KA24DET idling very lean, runs normal

[ZaK687]

So my ka-t has been idiling lean for a while. I thought it was an exhaust leak causing a bad reading at the wideband but after fixing the leak it still idles lean, anyone have any ideas? runs fine, idle sounds like its cammed, AFR is in normal range driving around and under boost. anyone got any ideas what it could be? tune is rs enthalpy, has run fine for the past 2 years.

[EnnEssEnnKAT]

Is the fuel pump 2 yrs old too? My friend had a similar issue, he was already running a walbro, and swapped to a new aem pump and the lean issue went away. Those pumps wear out, check your fuel pressure. Good luck!

Sent from mTalk

[EnnEssEnnKAT]

Duplocate too sorry

[EnnEssEnnKAT]

Duplicate sorry

[ZaK687]

It is more than 2 years old but I still have good fuel pressure

[ZaK687]

BUMP/UPDATE found a rip in a coupler on the hot side of my piping, wouldnt think that this would cause an off the charts lean idle because i run a blow through setup with the maf less than a foot upstream from the throttle body.

[FaLKoN240]

BUMP/UPDATE found a rip in a coupler on the hot side of my piping, wouldnt think that this would cause an off the charts lean idle because i run a blow through setup with the maf less than a foot upstream from the throttle body.

So did that fix it?

[ZaK687]

stand by for results, still at school waiting to take an exam ><

[ZaK687]

Update, changed out the busted coupler. As of now the car still idles very lean (beyond the range of the wideband but is towards the rich end when on the throttle. NEW DEVELOPMENT, turbo is now overboosting for some reason I can't figure out

[ZaK687]

Changed ignition rotor, spark plugs, and fuel filter. Idle is smoother and it starts easier but idle is still stupid lean. Im stumped, if anyone has any ideas or questions please come forward. Anything, even simple stuff

[feito]

Have you done an actual boost/vacuum leak test?

[ZaK687]

Yep, that's how I found the torn coupler

[ZaK687]

Pulled codes
11: camshaft position sensor
12: MAF
13: coolant temp sensor
21:Ignition signal in the primary circuit is not being entered to the ECU during cranking or tuning
34: Detonation (Knock) Sensor

I know that it threw 12 and 13 because the plugs came loose while I was messing with other stuff, not sure about 11 and 21.
34 my knock sensor was broken but luckily I had a spare

[ZaK687]

update, no more overboosting after I changed the knock sensor. still get some misfiring at idle and wideband still reads completly lean. While driving AFR falls into normal range as long as the throttle is a little bit open.

Someone correct me if Im wrong but idling lean means im not getting enough fuel. That makes me think injectors but they all work fine while driving, just not while idling.

[feito]

Knock sensor solving "overboosting"? What do you mean by overboosting?
And it wont be your injectors.
How old is your o2 sensor (ecu one)?

[ZaK687]

I dont think that changing the knock sensor solved anything. overboosting as in I have it set to 10 psi and it hit 20psi. o2 sensor is new less than 2 months old

[EnnEssEnnKAT]

If you fixed the items that caused several of the codes, I suggest to clear the codes and read them again after driving around a little. If you can do a compression check try that out. 20psi is a lot (not sure if your setup is good for this amount of boost)

[ZaK687]

the overboosting is no longer an issue and my setup has held up to that pressure on a smaller t25 fine. compression is perfect across the board 180 on all cylinders, will pull codes once i get the chance, right now im trying to get my electric power steering pump working again.

[Darri]

Probably you should think about doing vacuum or boost leak test?

[spooled240]

update, no more overboosting after I changed the knock sensor. still get some misfiring at idle and wideband still reads completly lean. While driving AFR falls into normal range as long as the throttle is a little bit open.

Someone correct me if Im wrong but idling lean means im not getting enough fuel. That makes me think injectors but they all work fine while driving, just not while idling.

Not necessarily. You could be misfiring at idle which would cause the wideband to read lean due to a lack of o2 from the uncombusted gases in the exhaust pipe.

I'm having a similar issue with my ka-t, although mine is more intermittent and started happening a few days ago. I haven't gone through much of it like you have so I'm not sure what could be causing my issue.

Where do you have your wastegate hooked up? If you have it hooked up to the intake manifold you could have a torn diaphram. Also check your FPR. I had a bad leak on my nismo which was causing both a bad boost leak and an unstable fuel condition at idle.

[spooled240]

double post

[ZaK687]

Not necessarily. You could be misfiring at idle which would cause the wideband to read lean due to a lack of o2 from the uncombusted gases in the exhaust pipe.

I'm having a similar issue with my ka-t, although mine is more intermittent and started happening a few days ago. I haven't gone through much of it like you have so I'm not sure what could be causing my issue.

Where do you have your wastegate hooked up? If you have it hooked up to the intake manifold you could have a torn diaphram. Also check your FPR. I had a bad leak on my nismo which was causing both a bad boost leak and an unstable fuel condition at idle.

ill have to look into this, as of right now I was able to confirm that my injectors were indeed toast. While I do not understand why I was able to drive with them so far out of spec, I now have 555cc sti yellow tops and I still have a lean idle. There was a brief period of time where it didnt want to run, every time I put it in gear it would die on me.

After changing the injectors, it runs fine once again but still idling lean. AFR stays in spec while driving but everytime I let off the gas it jumps off the lean end of the wideband. Im gonna try to do a boost leak test again, I suspect that my intercooler has a hole somewhere but since I have a blow through set up I still dont think this would cause it to run lean.

What would happen if I have a torn diaphragm?

[ZaK687]

UPDATE!

after changing out my distributor, my idle became smoother but now it runs lean while running. Under boost it reads around 14 and same at WOT, cruising would be around 16

[ZaK687]

tinkered with it again yesterday and after going for a short drive, it still idles lean but runs within acceptable range. I didnt have a dedicated vac line for my fpr but I rerouted all my lines to make the fpr have a single dedicated line. Im not sure what else I can look into for this issue ><

[spooled240]

You should check the TPS

[ZaK687]

Called martin at RS enthalpy, and he helped me find that the first two cylinders were not sealing at the fuel rail. checked this by spraying carb cleaner at the base of the fuel rail where it goes into the manifold. Unfortunately I determined that my rail was bent. After finding a new one it still leaks. I have confirmed that this bumps my afr back down to 14~.

As far as the TPS, my ka has an auto TPS on it, im not sure if that would make a difference

[ZaK687]

update, I HAVE NO CLUE HOW THIS THING STARTED EVERY MORNING. my lower intake manifold gasket was blown on cylinder 1, injectors were also way out of ohm spec, fuel rail was deffinetly not sealing, spark was weak due to a bad ignition rotor. A friend of mine is gonna give me another intake manifold because the one I have is just a lump of garbage at this point. Will report back with my results

[ZaK687]

It runs perfectly once more! thanks for all the suggestions!