FIXED 05 Honda Element 2.4 with P0172 Fuel Metering Too Rich

2005 Honda Element 2.4 AWD w/ K24A4 Dual Cam VTEC & 5 speed Auto. Speed Density (MAP) setup.



Complaint: Performance slightly sluggish but not alarming enough to keep owner from daily driving it. Has had CEL (P0172) for at least 1500 miles. Exhaust smells a tad foul (rich) especially at startup/idle.

History: Car purchased in Los Angeles with rod knock. Engine replaced with "JDM" engine. DTC P0172 appears within 100 miles of engine replacement. Car returned to mechanic who then replaces both O2's with new Denso units. Owner then drives car home to Portland, OR, and CEL turns back on during trip with same DTC. He then proceeds to live with the car in this condition since engine performance, though diminished, is adequate for his needs. W/ registration renewal and emissions testing approaching, he seeks my help since he knows I binge watch scannerdanner.

Tools: Autel MS908 & Snap-On Vantage Pro

DTC: P0172 "Fuel Metering Too Rich"
I/M Monitors: Catalyst Incomplete, all others PASS
Vehicle NOT equipped w/ EGR system.

STFT: -28
LTFT: -19.5

ECT voltage sweeps smoothly w/ no glitching and reaches normal operating temp at idle (200F +)

Both upstream A/F Wide Band sensor and downstream O2 sensor are the correct part number and are correctly installed. They both immediately react to snap throttle with smooth signals and no glitches.

Autel Mode6 data parameters (at least what the MaxiSys cares to display/decipher) shows OK

MAP voltage in Honda Factory Mode shows 0.94 volts at idle. Both MAP PIDS (voltage & calculated air) sweep smoothly with no glitches.

Other than the obvious very-negative fuel trim, none of the data on the scan tool really sticks out unless i'm missing something. All the sensors seem to be reacting and reporting as they should.

I did however, notice that this engine has higher than average blow-by from the dip-stick tube and the oil fill. Enough to sing loudly to the whole shop, funny and a very loud paper drum song after I put a sheet of printer paper over the oil fill hole. It made a few ppl chuckle, but That didn't sit well with me.

A quick and cheap compression test using the starter showed all cylinders at 150psi.

A Leakdown test was not done.

I did however manage to rig my Harbor Freight fuel pressure gauge. Fuel pressure was on the money at 50psi. Pressure dropped to 40 psi after 15 to 20 minutes and held 40. Again, this didn't SCREAM injector leak to me.. but it's possible. Still not off the table.

I also managed to capture all four injector waveforms on the Vantage Pro. I remember being able to see the Pintle Hump in many Danner videos but was not able to make them out on my Vantage Pro. Perhaps the aging Vantage Pro doesn't have the necessary resolution?

In retrospect, maybe all 4 injectors are stuck open?? Idk. Watch the vid and share your thoughts.

Here's my injector waveform capture video.

I also can't get the Blow-By out of my head.

Seems like this one's a good case study for me.

Seabass86 wrote: I also can't get the Blow-By out of my head. .

I wonder if much of the blow by could be a result of bore wash due to the extra fuel in the cylinders?
Rings not sealing so well any more?

Hmm. Haven't thought of that. Solid theory.

Hi Seabass,

Check also for contaminated oil, evap purge valve leaking.

Do the upstream and downstream sensors both agree about the rich condition?

I'm wondering if injectors got swapped when the engine did. :blink: If they did, they may not be the correct flow rate for this application. With the incorrect flow rate, the PCM will never be able to accurately control fuel.

If you can find a part number on one of the injectors, see if it matches what an '05 Element should have in it.

EVAP would throw a large leak DTC if there was an issue there.

Both O2's agree that the engine is running rich.

All four injectors have RK18 BBSV printed on them.

Googling those numbers don't yield any info.

Seabass86 wrote: Both O2's agree that the engine is running rich.

Nice. Thank you for checking that one!

All four injectors have RK18 BBSV printed on them.

Googling those numbers don't yield any info.

