Injector Multiplier Vs RPM & Cylair ?

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Injector Multiplier Vs RPM & Cylair ?

Postby JohnDee68 » Wed Nov 24, 2021 8:39 am

Hi guys,
I'm trying to get my head around all this tuning stuff.

I am not sure what the multiplier value actually adjusts. I presume by the description that the value is what the injectors pulse time on is multiplied by ?
If that is correct, then why are all the values in the table below zero, shouldn't they be 1.x something so as the rpm increases it should allow to add more fuel ?

Can anyone explain this reasoning to me please?

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Re: Injector Multiplier Vs RPM & Cylair ?

Postby antus » Wed Nov 24, 2021 11:41 am

Its like a trim only. The PCM should be able to calculate everything from the right inputs but for whatever reason you might need to apply a small fuel trim up or down in only a particular place. This is how you would do that. Its not your main fueling table, although having said that some people do tune with it.
Have you read the FAQ? For lots of information and links to significant threads see here: viewtopic.php?f=7&t=1396

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Re: Injector Multiplier Vs RPM & Cylair ?

Postby JohnDee68 » Wed Nov 24, 2021 3:05 pm

antus wrote:Its like a trim only. The PCM should be able to calculate everything from the right inputs but for whatever reason you might need to apply a small fuel trim up or down in only a particular place. This is how you would do that. Its not your main fueling table, although having said that some people do tune with it.


Thanks antus.
Sorry, I am always learning and this is new to me. Even the industry jargon today is not often what I am familiar with. When you say trim, are you meaning like finer adjustments?
What would be the main fueling table you refer for tuning ?

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Re: Injector Multiplier Vs RPM & Cylair ?

Postby antus » Wed Nov 24, 2021 3:11 pm

Yes that's right, fine adjustments. The main fueling is theoretical, and its injecting enough fuel to match the air it sees from the MAF. What I say next depends which operating system your talking about and what you've changed, but say the1s enhanced extends how many hz the maf can go up too as there is headroom there. Once the stock MAF is out of breathing room, then you get a larger maf or a card maf (there is information about options in the1s enhanced thread, then you need to update the maf hz to airflow to represent what the new maf is putting out. If nothing else has changed yet, you log like normal and update the maf tables until the fueling is right again. Then add the boost hardware and do the same for the higher ranges. Other people would use the injector multiplier table. I dont think everyone agrees which is the best way, so I wont go in to that.
Have you read the FAQ? For lots of information and links to significant threads see here: viewtopic.php?f=7&t=1396

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Re: Injector Multiplier Vs RPM & Cylair ?

Postby Charlescrown » Wed Nov 24, 2021 3:45 pm

It's all fine tuning from predicted to actual in the big mathematical equation.

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Re: Injector Multiplier Vs RPM & Cylair ?

Postby JohnDee68 » Wed Nov 24, 2021 3:53 pm

Thanks again antus.
I obviously need to get more hands on learning with this stuff as well as trial and practice more.

Is there anyway to somehow via this forum to find other tuner folk who might be close to the same location I am (South Australia) ?
Someone that might not mind and be able to let me spend some time looking over their shoulder and learning how to do a efi tune ?

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Re: Injector Multiplier Vs RPM & Cylair ?

Postby antus » Wed Nov 24, 2021 7:53 pm

You can always ask but Ive been trying to do that for years and for one reason or another its not something most people want to do, unfortunately. the only time it did work for me was when I paid up for a course and I had to go to vic for it.
Have you read the FAQ? For lots of information and links to significant threads see here: viewtopic.php?f=7&t=1396

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Re: Injector Multiplier Vs RPM & Cylair ?

Postby hsv08 » Thu Nov 25, 2021 7:13 am

The way i use the injector multiplier table is as a trim if the MAF cant accurately calculate for what ever reason.

For EG, perhaps you have a large overlap cam that creates reversion across the MAF at low RPM.

The MAF maybe reading inaccurately across a small range of load. I would then, instead of creating a ugly MAF curve down low, Id make my changes if possible in the multiplier tables instead.

Its can also be used if you have strange injector flow characteristics, so in order to keep the MAF curve smooth, you'd edit that.

Thats how i would do it anyway.

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Re: Injector Multiplier Vs RPM & Cylair ?

Postby JohnDee68 » Thu Dec 02, 2021 11:56 am

antus wrote:You can always ask but Ive been trying to do that for years and for one reason or another its not something most people want to do, unfortunately. the only time it did work for me was when I paid up for a course and I had to go to vic for it.


Yes, i feel it might be something that many don't want to do. But cant hurt to ask.

Going to Vic at the moment isn't a good option for me...lol

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