MAP Level Triggering

[RobJ]

Hello,

I am currently planning the system for my car. I am planning on running an Atom G4X as the engine is fairly simple, it's a 2.0L CIH Opel. It will be run on ITBs with an airbox with a front mounted air intake. I expect this airbox to become somewhat pressurised at higher speeds. I am planning to run a MAP sensor from the airbox and set this up as the BAP sensor. Then I will also set the fuel equation load source to BAP. Is this the correct way to do this? I expect a 1.15 bar MAP sensor will be sufficient?

I have a crank pulley trigger wheel but no cam signal. The distributor will be removed as I will be running COPs. Now, to run the injection and ignition fully sequential I am planning on running a second MAP sensor to one of the intake runners to use the MAP level sync function described in the G4X software help file. Does this necessarily have to be the intake runner of cylinder 1 or will any runner do? As I will need to drill and tap an extra hole in my manifold otherwise. Also, what does the MAP offset setting signify?

Could anyone let me know if this is the correct approach? I haven't found any further info on this sync strategy so I hope this may also help others.

Kind regards,

Rob

[Adamw]

22 minutes ago, RobJ said:

I am currently planning the system for my car. I am planning on running an Atom G4X as the engine is fairly simple, it's a 2.0L CIH Opel. It will be run on ITBs with an airbox with a front mounted air intake. I expect this airbox to become somewhat pressurised at higher speeds. I am planning to run a MAP sensor from the airbox and set this up as the BAP sensor. Then I will also set the fuel equation load source to BAP. Is this the correct way to do this? I expect a 1.15 bar MAP sensor will be sufficient?

Yes, perfect.  Great strategy for NA with ITB's, 115 KPa MAP will be ideal.

 

23 minutes ago, RobJ said:

I have a crank pulley trigger wheel but no cam signal. The distributor will be removed as I will be running COPs. Now, to run the injection and ignition fully sequential I am planning on running a second MAP sensor to one of the intake runners to use the MAP level sync function described in the G4X software help file. Does this necessarily have to be the intake runner of cylinder 1 or will any runner do? As I will need to drill and tap an extra hole in my manifold otherwise.

Doesnt need to be #1, any runner is fine, we are just looking for a unique event that happens once every 720 degs.  The trigger offset tells the ECU how far away TDC is from the missing tooth and the "sync tooth" setting tells the ecu how far away from the missing tooth to do the MAP level test.  Trigger wheel needs to be a missing tooth type for MAP sync.

 

25 minutes ago, RobJ said:

Also, what does the MAP offset setting signify?

I'll post a triggerscope from a MAP sync engine later if I remember.  But basically when the intake valve opens you will have a depression in MAP, once per two revs.  So you first do a trigger scope and look at where the minimum MAP occurs, lets say it is the 10th tooth after the missing tooth.  So set your sync tooth to 10.  Then in the trigger scope we look at what MAP value you have at tooth #10 in the first revolution and the MAP value in the same location on the 2nd revolution.  Lets say MAP was 100kpa at tooth 10 on the first rev and 85KPa on the 2nd rev.    In this  case you would set the MAP offset to something like 10Kpa.  So as long as the ECU sees a 10Kpa drop in MAP at the correct point in the cycle it then knows that is the intake stroke and can sync. 

That offset value is very engine specific, depending on how far the throttles are open and cam overlap etc.  Some you may see a 30kpa drop, others only a 5kpa drop.  The reason it is a relative offset rather than an absolute value is MAP/BAP varies from day to day so having an absolute value it means if the baro changed significantly you may never achieve your sync pressure.

Make sure the MAP sensor is connected to AN Volt 1 as this is logged with the triggerscope so you can use this to work out the correct value for your MAP offset.

[Loic]

Yes you can go with the MAP Sync we have done it on our citroen saxo and it works fine it syncs perfectly !!!!
we have had an issue with an injector so we were not able to finish the tune and now we are locked down thanks to this shit of COVID19 so we can't finish it but yes it works perfectly the only remark I can do to @Adamwis we have lost a lot of time because our car was not starting because of the fuelling but as the information of the Trigger 2 was not going to green we thought it was not synced but in fact everything was fine it is just that the trigger 2 does not go to green when you are using MAP Sync it would be nice to have the feedback with the green light.

 

[RobJ]

Thanks Loic and Adam for the great information. That's great to hear! I am excited to put everything together over winter. 

[RobJ]

Hi @adamw

I was wondering what setting this setup will need regarding fuel system type. Should this be set to "none" as I won't have a MAP signal that can be used for the necessary compensations?

I will be running a fuel pressure sensor as well if that changes things?

[mapper]

Use FP if it is connected to intake manifold. 

If not, it will work too, but VE are not representativ at part throttle. 

The Manifold pressure which is connected to the intake runner should also work if you apply some filtering in the MAP setup. But i don't know if the sync function still uses the raw (unfiltered) value of the sensor. 

 

[Adamw]

For ITB NA engines I usually connect the FPR reference to the airbox, connecting to the manifold just upsets fuel press too much.  It could possibly be done with a small vacuum manifold, but I have never tried and airbox reference has always worked fine for me.  

I also havent tried the FP sensor "fuel system type" with an NA ITB engine yet either - I have never had one with both a MAP sensor and FP sensor to try.  But I do have a little doubt it may do more harm than good since the MAP will be quite unstable at idle, so that will make the the calculated dif fuel press noisy, which will make the calculated inj PW noisy.  Worth a try though with a short high speed log of diff fuel press and PW you will soon if if its worth using or not.

