Honda / Acura K20a K24a Engine Forum banner

So, what is it?

  • 02 sensor

    Votes: 0 0.0%
  • Cat

    Votes: 0 0.0%
  • MAF

    Votes: 0 0.0%
  • Ground Wire

    Votes: 0 0.0%
  • Fuel Injectors

    Votes: 0 0.0%
  • Fuel Pump

    Votes: 0 0.0%
  • Loose gas gap (if this was it...)

    Votes: 0 0.0%
  • Leak

    Votes: 1 100.0%
  • Some ECU problem

    Votes: 0 0.0%
  • The ebay intake

    Votes: 0 0.0%
  • Other

    Votes: 0 0.0%
1 - 11 of 11 Posts

·
Registered
Joined
·
6 Posts
Discussion Starter #1 (Edited)
Hello, I have been perusing this forum now for awhile.
I just made an account to get some second opinions on this issue I have.
My car:
05 Honda Accord LX
K24a4 Motor, stock other than ebay intake.
I have a performance chip stuck in the obd2 port, from ebay as well.

The problem: I have been dealing with this code for several months now.
It is elusive, without reason, and seems to come and go as it pleases.
My car runs absolutely fine. I cannot find anything wrong with it,
as far as engine response goes, the intake helped that out, and I see no loss in that, nor power.
The issue started after installing the intake, though it took a good while for the code to pop up (more than 100 miles)
So, all the diagnostics I have done so far,
Cleaned MAF, I don't think its the MAF as this would cause other visible and tangible problems in the engine when running.
Looked at PCV valve, it looks fine, and again the car runs fine.
Have not checked 02 sensors nor Cat, the cat looks fine from the exterior.
I don't think it is the 02 sensor, because again, if it was I would have real problems coming up, not a stupid light.
The light stayed for a good while, it went away after I put 93 in my car and drove for a day or 2.
The light came back on after putting 87 back in my car.
Of course, my bet is on the fuel octane, but why is this happening?
I have no real problem other than monetarily putting higher octane in my car, and it runs better, and lasts longer off it.
But Im broke, so I filled her up with 87 last fill, as soon as I started it, light came on.
Now, here is the kicker, when I still had that 87 in my tank, the light was on for a day, then disappeared, I checked with obd2, zero codes pending.
A day later, the code is back. p0171 and p0171 Pd. I thought I had it with the octane, but with 87 in my car the code randomly went away?
Could this be something more unexpected? Bad ground wire? (mine looks really nasty and isnt installed in the right place, the last dude broke the ground nut off so its attached to a different bolt, but its not fully around the bolt, only 1/3 is held on by a nut)
I strongly disbelieve it is anything important thats shot as I would know in some way when I drive it, that being the 02, MAF, Cat, Ect.
All my monitors are ready.
I just filled her up with 93, and gonna see how that goes.
I suspect that the engine is in fact not running lean. when I start my car, a decent amount of carbon buildup drains from my exhaust especially on a cold start.
This is completely normal, but would not be happening if I was running lean, at least while starting. And again, I might have misfires, engine lag, rough idle, power loss, ect, but I have none of those things.
I inspected my car for leaks for a week when the CEL first came on, found nothing, I thought I did, sealed it up, but it wasn't it. Also I feel if it was a leak, the CEL would not randomly disappear without being cleared, as it would be constantly leaking.

The ebay air intake:
My old neighbor, who was in nascar, explained to me that In order to have an air intake, I needed a chip, and high octane.
This all makes sense to me, as to why I would need it, but what doesn't make sense is this strange code.
Most forums say that if there is a code, there is something wrong, and that it cant be just from the intake.
I looked at the diameter of both the new and stock intakes, and they looked exactly the same where the MAF sits.

I know yall could use more info, like fuel trims and what not, but if I could look at the fuel trims I wouldn't need to post this here.
I don't think its a leak, there are no codes relating to leaks, only p0171, bank 1 too lean.
To clarify incase anyone doesn't know, bank 1 is insignificant info as my I4 only has one bank anyway.

I believe thats all the crucial info, if you have any questions regarding my car or what ive done with it, feel free to ask!
Thank you

UPDATE: The light went out, then went back on again after adding 93. The light only comes on while driving, and only turns off when the car is off, when I will start the car, the light will be gone, then come back at some point.
 

