ITB Setup on M150

Hi all,

I am in the final stages of converting my plenum / MAP based flat 12 engine to ITBs. Would someone mind sharing the tuning steps necessary? I have vacuum coming off each cylinder's manifold to a shared vacuum block (where a MAP sensor and IACV are also connected).

I've seen posts / videos mentioning changing the Engine Load Normalized Mode to TPS, as well as updating the Inlet Manifold Pressure Estimate Main. Does this mean that the MAP sensor should be disconnected? Is anything else needed? Any other tables need to be updated?

Thanks in advance.

I am using TPS with my ITB's (M130 GPA, V6, DBW, one sensor per bank). The "recommended" method is detailed in Motec document CTN0036, I have attached it for reference. You need to read it a few times and follow the instructions to the letter.

This makes the ECU work "old" school just from the TPS with no requirement for a MAP sensor. I run a barometric sensor (and temperature) connected to the airboxes.

It works well, especially if you are used to older style ECU's.

One thing to note, this now renders the Motec startup map fairly useless. I worked the map back from the example and then modified to start (not easy with no exhaust manifolds and a stroppy neighbour!). I can post my map if it is of any use.

Thanks for this. Seems pretty intense (a lot more than I had surmised from the casual way it was being referenced in forum posts and videos).

You don't run a MAP sensor at all?

I don't. The theory is that the signal from a map sensor attached in the manner you described isn't going representative enough to be accurate. It might be acceptable on very mild cams but with my 316 degree inlet cams it just isn't going to be good enough.

I know some people do run with a combination of tps and MAP, they could probably add their input.

Thanks. I've been reading through the Motec forum as well to try and familiarize myself with this alternate setup. I may just try to run the car with MAP/VE to see if that's acceptable. I have mild cams on the car now, and I am curious if the combined volume of air between 12 manifolds and a vacuum block might be enough to be manageable.

Per the CTN0036 setup, it seems an Airbox Pressure Sensor is used. Do you know if the MAP sensors can be repurposed for this?

Thanks in advance,

Robert

Yes it could.

Great job Denis.

MAP sensor can be repurposed for that or for baro pressure if you don't already have a baro sensor.

If naturally aspirated, I like having baro and MAP, use baro for general correction, MAP for small compensation, and TPS has the vast majority of the impact.

If there's budget for it, airbox and exhaust pressure sensors can improve air mass calculation, but I wouldn't call them a requirement for most setups.

When I think what we had 30 years ago...it was amazing engines even worked!

Must have another look at Tune, now I have some more AV ports courtesy of a second hand ESDL3 I could add barometric! Good idea Mike.

We are absolutely spoiled these days and I love it. :)

Hi all, thanks for the input.

I started the car using the old MAP tune. The car started right up, and idled pretty well (might be due to the addition of an IACV). Although it ran better than I expected, it didn't run great. I then tried the CTN0036 settings; which appear to be working much better and tuning estimated manifold pressure is straightforward enough (although the "Q" function would be nice). So at least for my car (12 cylinders with 60mm manifolds connected to a small vacuum block), the CTN0036 suggestions from Motec seem to be the better route.

My question is regarding the airbox sensor. I have a MAP sensor that is now unused. How is an airbox sensor "setup"? It is the same type of pressure sensor that is used for MAP being configured to pull "vacuum" from an airbox around the trumpets? I'm not running an "airbox", so should I just run the sensor in open air?

Thanks in advance,

Robert

Just mount the sensor in the same environment as your inlet trumpets. if you later build an airbox, this will then reflect any "ram air" pressure you are able to achieve at higher speeds.

Beautiful setup BTW.

What David said. Gorgeous engine.

I am going to fit an extra sensor in the engine bay just for barometric pressure...as I have airboxes I am already accounting for any ram effect.

See attached for my airbox pressure sensor setup, just for info. Apologies for the dust, in the middle of a bunch of laminating.

Thanks all for the input and compliments. I am biased, but I really like the aesthetics of this configuration. This is a 1983 Ferrari 512 BBi; which uses mechanical injection / common plenums. I am going for an aesthetic similar to the BBLM race cars of the 80s – which had the same engine but used Lucas fuel injection and trumpets.

Anyway, I've made the CTN0036 changes, and now I'm just working through the pressure estimate table bit by bit!

Thanks again.

You can also change the Engine Efficiency table in the Tuning | Fuel Worksheet to be the Inlet Manifold Pressure Estimate Main table as well, to make it easier to find and work on. I also set the 0 RPM column to show 100% for all throttle positions as this is representative of the engine when it is not turning.