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Title: HPX-E MAF on 2.7T Post by: thglf on March 04, 2024, 10:34:40 AM Hi
I just installed a HPX-E MAF in a 3.5" tube and used their excel sheet to have values for MLHFM, but after the first tests, the scaling is completely out of whack. The engine runs super lean and even +25% STFTs isn't enough. KRKTE is correct as I was running an OEM MAF before. This sensor can read backwards flow as well so the first couple of values are negative, so in MLHFM I've set those to zero first, then I've also tried with an offset set, so that there are no zero values in MLHFM, and adjusted MLOFS and MLHFM properly, but it achieved the same results. Does anyone have experience with these MAF sensors and could spoonfeed me a bit please? https://pmas-maf.com/product/hpx-e-mass-airflow-sensor-ext-range-tune-required/ https://pmas-maf.com/wp-content/uploads/2019/06/hpx-e_2019.xls Thank you! Title: Re: HPX-E MAF on 2.7T Post by: ratosluaf on March 04, 2024, 01:42:52 PM You have to offset whole table by highest negative number to make mlhfm start from 0, then put this value in mlofs in order to read properly - you just cannot store negative value in hexadecimal.
Also, i have read somewhere on this board that this linearization value is about 30% off. So... get idle logs and wot logs with known working setup, then just try to adjust new setup to match latest known working. If problem is linear, then just scale this sheet properly and you will be good to go. If not, then I'd personally trash it. Title: Re: HPX-E MAF on 2.7T Post by: thglf on March 04, 2024, 02:56:39 PM This is what I did. Please correct me if I did something wrong.
Code: HPX-E | MLOFS=110.33 Title: Re: HPX-E MAF on 2.7T Post by: prj on March 04, 2024, 03:41:53 PM Keep the MLOFS at 200 for ease of use and start the table with an offset, otherwise it's pain in the ass to read.
It does not have to start with 0. You can try to multiply the entire table by a constant, if you have +25% fuel trim everywhere, try 1.25* for starters. Title: Re: HPX-E MAF on 2.7T Post by: thglf on March 05, 2024, 04:41:48 AM Keep the MLOFS at 200 for ease of use and start the table with an offset, otherwise it's pain in the ass to read. It does not have to start with 0. You can try to multiply the entire table by a constant, if you have +25% fuel trim everywhere, try 1.25* for starters. I've used MLOFS=200 today and multiplied the whole table by 1.38 before applying MLOFS to it and this way I came close to what WOT fueling should be. That seems way off to be honest and I am starting to think that there is something else wrong, or i might have fucked something up with the wiring. I've only hooked up the signal, +12v and ground to the HPX maf, and I was wondering if pin4 (MAF RTN ground) should be hooked up as well? Should that go to chassis ground or should I just share that ground with the other one coming in from the engine side's MAF ground? Title: Re: HPX-E MAF on 2.7T Post by: prj on March 05, 2024, 04:49:36 AM That is signal ground. Pin 3 on HFM5 connector.
If you don't connect that and connect another ground to chassis then you can have an offset voltage and then the reading is wrong. If you connected to Pin 3 in connector then you should tie the grounds together. HFM5 only has a signal ground, no other ground. Title: Re: HPX-E MAF on 2.7T Post by: thglf on March 05, 2024, 04:59:47 AM That is signal ground. Pin 3 on HFM5 connector. If you don't connect that and connect another ground to chassis then you can have an offset voltage and then the reading is wrong. If you connected to Pin 3 in connector then you should tie the grounds together. HFM5 only has a signal ground, no other ground. I've connected HFM pin 3 to HPX pin 5 and that is all. Pin 4 (MAF RTN GND) is not connected anywhere at the moment. Should I connect that to HFM pin3 as well and call it a day? I've seen that some people connect that to chassis ground. Title: Re: HPX-E MAF on 2.7T Post by: prj on March 05, 2024, 05:06:34 AM I would connect them together. If it's left floating it can also create issues, you have to ask the manufacturer if you need to know exactly.