·
Registered
Joined
·
6 Posts
Discussion Starter #3
What does 'performance Chip' mean? Please show details of its specification.
Its unrelated to the issue. It is a gearbox performance tuning chip, you stick it in the Obd2, and it tweaks the ECUs settings. Its like KTuner but the values are set and you cant change them + No interface.
I know its unrelated because the issue came up before I installed the chip.
 

·
Premium Member
Joined
·
10,420 Posts
Can we get a few details on the intake?
If the car is originally MAF based for tuning, and you change the intake diameter at the MAF sensor then it won't properly read the air volume potentially causing a lean code. You said it is the same diameter but is it straight uninterrupted like the factory. The injen cold air for an 8th gen is a good example of how to work with the stock MAF system. Do you simply have a sensor that is on its way out?

How many miles on the car?

Try running with no performance chip and intake installed. The swap, no intake and with performance chip. I'm very suspect of all the 'chips' that just plug in and nothing else is done. You need to isolate wether this caused by a modification or exasperated by the modifications.

The code is most likely caused by an unmetered air leak or a faulty MAF. Followed by O2 sensor, possibly clogged egr passages. After that I would think bad injectors/fuel system issues.
 

·
Registered
Joined
·
6 Posts
Discussion Starter #5
As I have already said the light came before the chip. its not the chip anyway, i took it out, it was a scam (surprising). It could be due to diameter, though I think it is not related to MAF and is literally just too much air. The car knows how much air is coming in, its just too much. However it does not have a bend in getting smaller in diameter at the MAF point, like the injen. I compared the stock intake to the new one and they look exactly the same diameter from the outside. It isn't a sensor. the interior of the stock intake at the MAF point may be smaller, causing the issue. STFT ~10-20%, LTFT 16%, at both idle and moving. It is not a leak because of the consistent fuel trims.
I have cleaned the MAF 4x and the readings look good, 3-4g/s at idle, ~116 g/s at full T/B.
02s are both fine, wide and narrow.
EGR is a possibility, as is bad injects/fuel, however may car suffers no symptoms in power, and the "lean" condition has been present for awhile now.
The car doesn't actually run lean. The only time it runs lean, is right after releasing throttle (which is normal), and rarely at idle.
Basically, i think the new intake gets more air, as it should. The computer is set to get a certain amount of air.
The difference in air causes the ECU to get involved more than normal, with fuel trims.
The fuels trims overcompensate because the car is used to a set MAF reading at each T/B value, as a function (I would assume I don't really know),
the increase in air causes the ECU to over compensate and actually cause my car to run rich 90% of the time.
That also rules out any fuel/injection issues.
The code has been off for 2 days now, and I just stopped messing with my car.
I think resetting the code in my attempts at diagnostic, didn't allow the computer to learn this new component.
 

·
Arouse the DAMPFHAMMER!
Joined
·
6,603 Posts
Ok, I forget about the performance chip.

...STFT ~10-20%, LTFT 16%, at both idle and moving...3-4g/s at idle, ~116 g/s at full T/B.
Ok, if LTFT is already at 16 % and you still see an increasing STFT your engine see much more air, but I have some doubts that over 20 % VE improvement comes from an intake.

Do you smell fuel after a ride when it stand still? Did you test for leakages at the header (before the position of wideband probe)?
 

·
Registered
Joined
·
6 Posts
Discussion Starter #7 (Edited)
"Ok, if LTFT is already at 16 %..." Correct, it does see much more air, and it does seem unlikely,
however a leak seems more unlikely. The FT are capped where they are, meaning not at the limit, but not increasing. It is actually lower now, (with no code) at 16%, back when the code first came up it was at 18%. This leads me to believe (along with unchanging fuel trims (When there is a leak the STFT will be much higher at idle, as the leak will be more significant the less T/B is open)) that this is not a leak. I think the STFT changes are relatively normal, STFT usually resides anywhere from -3 to +3 and that is considered healthy, my trims bounce between 15% and 20%, so the oscillation in the %s doesn't concern me, should it?
I have not properly tested for leaks yet at all. I have sprayed break clean in with no changes in idle sound, I was actually able to get a sound change by clamping different hoses, thought it was the VTEC solenoid tubes, sealed em up, was not that.
As far as the header goes: No, I have not tested the header, the head gasket actually looked a little strange in one area, which made me shit my pants, but I sincerely doubt its that. As far as the header goes, ive looked at it, and it looks fine.
I haven't heard any leaks going on, though my belt is reaching its end which makes listening for them hard, because the sound the belt makes sounds very similar to a leak.
I will look at the intake header more closely, not sure what they are, but tubes with a metal connector connecting them to the header are there, they look a little strange, in that they are about 1-2mm up from the header, not touching, but they are all like that, so I assume its normal.
Additionally, leaks get progressively worse over time, and I have had this for I believe 2 months, and there are still no physical symptoms in the car.
Don't smell fuel after a ride at stand still, only time I smell fuel is right after full throttle, or generally driving the car very aggressively.

