My thinking is that a slightly larger housing with the same sensor would only decrease the voltage a small amount. Hopefully small enough that the engine could correct that voltage reading in conjunction with the O2 sensor readings over time. It may run a little bit lean for a day or two, but after that the adaptive values should, well, adapt.

If I had to go through all the trouble to find someone willing and able to touch it, which I've had no luck with in the past, then I'd be just as inclined to go to an aftermarket ECU that I could program myself. That would be a ways down the road though.

I'm not really sure what the injectors are doing. I haven't watched their readings. I have looked into larger injectors in the past, however. Perhaps if I increased injector size by the same percentage of MAF housing size they would equal out. In theory that would work. If it's reading less air it will try to release less fuel, so by increasing injector size you would release more fuel and then stay stoic.

 

The issue with a larger MAF with different calibration is that while it may work at WOT, partial throttle will always be a problem. The MAF in these trucks will be sufficient to flow the air, it just needs to be calibrated for more WOT flow. Partial throttle will flow the same no matter what is done in terms of cam, intake and exhaust. The MAF will send an incorrect signal to the computer, because the MAP and O2s will be reading differently for that partial throttle and load. Put it this way, at 70 MPH cruise on the highway, your computer might be looking for say 3lbs/s of air flow. With a larger meter, the MAF may now be sending say 5lbs/s of signal. But, the MAP and O2s will be reading that 5lbs/s is incorrect for their readings. Engine light illuminates and may even put the car in limp mode.

I'm not saying for sure it will happen, but there's a very high possibility that a larger MAF will cause more issues than correct. Doing more research, Overfinch may have an off the shelf solution for you.

The guys that swap 2.0 sensors into their 1.8s do that because their changing the flow in their engines by a significant amount. Forced induction will add more flow than any work we can do to a poor N/A. You might have more flow, but I bet in reality it's not significant. This engine design isn't great at all, RPM is very low and port sizes are tiny in comparison to other engines of comparable size.

 

Try resetting/erasing both ECU and ECM adaptions.
I did this when I installed a new MAF sensor.

 

The V8 trucks didn't get a dedicated MAP sensor. Only a MAF.



You're correct that partial throttle flow will remain the same, but with a larger diam MAF sensor it would read a lower amount of air flow because of the decreased air speed across the sensor. That's where the larger injectors would come in. The computer would tell them to release less fuel, but if they're larger then they would just open for less time and would actually release the correct amount, if done proportionally. Right? Then the O2s would still read stoic because it would still be stoic.



I mean, this is of course theoretical, but my inclination is that it would work.


I'm not saying the MAF is allowing the max amount of air through that it can; I know that's not the case. The sensor and programming needs more head room though without someone going in and reprogramming the computer, which isn't really an option for me right now. She's a tight budget daily driver; I can't really do pricy off the shelf options or travelling half way across the country to find someone who can tune it.

 

I don't have knowledge of the LR ECU programming, but I have done a lot of work on GM style programming so hopefully this general knowledge helps.

First, you need a wide band 02 sensor - good to get one that can be programmed to simulate the narrowband.

Engines make best power at about 12.7 to 13 to 1, Stoic (best emissions) is 14.7 on gas, best economy is about 16.

Most ECU's go in to power enrichment mode at about 80% throttle position - ignoring the 02 sensors and relying only on the MAF or MAP sensor. If you are lean at WOT you can ratio increase the injector size and get back to 13.1. A bigger intake tract will reduce the velocity of the airflow and tell the computer the engine is flowing less air than it actually is. Bigger injectors will compensate for that by providing more fuel than it thinks it needs.

At part throttle the ecu will rely on the 02 sensors and fuel to stoic, might throw a code for lean operation due to the LT fuel trims being off.

I recommend the HP tuners or EFILIVE forums for more ideas and information.

 

Some BMW's use a Bosch MAF that is very similar to the ones in our D2/P38's, but on the BMW's they have much larger intake tubes, and the MAF mounts the exact same with the only difference being on the actual sensor part of the MAF. I know this for a fact because I bought an 02 once and it would always set an MAF CEL at idle. I went to swap it out and found a sensor used in 7 series if I'm not mistaken. The guy I bought it from said he'd just replaced it.

 

Ok, that's the info I 2ass looking for a confirmation on. So as long as I increase injector size 1:1 (percentage wise) with the cross sectional area of the MAF sensor, theoretically I should be ok.

I think the next size up injector is 24 lbs. That's roughly a 26% increase. The MAF sensor (OD) is 3.25" on a 4.6. I think the walls are roughly 1/8" (from memory, I will confirm), so make that a 3" ID. That give a 22in² area, multiplied by 1.26 is just shy of 28in². A 3.25" ID would give 26in². That's only 7.5% off, which is probably close enough for govt work. May even cure that WOT lag around 3k RPM. I swear it feels like the bog from improperly sprung vacuum secondaries opening on a carb.

I actually didn't know they made wideband O2s that imitate narrow band O2 readings. That would be super useful.

 

Good info, Best! I'll look into the BMW MAF to see what the sizes are and if I could use one instead of fabbing a new housing.

If that doesn't work out, I could probably make a 3d model and find someone to print it for me.

 

I've used Innovate MTX-L wideband's in a number of cars, they output a narrowband lookalike signal in addition to wideband data. Never had any issues with them.