Title: Re: HPX-E MAF on 2.7T Post by: thglf on March 06, 2024, 10:33:11 AM I would connect them together. If it's left floating it can also create issues, you have to ask the manufacturer if you need to know exactly. Did that now and it is even more lean now. Something is really f'd up. I've also contacted the manufacturer but no reply yet. Title: Re: HPX-E MAF on 2.7T Post by: prj on March 07, 2024, 02:04:04 AM MAF should be in a straight pipe and you probably need a flow straightener as well before it, otherwise with a 3.5" pipe a lot of the air might not be hitting it right.
That said, I am not sure why you did not use the RS4 MAF - are you exceeding 600hp? Title: Re: HPX-E MAF on 2.7T Post by: thglf on March 07, 2024, 03:00:33 AM MAF should be in a straight pipe and you probably need a flow straightener as well before it, otherwise with a 3.5" pipe a lot of the air might not be hitting it right. That said, I am not sure why you did not use the RS4 MAF - are you exceeding 600hp? Because I have read on here that the RS4 MAF will not work properly in a bigger MAF housing and yes i am trying to exceed 600hp, I have just installed gtx2871 turbos. Title: Re: HPX-E MAF on 2.7T Post by: BlackT on March 07, 2024, 08:35:48 AM Log maf voltage
Title: Re: HPX-E MAF on 2.7T Post by: vwmaniac on March 08, 2024, 08:48:12 AM if you are trying to work backwards from a file with a maf that was already scaled you might need to use data from hpx for a smaller housing
Title: Re: HPX-E MAF on 2.7T Post by: thglf on March 11, 2024, 06:52:26 AM if you are trying to work backwards from a file with a maf that was already scaled you might need to use data from hpx for a smaller housing I am working from an OEM RS4 MAF, no scaling at all before switching to HPX. Title: Re: HPX-E MAF on 2.7T Post by: thglf on March 11, 2024, 07:00:14 AM MAF should be in a straight pipe and you probably need a flow straightener as well before it, otherwise with a 3.5" pipe a lot of the air might not be hitting it right. Okay I've tried with a flow straightener in the 3.5" pipe, no change. Then I've sourced a 3.0 Bi-TDi MAF (059906461Q) that is using a slot style sensor and perfectly fits the RS4 airbox and installed that to have the original intake (the rs4 airbox has a velocity stack installed from factory). I've re-scaled the HPX-E MAF with the transfer function to the new maf housing and I had to do the same thing again and scale it up by 33% to match fueling to what it was before. HPX also replied to my email and they said that they never had to scale up or down that extremely and that there is either another multiplier in the software or there might be a vacuum leak, but then I should have seen that with the OEM MAF setup as well. I've also uploaded the MAF voltage as requested. Title: Re: HPX-E MAF on 2.7T Post by: prj on March 11, 2024, 08:47:19 AM Does your rl_w now match the RS4 MAF rl_w at the same boost?
Title: Re: HPX-E MAF on 2.7T Post by: thglf on March 12, 2024, 02:20:33 AM Does your rl_w now match the RS4 MAF rl_w at the same boost? Boost was a wee bit higher with the rs4 maf even though I had 0% WGDC set for both runs, but they seem to line up pretty good. Title: Re: HPX-E MAF on 2.7T Post by: prj on March 12, 2024, 02:26:56 AM Well, then if it's consistent then that's the scaling....
Title: Re: HPX-E MAF on 2.7T Post by: eg4 on March 12, 2024, 08:12:25 AM the hpx-e sensor fits in the bitdi housing?
Title: Re: HPX-E MAF on 2.7T Post by: rnagy86 on March 12, 2024, 11:18:57 AM the hpx-e sensor fits in the bitdi housing? Yes. Same slot type sensor. I told the OP to get one and see if it fits. |