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Lean AFR under electrical loads

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Hi guys,

My car afr reads lean when i switched on the head lights, what do you think?

Inj Dead time or alternator problem?

I relocate the battery to the car rear trunk

Engine is toyota 4efte

Also the fuel pressure is constant at 4 bar even i fully loose the regulator adjustable bolt, but in the seeting i put fuel pressure value of 310kpa, i am using haltech platinium 500

Furthermore, when i wot at idle suddenly engine surged at higher rpms and there is no response untill the rpm is got back to lower rpms

I run throttle body without idle control valve ( canceled) oem nissan 3 wires tps

Any help will be highly appriciated


If your AFR fluctuates with electrical load then I'd be suspicious of the dead time values for your injectors. Given that you've moved the battery to the boot though this could be a partial problem too. What does the voltage displayed on the ECU show when you switch a load on and off?

If you can't drop the fuel pressure below 4 bar, chances are that either your fuel pressure regulator or your return line are too small to cope with the amount of fuel your pump is supplying.

I'm not sure I understand your last issue though? Are you saying the engine doesn't respond well to throttle input from idle?

Hi Andre,

Thanks for your kind help, i did the dead time correctly today and the afr is ok now when i switch on lights, thermo fan , side widows one issue is solved but still i have the fuel pressure issue and the engine cuttoff at high rpm ( car not driving) while try idling tune i use dash10 lines inlet and return same size, ls400 1uz denso fuel pump oem. Whatsmore, the engine rev limtter some times it hits the limitter normally and most of trials engine surged and the afr reading super lean , no number shown but the red dots hide into clock wise direction, also the file which i used had a method of injection time not ve, i changed it to ve to implement what i have learned in HPA courses i taken , inj flow rate, inj dead time were set, so when i go to the fuel base and try to tune the values using ve % the numbers were high and strange to me, like 90s % on idle which give me 14. Something afr

Thank you dear for your help

If your ve numbers are that high, i would suggest looking at the injector sizing on your tables on the left. Is the injector size set correctly? This is often the problem with high VE numbers on the Haltechs.

Also, as far as your voltage stabilities, the problem could be as simple as improper ground. Did you run a ground wire back up front from the battery to the chassis/engine block? Sometimes ive noted voltage drop issues, and it turned out that grounding to a lug in the trunk was not sufficient to ground the electronics up front.

Let us know if the fuel injector size values are set correctly. Also, would be nice to know what injectors you are running and if you have a dead time list from the manufacturer

Dear 13bjunkie

I solved this issue, it was inj dead time values, befor i put the numbers which came from DW inj sheet, unfortunately there were incorrect, the i put the oem bosch 550cc values and now every thing perfect

Thanks for replay and asking dear



Hi Khalifa, it sounds like you've got good progress which is great. Just to touch on something you said in your earlier post - When you hit a limiter you will see the AFR read lean due to unburnt oxygen passing through the cylinders and making it into the exhaust. This is normal and not something to worry about.

Thanks Andre,

Little thing is noticed today, some times engin hits the rev limitter and some times not, i feel that engine cuts the fuel on higher rpm while idle tuning, i removed tps connector then it hits the limitter normaly, is that a symptom of bad tps or a safety by the ecu it self? I am using haltech Platinium 500 on 4efte engine with nissan tb48 throttle body+tps


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