MAF Honeycomb now in service
10-17-2013, 02:51 AM
#18
Under the Lift
Lifetime Rennlist
Member
Lifetime Rennlist
Member
With some modified air intakes the airflow makes abrupt changes in direction so near the MAF that this causes turbulence that produces erratic readings and driveability issues. The honeycomb is an attempt to stabilize the airflow as it enters the MAF.
10-17-2013, 03:03 AM
#19
Rennlist Member
Thread Starter
Some folks have complained about the stability of the idle on the 928 and indeed a well to do friend of mine who purchased a brand new GTS just after they came out complained about this and Porsche could do nothing about it for him. Eventually he got rid of the car because it annoyed him so much.
I noticed something similar on my late S4 motor [now in my GTS], it varies a bit [air temp?] and when sharktuning tried to tune this out. Got some perception of improvement but the lumpiness still persisted. No idea if all 928s are like this but anyway with the advent of folks force feeding their motors it seemed the prevalence of such observations increased.
There is a belief in some quarters that accuracy of air measurement in the MAF is enhanced by fitting such honeycomb devices in the MAF inlet. I am not convinced about this but someone posted a link to an outfit that makes such. That someone actually goes to the bother of making this thing and there is a demand for such says something- but of course it could be a load of nonsense.
Out of interest I ordered this item nearly a year ago and just did not get round to doing anything with it. I usually do some shark tuning checks every year to see how my work is holdung up. Shortly winter season and the nice weather will arrive so a good time to revisit this activity [I also do more driving].
What I have noticed whilst sharktuning is that in each cell of the fuel map there is a scatter of AFR readings that can vary by plus or minus .3 to .4 in a field of values where we target to get numbers in the range of 12.4 at full load and numbers closer to 14.7 whilst cruising.
If these things do what they are aimed at, then I might expect to see more consistent AFR readings at any given operating point. I have a feeling I will not see any difference but I am open minded as to the possibilities.
Jeff has just tried this device on his forced induction system and found it stopped an annoying surge at idle- my first reaction yesterday was something similar.
For the cost of 30 dollars or so I thought it was something interesting to experiment with. That the S4 ticks over at lower rpm's than the GT motor tells us something- doubtless the difference being the impact of reversion pulses- whether the honeycomb can help filter such out would be something worth investigating for those with GT cams. I am sort of halway there with the GTS inlet cams in my S4 motor which may explain why my idle is a tad lumpier than it used to be.
Trust the above of interest.
Regards
Fred
I noticed something similar on my late S4 motor [now in my GTS], it varies a bit [air temp?] and when sharktuning tried to tune this out. Got some perception of improvement but the lumpiness still persisted. No idea if all 928s are like this but anyway with the advent of folks force feeding their motors it seemed the prevalence of such observations increased.
There is a belief in some quarters that accuracy of air measurement in the MAF is enhanced by fitting such honeycomb devices in the MAF inlet. I am not convinced about this but someone posted a link to an outfit that makes such. That someone actually goes to the bother of making this thing and there is a demand for such says something- but of course it could be a load of nonsense.
Out of interest I ordered this item nearly a year ago and just did not get round to doing anything with it. I usually do some shark tuning checks every year to see how my work is holdung up. Shortly winter season and the nice weather will arrive so a good time to revisit this activity [I also do more driving].
What I have noticed whilst sharktuning is that in each cell of the fuel map there is a scatter of AFR readings that can vary by plus or minus .3 to .4 in a field of values where we target to get numbers in the range of 12.4 at full load and numbers closer to 14.7 whilst cruising.
If these things do what they are aimed at, then I might expect to see more consistent AFR readings at any given operating point. I have a feeling I will not see any difference but I am open minded as to the possibilities.
Jeff has just tried this device on his forced induction system and found it stopped an annoying surge at idle- my first reaction yesterday was something similar.
For the cost of 30 dollars or so I thought it was something interesting to experiment with. That the S4 ticks over at lower rpm's than the GT motor tells us something- doubtless the difference being the impact of reversion pulses- whether the honeycomb can help filter such out would be something worth investigating for those with GT cams. I am sort of halway there with the GTS inlet cams in my S4 motor which may explain why my idle is a tad lumpier than it used to be.
Trust the above of interest.
Regards
Fred