MAP Adjuster Build Issues

[NelsonATC]

Offtopic....Are you a controller?

No, Athletic Trainer, Certified

[karl4x4]

Ok, my 2 cents again on MAP adjuster.

I did built a 4.7 stroker and am using the 1988 renix computer to run it. I was wondering how anybody can tell if they are running rich or lean. (Still am ???)
So I bought a wideband O2 sensor http://www.innovatemotorsports.com/products/MTXL.php and installed it just before my catalytic converter. (awesome piece of kit)

Test 1: unmodified engine with 505,000.0km engine just to see what would change kind of like a before and after picture. Come to find out, once warmed up, the air/fuel ration is always optimal 14.7 +- 1.5ish regardless of throttle inputs. It runs a little richer at WOT but that is perfect. It would start running a little rich (12.5 ish) when in slow traffic or just going slow on a trail (little engine work) and yes, the O2 heather works fine.

Test 2: Modified engine, same computer and sensors, Stroked it to 4.7, HO head, max torque cam from 505 performance, 1994 throttle body and intake manifold, Amsoil cone type air filter(inside the old box to keep it cool), 24lbs ford injectors with factory fuel rail pressure regulator and pump. AIR FUEL RATIO IS UNCHANGED. the only difference is at WOT, it does not run richer, it stays between at 14.7 +-1.5 ish

I had all the parts to built a MAP sensor adjuster but now I know that I do not need it. Gas mileage is unchanged if I drive exactly the same way but if I take advantage of the extra HP, of course it will burn more gas. Duh..

Now, a little over 10000km later, it runs as smooth as ever, power is very (very) good and it can tow.. omg can it ever. Transmission (5speed) not so happy with it. I will be converting to a Mercedes 6 speed in a couple weeks(note, old trainy has 514,000.0 km)

Lesson of the day: If it aint broke dont fix it. If you are not sure if it is broken, make sure it is before you fix it.

[SilverXJ]

Running 14.7:1 at WOT is not a good idea.

[W_A_Watson_II]

The MAP Adjuster, is to allow you to fine tune the full throttle A/F ration right? OK, if so under hard acceleration full throttle what should the A/F ratio be on a stroked engine?

I ask as at idle and constant speed I run in the 14.6'ish range, and drop to 11'ish when WOT as above, but I'm clearly running rich some where as my bumper it getting black soot on it from the tail pipe.

[SilverXJ]

12.5-13 for WOT.

[Retlaw01XJ]

The MAP Adjuster, is to allow you to fine tune the full throttle A/F ration right?

I thought that WOT was 'open loop' and the MAP wasn't involved?
Therefore injector sizing and fuel pressure is the only way to richen the mixture at WOT.
Correct me if I'm wrong....

[Cheromaniac]

I thought that WOT was 'open loop' and the MAP wasn't involved?

Nope. It's when the engine computer is in open loop mode that the MAP adjuster is effective. When it's in closed loop, the effect of the MAP adjuster is negated by the O2 sensor inputs.

[Retlaw01XJ]

I thought that WOT was 'open loop' and the MAP wasn't involved?

Nope. It's when the engine computer is in open loop mode that the MAP adjuster is effective. When it's in closed loop, the effect of the MAP adjuster is negated by the O2 sensor inputs.

Thanks for the clarification!

[karl4x4]

That is correct. It would only affect WOT. So, in real life, how often does one go WOT? I sure don't do it often. Trany started making noise only a few weeks after the build up and brake in period and unless I'm trying to show off, I never go WOT. But if I did, it could use to run slightly richer for cooling of the combustion area and also Fuel burn speed

[SilverXJ]

That is correct. It would only affect WOT. So, in real life, how often does one go WOT? But if I did, it could use to run slightly richer for cooling of the combustion area and also Fuel burn speed

If you ran WOT at 14.7:1 for any extended period of time you will be pulling the head off to replace the tulip-ed valves. Example, pulling a load up a hill.

[karl4x4]

That is correct. It would only affect WOT. So, in real life, how often does one go WOT? But if I did, it could use to run slightly richer for cooling of the combustion area and also Fuel burn speed

If you ran WOT at 14.7:1 for any extended period of time you will be pulling the head off to replace the tulip-ed valves. Example, pulling a load up a hill.

this WOT is kind of funny. WOT (open loop) just kicks in the very last bit of throttle. so if one is to back up food 1/4 inch, it goes back into closed loop. so, extended period at full throttle -1/4 of a inch is bad?....?????

[SilverXJ]

Despite it being the last percent it can still last through much of the RPM band.