Otherwise, if you still want some form of fuel pressure correction for safety you can set up a 4D fuel table to do basically the same but without the MAP reference.

[RobJ]

Adam,

Thanks for the response. I'll hook the pressure regulator to the airbox.

Am I correct in understanding that you normally have fuel system type set to "none" for NA ITBs then?

If using the MAP signal from the runner this would only give the correct differential pressure for that runner's injector. Wouldn' the other injectors have an unrepresentative MAP value (and thus differential pressure) when firing?

I wasn't really thinking about safety, more thinking in the lines of having the injector characteristics right at idle and low load to get the best driveability possible. I may be overthinking this perhaps.

[Adamw]

Yes, I normally have fuel system type set to none if Im using modelled mode with NA ITB.  

I think as Mapper suggested the FP sensor method would probably work fine with some MAP filtering but just I have never tried to confidently say go for it.  I think the average MAP in each runner would usually be fairly similar so the fact you are only measuring MAP in one runner doesnt concern me much.

6 hours ago, RobJ said:

I wasn't really thinking about safety, more thinking in the lines of having the injector characteristics right at idle and low load to get the best driveability possible. I may be overthinking this perhaps.

Yeah maybe overthinking it.  You usually have pretty odd looking VE numbers at low loads with ITB's anyhow and I have never had much drama getting them to work well with consistent fueling.

[RobJ]

Ok thanks for the great information Adam!

[RobJ]

I actually ended up ordering a MonsoonX now. Is the internal MAP sensor signal included in the trigger scope? If it isn't what would be the best way to set up MAP level trigger timing? Using an external oscilloscope?

Thanks in advance for the help.

[Adamw]

11 hours ago, RobJ said:

Is the internal MAP sensor signal included in the trigger scope?

Its not at present unfortunately but there are a couple of work arounds we can try.  If you had an external scope that would make it easy but most likely we can work it out without one.  

Make sure ITB's are synced as good as possible by eye, throttle stops are set at a realistic idle opening, then set up ECU logging to log all the time and log parameters Trigger 1 state, MAP and Internal MAP at 1000Hz, and give us a log of a cranking attempt.  That may give us enough to get it right. 

[RobJ]

Okay thanks for the help. I'll still be 2 months I reckon before I get to that stage but at least I know I can use the internal MAP sensor for the triggering then.

[Btune]

On 11/28/2020 at 3:43 AM, Adamw said:

Its not at present unfortunately but there are a couple of work arounds we can try.  If you had an external scope that would make it easy but most likely we can work it out without one.  

Make sure ITB's are synced as good as possible by eye, throttle stops are set at a realistic idle opening, then set up ECU logging to log all the time and log parameters Trigger 1 state, MAP and Internal MAP at 1000Hz, and give us a log of a cranking attempt.  That may give us enough to get it right. 

Hello guys,

I've been trying to setup a similar setup and having some issues with the map sync. 

I attach a log of the car idling. 

Any suggestions for the sync tooth and map offset?

It would be nice if there was a way to verify the sync from Map level when using this strategy.

Thanks

 

 

said log1.llgx

[Adamw]

Can you do a similar log of it cranking rather than idling - you can turn off ign or fuel so it doesnt start. Also do us a triggerscope of it cranking.

[Btune]

Here you go Adam.

 

ECU Log 2021-01-4 11_53_46 am.llgx

[Adamw]

14 hours ago, Adamw said:

Also do us a triggerscope of it cranking.

 

[Btune]

Sorry, missed it.

TriggerScopeLognew.llgx

[Adamw]

Ok, so you have the most difference around sync tooth 21.  You have about 30kpa depression on the intake revolution Vs only 4kpa depression on the next revolution.

So, set your trig 1 sync tooth to 21, set your trig 2 MAP level to -10kpa should give plenty of margin for slow cranking etc.

If it doesnt start with these settings then you will need to change your trigger offset by 360.

 

 

[Btune]

Hey AdamW,

The car starts OK. However I was hoping it would stall or throw trigger errors when the vacuum disconnected.

Also im having a hard time controlling the fueling. If I change my master fuel value by 1 it swings from 8afr to 20afr. 

Will try with the settings you mention.

thanks!

[Adamw]

9 minutes ago, Btune said:

The car starts OK. However I was hoping it would stall or throw trigger errors when the vacuum disconnected.

The ecu just checks if there was the correct depression at the point you tell it or not, if not then it assumes it is on the opposite phase.  So, if you disconnect the vacuum signal there will still be a 50% chance it will spark on the correct stroke.

The reason I say it may need the offset changed with the suggested settings is because if your settings were wrong previously then it may have been syncing randomly or on the opposite stroke.

Fueling is not related to the sync.  Start a new thread and attach the tune and some logs if you want help with the fuel.

[Loic]

Hi all to add some more information on this topic i have fine tuned the trigger 1 sync tooth for the map sync function using the trigger scope and the logging at 1000Hz  as @Adamw recommended because some times we found the engine was trying not starting at first time and we need 2 or 3 attempts to get it to start.

the result is impressive the car now starts perfectely. you can see on the lifeview screenshot below the yellow mark was our previous setup and now our actual setup is the white mark on tooth 44 where the map is sitting at 55.2 kpa.

so big thanks adam for the technique it shows once again the benefit of a nice data logging functionnality.