Jameswsb

M5 MAF test a tad low

38 posts in this topic

Yes I was using the OBC test and running 3rd gear up to just before the limiter. To be honest I have very little confidence with these MAF's after the issues I had with the one on the B10. It would be good to test a pair that are known to be in good nick to see if that is the issue, otherwise I think I might bin them off and go for Alpha N when funds allow. 

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You may actually running okay, take it all the way to the limiter and have someone video the readout to actually get the max figures. It my be higher than you are seeing if you are backing off before the limiter.

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3 hours ago, Seesure said:

You may actually running okay, take it all the way to the limiter and have someone video the readout to actually get the max figures. It my be higher than you are seeing if you are backing off before the limiter.

To be honest I'm not keen on slamming into the limiter. I was backing off at almost exactly 7k revs so I'm confident that c128 is the true maximum figure. I would like to test a set of known quality mafs to see if I get any different figures, its just a case of borrowing some. I'm off to a club meet on Sunday so perhaps I can beg and borrow a pair from some kind hearted soul! 

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128 L/H before the limiter is not too bad.  You really need to reset all fuel trims and go for it, or allow a few hundred miles.

 

You should slam into the limiter, but fair enough if you don't want to, but it has to hit the limiter.

 

Also as others have mentioned better to get a passenger to read the highest actual number, as the driver sometimes does not see the peak value.....ask me how I know.

 

There is also some document out there that shows some compensation for these peak L/H per numbers, which compensate for altitude, ambient temps etc etc I believe.  So a reading of 130 L/H may equate to 140 once compensated by the above document.

 

The trick with removing Vanos Solenoid is to unscrew the hex bolts a few revs, then crank the engine over in neutral (do not let it start, just roll the starter for a couple of milliseconds) and hey presto the Vanos Solenoids have been released from their tight seal, and when you remove all hex securing bolts, the board should now be free.

 

 

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1 hour ago, M5 London said:

128 L/H before the limiter is not too bad.  You really need to reset all fuel trims and go for it, or allow a few hundred miles.

 

You should slam into the limiter, but fair enough if you don't want to, but it has to hit the limiter.

 

Also as others have mentioned better to get a passenger to read the highest actual number, as the driver sometimes does not see the peak value.....ask me how I know.

 

There is also some document out there that shows some compensation for these peak L/H per numbers, which compensate for altitude, ambient temps etc etc I believe.  So a reading of 130 L/H may equate to 140 once compensated by the above document.

 

The trick with removing Vanos Solenoid is to unscrew the hex bolts a few revs, then crank the engine over in neutral (do not let it start, just roll the starter for a couple of milliseconds) and hey presto the Vanos Solenoids have been released from their tight seal, and when you remove all hex securing bolts, the board should now be free.

 

 

Thanks, I'll reset the fuel trims and see if that makes a difference. Is resetting fuel trims the same as resetting adaptions??

 

You are the second person to mention that trick with the solenoids! wish I had known that at the time it would have saved a lot of swearing! :rolleyes::D

Edited by Jameswsb
Additional info

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7 hours ago, Jameswsb said:

Thanks, I'll reset the fuel trims and see if that makes a difference. Is resetting fuel trims the same as resetting adaptions??

 

You are the second person to mention that trick with the solenoids! wish I had known that at the time it would have saved a lot of swearing! :rolleyes::D

Yes same as resetting adaptations.

 

Have you given us your fuel trim values yet at all? 

 

Yep when I changed out my vanos solenoid boards back in 2008 I had no idea about the trick......Having said that I don't think many people even understood that vanos solenoids were an issue and ended up replacing complete vanon units.

Edited by M5 London

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Thanks M5 London. I'll have a look at the fuel trims and post as soon as I get chance.

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Calling M5London and Jamie Peers! Here are my INPA values:

 

Adaption values are bugger all. Does this look all good?

Adaption values.docx

Edited by Jameswsb

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They look good (the bottom two rows in both columns (each engine bank)).

 

Also do your top two rows in both columns actually fluctuate when viewing them (voltage should be switching)

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So I had the car on the dyno on Saturday...

 

595a3185ce4c0_20170701_132249(1).thumb.jpg.3c2860e9aa6e914145cc9e974a61f0b7.jpg 

 

Needless to say the torque max torque figure is incorrect as it measured the slip on the rollers at the start of the run. Still around 380-385lbft is pretty handy for a standard car! Looks like the car is in rude health.  Thanks to all contributers for the help/pointers, its much appreciated.  

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Great numbers there! Think I'll get mine down to Riverside racing at some point too

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Well worth a run imo. Plus they do a full diagnostic while the car is being run to monitor just about everything, so if there is an issue then it should identify the problem fairly easily. Top lads there too.

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