How would you recommend testing for leaks? I don't have a smoke/fog machine for proper testing or anything like that which is why i haven't done it

Ive been to told to vape or smoke into it, I have plenty of that, but I have been reluctant as blowing cigar smoke into a running engine doesn't sound the best for your cars health.

Thank you very much for the replies, BTW check engine is still off, after 3 days now, LTFT still at 16%
EDIT
Do you think this could be due to an improper install?
I did not plug or seal the manifold openings while doing it, or any openings, the MAF was unplugged and the negative node was disconnected, but I didn't think about sealing anything. All the tubes are on tight with new intake, and im sure they are not leaking. But this was a while ago; I don't see how the issue could continue unless the not sealing the open tube ports broke something I haven't thought of yet.
 

·
Premium Member
Joined
·
10,420 Posts
Fuel trim being that far out (I'd say more than 10% from 0) there is an issue, somewhere. Could be a sensor getting lazy or an actual unmetered air leak that is now compensated (since fuel trims are steady). This is one of those issues that without seeing it, and if now the CEL has been off, is extremely difficult to track down. Personal experience makes me point towards a sensor issue. But with all the other variables at play its too tough to actually point a definite finger in one direction.

My advise is to smoke test the intake and if it is all checking out then, with no further codes, run it. See if long terms come back into the good range, if not, there is an issue somewhere. Resetting the fuel trims wouldn't hurt anything at this point. But why bother since short terms are now in check.
 

·
Registered
Joined
·
6 Posts
Discussion Starter #9
Fuel trim being that far out (I'd say more than 10% from 0) there is an issue, somewhere. Could be a sensor getting lazy or an actual unmetered air leak that is now compensated (since fuel trims are steady). This is one of those issues that without seeing it, and if now the CEL has been off, is extremely difficult to track down. Personal experience makes me point towards a sensor issue. But with all the other variables at play its too tough to actually point a definite finger in one direction.

My advise is to smoke test the intake and if it is all checking out then, with no further codes, run it. See if long terms come back into the good range, if not, there is an issue somewhere. Resetting the fuel trims wouldn't hurt anything at this point. But why bother since short terms are now in check.
The fuel trims are lower now. It has been 4 days with no CEL. My guess is the higher octane fuel lowers the trims a bit (they are now at 13%). So, the trims are at a level that it is not flagging the light quite yet. The long term trims have progressively been going down, while the STFT consistently has been hovering around 10%-20%, at least thats what ive observed. If it was anything broken, why would it be getting better with time? At least, why would the air to fuel ratio be getting more nominal? The sensors look normal, with what they read, they coincide with eachother and the trims. Narrowband reads, .4-.8 usually hovering around .5 as it should, the wideband did seem a little odd with its readings but they roughly coincide with the narrowband so im not sure. Wideband readings fluctuate between -.04 and .04, when my friend was looking at the data, while I was driving, he said it shot down to -18 or something like that, but I wasn't there to see, and he didn't understand how to read the tool completely. If anything is broken, my bet would be that rear 02, or possibly it could be due to the intake resonator removal? Unlikely, but this issue is very difficult because of the unlimited possibilities with limited knowledge.
 

·
Arouse the DAMPFHAMMER!
Joined
·
6,603 Posts
How would you recommend testing for leaks?
Let the engine idle, go the the muffler, put your hand and seal with it the outlet of the muffler. If there is an leakage the engine won't stall.

My guess is the higher octane fuel lowers the trims a bit (they are now at 13%).
The higher the octane number of pump gas, the less oxygen it does need because of integrands like MBTF. So fuel is not the cause.

