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Dual Duty '01 2ZZ/C60
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Discussion Starter · #1 ·
Alright gang, I've been at this issue for a while, car started idling about 100-150 rpm high a couple months back, misfire under light revs that has now spread into high rpm. I believe there's a lean condition as well. (o2 sensor readings at 0v or near 0v under revs)

I've had major issues trying to find the culprit, only have the Apexi, sigh, here's a list of things I have replaced:

MAF (denso OEM)
Throttle body (rebuilt at maxbore)
IACV (denso OEM)
TPS
Spark plugs (NGK)
Coil packs
Fuel pump (denso OEM)
Fuel injectors (denso OEM)
Fuel pressure regulator
OEM PCV and PCV breather hoses

When I replaced the fuel injectors, the idle has come down some (around 960-1000rpm, set at 950 I believe) but the misfire/possible lean condition remain.

Mods are as follows:

2zz/C60 (est. 100k-110k miles)
MWR intake (been running fine since 2016)
K&N oil type air filter (clean)
Custom dual catch can setup (have installed OEM PCV hoses to see if this is the culprit, no bueno)
PPE 4-1 headers
PPE 2.5in midpipe w/ high flow cat
Magnaflow single exit muffler
Lightweight flywheel (allegedly)
Apexi PFC

Car was tuned by MWR, haven't had many issues out of it but I'm baffled.

Currently engine bay (pcv routing looks weird to prevent hoses from collapsing but pcv goes to intake manifold, breather goes to TB)
Motor vehicle Automotive fuel system Automotive air manifold Automotive exterior Gas


I suspect a vacuum leak but I cannot find one for the life of me. Any help would be greatly appreciated!
 

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dual catchcans on a NA? Why? Dave the Dude who is otherwise pretty knowledgeable maintains there is a reversal of airflow at/near WOT, but in practice you will never catch a drop of oil in the crankcase breather tube. Get rid of it, that's one less thing to suck unmetered air into the motor.

PS. I'm confused. You have a PFC. If you are running leaner than you'd like, add fuel to whatever area of the map is running lean. That is what a PFC is for. Over time, the condition of the engine components will drift. A tune that was good five years ago will need to be updated for today's conditions.
 

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Dual Duty '01 2ZZ/C60
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46 Posts
Discussion Starter · #3 ·
dual catchcans on a NA? Why? Dave the Dude who is otherwise pretty knowledgeable maintains there is a reversal of airflow at/near WOT, but in practice you will never catch a drop of oil in the crankcase breather tube. Get rid of it, that's one less thing to suck unmetered air into the motor.

PS. I'm confused. You have a PFC. If you are running leaner than you'd like, add fuel to whatever area of the map is running lean. That is what a PFC is for. Over time, the condition of the engine components will drift. A tune that was good five years ago will need to be updated for today's conditions.
Thanks Frank, will drop the breather catch can. As for the PFC, I admit my ignorance is preventing me from tampering with the tune, I also lack a DataLogit.

The car runs well under 50% throttle and under 4000rpm but hits a wall if you go WOT or above 4000.

Have been testing sensors and relays according to BGB and found my EVAP VSV is not functioning correctly, I also cannot pick up any resistance in the terminals of the TPS (should have gone OEM TPS)
 

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This is likely my course of action once I locate one. Will also be investing in some gauges (afr, oil pres., Oil temp.)
The prices now are so bad - I remember when I did the swap they were 150$ on ebay. If you are near RI my 83 ECU sits on the shelf until inspection time - We can put it in the car to see how it runs as a test.
 

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Dual Duty '01 2ZZ/C60
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Discussion Starter · #10 ·
The prices now are so bad - I remember when I did the swap they were 150$ on ebay. If you are near RI my 83 ECU sits on the shelf until inspection time - We can put it in the car to see how it runs as a test.
Darn, that would be awesome but I'm in KY...

Sad part is I had an 82 ECU that came with the car and I sold it before realizing it's diagnostic capabilities face palm
 

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Dual Duty '01 2ZZ/C60
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Discussion Starter · #13 ·
Oof yep you sold the ecu. Hope you got her fixed I miss her!
Got another 82 ECU now, popped P0171 pretty quickly. I'm still thinking vacuum leak somewhere, intake manifold gasket perhaps? Not having any luck finding anything with smoke machine nor starter fluid. Next on the list is an OBDII reader and torque pro to read fuel trims.
 

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When I had this code I changed the MAF, PCV valve, and gas cap at the same time and got rid of it. The code was a thorn in my side for a year. See how far off your fuel trims are for a couple of days with the OBD2.
 

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P0171 on a previously good install usually vac leak somewhere downstream of the MAF, or some kind of exhaust leak upstream of the first O2 sensor that can cause oxygen from the air to enter the exhaust system and fool the ECM into thinking it's running lean.

Can also be injector size or a MAF tube issue but those are more likely on a new build.
 
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