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Anthony Parle

Link MAP sensor details

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I have the older style silver MAP sensor I brought from you guys a few years back any chance you can tell me the voltage pressure scale relationship.  I am logging the manifold pressure of a engine with the original ECU using the silver Link MAP sensor so I can use that info to make it easier for me to do the change to a G4.  I think from memory it was a 2.5 Bar MAP

Also I am setting up the fuel and timing table with rpm & MAP as the two scales is that the best way or is there other inputs that should be used for the tables?

Edited by Anthony Parle

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Hi Anthony, 

Our 2.5 bar MAP sensors had a cal of:

  • 0.2V = 20 kPa
  • 4.8V = 250 kPa

If you have stable manifold pressure then use engines speed and MGP as your fuel and ignition table axis. Also set the 'Equation Load Source' to Load=MAP.

 

Scott

Edited by Scott

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Hi Scott,

Thank you for the quick response, its greatly appreciated.

I am interested to know if you think I can use the MAP, attached is the results of the logging,  If not whats the best way for me to approach the tune maps?

 I will try at the back of the manifold in clearer airflow and see how that goes

 

MAP Sensor plugged into manifold at pressure reg location.jpg

Edited by Anthony Parle

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It's more going to be a case of the MAP reading at idle Vs full throttle

A engine with say a big overlap cam is not going to make good vacuum at idle and so might be better suited to TPS tuning. Much the same for a multi butterfly engine the change in map will be great for a small change in throttle and again TPS tuning is a better option.

If the engine can make ok vacuum at idle and is single butterfly then MAP tuning will be fine.

 

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Hi Simon,

The engine is a Subaru flat 6 EG33, engine is in a race car so really only care about full throttle.  Want to end up revving to 10,000 rpm NA, it has two butterfly's in the one throttle body.  The point I took the reading was were the fuel pressure reg vacuum was taken off which on examination goes into a inlet track.

What I will do is install new vacuum take off points into the right and left side on the manifold and see what the reading are then.  Will also do a reading as I open the throttle slowly.

Thanks for the help.

Edited by Anthony Parle

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Hi Anthony, 

Our 2.5 bar MAP sensors had a cal of:

  • 0.2V = 20 kPa
  • 4.8V = 250 kPa

If you have stable manifold pressure then use engines speed and MGP as your fuel and ignition table axis. Also set the 'Equation Load Source' to Load=MAP.

 

Scott

Hi Scott,

Now I have this MAP sensor running it shows atomsphereic at 1.7V, the setting in the G4 works it out correctly but I can relate 1.7 v to what you are saying.  Remember its the older silver MAP sensor.

Tony

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Tony,

An engine like this will need significant valve timing overlap so a MAP based load will not work well even with a single throttle body.  NA race engines is mostly all I do (normally ITB though) so I know this application well.  I normally still have a MAP sensor connected but only plumbed to the airbox to allow for aero effects at highspeed.  I would normally have the  FPR reference tee'd to the same location.  Load axis for both fuel & ign maps should be TPS.  You say "I only care about full throttle", but remember the engine must still accelerate out of low speed corners and must drive in pits and idle at dummy grid etc.

Another observation; your MAP on the graph above shows a significant trend downwards with increasing RPM.  To me that suggests your intake is very restrictive and is already loosing you power at just 6000RPM.  You will need to rethink that if you intend to make power at 10000...

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Hi Adam,

You must be the only guy on the planet that does NA race engine, every man and his dog has moved to turbo etc.

The motor is totally standard from the throttle body to the exhaust flange.  I am a nut case information and knowledge hound so I measure everything I can.  People were giving me grief saying I had to change the cams but I wanted to first understand what is happening with the intake and exhaust.

So this test I have removed the MAF and changed the filter to a large pod.  Torque was better but still flat to soon up the rev range.  The car had header, into 1 then the two sides into one and out the back with a 2 1/2 pipe.  When I ran the maths over this set up I came up with 1 of 2 1/2 pipe is only good for 200 hp.  Last week had the system re done from the headers back.  Now each bank has the header but each side goes into a single pipe of 2 1/2 and it goes out the back so the left and right bank don't meet at all.

Head back to the track mid last week and the engine goes from 12.5 AFR the week before to 16 after the exhaust change, was measuring the the intake MAP and logging it at 100 HZ and the intake problem pocked its head up again and was the restriction.  I have ITB for the engine but we can't clear the bonet and don't want to cut it.

As you say Adam the intake is a problem, what amazes me about NA engine is how many incorrect theories or folk law about what you need to do to get power.  I have attached a bit more info from the change etc.  Based on your comment on the other thread I moved the fuel table near to the 100% as you suggested.

 

Increased Airflow from changed exhausted.jpg

Increase Vacuum in intake.jpg

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