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adjusting MAF tables will upset timming?

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Old Jun 15, 2002 | 11:21 AM
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adjusting MAF tables will upset timming?

Grumpy advises not to adjust the MAF tables to alter fueling. Could a reason for this be that LV8 is calculated from MAF and RPM so if you change the MAF table it will alter LV8 values and so alter ignition timming?

For example most of my MAF tables are set to zero to prevent gas flowing as I use propane. Problem is the ECU doesnt see any load on the engine so I can only adjust timming against rpm and not LV8 also.

Simon
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Old Jun 16, 2002 | 06:06 PM
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what ecm mask?
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Old Jun 17, 2002 | 11:56 AM
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6e ARAP
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Old Jun 17, 2002 | 04:21 PM
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Grumpy advises not to adjust the MAF tables to alter fueling. Could a reason for this be that LV8 is calculated from MAF and RPM so if you change the MAF table it will alter LV8 values and so alter ignition timming?
Yes your right.But I believe the lv8 effects alot more than timing.


For example most of my MAF tables are set to zero to prevent gas flowing as I use propane. Problem is the ECU doesnt see any load on the engine so I can only adjust timming against rpm and not LV8 also.
If you dont want the injectors firing then unplug them and hook the maf up/use stock tables.If you want to turn the injectors off until X rpm then speed density ,I think would be better.
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Old Jun 18, 2002 | 12:35 PM
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Thanks for replying KVU.

I'm sure there are a lot of other things I have not considered with my setup. However my car is running great at the moment. Never seen another camaro in the UK to compare with though.

I run on propane only to a certain airflow above which I need to add gas otherwise mixture is lean. I'm not sure if adding gas at a certain rpm value would work as it doesnt take into account load. But there again is MAF voltage proportional to fuel demand?
My method of adjusting the MAF tables is to look at a voltmeter monitoring MAF voltage and lambda voltage as I accelerate hard. When the mixture goes lean I note the MAF voltage and add gas at and above that point. So now when I accelerate the mixture never goes lean. Small increases in the MaF tables hopefully means I'm not too rich.


I have not considered converting to a SD system as parts are not available here. Well not cheaply.

Thanks

Simon
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Old Jun 19, 2002 | 09:56 AM
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I'm not an expert on sd or propane but I think speed density would work like a dream.I have seen positive results using the maf tables though.Thats just minor changes.But for your app,I think slamming the table(s) might have a dramatic effect on lv8.I'm not saying your car does'nt run good.Just that sd would really make it come alive.It's an easy swap.All you need to buy is an ecm,prom and map sensor.Many gm cars have 730 ecms in them. You just need to find certain 90's fwd car in the salvage yard.I can get one for $20 round here.The prom is $40 through gm,I think.I'm not sure how much the map is,$20 maybe.It might be something to look into.When your maf goes it will be $150.Thats why I'll be doing the swap.
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Old Jun 19, 2002 | 12:37 PM
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Engine: 5.7L V8
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kvu, remember you need a new knock sensor as well.
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Old Jun 19, 2002 | 12:46 PM
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There is a way to use his existing one,actually.
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Old Jun 20, 2002 | 11:00 AM
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Thanks guys I'll consider SD if my MAF sensor fails

simon
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