Upgraded maf

[Damienharris]

Hi guys I have purchased a ls1 maf and ported and polished it. It is ready to go in and start up the car but was just asking I know I need to reset the computer but after that will I come into any problems as my l67 was maxing out the current maf and the tables had to be extended will I have to change any settings as it will be getting more air flow than it is used to. As in changing settings in tuner pro or anything any help would be appreciated thanks

[Holden202T]

yes you will need to re-calibrate the MAF tables in the tune after changing it.

[VX L67 Getrag]

You can just leave them as stock & increase the base injector figure to suit then you sort of steal 20% more range but will need retune either way!

[Damienharris]

thanks for the replys which off these would be the easier to do so that I can get the car running better because its reading more air it is leaning the fuel out.any advice on this would be appreciated but in the mean time I was going to put the stock maf back on the car as it was basically undrivable the way it was thanks

[VX L67 Getrag]

Personally I would just bump the injector rate (I think last 1 I did had to go from 213 to around 275) then you need to log & adjust the injector multiplier with your STFT history logged & making sure your LTFT is disabled.

[antus]

Note that if you change the injector rate your adjusting the amount of fuel delivered but not the amount of air measured and as spark is mapped between airflow and rpm you will be offsetting the whole spark table and you'll need to adjust that to bring it back to where it was. If you tune the maf tables then spark will come back in to line with the fuel as you tune.

[Damienharris]

Ok thanks for that advice I might need to do more reading and working my way around the tuning program's for a bit longer so I know what I'm doing and I don't get any off the data changes wrong. Apreciate all the help will keep you all posted on my progress thanks

[brindo]

Note that if you change the injector rate your adjusting the amount of fuel delivered but not the amount of air measured and as spark is mapped between airflow and rpm you will be offsetting the whole spark table and you'll need to adjust that to bring it back to where it was. If you tune the maf tables then spark will come back in to line with the fuel as you tune.

Hi,
Any chance we could get an expanded explaination of this just to help understand this a little better please? If fitting larger injectors, should the base injector rate not be tampered with?

Thanks Andrew

[VX L67 Getrag]

Well it's 2 completely different things that base injector rate change was just for the maf to bring the stock injectors back into it's line, but it does put all the reference points out for the MAF configuration hence needing re-tune!

But with what your asking if you change the injectors & leave the maf stock then it just needs the injector rate changed & everything should be fairly close!

[antus]

Yeah. The engine computer is measuring air. It needs to know how much air is in the cylinder (and its temperature etc). The tune is calibrated to so the pcm knows how many hz from the MAF represents how much air. Then it applies heaps of different calculations to eventually decide how much fuel is needed at that exact situation and moment, and then it uses the injector rate (and the opening delay tables) to calculate how many milliseconds to open the injector for to inject that amount of fuel. When you change the MAF, the MAF tables are the ones that are no longer correct.

Have a look at the tables, and look for any where one of the axis are labeled mgc -MilliGrams per Cylinder (of air). Mostly this is spark. The references for these tables will be thrown out by the new MAF, so you need to tune the MAF tables to sort that out.

Generally the injector rate (and injector offset vs battery volts) are for when you change the injectors, so that the pcm can know how long the injectors will take to start injecting at the current voltage, and then how quickly the fuel will flow out.