hpx maf blow thru wont start or idle?

[Matt]

Today went out and used a piece of PVC pipe (65mm) which was excellent for cutting and drilling the screw and sensor holes for the HPX. Thanks to PL for the tip

After some cutting and drilling and swearing getting the tubes back into the silicone hoses, the HPX is now located after the intercooler piping going into the plenum piping in my R34

So far tonight have tried with the 2.5" adjustments which are in 0.10.19 and got the K down so it idles fine and there is no lean/cuts etc on decel. Blow through is the only way I can so far see HPX working stabily without reacting to air swirls

This is compared previously to the other night where I had it suck through in the VMP 3" tubing with no air filter (wont fit)

Even going back to Z32 MAF afterwards in suck through but no air filter this time the swirling affects idle operation of the vehicle. So placement of any MAF is a must but with the HPX it is even more critical due to the dynamics of the sensor

However accelerating gradually the mixtures start leaning out with that VQ map although it did drive well and once again no stalling.. I'm going to have to adjust the VQ for that specific PVC pipe size using the spreadsheet tweak the VQ map some more around the bottom end. More news to follow tomorrow

[skylinegtrhr]

Today went out and used a piece of PVC pipe (65mm) which was excellent for cutting and drilling the screw and sensor holes for the HPX. Thanks to PL for the tip

After some cutting and drilling and swearing getting the tubes back into the silicone hoses, the HPX is now located after the intercooler piping going into the plenum piping in my R34

So far tonight have tried with the 2.5" adjustments which are in 0.10.19 and got the K down so it idles fine and there is no lean/cuts etc on decel. Blow through is the only way I can so far see HPX working stabily without reacting to air swirls

This is compared previously to the other night where I had it suck through in the VMP 3" tubing with no air filter (wont fit)

Even going back to Z32 MAF afterwards in suck through but no air filter this time the swirling affects idle operation of the vehicle. So placement of any MAF is a must but with the HPX it is even more critical due to the dynamics of the sensor

However accelerating gradually the mixtures start leaning out with that VQ map although it did drive well and once again no stalling.. I'm going to have to adjust the VQ for that specific PVC pipe size using the spreadsheet tweak the VQ map some more around the bottom end. More news to follow tomorrow

So 2,5 pipe is only 65mm insert?
I'm interested to know how long should be straight pipe in which HPX is placed,can You please put some pictures?

[Matt]

I'll get there with the pics and information. Another busy day including getting the bits and this got left to the end so was dark by the time I finished. Continuing tomorrow

[meet07]

Are you using 2.5 pvc b/c you had it laying around? Im mean If I'm gonna have to set this hpx up as draw through then it will be fitted into a 4 inch pipe...smallest being a 3.5 since the software supports that.

[Matt]

What is the smallest pipe size you have draw through and afterwards blow through? The HPX supports upto 3.5" but anything larger the resolution gets too low and idle and bottom range will be crap

I'm using 2.44" piping (62mm) on my intercooler just before the inlet manifold at the moment.

Having troubles with getting the VQ map consistent. It seems to lean out going in load. Too difficult to tune on the road so we are going in for a dyno session on Thursday. Going to try the VQ map auto tuner function to see if that can pull into shape

Attached is the sheet I've been using. You copy/paste the Nissan VQ map cells into the VQ map in Nistune whilst adjusting.

Appears on my car the curve needs to be sharper than the calculations work out. Not sure why that is but on larger size tubes then it gets flatter

HPX seems to suffer from reversion also (spike in MAF signal on reverse airflow). Was hoping these would not do this since it causes pops on decel

[bachig24u]

Guys, this MAF unlike most other horrible neesan ones is completely different.
ensure it's 10mm opening is within a very small offset of tube centre line.
You can' simply tune a vq to fix everything as some are finding out.

