vss irvine
Well-Known Member
looks like you should have just gone to ed in the first place.....
Weird mapping issues with blow through MAF
- Thread starter skiddusmarkus
- Start date
skiddusmarkus
Active Member
In an ideal world I'd live just down the road from Ed but I have had various other things done and it would have taken more than a day to do this and the mapping so a local place was more convenient.
I'm sure if I left it to the guy doing it to find the problem he could, but I could be looking at a massive labour bill for fault finding which might be something I can do myself with a bit of guidance.
I'm sure if I left it to the guy doing it to find the problem he could, but I could be looking at a massive labour bill for fault finding which might be something I can do myself with a bit of guidance.
skiddusmarkus
Active Member
Did you get the file I sent Ed?
Simon, tracking back through your posts you've got 2 ecus, 2 maps and 2 sensors as the main differences.
The MAF voltages on a blow through vs draw will likely be different for a given rpm and load. 2 MAF voltages in a std location can also vary which is why modern car ecus use the lambda sensor to alter a long term fuel trim for the ECU.
To convert a MAF sensor voltage into a load for mapping, the ECU uses a calibration table but this is normally left alone and mapping is done at the load vs rpm cell map, air flow compensation table or both.
There is also a MAF calibration table I've changed as the standard settings in the PFC pro were wrong for myself and another member here. After lots of careful mapping we both found there was a lean arc across the load cells that we had to map around. Mechanically this did not make sense and as the voltage is what it is then re-calibrating the conversion of that voltage into the correct load cell was the "OCD" solution. What I'm saying is swapping MAFs can cause issues even in the simplest of setups.
I think in your tests what you're showing are consistent rich spots? Please confirm which map you used for the blow through and draw through otherwise it's impossible to draw any conclusions?
In your original post, the local mapper complained of random rich spots. Assuming he's competent then he has normalised the fuelling between the 2 MAF meaning WOT at 6Krpm is about 74% inj/duty on either ECU whatever the MAF reading is. If he's complaining of random rich spots then he's saying it's not the map because it's random so you can't map around it. Alternatively he's saying the MAF readings are inconsistent which might be highlighting a non mapping issue
I would also like to know what the mapper meant by random as many mechanical faults follow a pattern so you can map around an air leak as long as it blows the same amount. I mapped around a leaky inlet manifold gasket which had me scratching my head the next time I changed it :lol:
Finally, please confirm if you have a local earth at the MAF if only to appease me.
Jim
The MAF voltages on a blow through vs draw will likely be different for a given rpm and load. 2 MAF voltages in a std location can also vary which is why modern car ecus use the lambda sensor to alter a long term fuel trim for the ECU.
To convert a MAF sensor voltage into a load for mapping, the ECU uses a calibration table but this is normally left alone and mapping is done at the load vs rpm cell map, air flow compensation table or both.
There is also a MAF calibration table I've changed as the standard settings in the PFC pro were wrong for myself and another member here. After lots of careful mapping we both found there was a lean arc across the load cells that we had to map around. Mechanically this did not make sense and as the voltage is what it is then re-calibrating the conversion of that voltage into the correct load cell was the "OCD" solution. What I'm saying is swapping MAFs can cause issues even in the simplest of setups.
I think in your tests what you're showing are consistent rich spots? Please confirm which map you used for the blow through and draw through otherwise it's impossible to draw any conclusions?
In your original post, the local mapper complained of random rich spots. Assuming he's competent then he has normalised the fuelling between the 2 MAF meaning WOT at 6Krpm is about 74% inj/duty on either ECU whatever the MAF reading is. If he's complaining of random rich spots then he's saying it's not the map because it's random so you can't map around it. Alternatively he's saying the MAF readings are inconsistent which might be highlighting a non mapping issue
I would also like to know what the mapper meant by random as many mechanical faults follow a pattern so you can map around an air leak as long as it blows the same amount. I mapped around a leaky inlet manifold gasket which had me scratching my head the next time I changed it :lol:
Finally, please confirm if you have a local earth at the MAF if only to appease me.
Jim
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skiddusmarkus
Active Member
Jim, to clarify I logged on just 1 map with the only difference being disconnnecting the plug from one maf and putting it on the other.Both maf's were left in place for simplicity and consitancy of logging.
I don't think it's the map, as it's been totally fine on Ed's tune.
The MAF just has a regular earth, no extra one added.
I don't think it's the map, as it's been totally fine on Ed's tune.
The MAF just has a regular earth, no extra one added.
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Hello Simon, I'll reply here so everyone can chip in. I didn't get the csv file but using the same map on effectively different control systems doesn't prove much a part from the need to re-map cars after changes. A 20% rise in MAF voltage on boost sounds high and we might be looking for something else. As your sensor is remounted in a different housing, is the ID of the housing the same as standard?
The only way to prove the fundamental operation of your blow through sensor with Ed's map is to make it work as a draw through.
The only way to prove the fundamental operation of your blow through sensor with Ed's map is to make it work as a draw through.
skiddusmarkus
Active Member
Ed, no extra earths it's just as you left it after fitting the pigtail.You did remove one I had on though.
Can you remember if you had to rescale this blow thought maf when you mapped it for Danny?
Can you remember if you had to rescale this blow thought maf when you mapped it for Danny?