To clear that out. LTFT should be at zero. What you see is an alarming warning engine system. LTFT is to compensate for wear of parts, like injectors, intake filters and so on. On a well maintained engine it should be at 0 %. STFT is always correcting, due to deviation in maps from reality, due to transient delays of the wideband, and so on. When it shows a constant bary center in plus or minus direction LTFT will react. As LTFT did react you need to follow the failure down until you found the root of it.

Again, your engine has an alarming issue, you need to solve. You need to walk through every part from intake filter down to the muffler and prove every expected influence on fuel air mixture. Start at intake. Your items to look:
  • condition
  • sealing
  • noises
  • function
  • influence on AFR Yes/No
    • Yes, which and does it work properly
    • No, next one...
Please go through every part and post the result. I am sure if you follow that approach you will find the issue.
 

·
Registered
Joined
·
6 Posts
Discussion Starter #11 (Edited)
Let the engine idle, go the the muffler, put your hand and seal with it the outlet of the muffler. If there is an leakage the engine won't stall.

The higher the octane number of pump gas, the less oxygen it does need because of integrands like MBTF. So fuel is not the cause.

To clear that out. LTFT should be at zero. What you see is an alarming warning engine system. LTFT is to compensate for wear of parts, like injectors, intake filters and so on. On a well maintained engine it should be at 0 %. STFT is always correcting, due to deviation in maps from reality, due to transient delays of the wideband, and so on. When it shows a constant bary center in plus or minus direction LTFT will react. As LTFT did react you need to follow the failure down until you found the root of it.

Again, your engine has an alarming issue, you need to solve. You need to walk through every part from intake filter down to the muffler and prove every expected influence on fuel air mixture. Start at intake. Your items to look:
  • condition
  • sealing
  • noises
  • function
  • influence on AFR Yes/No
    • Yes, which and does it work properly
    • No, next one...
Please go through every part and post the result. I am sure if you follow that approach you will find the issue.
Okay, I believe it is a leak now.

Reason being that my LTFT was back all the way to 18.8%, this was on a cold start, and for the rest of the ride. Is it not very odd though? That my LTFT could just jump 5% from one start to another? The CEL is back on now at 18.8%
Was doubtful of leak because of how strange the trims were acting, it didn't act like a leak.

As far as the octane fuel mixture, I never said it was the cause, though it does have an impact on it which is not surprising. Higher Octane burns slower than lower octane. If there is too much air, you will want a slower burning fuel, that is why forced inductions and tuned up engines all use higher octane. I have more air than normal, so the higher octane does help, but it is most certainly not causing the issue. I thought it had more impact on the issue than it did, however.

Okay I get what you are saying, go through every part,
how would you recommend I do that?
I have checked the whole intake system (Not exhaust)
for everything above, condition, the new intake obviously looks new, the old one actually had cracks developing which is why I have been reluctant to put the old one back in. Otherwise as condition goes, it all seems pretty good. Sealing, this is the hardest one for me to determine. I don't have smoke to properly smoke test, where would you recommend I get that? Noises, again, my belt is going, so this one is more difficult than the others, but as far as the new intake looks there are no odd noises, other than the increases air volume and sounds heard from the engine. Function, the new CAI definitely functions. So, I was thinking it could actually be an exhaust leak as well, but my friend said it would be so loud that we'd know.

I am going to do the muffler thing next time I start my car, I will let you know the outcome.

Thank you again

EDIT: I have covered the exhaust exit, and the car did not stall. It is infact a leak. How quick is a normal car to stall; if you covered half the exhaust, would the car stall? Or does it have to be all of it? because my exhaust comes out with so much pressure that its hard to completely cover, I had it covered for several seconds, where I heard no sound, only by stuffing two rags into it, then putting a board behind the rags to push it in completely. It took a couple attempts of increasing blockage before being able to completely block it, and when I did the idle changed. It sounded almost like straight air with a hint of combustion when the idle changed.
Okay, so its a leak, it has to be in my intake, as if it was in my exhaust my car would still stall, correct?
Leaks are relative to the MAF correct? Meaning the air filter doesnt matter in a sense, and could be an open tube.
My MAF is fine, pretty sure, I cleaned it 4 times, every time I was tinkering with the intake I took it out and cleaned it, I tinkered with the new intake a significant amount and continue to check on it, all the hose clamps are literally as tight as they can be.
Can I smoke into my car, and if so what would be the best thing to do? I have tobacco and reefer, and a nicotine vape. Can that damage the car? I know it damages me lmao.
 
1 - 11 of 11 Posts
Top