Megasquirt rb26 maps? Curious to compare my tuning numbers....

[Guest wyldemannn]

So I was wondering if there were any people out here running RB26 megasquirt setups and what their .msq's looked like. My fiance and I just got hers off the ground and running this weekend and got the cold start/warmup/ hot idle dialed in fairly well. Just wanted to see if anyone had a better map for me to compare to than mine. We are running MS v3.0 with the nissan ecm handling spark at the moment, stock 440cc injectors and Walbro 255 fuel pump, GTR front mount with 80mm IC piping and Holset H2 sitting on custom built manifold w/ 100mm dp and exhaust.

[Bob_H]

I think you are the first I have heard that is running a MS on the RB26. Are you still running individual throttle bodies or did you convert to a single throttle body? If you didn't, where are you getting your vacuum signal from?(load signal).

-Bob

[bryan01]

i'll have a rb25 tuned map in a day or so. i just dropped my car off at the shop to get a new VE table on the dyno. it would give you something decent to start with for your rb26 depending on how close your fuel setup is to mine. i'm going to post up the results in a few days

[Guest wyldemannn]

Awesome! Thanks a lot man. We're going to get back on tuning tonight with it.

 

Bob, still running ITB's, getting the vac ref from the FPR port which should be a great signal, showing 50kpa on the MS so I got some tuning to do but the signal is steady. I'm having some issues pulling VE below 65-70 percent at idle, which is super rich but the only place it likes to idle.

[mjfawke]

The only way the major aftermarket ECU's managed to get the RB26 ITB's to work was to use combined TPS/MAP input to overcome the idle/low speed issues (Autronic was the first, I think). Unless MegaSquirt can use TPS for low speed operation, you are going to have to convert to a single TB.

[Careless]

The only way the major aftermarket ECU's managed to get the RB26 ITB's to work was to use combined TPS/MAP input to overcome the idle/low speed issues (Autronic was the first, I think). Unless MegaSquirt can use TPS for low speed operation, you are going to have to convert to a single TB.

 

so the balance tube can't be used because the megasquirt map sensor is engineered to sense positive pressure only? or can we not use the balance tube beneath the ITB's?

[Bob_H]

... or can we not use the balance tube beneath the ITB's?

You mean the balance tube above the ITB's? The tube below the ITB's is for coolant. Just checking? It should be the same one the PVC valve screws into. And my thought would be that with it pulling from all 6 ITB's, it should see a strong enough vacuum signal to run it at idle - however I have no direct experience with that.

-Bob

[mario_82_ZXT]

so the balance tube can't be used because the megasquirt map sensor is engineered to sense positive pressure only? or can we not use the balance tube beneath the ITB's?

 

The MAP sensor senses ABSOLUTE pressure. While we may think of the motor being under vacuum at times, in reality it is still under atmospheric pressure.

 

MAP systems don't like insanely loppy cams or other setups that have erratic vacuum, I think you'll be fine with the stock ITBs.

 

Mario

[Careless]

The MAP sensor senses ABSOLUTE pressure. While we may think of the motor being under vacuum at times, in reality it is still under atmospheric pressure.

 

MAP systems don't like insanely loppy cams or other setups that have erratic vacuum, I think you'll be fine with the stock ITBs.

 

Mario

 

so you mean that it never drops into the negative in relation to integers, but in relation to absolute, it drops below the 14.7 atmospheric pressure at 0 above/below sea level.

 

therefore the balance tube will still be able to send proper pressure to the MAP sensor?

[synthtk]

therefore the balance tube will still be able to send proper pressure to the MAP sensor?

 

I have found using the small port off the back of the balance tube just fine for my MAP based Defi Boost Gauge, my 3.5 bar map for my AEM EMS is T'd off the clutch booster port along with my BOV.

[Careless]

I have found using the small port off the back of the balance tube just fine for my MAP based Defi Boost Gauge, my 3.5 bar map for my AEM EMS is T'd off the clutch booster port along with my BOV.

 

well since i'm not using a turbo or any sort of forced induction, I guess I could hold off on the manifold pressure guage.

 

should I then use that same rear balance tube port for my EMS?

[synthtk]

well since i'm not using a turbo or any sort of forced induction, I guess I could hold off on the manifold pressure guage.

 

should I then use that same rear balance tube port for my EMS?

 

Definitely, any port on the plenum alone will never see the correct vacuum/positive pressure readings if you are using ITBs. You would want to use the small port off the balance tube.

[cygnusx1]

You can, and it is common, build a collection reservoir for the MAP sensor to read from. Run a hose from each intake runner to a cannister and then connect the cannister to the MS sensor. This should give your sensor a fairly stable read on MAP.

 

http://www.msefi.com/viewtopic.php?t=26050

[Careless]

You can, and it is common, build a collection reservoir for the MAP sensor to read from. Run a hose from each intake runner to a cannister and then connect the cannister to the MS sensor. This should give your sensor a fairly stable read on MAP.

 

http://www.msefi.com/viewtopic.php?t=26050

 

i thought thats what the balance tube was.