using 3.8l MAF system on 4.9 (upsize MAF & Injectors?)

[Anonymous]

so, can one use the MAF computer out of a 3.8 (or 3.0) v-6 and lie to it with a bigger MAF and use bigger injectors to bluff the computer into thinking everything's copasetic?

Basically, what I'm asking is: is there a ratio between teh size of the MAF and the size of the injectors, that if you increase them both in proportion with the size of each-other and the displacement of the engine that the computer won't think that you're bull$#itting it?

*ponders*
Thanks

 

[Anonymous]

A 300 has a higher CFM than a 3.8. so the Mass airflow will read wahteve the mass of the air is flowing through it at what rate. But the compatibility between the MAF on a 300 and the MAF on a 3.8 with the ECM may be different.

The 300 uses smaller 14 LB injectors, but uses a higher fuel pressure. So the lb. per hour is raised above 14. so stock injectors should even wrok just fine as longas you use a 300 fuel pressure regualtor. If not..id use injectors from the 3.8L.

the ECM controls the injector PWM output according to the reading from the MAF. So depending on the MAF input, the injectors will open and close accordingly to the Mass air flow rate. The correct injectors should be used unless the ECM knows taht the fuel needed is more than the stock setting.

If the ECM knew it needed to send an output for larger injectors, not stock ones, then the PWM would be adjusted accordingly. that is with no change in fuel pressure. Fuel pressure is a mechanical change that the computer has no control over. higher fuel pressure automatically raises the Lb. per hour rating on the injector. but since the 14 lb per hour ones at 65 psi are about equal to 19 lb i beleive. So whatever injectors are used in the 3.8L (i think they are 19 lb per hour) is what the 3.8L computer will send to them in PWM signal.

Make sense?..lol...i hope so...i tlak to much..ill be quiet...

 

[StrangeRanger]

I'm not sure what you're trying to acheive here but:

The various size injectors not only have differing thruputs, they also have differing cycle times. The air meter and PCM must be calibrated for the injectors you're using.

Thruput varies as the square root of the change in pressure. The 14# injectors on the 4.9 actually put out (14 * (58/39)^0.5) = 17.1 lbs/hr.
Run a set of 19# injectors at the 58 PSI of a 4.9 and you get 23.2 lbs/hr.

I don't know squat about the 3.8 but it seemd that a MAF system from one could be adapted to a 4.9 if all the sensors are compatible. The big one is the PIP (profile ignition pickup) sensor in the distributor which gives crank position. Unless the 3.8 uses a PIP sensor rather than a crank position sensor you may have big problems adapting it.