new to the forum, working on a customers 2017 honda fit with 80k miles. customer brought car in limp mode to me. so far I have pulled/moved around plugs and coil packs, continue to get misfire cylinder 3. All valves have been adjusted to spec, only a few exhaust valves were slightly out of spec. injectors are all fogging 6 nice streams. cylinder 3 plug is black compared to the other 3. the valves looked like rock candy, I soaked them and got them fairly clean. top stream o2 sensor is showing 1 volt to less, downstream 02 sensor never drops under 2 volts... is this normal. Im guessing its pegging due to rich fuel call out. ill do a compression check in a day when it shows up from amazon, I need the small adapter for the expensive plugs this car uses. The car when driving has plenty of pickup, well over 5k, but while in park it hits a rev limit at 3 to 4K, and will not go over that. if you keep on it, eventually the cel will start flashing. what am I missing.... I feel im a pretty good mechanic, but this one has me stumped...

 

What's the code with the CEL?

 

I don't have a GK Fit to test, but most modern cars now have a rev limiter that won't let you rev beyond a set RPM when in park or neutral. This is to avoid potential neutral drops by revving and dropping into gear.

The CEL is probably triggering after being on the limiter for too long giving it a fault code for fueling and ignition issues caused by the spark cut.

 

When customer brought me the car, there was 6 active codes:
P2096, Post Catalyst Fuel Trim System Too Lean Bank 1
P0304 Cylinder 4 Misfire Detected
P0300 Random Misfire Detected
P219? Generic Definition
P0301 Cylinder 1 Misfire Detected
P219? Generic Definition

After cleaning the valves on the car, adjusting the intake and exhaust valves, cleaning the Mass Air Flow Meter, moving coil packs around along with moving spark plugs around and driving the car approx. 15 miles last night, I had no hesitation with the car, slight rough idle, and no CELs on the dash. However my reader did detect 2 codes pending:

P0420 Catalyst System Efficiency Below Threshold Bank 1
P2096 Post Catalyst Fuel Trim System Too Lean Bank 1

I'm still pointing to a faulty downstream O2 sensor, simply because of the high voltage readings, 3V+... But I understand that could be a faulty CAT causing the readings to be so high.

If anyone can test the rev limiter of there 2017 Honda Fit, I would be much appreciative. Customer does not believe this is normal. But cannot recall "revving" the motor in park.

 

A user on here chased similar codes for quite some time before finally replacing the MAF sensor. Solved his problem.

The 02 sensors and catalytic converter on these seem to be pretty durable provided the injectors aren't trashing them by running super rich. That happened in '15 models, but I don't believe we've seen a '16+ with injector issues.

FWIW, I did a quick google search and I see that Insights, Civics, Ridgelines, etc have a limiter in Park. I'm betting the Fit does as well.

 

GAFIT, Thank you so much!!! That was gonna be my second part to start troubleshooting, the MAF sensor. I worked on a Nissan Altima about a month ago, and that ended up being the culprit. Also thank you for checking the rev limiter scenario. More to follow.

 

Unplugged MAF sensor and car ran significantly worse, and started throwing codes about it, so I’m pretty sure this component is working. I’m able to make the car throw P0303 codes if I hold the rpms at 2500k, you can hear it backfireing, and eventually a limp mode is produced. At that point car won’t rev over 2k. I’ve closed what the plugs look like about about 15 miles of driving. Notice how black the 3rd plug is. Super rich!! Maybe a bent valve? Compression test or will be hear tomorrow.

 

I tried to upload pics of the plugs, but they are lost in cyber space somewhere.... 3 are golden brown, one is black as tar, cylinder 3. Gonna compression test it tomorrow, and see whats going on. Not sure what the psi should be, but if 3 is considerably less than the other 3 cylinders, then ill know, its fatal.... I also noticed tonight, the fuel pressure is registering 500 to 700 psi!!!??? is that right? When I unplug fuel pump, car idles perfect, like a kitten arounds its mother. course I have no power, but it sounds great!! disconnecting the fuel pump brings the pressure down to 40psi, which I would think is acceptable, not 700psi... if anyone has a fit they can plug in, and tell me what they see, id be so grateful!!! unplugging the MAF sensor made the car run terrible, so im assuming its working right.

