1JZCK

Hello all, I recently installed a wideband on my sc to see what my 1j is doing. When cold, it idles and cruises great in the 14s but under boost it dives into the 10s. After driving for a little bit it seems to have periods where it'll richen up, idle in the 13s and cruise in the 11s and 12s but this seems to come and go kinda. Then today after driving for maybe 30min and doing some pulls it started to cruise lean in the 15s and idled at in the 17s until it maxed out and I shut the car off and here I am ha. I'm new to widebands and afrs so I'm not really sure where to start troubleshooting. I've browsed around online but haven't really been able to find anything relateable. Any help is appreciated, thanks!

1JZCK

Also I'm on stock twins on stock boost, only mod is a front mount. Spark plugs are NGK bkre6eix that are pregapped to .44.

INTIMAZY

iTrader: (5)

Under idle these cars like to go into the 14.1-15.3 area. Under decal, the injectors turn off so it goes super lean. 10s are not uncommon for these ECUs. Toyota really tuned them conservatively. That's why its so common to see bolt-ons without a retune on these turbo platforms.

1JZCK

That's what I've read but in my case I'm having a power loss and minor higher rpm stumble and the afr will peg at 10.0 wot. I'm starting to think it might be coolant sensor related. The temp gauge only works when the car is at operating temp, otherwise it's pegged down until then no in between. I've noticed that when it goes into periods of driving rich (11s and 12s while cruising) it is related to the gauge moving down to all the way cold or back up to temp. I'm going to go over the grounds today and probably order a new coolant temp sensor. The only thing that confuses me is that if there's 2 sensors, one for the ecu and one for the cluster, then the needle on the cluster should be unaffected wouldn't it? Idk just rambling on ha

INTIMAZY

iTrader: (5)

For lack of better reason, I will just leave the generic "replace your capacitors" comment and walk away


The 1JZ has a fairly well described part throttle mid-upper RPM lean spot that's exacerbated by any breathing mods. Especially large intercoolers and aftermarket downpipes.

I'm not sure about a rich spot. 1JZs do commonly ride in the high 10s at WOT higher RPMs but that's just Toyota being a grandpa.

Best cheap fix? SAFC.

INTIMAZY

iTrader: (5)

Oh and be careful about the readouts of coolant temp sensors. They are NOT linear from the factory and really act more like a "Cold vs operating temp vs OMG OVERHEAT" sensor unless you have a standalone ECU.

hihopes

iTrader: (7)

im not sure if this could help with your problem, but i think the recommended spark plug gap is around .028 on a stock 1j