1jz running lean

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mensrea

New Member
Sep 6, 2009
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Schofield Barracks, HI
Got a problem with my 1jz here.
I did a single swap a while ago, and everything was fine, put a wideband in, adjusted the AFR and it was pretty good (around 10.5-10.9 WOT), car ran fine, except it would cut out/sputter at WOT around 5K.
Anyway, about 2 weeks ago, it started to go lean, I'm talking 14.5-15.1 at low throttle and about the same at WOT. Tried adjusting it with SAFC 2 but it would not change a thing. Figured my injectors are starting to die on me. So I got a set of used 440's a week ago, put them in the other night. Started it this morning... took a while. and there is no change in AFR. it runs pretty shi**y I managed to get 13.8 at WOT by doing ~+40-50% on SAFC 2.
Also checked my FP, and set it at 50PSI with vac off...
Can't think of anything else at this point...
Mods are T-61, FMIC, intank walbro 255 (less than 1k on it), brand new fuel filter, 440's, SAFC 2, AVCR, AFPR, AEM UEGO, Blitz ECU (got STEALTH ecu as well, might try swapping them in case blitz is messed up), 12v Mod+ no fuel pump resistor.
Any ideas?
Also, I checked the codes and got 21 (O2 is unplugged) and 31. Have no idea what code 31 means on 1jz, since there is no AFM, or am I wrong?

Also, its kinda weird but in sensor selec on SAFC 2 I have it running off of hotwire, not pressure (MAP). If I do switch it to MAP, it runs like crap, even back when it used to get good AFRs. My guess is that the person that did install before I got the car messed it up... don't know if that means anything.
Thanks for any help.
 
RacerXJ220

RacerXJ220

Interdimensional
Mar 30, 2005
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Abalama
Mmmm fuel pump or regulator (vacuum hose) maybe.

That's if you didn't change any of the settings in the SAFC since before it began to give you problems.

Code 31 is mass air flow on a 2JZ, yes.

I know you said the pump's only 1K old. I still think it's suspect (after all it is a walbro)...

I have bad caps on my Blitz, it runs rich... Not sure about a lean condition tho...

How much boost before it goes lean?
 
M

mensrea

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Sep 6, 2009
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Schofield Barracks, HI
I've check the fuel pump, its practically brand new. FP is fine, I've checked that too, it holds just fine.
Yeah, I just done a search, and code 31 is MAP... stupid me, should have searched before asking.
I'm gonna get a used MAP tomorrow and try it on.
2jz map is the same as 1jz, correct?
Could TPS be bad, and cause the same issue by any chance?

@RacerXJ220
I forgot to say, that I put in the new fuel pump and a brand new fuel filter after it started to run lean. So I highly doubt that its bad. it made no difference with old in injectors, that's what made me get a set of other ones.
 
M

mensrea

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Sep 6, 2009
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Schofield Barracks, HI
RacerXJ220,
It runs lean on idle... stays lean all the way to around 15psi at ~13.7-13.8.

Are there any step by step instructions for SAFC 2 on 1jz, as far as settings go that is..?
 
M

mensrea

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Sep 6, 2009
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RacerXJ220;1477391 said:
If you unplug the MAP, do you then run very rich?
Click to expand...
I'm gonna go check that right now. It stalls and dies if I unplug the Vac line on MAP thu.

EDIT:
I set SAFC to run pressure (MAP) and unplugged the MAP, it just ran crappier, rpm dropped down to around 590-600. wasn't rich thu, same AFR. when I DC the VAC line on MAP, it dies thu. Oh yeah, I do need a new one now, since that little nipple where VAC line connects to broke off on me, I guess it was glued on there by the previous owner, maybe it was leaking..
Gonna find out tomorrow when I get a replacement.

Also, injector duty went up from ~1.5-1.7% to around 3.0-3.2% with MAP unplugged on idle.
 
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M

mensrea

New Member
Sep 6, 2009
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Schofield Barracks, HI
I've got the "new" MAP sensor this morning, put it in the car, and decided to check the coil packs before I start it.. well, they turned out to be cracked, as usual, around the corners, for the most part. Had to do the old nail polish trick, which seems to be working so far, runs way smoother, and doesn't sputter/cuts out at WOT/boost no more. I managed to get the AFRs to around 13.2-13.4 at WOT won't go lower than that no matter what I do... that's adding around 30-40% via SAFC. Could 440's be maxed out at this point already? I set my FP at 44 PSI with Vac line off. Should I crank it up a bit more?
 
M

mensrea

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Sep 6, 2009
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Schofield Barracks, HI
Got some updates on the situation.
Went out and got a new O2 sensor as well as CTS, plugged both in, and ran the car in the garage. Cold started like it should, went up to ~1400 rpm, and than gradually went down to ~790-800, so that thing was definitely bad. checked for codes, and got nothing.
Still have to take it for a road test tomorrow and see if it's still gonna run lean.
 
M

mensrea

New Member
Sep 6, 2009
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Schofield Barracks, HI
Got some more updates...
Got a brand new AFPR, put it in, set base FP at 44PSI with vac off car running.
Took it out for a drive... well, seen a little difference AFR vise. crusing on low RPM about 1500-2500 AFR goes to around 13.5-13.8 thats with 0% +/- on SAFC. As soon as I hit high throttle and/or go positive it goes to around 13.7-14.1, thats with anywhere around 0% to +20% - +40% on SAFC... makes no goddamn sense, since I was doing 10.9-11.1 on stock pump+injectors+fuel filter... I have no idea what else might be wrong..
So far I've replaced CTS, MAP, triyed different ECU's, check the pump wiring, which should be good, since the problem started before I put it in... Don't think I have a leaky intake manifold, since I'm holding boost just fine, according to my gauge, SAFC, and AVCR. Plug gap was .26 when I put them in about 3-4k ago, doesn't sputter after I fixed the coil packs, don't see that being an issue, wouldn't it run rich anyway if plugs were bad?
As far as base FP, it got to be 42-43 PSI with Vac off or on? 44+17= ~61 PSI at 17 PSI Boost is that enough pressure with T-61?
Should I up it more to maybe like 50 PSI on idle?

Also, why am I sputtering when I switch SAFC to run off MAP? it won't pull past 4K. Works just fine on Hotwire thu...
 
M

mensrea

New Member
Sep 6, 2009
211
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Schofield Barracks, HI
It's one of those $25 Champion filters. I will check the pump again, but like I said before, I put all that stuff in after it started to run lean. I upped base FP to 40 PSI with Vac line on, will see if that's gonna make a difference tomorrow.
That's the one thing I need to check, thanks for bringing that up. I don't have a lift/jack where I'm at right now, but I'll check it whenever I can this week.
 
RacerXJ220

RacerXJ220

Interdimensional
Mar 30, 2005
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Abalama
mensrea;1486894 said:
Also, why am I sputtering when I switch SAFC to run off MAP? it won't pull past 4K. Works just fine on Hotwire thu...
Click to expand...

It's supposed to be on "Pressure" isn't it?

It's been a while since I looked at one.
 
R

Ryan_V

New Member
Mar 1, 2009
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Austin
Dead end.....damn I'm seeing this exact same lean condition, even the AFR's are the same. Basically when I hit boost, it's not going rich anymore, it's acting like it does cruising off boost.

The similarity I see to the original poster is that I also have a Walbro pump.
 
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