MrFairlady

iTrader: (1)

For some Reason when driving and Revs get to 3k rpms my wideband reads Super lean (15-16) for a Sec and THEN Goes Normal past that? this is only at like 12-20% throttle.I have not Boosted It Yet due to that.haven't Checked to see if Free Rev does The same but Def Under Load it does.
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car is a SC400 with 1jZ/R154
JDM 440's,DM 57trim Single,Aeromotive FPR,Walbro,NGK Copper Plugs & SAFC
12v Fuel Mod,AEM wideband Mounted right after Factory o2 sensor
ALL aftermarkert parts are new as I just got it running.
Only Running Downpipe so far (waiting on Supra Exhaust Install)

I've tried adding on the SAFC at 3000rpms to +3,4 to Counter-act but Still does it.Tried bumping Fuel Pressure Up also.
Car does Not Break Up or anything but Has that 1 Spot that I'm questionable about before Boosting.

-sound like Coilpack Issue maybe/Loss of spark?
-Crank Postioni Sensor?
-Running Downpipe only the Cause
-walbro Fuel Pump issue??

most of my Coils where Cracked but I Glued them but Still wonder about them
Overall my car Runs/idles Fine besides that...keeping me for Boost pleasure.

StiCk3

iTrader: (5)

I found this a while back while surfing supraforums, apparently they like to lean out around 3k then jump back in place. go onto supraforums and in the MKIII 1JZ section type in "lean spot" and a few threads come up. Here's one thread i found:

http://www.supraforums.com/forum/sho...ight=lean+spot

MrFairlady

iTrader: (1)

Wow...nice find.thank you sir.
I tried Free rev'ing it in Neutral today and It didn't really do it but 1 time.I slowly revved it to 3k and it did it and jumped back to normal.
did it again same way and it didn't do it.

I did check all my Coils again and Found 1 spark plug not as tight as the others.Not crazy loose.Thought that may have done it.
I also unplugged some things while it was idling and only thing I did notice is unplugging the Air intake temp sensor,the car Ran the exact same.Should it have changed?

I just hope that doesn't hurt anything but Still may ditch the walbro and get a Supra Pump anyway.
may Switch Plugs too - to NGK BKR7EIX's...I'm running the "Boosted Supra Standard" NGK Copper 3330's with only 3 miles on them,...but, alot or Rich/lean idling Miles while trying to dial everything in.

1sxyrxy

at 10 to 20% throttle i wouldn't worry about it, mine runs at about 16 to 15 AFR under light acceleration. i would only worry about your full throttle at high boost. the walbro pump is fine, i have been running mine with no problems. i am running stock ECU on stock injectors on single turbo, don't even have a SAFC and haven't heard a single ping

whomiked

Did you ever correct this issue?

INTIMAZY

iTrader: (5)

Standalone.


But seriously I would love a fix.

Vrank

iTrader: (4)

Nice grave dig. Out of curiosity, how many of you guys with this problem have replaced your injector o-rings lately?

INTIMAZY

iTrader: (5)

Went with all new domestic style injectors.

Problem persisted.

1JZPWRD

iTrader: (59)

I have mentioned this lean spot before in another thread. I changed out the plugs, coils, and 02 sensor all with new ones. Made no change. The problem that I was having was at 10% on the throttle or cruising speed. The wide band will be above 15 and then read --- across it. This is when the car would kinda buck and surge. I was thinking it was the tune, needed to be adjusted. I also had a surge at idle, the tuner added more fuel at idle and it went away for now. Steady idle, but very rich, at 11.5- 12.5 on the wide band. I am still curious about the light throttle or cruising issue. At full boost and wide open throttle, the widband is showing 11.1.

whomiked

Are you running a standalone?

Vrank

iTrader: (4)

1jzpwrd your problem is your tune. As for stock ecu guys idk.

1JZPWRD

iTrader: (59)

Ye sir it is. And I am running a standalone. AEM V2.

INTIMAZY

iTrader: (5)

The phenomenon OP is talking about is with factory ECU. I'm suspicious that most stock ECU 1JZ's have this problem but it's well masked by the stock twins coming into boost and the MAP sensor richening up. With something like a 60-1, that 3000rpm area is still in vacuum so that lean spot become very obvious as you wait for the turbo to spool.

My theory is that the factory ECU leans out at that point to spool the twins quicker since it's relatively safe to lean out at low RPMs under low load, out of boost. Sure it spikes EGTs, but the ceramic turbines handle heat well, just not vibration or overspinning.

Just a theory. I haven't head any other idea why.

whomiked

This really sucks when you don't have $1400 to spend on a standalone

MrFairlady

iTrader: (1)

Removal of fuel pulse dampener was the cause.
As soon as I put it back it as perfect.