Yeah, I didn't get anything out of that, either. New OEM injectors are a bit too expensive to just throw at it, IMO. I suppose if you could get a hold of a cheap set, it may be worth a shot? Before calling a bad replacement engine, anyway. :silly:

Maybe now is the time for that leakdown test. You know you're gonna hear leakage in the crankcase, but how much? IMO any reading less than 90% is a problem.

EVAP would throw a large leak DTC if there was an issue there.

Maybe pinch the purge hose anyway? I'd normally agree 100%, then I got burned on a leaking purge last week.

VAlve adjustment? I’ve seen that cause a rich code on hondas

Did you disconnect the brake booster and see if the O2 sensors start reading the other way, or maybe you've already fully checked the sensors

missed the snap throttle o2 sensor change thing, never mind

Just checked Valve clearances. They're on the money, .008 intake & .012 exhaust. Still very negative trims. (-20 and below) .

I've heard rumors that only the Honda OEM a/f sensor should be used. But these are Denso, i figured Denso is pretty darn OEM for Japanese.

Where should I go next?

You check pcv valve? Fuel quality?

I'm OK with the Denso you have installed. Non-OEM sensors have been known to cause issues, BUT the fact that the downstream and upstream agree on the rich condition makes me feel better about it. If you had the upstream reading rich, and the downstream reading lean, I'd be more inclined to suspect a sensor problem.

I suppose if you really wanted to verify the rich condition, you could pull a spark plug? Should be coal black at this point. :lol:

Still say it's leakdown time.

Yep, nothing looks out of ordinary with the pcv. It's connected, it looks good, flows when you blow through it. Unsure of fuel quality. He's been daily driving it, I assume he goes to a Chevron across the way from his house or to Kroger fuel.

If I missed it have you checked to see if the timing was off?? But not enough to cause a cam crank correlation code

Hi Seabass,

Could not be your case, but i have had fuel trims at -40% with no codes and bad evap valves.

I hope it helps.

I confess, the plugs weren't soaked. (White electrodes, and dry too).

So we'll revisit O2 data again and make extra sure things look normal.

I went home for the night, but here's tomorrow morning's plan.

Watch O2 Data more closely and

Pinch off the purge, look for a reaction.

Then leakdown test this sucker if I get nowhere with that.

Thanks again homies!

Seabass86 wrote: I confess, the plugs weren't soaked. (White electrodes, and dry too).

Oh really? :huh: I honestly didn't expect that.

Possible false rich, then. Plugged cat is possible, but it'd have to be VERY plugged to generate those trims at idle. It'd have a hard time making it out of the parking lot. :silly:

Here's some known good data from an '05 Element, if it helps at all:

Idle: www.scanshare.io/share/07plWyPs902D0ornk...0,4,5,6,7,8,35,40,55

Driving: www.scanshare.io/share/wGC-pIqurUK1SDjnn...1,4,5,6,7,8,34,40,55

When was your MAP reading of .96V taken? I was mostly OK with that reading at first, but now I'm wondering if it's a bit on the high side.

Sorry for the delay on this one, life really got distracting.

Turns out this issue was indeed caused by the mechanic who replaced the engine.

This is why you've gotta approach diags on cars that have had swaps with an extra level of care and attention.

Turns out he swapped in a Honda K24A2 instead of the stock K24A4 engine the Element normally uses.

This engine is a hotter version with more aggressive VTEC for both cams and higher flow injectors.

The rich condition (and accompanying DTC) was from the PCM thinking it was pulsing 270cc injectors when in fact, they were 310cc.

The injectors were swapped out for stock ones and the issue was fixed. This issue was discovered by someone in a Facebook Honda Element Owners group when I shared a video of me performing a leakdown test with the valve cover removed. They immediately identified the engine by it's cam shaft with the the extra lobe.

Thanks for the guidance on this one though. It was a fun one.

The owner is happy with his car and has since drove it to Burning Man.

Thanks for the update.

If I understand you correctly, then the injector part number you mentioned earlier in the thread IS an OE part number. Just not for this car. :silly: That's a tricky one.