 

Maybe the PCV system isn't working correctly? Generally speaking if a car has one plug getting oil fouled, the PCV dumps in that cylinder and has failed. Once again, I don't own a newer Fit, but my other DI cars have complex PCV systems that incorporate an oil separator into the system. If they fail, it could dump oil into the cylinder.

That fuel pressure sounds about right at idle, but should be much higher as rpm climbs. There are two pumps. One low pressure (40-50 psi) feed pump in the tank and the mechanical high pressure pump on the valve cover. 1500-2500 psi is common for DI vehicles at operating rpm.

I doubt it's fatal. These motors can go 400,000+ miles under good care.

 

GAFIT, thank you again for another reply! I wish the pics of the plugs would show up, or maybe they did in some other forum... Plug #3, is not wet from oil, but very sooty, like an over rich scenario. But that is one system i have not looked at, ill check the PCV valve and make sure its clicking. The highest fuel pressure i have seen is approx. 750psi @ 3500rpm. I should get my compression tester today, and I'm hoping for good numbers, 120-140psi(?), that would rule out a burnt valve scenario. As for maintaining the car, i can say the customer said he did regular oil changes, and when i pulled the valve cover, it was evident of good oil changes. As for selection of gas, he buys regular gas at FastTrip, a local gas station to him. The valves looked terrible, when i looked into the intake ports. Again, i cleaned them up the best i could from the intake ports, soaked them, and scraped the sludge off. When I was done, they looked pretty good. The local dealer also pulled off the intake, took one look, and said your injectors are leaking and need to be replaced. They quoted him 1700.00, he declined, and was charged 390.00 to remove the intake, and inspect the valves.

 

 

Yeah, that #3 plug shows signs of being super rich in that cylinder. It might have a leaking injector, but I would only replace #3.

Make sure to use Denso or NGK iridium plugs. OEM's are iridium.

These DI motors have so many problems.

 

Did the compression test tonight, #1-110psi, #2-105psi, #3-108psi, #4-109psi. I kinda thought it would be up to 120 or 140, but they are all consistent, so gonna check it off the cylinders, pistons, and valves are all good. My final check will be to disassemble the injector rail again, and move #3 injector to another cylinder and see if that plug starts to foul out. If it does, we will know for sure the #3 injector is bad. PITA, but I gotta know for sure before I buy parts...

 

Swapped around fuel injectors, 1 to 3, and 2 to 4..... and viola!!! now we have cylinder 1 misfires!!! im gonna go with the customer has a bad fuel injector, which is now in cylinder 1.... and customer only wants to buy one injector.... deep sigh.

 

Well after some quick research, you cant buy just one... they wanna sell all 4 with a new fuel rail... 630.00 is the best I found. Any one know of something else?

 

Maybe go with a used one?

https://www.ebay.com/itm/16-17-18-19...QAAOSwqFBbu~4N

 

Thanks for consistently updating here henryweston, I'm sure others will stumble across this thread with similar problems in the future.

DI engines... I say no thanks!!

 

So customer agreed to purchase the injector kit, which comes with all the seals, new injectors, and fuel rail. Not sure why the fuel rail, but its included none the less... cost of parts 618.30, shipping 24.72, grand total for parts, 643.02. I ordered the kit from HondaPartsConnection.com. Cheapest i could find it. Hey GAFIT, i wonder if that injector is from cylinder 3??? LOL... its odd he only has one for sale... maybe the customer can recoup some of his money by selling his 3 good ones. So the dealer wanted 1900.00 for this job... I was thinking 1200.00 total, does that seem fair? If i didn't do all the troubleshooting, it would be a lot less. Takes about 30 mins to replace all 4 injectors, maybe 45....

Petelite, your very welcome. Its been a great place to vent!!

 

Final post.... FINALLY got damn fuel injectors... what a PITA. Parts traveled the country before finally landing in Lancaster CA. Anywho, they are here and installed. Car still stops revving at approx. 4K, by design, no drag racing in this fit... But Im happy to report the cylinder misfires have stopped, and car seems to be running well. So one injector was definitely bad. Hope this helps anyone else. I told the customer to keep the receipt,as im sure Honda will recall the 2017 injectors like they did for 15 and 16..... Thanks to all who posted to help. Henry.