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I'm thinking of changing my fuel map axis from manifold air pressure and rpm's, to throttle position and rpm's. I have a very choppy map signal at lower rpm's due to the individual throttle bodies and the cam overlap. My map signal jumps back and forth from 70 kpa's to 80 kpa's at idle (1100 rpm's) with the throttle position sensor at 0. This seems to be causing fueling nightmares.
Going down the track at wide open the map reading stays steady at 99 kpa's.
What are the advantages and disadvantages of switching?
There is a 4D and 5D function but at this time I don't think I'm advanced enough to use them.

Due to poor MAP signals you have with your kind of manifold I would use Alpha N, TPS versus RPM. If you always see 99 KPA at WOT you sure race in better air than we do here in Div 4. LOL

Don't recall who's system you're using but I'll bet there is a forum somewhere on the net. Sounds like you'll need to blend a TPSvsRPM map to the base map. Alot of systems seem to have this, however getting them right can be a bit tricky...I'm still tweeaking mine. If you understand how to blend the 2 tables....typically there is a TPS % blend table that will allow you to dictate how much of the TPS to use and in what range of the map. You then can manipulate the Idle portion using the Alpha N map for low RPM driving and let it switch over to the Load (MAP) table in the higher TPS ranges. Maybe start out with 100% TPS at say 25% and less throttle angle and maybe up to 2000-2500RPM at that point you should have a fairly stable MAP signal to allow the load map(MAPvsRPM) table to operate. Basically it will allow you to "drive" the car. Joe Oh and NO I do not consider myself a "tuner" just learned a few things by trial and lots of error.

Quote:

Originally Posted by buzzinhalfdozen (Post 359715)

I'm running a Vi-Pec V44 I'm in alpha-n mode (open loop?) not speed density (closed loop?). The wide band is for tuning after the run.
I have been on their forums (that is how I got it this far). One thing though is that there is very little drag racing where they are from (Australia and New Zealand).
Their engineers are supposed to be writing a map for me. The company has been very helpful even putting a 2 step function in the firmware for me.
At the PRI show their rep told me to use the 4D or 5D map like you said. But I'm not that savy "Yet". I'll work on it over the winter (8 weeks). I have learned how to program the cold start fuel enrichment. I'll be doing that to.

I try to gather as much info as I can then insert it in my brain (yes I have one. even though it may be small LOL).

Quote:

Originally Posted by Ed Wright (Post 359706)

Due to poor MAP signals you have with your kind of manifold I would use Alpha N, TPS versus RPM. If you always see 99 KPA at WOT you sure race in better air than we do here in Div 4. LOL

Ed the air in the bap sensor is usually 1 or 2 higher than the map. The bap sensor said it was 101. My Tag showed 950' air density.

Quote:

Originally Posted by art leong (Post 359757)

Ed the air in the bap sensor is usually 1 or 2 higher than the map. The bap sensor said it was 101. My Tag showed 950' air density.

I don't remember the last time I saw 950'.

Quote:

Originally Posted by Ed Wright (Post 359764)

I don't remember the last time I saw 950'.

To me fast is 500 or less. Saw that a lot up north. Don't see it that much here, but it does happen.

Get much under 2000' around here we get to feeling all racy. LOL

have you tried putting a restrictor in line of the map sensor?

Quote:

Originally Posted by THoagland (Post 359790)

have you tried putting a restrictor in line of the map sensor?

I'll look into that. I remember I used them on the turbo car to slow down the boost signal. Might work.