I've increased the air intake into my rig by putting in some new MAF ends. The engine cranks, but dies almost immediately. I'm getting loud pings when it's running and have to keep the gas on. As far as I can tell, it's running really lean because the ECM isn't expecting all the extra airflow. Basically, I'm getting about a 30-35% increase in airflow with these new MAF ends. It's the same sensor, just with wider ports. Anyone know how I can advance the timing to allow for more fuel to meet the engine requirements now that I have more air moving through? For the record, if I put my stock MAF ends back on the sensor, it works fine.

Running really lean is not good for engine parts... I don't think you can fool the computer with timing or temperature and wind up with results consistent enough to run well or even avoid engine damage. The only way to really take advantage of the change in airflow IMHO would be to have a skilled tuner spend some dyno time to instrument a few different setups and burn a chip with a new fuel map... and even that would require a level of familiarity with Isuzu programming that may or may not exist in North America.

If you're dead set on trying this, look at the CSK or Pro-M MAF modificatons, but do it with a skeptical eye and an ability to do research, because both of these claim to be 'matched' to fuel injectors, which IMHO is a pretty good bend of the truth. The trick to this is staying within the 15-25% adaptability range of the stock computer's fuel map -- and IMHO, it is a real crap shoot in across the range of daily driving situations. It has to work on the dyno, at the track, **AND** on the street, for me...

Randii

Xanatos,
Increasing the timing is not the answer. Your timing should remain the same. You need larger injector to increase your fuel delivery. You could alternatively jack up the fuel pressure with an adjustable fuel pump. Either way, if your increasing air flow, you need to increase fuel flow as well to retain "stochisity". Good-luck,
Rich - Ashburn, VA

Has anyone tried using one of those aftermarket air/fuel gauges? How accurate are they? From what I understand, they tap into the oxygen sensor and ween their data from that correct? Is that a good way to guesstimate the correct air fuel ratio? Anyone know what the correct ratio would be for the 3.2 v6?

If less than $200, not very accurate. Google a bit on narrow-band vs. wide-band 02 sensors to see why. In a nutshell, the cheaper narrow-band sensors test for a given state -- and the results indicate whether the gas mix is in that state (the narrow band), above it, or below it. Thus, all you can really strive for is a fast cycle alternating up and down. Wide-band 02 sensors actually provide useful numbers across a calibrated range... but I haven't seen one for under $400.


No, for a narrow-band o2 sensor. Yes, for a wide-band o2 sensor.


That's easy -- the ratio is the same for all gas motors. You're shooting for stoich, at 14.7 or so.

Here's a tool I'd love to have: http://www.widebandcommander.com/

..and here's a relevant FAQ which should get you started:
http://www.widebandcommander.com/faq.htm#1

Randii

I'm confused. What is it exactly that you did? What are "larger MAF ends"? Did you add new tubes before and after the stock MAF?

I susupect that you have an installation problem and maybe not a MAF problem.

Michael

I question if either of these are really necessary. Reason being, the S.A Alpine supercharger kit supposedly requires no modifications to the fuel system, however, a greater fuel delivery would be a must for these to operate correctly. This would have me believe that the stock fuel system would be adequate for the increased airflow.


I agree with Michael... from what you describe it sounds as though the intake diameter around the MAF is still the stock size, which should still read the velocity/amount of air entering the engine accurately. The modification you made sounds like a sort of velocity stack before and after the stock MAF. This setup could possibly be causing some turbulence around the MAF and confusing it a bit. Being that the MAF is a very delicate electronic, perhaps it was damaged during the modification process and all you need is a new stocker. But then again you say the stock 'ends' correct the issue???? At any rate, so long as turbulence is not an issue, I'd have to believe there's a more simple 'fix' to this than upgrading the fuel system and/or remapping the ECU, perhaps a resistor or capacitor or something to correct the [insufficient] signal from the MAF to the ECU... afterall, these are analog devices, correct?
G/L
Eric

if the maf is compatible with the system increased air flow would not cause a lean or rich condition as the maf reports the amount of air going in the motor an computer deals with it...I suspect the maf is not compatible but if it runs without the mod than the mod is causing the maf to report wrong info to computer so backup your mod its not working....maf mods usually only needed when your pulling top rpm's an the maf is restricting air flow for top hp....good luck...dan

Yes, I set up new tubes with all the correct hardware in the proper place and in the correct directions. The problem is purely an air/fuel ratio from what I've been researching on at this point. I'll let everyone know about any performance gains if it works out. Here's the suckers I'm using now.

http://www.rksport.com/product/p_01021901/view_detail

They're pretty slick. Opens up at least a 30-35% in flow area. I'm pretty sure the computer just isn't expecting the amount of airflow it is receiving. Similar to supercharging it, but less so. Basically, can't keep the engine started for more than a few seconds and it sputters and pops tremendously. Increadibly lean I guess. I've ordered a fuel management device today, pricey little suckers, in order to compensate for the extra air flow. If all this works, I'm going to be hooking up my huge hood scoop to it for a nice fresh air intake. I'm thinking I should probably go ahead and replace the stock injectors with larger ones. Anyone know what the stock injectors lb rate is? Probably going to need a new fuel pump as well to keep up. I am planning on getting a wide band air/fuel gauge when I can but that's another paycheck away. I'll have to do with a narrow one for now. $50 sure beats the $400-500 I've seen these things going for. Thanks Randii for the tip on that. I've been reading up on them. Huge difference. All in all, with what I'm planning on eventually doing, I'm going to need all that equipment later anyway.

Rheteric, as far as a problem with the install, no. The MAF still works fine when put back in it's original MAF ends. This is my daily driver, so I had to put it back in temporarily. As far as I can tell, it's not a turbulence problem either. I've got larger tubes and a huge K&N filter. I've tried it with another MAF sensor I have as well and I get the exact same results.

Trailbuggy, as far as the mod being the issue, it's purely just larger openings on the same sensor with less resistance. From what I understand about engines, correct me if I'm wrong here, but a fuel map is setup in an EFI system according to a set of know system components. If you start increasing the outer boundries, the system would then have to be shifted forward to compensate for the additional air flow. Here's my reasoning. Injectors are basically timed open/close at a certain pressure which results in a known volume of fuel being dispensed during each open/close cycle. The computer calculated how long to keep the "stock" injector open to add fuel to a certain amount of air. I figure there is a tolerence level that at this point has been exceeded. Now I guess I won't have a timing issue unless I'm actually pressurizing the air flow??? Somebody correct me if I'm wrong on that.

In any event, I'll be trying an el-cheapo air-fuel gauge tonight to verify I'm running lean. If all's good and I actually get a performance gain, I'll post my mods for everyone with photos.

I have a very difficult time believing that the problem is due to an increased intake area. The primary restriction on an engine is the throttle, followed by the manifold, not the intake sensor. Considering that you can't get the car to start, and keep running at idle (throttle restriction), your new MAF sensor is probably putting out the wrong numbers. Take an ohm meter and measure the resistance of your old MAF sensor and the new one. Let us know how they compare.

Remember that your fuel pump/injectors can run all day at highway engine speeds, so you should be able to idle with minimal air flow all day on stock fuel pumps and injectors.