Hi

Looking at Tuner Cat's pdf data parameter sheet for the $58A mask, (http://www.tunercat.com./pdfs/ecm_$58A.pdf),
under "ECM Switch Parameters" it is written " Two Atmosphere Map Sensor".

I assume this is a "toggle on or off" and this will allow for the use of a 2 bar map sensor for someone wishing to use boost pressures about 15 psi.

Am I correct in my assumption?

Thanks

Mark

 

Yes, probably. There are several code that accept 2bar MAP.

Example the $58 code is a 2bar code from a GMC Syclone. If you want to run it in a V8 you should use $58B code... Do a search and you will find some info..

/N.

 

I think my assumption is wrong.

I think a 2 bar map sensor is good to 14.7 psi above 1 atmosphere. (anotherwords, for a turbo/supercharged engine that produces up to 15 psi of boost).

A 1 bar map is a standard map sensor for NA cars.

My initial thought was a 2 bar was good to 14.7 x 2 or aprox 30 psi, but I think I was wrong.

Anotherwords, this "toggle on or off" feature in the $58A mask is to allow for the use of a 1 bar for a NA car and 2 bar for a car that produces 14.7 psi of boost.

Please correct me, either way.

Thanks

Mark

 

It's just 58.
Yes.
The code was used in some Quad Fours N/A, and some 4.3L turbo applications.

 

THanks Grumpy

My first post was SUPPOSED to read ;

I assume this is a "toggle on or off" and this will allow for the use of a 2 bar map sensor for someone wishing to use boost pressures ABOVE 15 psi. (not ABOUT 15 psi).

Thus the possible confusion with my second post.

You have made it clear, and I thank you.

My situation is this.....

I am considering using a 1227749 and the 58 mask to run a 4 cylinder Ford engine. However, the boost pressure I'll be dealing with is in excess of 15 psi, it will be more like 20.

The HEI ignition is familiar to me and I can adapt it to the Ford dizzy and use a GM IAC motor/ throttle body and change the wiring over easy enough. The 7749 is very simple in terms of wiring, I've been studying it.

But what can be done about this boost situation? If anything? May be just running it a little richer at WOT will be Ok for those last few lbs of boost.... (as well as my huge fuel pump and adjustable FPR that will raise fuel pressure as boost increases). I can always play with the dizzy if I get knock, then add spark in the lower RPMS to make up. I don't want a FMU or add-on knock control, I want it all done in the computer anotherwords.

Thanks in advance for any ideas you can send my way.

Mark

 

Your fine.
The 2 bar cal uses a boost multiplier for enrichment, so just set the last entry a little high, IF needed.

Depending on when you actually get to 20 PSI you might be able to take care of that with the VE and VE adder tables.

The Boost vs RPM is very engine specific, so there's not going to be any one predicable answer in my book.

Plus, there's is a 3 bar GM sensor. So a code tweak would take care of that anyway, if you need or have to have some fine resolution up there.

One of the beauties of the 58 code is that it's designed for boost, and uses a plenum mounted MAT sensor. At higher boost levels the charge temp gets critical, and the 58 allows for tayloring to that.

 

Thank you once again.

Was reading the P4 document and noticed this "boost multiplier" you speak of that is part of the final Pulse Width calculation.

It was my thought, and it seems I was correct based on your reply, these numbers can be manipulated.

Now I need to go read again to understand how MAT is figured in being as it's plenum mounted. It must be rooted in the BPW calculation as opposed to some base look up chart, like coolant temp.

Mark