tight.

 

^^^ That is a reasonable price for the valve adjustment.

If you haven't replaced the coils yet, DO IT.

Tell the shop you want the Hitachi coils, part # ending in 0053. Otherwise, who knows what brand they will use.

Speaking of that, what brand/part # plugs did the mechanic use? If he didn't use Denso Iridium he did you a mis-service...




+++++++++

Our Fit's coils acted up around 125K also (despite valve adjustments every 60K miles).

 

^^^ I didn't know enough to ask what brand of spark plugs he used. I have to find out when I go in.

I'll ask him about the coils too -- thanks for the tip.

 

That's OK, because unless your shop knows Honda Fits, they might have used whatever their parts suppliers provided, 'cause they don't know better, either.

 

Toofittoquit007, I am assuming that you are N/A, have you tried closing the gap on you OEM plugs yet? I had the same problem 10 years ago and was able to lessen the problem by gapping the NGK (6774) IZFR6K13 plugs down to .035". I later went to Denso IK22 plugs gapped at .028" which solved my P0301 problem. I am thinking the OEM NGK plugs were too "hot", and that the one step colder IK22s better suited my driving style.
As for coil packs, I am still running OEM coil packs, PN: 30520-PWC-S01. I am still running 3 of the original coil packs since I got the car back in April 26, 2006. BTW, I have also had good experience with Hitachi coilpacks, PN: IGC0053.

If you are boosted, maybe this might interest you:
Last year I installed an HKS Turbo and have been fighting the P0301 ever since. I have installed all new parts, new plugs (BKR7EIX), new Hitachi coils (IGC0053), and new injectors (PN:16-450-PRB-A01), new parts were not the problem. The problem seems to be the kind of spark plugs, and how they are gapped.
My misfire gremlins improved tremendously when I went from one heat range colder, down to two heat ranges colder (from BKR7EIX to BKR8EIX). Then I saw more improvement as I closed the gap from .028" down to .022". Seeing a trend here, I closed it down to .018" and saw more improvement. I am now running a .010" gap. However, I am still getting an occasional P0301 when I push it "WOT" over 5,000 rpm. I am thinking I need to go down to 3 steps colder. I ordered up some BKR9EIX plugs today. I can't wait to pick them up tomorrow. My plan is to start off with a .022' gap. Hopefully this plug will solve my present P0301 problem.

 

Thanks for posting that Macbuddy! I'm close to boosting ours and that info will probably come in handy!

 

For the record, installing 3 step lower plugs did not solve my P0301 misfire. I did fix the problem however, after patiently doing a 3 hour valve adjustment. It turns out that all valve clearances were way too tight. I set my intakes at .015", and the exhausts at .030" gaps.
As a result, the P0301 code has not come back since. I am also seeing a smoother idle, and MPG is up a bit too.