HPX (slot) design leaves little scope for reversion but if its sitting at the bottom of an undersized pipe like 2.5,3" you will need to raise it to correct this.
I have made a few silicone seals for those who insisted on a pressure pipe MAF but its easier to just machine the mounting block flat and weld the right amount of material to it.

btw, when your turbo seals let go, be prepared to replace the MAF as well and also
the plastic glues used when the MAF was modified may not like boost juice so keep in mind if trying to get the advantage of water/meth spraying.

[Matt]

How have you gone with suck through configuration? I'm finding too much instability around idle but that is also due to lack of air filter which affects the Z32 MAF as well which is why I'm trying blow through

The R34 doesnt have much room for placement preturbo and I'm using the HPX tube at the moment with 3" setup when initially trying suck through but its too large so something custom would be required (same length as Z32 MAF) for a more permanent solution

Interesting note with the placement of the offset. It wouldnt be measuring the same amount of airflow as the centre of the tube which explains the leaning out problem I'm having

Was looking into R35 GTR MAFs as I obtained the VQ map for this one today. Appears to be an insert type also
http://www.ebay.com/itm/2009-2012-Nissa ... 0967583321
http://www.amsperformance.com/cart/ams- ... nsors.html

[skylinegtrhr]

Guys, this MAF unlike most other horrible neesan ones is completely different.
ensure it's 10mm opening is within a very small offset of tube centre line.
You can' simply tune a vq to fix everything as some are finding out.

HPX (slot) design leaves little scope for reversion but if its sitting at the bottom of an undersized pipe like 2.5,3" you will need to raise it to correct this.

Can You please put some picture or drawing of correct offset installation?

[Matt]

Looking into these with the GTR MAFs
http://minkara.carview.co.jp/userid/960 ... /25813390/

Same size as the Z32 MAF but with the GTR insert. Might also take my HPX insert using that bracket

[bachig24u]

How have you gone with suck through configuration? I'm finding too much instability around idle but that is also due to lack of air filter which affects the Z32 MAF as well which is why I'm trying blow through

The R34 doesnt have much room for placement preturbo and I'm using the HPX tube at the moment with 3" setup when initially trying suck through but its too large so something custom would be required (same length as Z32 MAF) for a more permanent solution

Interesting note with the placement of the offset. It wouldnt be measuring the same amount of airflow as the centre of the tube which explains the leaning out problem I'm having

Was looking into R35 GTR MAFs as I obtained the VQ map for this one today. Appears to be an insert type also
http://www.ebay.com/itm/2009-2012-Nissa ... 0967583321
http://www.amsperformance.com/cart/ams- ... nsors.html

yeah, definitely an air cleaner for draw through.
Air tends to take the path of less resistance hence readings being higher if the MAF is positioned correctly.

[bachig24u]

Guys, this MAF unlike most other horrible neesan ones is completely different.
ensure it's 10mm opening is within a very small offset of tube centre line.
You can' simply tune a vq to fix everything as some are finding out.

HPX (slot) design leaves little scope for reversion but if its sitting at the bottom of an undersized pipe like 2.5,3" you will need to raise it to correct this.

Can You please put some picture or drawing of correct offset installation?

When you have the MAF in your hand you'll see why its position depth in the tube is important to its correct function.

[Matt]

We couldnt get the dyno this week to try out the HPX

In addition the current placement isnt going to work with standard VQ maps (due to now realised offset of the sensor in the tube) so trying to source a GTR sensor and tube at the moment and will continue from there

[skylinegtrhr]

So any news regarding HPX?

[Matt]

Been spending this week still trying to find a GTR MAF tube and sensor from Japan. No response from one company and another Low Brain is out of units at the moment

http://low-brain.com/?p=529

My neighbour has an S14 with the GTR MAF tube and sensor so he might get to try that before me. The sensor looks the same as the HPX so I'm hoping to use both in the one tube using suck through setup since blow through in a small tube is not measuring the air properly

[meet07]

So is it safe to say that the hpx is way to complicated for nistune to run properly and your done it it? If so I will sell mine.