MoTeC Global Forum

All,
I have a turbo engine equipped with a 3-bar map sensor using M400. I brought my car to a shop for tuning and the tuner has 20+ yrs of experience with Motec and they have a full shop of Porches/Lambo/Ferarri running Motec as well.

Two days into the tuning, my engine blew up, therefore I'm currently in the process dropping in a freshly built engine.

During the down time, I download the M400 config file and was going through reviewing the setting and realized that the tuner was using Throttle % as the load point on the fuel map instead of using map sensor's pressure as load point?

During the tuning session, the custom made intake manifold cracked which causes leaked. I'm not saying this is the reason why the engine blew up BUT!! using the throttle % as load point meaning that if there is any leak anywhere in the intake, the pressure will be different with the same throttle % which can cause either running lean or rich right?

Ok.. enough said! What is the up sides and down sides of using either throttle % or Map as the load point for fuel map? I want to use this as a decision making of whether I should be using the same tuner for my car after the new engine has been dropped in. Personally, I'd use nothing but the map/pressure as the load point on my fuel map table.

I need your opinions! Thank you...

Cheers
andy

Andy:

I speak from limited experience, but I understand that using the TP as load point is the usual method for aspirated engine. That is what I use on my motorcycle. The output from the MAP sensor can still be used to compensate fueling and ignition. See, e.g., menu under Adjust ---> Ignitions ---> Compensations ---> MAP Comp

Best

P.S. Based on your post, you seem more interested in what controls fueling, which is determined by the Efficiency Calc Method rather than the Load Calc Method you mentioned, which refers to the ignition tables. You can check whether your tuner is using a different method for fueling, but that would surprise me.

Yeah! Totally agree with using the Throttle % for NA engine.

I am sorry, but I missed the beginning part of your post that indicated it was a turbo. I have no experience with those whatsoever.

Let's rephrased the question.

What is the pros and cons between

1) Throttle% as load point on fuel map + map compensation

or

2) Map/EMap as load point on fuel map + throttle% compensation?

Is it really a huge different or it's just the style of a tuner?

Cheers
andy

For turbo engines with multiple throttle bodies, it is not unusual to use TPS as X axis for the fuel table.
There should of course be MAP Comp set up correctly. This is tried and tested. A popular example would be the RB26.
For ignition timing, MAP as Load should be used though.

Personally I like using TPS to tune the main map with a secondary load table for MAP ( boost ).
This works particularity well on multi-throttle engines as they tend to be more sensitive at low loads to fueling changes that are hard to accommodate with MAP.
This tuning method is totally acceptable but is no better or worse than other ways of doing the same job, like everything it just comes down to the experience of the tuner and working out what works best.
Also what type of engine is this ?

This is a 3SGTE in a MR2-Turbo. It's pair with a T3/T4 turbo.

I guess the conclusion is that there is really no advantage or disadvantage in choosing between these two?