Full bridgeport with Microtech LT10s...
 

I have recently gone full bridgeport with all the necessary xtras... FMIC, Masterpower T70 (1.0 hotside), 50mm gate, 1000cc secondaries, 800hp intake fuel pump etc etc... and a Microtech Lt10s with Bosch coils...

Car is a 1988 s4 Rx7... Currently it is road tuned in Normal mode using the Map sensor load function for both vac and boost. (Screen 31). I have read from Microtech manual that for ported rotaries and other engines with large Cam overlap, the TPS load function, using TPS % for Vac and MAP for boost apparently works better as it is not affected by the irregular vacum readings at low rpm due to the significant overlap...

"Low or irregular vacuum applications such as ported rotary engines, motorcycles, or performance engines with large cam overlaps and radical inlet manifold designs may have wide vacuum fluctuations at idle and low revs, which will give false readings proportional to load. The T.P.S. function overcomes this problem by sensing engine load using the throttle position sensor rather than vacuum as the primary load source. To configure the MT ECU to operate in T.P.S. mode, go to the configuration set-up screens (Screen31) and move to the LOAD= screen. The default setting is "LOAD= MAP", i.e.: the MT ECU is configured to work in
MAP mode. Switch to program mode and press one of the ADJ buttons, and the screen will change to read "LOAD= TPS". Switch out of program mode again; the MT ECU is now configured to operate in T.P.S. mode. Set up TPS mode the same way as for MAP mode, except the settings refer to the percentage of throttle opening rather than manifold vacuum. Boost pressure screens remain the same in either MAP or TPS mode."

*Copied straight from the Manual*

Does anyone have any information/experience using this function? and if so does anyone have any values they'd be willing to share so i can try it out.

Cheers.

Switch it into matrix mode and you'll get a much better result. The vacuum signals in a bridgeport can be very ambiguous, especially with such a small hotside.

So TPS thing is a no go then? im not doubting you, but can I ask why Matrix would give a better result still using the MAP sensor? (Just for my own knowledge)

Also yea I know a 1.0 Hotside is kinda small, but i wanted a quick spool.. well if u call 4500rpm quick? How does the size of the hotside effect the vacume readings? backpressure?

Would a 1.32 hotside be better suited for this application?

cheers for ur reply.

Matrix mode offers better resolution, so it's more suited to fine tuning needed with high overlap engines. What is your vacuum signal like?

Using the TPS is really only necessary when you have very low vacuum engines (ie. ITBs, etc.). Bridgeports tend to still generate a good vacuum signal.

Ahhh..it all makes sense now... im pulling approx 12hg of vac @1750rpm... the only thing is that it does seem to rapidly fluctuate between 12-14hg causing the ECU to alternate between idle mixes for 10hg and 15hg cos it go to the closest one, which subsequently effects the idle speed etc.. its not a biggie just i want it to be perfect.. Matrix mode sounds like the answer.. damnit more tuning...

Also when i was doing a few power runs and data loggin them, i noticed that on decel the mode went into TPS_cal and then once at idle alternated between TPS_cal and Idle like this...

Idle
Idle
Idle
TPS_cal
Idle
Idle
Idle
TPS_cal.????

Is this normal?

just a question.......but where in the intake track are you getting the vac signal from? Some spots create more fluctuation than others. However from your desription it doesn't sound *that* bad.

not its not that bad really..

im getting it off the nipple underneath the BAC, down just to the left...which has been removed and blocked off ages ago.

As I recall that nipple comes from one of the primary runners only. If you pull it from the throttle body, things will be happier.

It's been a while since I watched the screen on my Microtech but it sounds like your TPS is out. Did you calibrated it properly and end up with an astrisk (*) at zero percent?

yea just recalibrated it.. ill hav a play with the TB...cheers.