1jz lean spot/hesitation

[Sami Waschko]

i have problem with lean spot and hesitation when pressing throttle pedal. idles fine but afr jumps to max lean and comes back to 14-16 and hesitates every time i try to accelerate. i have changed plugs and coils but it didnt help and plugs are completely white so im running lean. this started suddenly at dyno while tuning high rpms. first went lean on area what we were tuning and adding more fuel didnt help so we checked earlier rpms and they went also lean. so what could start suddenly and cause lean spot and what to test next? This was working setup but needed little tune

1992 mk3 supra MA70
1JZ-GTE single turbo from JZA70
"Tial" external wastegate
850cc Bosch high impedans injectors
SARD fuel pressure regulator
AEM 320lph fuel pump + 12v mod
new OEM fuel filter
new set of coils and plugs
AEM EMS v2
Innovate MTX-L wideband
GM 3bar MAP sensor

I have checked TPS position, fuel pressure, CAM and CRANK sensors, tried another ignitor... cant even remember what else
(sorry for my english )

 

[Radial]

What kind of fuel are you using? E85 on stock lines?
If so, check for injector clogging and fuel pump clogging inside the tank.

Another thing is crank/cam sync in your EMS... the most common problem on any EMS is noise on teese sensors causing the EMS to count the incorrect number of teeth - Loosing sync before it sync's up again for a couple of revs and looses it again causing unstable AFR's as you describe.

 

[Christian]

Have you checked all the standards already?
Is the timing still alright?
Are the injectors being controlled properly by the ECU? Does the ECU open them long enough?
Any vacuum leaks?
Is your MAP sensor working properly? So the ECU knows the right amount of air that goes into your engine.

 

[Sami Waschko]

i use normal 98 octane fuel and i have checked inside my fueltank and it looks like brand new.
stock lines under car but at firewall changes to braided hose.
timing is checked and set with timinglight to aem.
i have sprayed silicone spray to intake manifold but couldnt find any vacuum leaks and MAP shows same readings as boostgauge at aem so i think its ok.
what should be looking when inspecting injector control? but can it change suddenly because this started while dyno/tuning

 

[thesupragod]

Are you by chance using a 'J-tube' bypass? I have the same issue with my 1j, just no time to work on the car. Its a garage queen as of late.

 

[Sami Waschko]

yes, i have bypassed that "j-tube" and "damper"

 

[thesupragod]

I have heard of some success re-adding the jtube in the loop.... Maybe try it and see what happens.

 

[Radial]

I've heard about the fuel dampener issue before, but that's almost always with OEM electronics tuned with SAFC or similar.

 

[87supramario]

Found the issue yet? Mine has a similar issue and I'm suspecting it might be the MAP sensor.