Yup..old trick in the 90s dark ages was to run bigger injectors for more power via supercharger or whatever, but adjusting the maf tube area to compensate without having to actually tune the ECU.

So if your new injectors flow 50% more than stock you'd fit a MAF housing with ~50% more cross section and the ECU generally didn't know the difference, within reason. It did actually work with trial and error of sizing (especially mafs with sampling tubes).

But when the ECU is setup for a specific MAF that's already large enough for more power, and the MAF is a mid 2000s or later design, it works just as well idling as it does wot and high power.

Side note... when i first fitted the MAF i had to reset the throttle body idle bypass screw and throttle stop screw.

The MAF lets so much more air in even idling vs the AFM that it would run lean with AFM idle screw settings...check that, also check your O2 sensor.

 

Than why are you bringing up something I stated that was correct at the time. In an effort to ridicule me today?

 

My impression was that you were thinking modern MAF kits still "cheated" like that, and that injectors bigger than really necessary would cause idle issues.

I was saying that the modern MAF and an ECU tuned specifically for that MAF/injector combo does not face those problems.

My apologies if I came across as ridiculing you.

 

I have no basis to comment from the other side of the country. I was really just responding to your comments about having to choose between drivability and power. Wish I were closer to help you with the idle. It's probably something simple honestly, if the car runs fine at all other times. The MAF supplies one simple input at idle (a DC voltage you can monitor), so it is uber easy to see if that's the root cause.

Re Time Capsules, I have that discussion all the time with Crazy Eddie. He always says his car is a time capsule and has no miles, so the parts are like new. They aren't. They are 30 years old. There are very few things on earth that don't suffer the ravages of Father Time, and a car certainly isn't one of them. I can think of at least a couple of bets I've won with him claiming xyz is "brand new" so can't be bad... (catalytic converters, cracked solder joints, probably other stuff I'm forgetting).

 

Ok, no worries than. I do kinda disagree with what your stating though. What exactly changed? The dme is still the same as its always been. I'm sure some kind of cheating to allow for a maf meter to work. Like rescaling the fuel and timing to match the maf meter calibration. Bench testing and logging the afm's cfm along with a maf meters can easily give you voltage out readings. Then transfering that data over to a chip. Wouldn't even require you to go to a dyno.
My point is that when you have a large maf meter capable of reading up to 600 hp is going to limit resolution. Simply by not utilizing the 5 volt signal within the boundaries of the hp the car makes. In other words if the car is only making 300 hp and the fueling is done within a certain voltage. That voltage being halved to 2.5 volt. So the resolution isn't as refined as say a maf meter that is sized to the application.

 

Well thanks for the offer to help and yes 30 year is a long time. We also seem to think alike and that is why I reverted back to stock in hopes of finding an issue with the car. But the car runs great with the afm. So yes its frustrating and the car seems to not like the maf. Thats why I believe there is something wrong with it. The last VR system I had on my last 951 was much better. I understand every vehicle is a little different and this could be the case as well.

 

The construction and circuitry used in newer MAFs is way more sensitive than the original simple hot wire setup. So they can idle great and read 500hp.

Injectors have lighter pintles or even disc setups which are easier to control with the improved solenoids.

 

I understand these components are made better and more efficient today. That doesn't discount the resolution issue where the dme is using only half of the lookup tables.

 

Got it, and I think to partially address that at least the Rogue MAFs added a 3rd dimension to the maps (load, rpm, and MAP iirc) to make it better.

 

As did VR. That is why I mentioned earlier the possiblity that the developer may be the same person. Or it could be they are just reverse engineering each other.

The 944 market is rather dwindling so I don't see to much more development down the road.

I think the e 85 craze made them push for higher output and the use of larger injectors and scaling. I would have been happy with the older version.

 

Jimbo, it wasn't the E85 craze. New high-impedance injectors came out a decade ago (or so) and they opened up a whole new range of possibilities, so it was only natural for companies like Vitesse and Rogue to take advantage of them. You seem convinced that your problems are due to the system having too much top end potential, but that's honestly just not the case. I wish you were local so I could give you a ride to prove it to you. Something isn't right with your car, and I'm sure that's frustrating, but it's not because anyone has pushed too hard, or that the older version worked better. I have VR's latest stuff, huge injectors, a perfect idle, and have put down 500/500 on a dynojet. The system as designed works really well. Something is wrong with your car or your parts, not the new generation of MAFs. They are nothing but way better than the old days, seriously.

 

I might give it another try next week. But, why does the car idle so well with the afm? If its a faulty part with the maf then why should I be the beta tester. These systems should be tested before delivery. Im not on VRs payroll.

 

Did you see my note about adjusting idle settings with MAF vs afm?

 

I must have missed it. Just too clarity and reiterate. I'm just a typical end user with a good degree of mechanical knowledge.
I'm not purchasing individual parts. Anybody can do that. I'm purchasing a system. Once the parts are in said persons hands. He has to sell a system that works pre installation period. Said person becomes a subcontractor and not a parts seller. QC is a vital part of distribution. Nobody sells a system that hasn't been tested. It doesn't become my problem it's his problem.

 

Just curious...did you buy your Vitesse Racing new from John at Vitesse or used? Cause even used he's always offered some type of support given you ask politely. I know this from experience. Vitesse Racing MAF setup has been around for almost 20 years, tried and tested by many here on the forum. If it's a new kit you bought that is faulty, then yes ,it's John's responsibility to correct it. Used, as everything buying used, buy at your own risk.