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1uz misfiring at idle

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Hi guys,

I have a problem with 1uz engine whic misfiring at idle, the misfire dis appear if i add extream amount of fuel at idle upto 11 afr which is not logic, i did vacum leak tests using carb clearner spray, i faced a problem with timing drift also after lock timing to 10 degrees and reving the engine, timing was moving by 3 degrees,

1uz engine

Aftermarket Intake plenum

Siemens Deka 630cc high imp injectors ( these injectors have very low value of dead time like 0.28

@14v according to the rehub website, so here is my modes i did :

Stock fuel rail ( pulsation damper + stock fpr removed)

Automotive afpr

T04e turbo charger

COP 1mz coils

Wasted apark setup + semi sequiensial injection setup

Haltech ps1000

Any input will be highly appriciated

Have a nice holiday

With your trigger issues, you can use the variable trigger option with haltech. Then you rev it with a timing light on it, observe the error, and program the 2d table for the trigger, to get the error out of it.

As far as your problems some information would be good

-What is the current dwell setting

-what is the injection angle

-What is the fuel pressure with NO vacuum connected?

Also, with a sport 1000 that would mean that you are running wasted spark/batch fire? Because batch fire requires different dead times.

I have also found these motors to misfire at idle if your sparkplug gap is to small or sparkplugs the wrong heat range. Adding fuel will make the misfire go away as well.

Dear 13bjunkie,

Thanks for ur replay and input,

Regarding the trigger angle table, is this notmal for 1uz engines or i have to change the trigger edge from falling to rising, I didn't check the polarity of crank sensor wires also i dont have osiliscop to check the wave edges.

My sitting is:

Engine started at 65 tdc angle and 22 offset

Dwell time for coils is 2.5ms

Injection angle table didn't touch yet ( i dont know how to adjust it and where to start)

Fuel pressure without vac line is 43psi

Yes i am running wasted spark and semi sequential not batch

Dear Chris,

What is your advice and r commendation for spark plugs?

Heat range and gap for this engine?

Thank you all


Yes this is normal for these triggers. They are VR and can be noisy, and do tend to drift a bit. I dont think you need to set your edge differently. Those settings sound correct. The variable trigger angle table is just to help phase some of this drift out. I find that they usually drift to the retarded side anyways, so not as dangerous.

Chris has a good point. I would start with factory gapped plugs and go from there. It does sound like an ignition problem.

I would make sure that those dead times work with semi sequential. Im not familiar with working deadtimes into batch fire/semi sequential setups.

As a form of troubleshooting, you could try bumping your dwell up to like 3.5 and see if it makes a difference. One time with a 2jz, i had a repeatable misfire, and i found that turning the dwell up made it go away. It turned out to be one of the plug boots was leaking spark energy to the head.

Hope that helped.

Thanks allot dear, i will start to work with ignition setup such as spark plugs, dwell time and i will be nack with the feedback

Appreciate your inputs dear 13bjunkie and Chris

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