Eric,

Mine applies the set bias at idle. I do not know how the bias changes, if at all, as the air flow increases.

I will check that when the rain lets up here in a couple of days (I hope!)

 

FYI, I was on the phone with someone at FORD PERFORMANCE (thats Ford Motorsports, the guys that made the MAS kits for trucks + mustangs and many other things) and I was told by them that the computers they use are nothing but 89-93 MAS Mustang computers...no adjustmens made to them and they have been working for them just fine.

 

I found this on the Ford site.



I thought my truck had very little corrosion. My resistance was .5 ohms when cold! I ran a ground wire from the battery neg post to the pcm harness. It raised the MAF voltage by .10vdc and reduced pinging WITHOUT the Air Adjuster. I still need the Air Adjuster though.

 

That's definitely something to look into. I think I have a ground issue present, not necessarily with the computer, but I have gone through two or three heater cores in the 8 years I've had my truck, leading me to believe I've got some stray voltage through the cooling system eating up the heater cores.

 

I contacted the people at IST ( air-adjuster) company, because I am experiencing the SAME problem w/ my SD to MAF conversion(5.8 to stroked 408 ci) . They told me that the air adjuster can solve my probs. like they did yur, but some of my problem can also be w/ my PRO-M air meter...They said the C&L meter is better suited for our application, which Meter do u have??

 

I had the computer out of my truck yesterday to verify the catch code in preparation to get a tuner of some type..right now leaning towards the Tweecer.. but I digress. The computer I have.. which is part of Ford's MAF conversion kit, is a C3W ECU.

 

Wayne,

I have a C & L 73mm that I bought from IST. It was calibrated by IST to 19#. It came sensorless. I put one in from a '93 19# V8 Mustang.

I wanted to go with the 76mm but they talked me out of it!

FWIW, all the truck MAF conversion kits they sell include an air adjuster.

 

You can't really expect a computer designed to run a 302 to run a 408 properly though. Sure you can make it run.. OK... but it's gonna be way off on a lot of parameters.

 

What exactly do you plan to accomplish with the tuner?

And pardon my ignorance, but what does it mean to be a C3W computer?

The computer in my Ford mass air kit says:

EEC-IV SFI - MA12A 00M05 C3W1 (bigger letters + numbers)
F3Zf - 12A650 - FB
61SM12AF13 - AC 71533 - 84

I must admit that I don't know what any of this really means other than "EEC-IV SFI - MA..." which is fairly obvious.

 

Like I was saying above, these computers are calibrated to run a 5.0 with 19lb injectors. It'll work to some extent on a bigger more powerful motor, but the further you get away from a stock 5.0HO the further off the fuel and ignition curves will be. A tuner like the Tweecer allows you to change the various parameters that the computer uses to calculate how much fuel and spark to apply at any given time. You can change the engine displacement, injector size, MAF meter transfer function, ignition advance, and much more. You can also make use of an combination of parts, like a 70mm MAF meter with 19lb/hr sensor and 30lb injectors on a 393 stroker. You can also disable things like the speed limiter, EGR or air injection, and tune WOT fuel curves to match your motor(with a wideband O2 sensor).

Looks like you have the same computer I have. The catch code is that C3W1 number, it's just a sequence commonly used to identify these processors.. same a A9L.

 

Paul,

You have the FMS 9000-51 kit?

What does the MAS look like? Is it a tube with indentations on either end and a bracket mount bolt holes like a Mustang? Does it have a flange at one end like the Town Car 5.0 or the '95 MAF trucks? The '50 FMS kit for a manual tranny that I had contained a smooth shelled exterior MAS like third party manufacturers, not normal production.

My thought is that the MAS is what has been "re-calibrated" for the truck kits by using a sensing tube in the MAS (14# or 17# diameter) that would fake out the PCM by calling for longer duty cycles on the injectors to make it run richer and reduce the ping.

It seems that people that use the Ford kits have fewer ping problems than those that build their own. I have no stats to back that up. It is just my unscientific observation.

 

Yes, that's the kit I have. I have 2 meters actually that look very similar and both work on this motor, the 55mm unit from the kit and this 70mm Cobra meter... http://cgi.ebay.com/ebaymotors/FORD-MUSTANG-COBRA-MAF-MASS-AIR-FLOW-METER-70-MM-RACE_W0QQcmdZViewItemQQcategoryZ42604QQihZ006QQite mZ160202014998QQrdZ1QQsspagenameZWDVW

Both these use the exact same sensor and I see no indication they are modified.

 

I recently changed the FUEL PRESSURE REGULATOR from my original stock one to an adjustable Accel (74561) one. I disconnected my Air Adjuster also.

The old stock one tested at 40# with no vacuum and 31.5# with vacuum. This fits Ford specs. There was no leak-down. I adjusted the new one to 40.5# no vacuum and 35# with vacuum. I don't know if the extra 4# of pressure under load made the difference or if the old one was to slow to respond under load. Whatever the case is, with a 5.0 SD the knock detector will remove the pinging, so I never saw it with the old.

I tried several other things to remove the pinging without the Air Adjuster:
1) 180* thermostat, was 192* - no change
2) rebuilt distributor and replaced stator sensor - no change
3) replaced the ACT (again) - no change
4) removed EGR - no change
5) replaced all vacuum tubing - no change
6) replaced plenum gasket - no change
7) replaced EGR input tube - no change
8) put in one step colder spark plugs - delayed onset of pinging by several minutes.
9) replaced fuel pressure regulator - problem solved!

Since we had a warm day here (over 85*), I got a chance to try my new setup. I made two long drives. The first was at 12*BTDC. I would get only the slightest pinging going up a grade at 70mph while lugging the engine. I made a second run at 10*BTDC and I could not cause pinging under any conditions! I am too burned out on this project to try at 11* BTDC!

Last mileage I measured was 16.7 city driving (downtown LA commute) at 7.5*BTDC.

I want to thank everybody for their help and encouragement!

 

Is all of this on regular 87 octane? Thanks for the updates, and I'm glad you have made progress on figuring out the pinging.