Fast355

iTrader: (2)

You read it right, I am about to experiment with a ford 70 mm MAF for a Ford Thunderbird S/C. It is ALOT cheaper than the GM style frequency MAF, appears to have great resolution at lower flows(good driveability and fuel economy), and eliminates the burn-off. Appears that it might work well in conjunction with a 165 ECM in a TBI swap scenario. Apply +12VDC power, common PCM ground, and input signal to the ECM. Then reprogram the 165 to work with the Analog MAF by checking the Analog MAF bit and then changing the MAF flow tables to the Ford 70mm T-Bird MAF equivalent. Will let you know when I have it up and running. Seems much simpler than dicking with the SD VE table everytime you make a small change to the engine. This unit flows around 600 cfm, but if it works, I might go for the 4.6 ford one that is 80 mm and flows over 800 cfm since it lacks the backflow ring that chokes the V6 70mm MAF. The only reason I choose the 70mm one is that I have one sitting around that was put on and removed from a car due to a mis-diagnosis.

The new Ford MAF is only 189.00 out-right vs. a remaned GM unit for 168.99 exchange ($80.00 core).

The flow curve maxes out at 261 gms/sec @ 5.00 volts, so it is a good match for our stock 165 ecms with their 255 gm/sec calculation limit.

Stock T-Bird MAF Table

Volts----GMS/SEC Flow
0.0-----00.000
0.4-----02.778
0.6-----04.167
0.8-----05.556
1.0-----07.778
1.2-----010.83
1.3-----012.50
1.4-----014.17
1.5-----016.39
1.6-----018.33
1.7-----020.56
1.8-----022.78
1.9-----025.56
2.0-----028.06
2.1-----031.67
2.2-----035.28
2.4-----043.06
2.6-----052.50
2.8-----062.50
3.0-----073.61
3.2-----085.56
3.4-----100.56
3.6-----116.39
3.8-----134.17
4.0-----153.06
4.25----174.72
4.50----204.17
4.75----230.56
5.00----260.83

oldred95

Is this going to be for your 3.5 liter hybrid? Seems like a nice fit for it. I'm assuming thats the reason for the smaller MAF, because it sees low flow numbers better then the bigger MAF's do. The 85 mm GM MAF is still a good choice for a V8 right?

Fast355

iTrader: (2)

You caught me, it IS going onto the 3.4/3500 Hybrid that is going into the S10. Pulled the old engine tonight, junkyard 3.4 is in the bed of my truck, 3500 top-end is in the garage. I have 6 LT1 injectors to go into it too (24#hr).

oldred95

That 3.1 can't have more then a few thousand miles on it. Those frame rails are gonna be as loose as the rails on your van before too long. 4L60E and a MAF huh? You **** me off sometimes.

Fast355

iTrader: (2)

Its got about 15K on it, but it also blew the heater core out of it, overheated before the problem was noticed, and died. The 3.1 after coolant was added, promptly drained the radiator over the course of a couple of days into the crankcase. The heads are trashed and the bearings trashed. In short the engine is trashed. I will be running the 3.4 DIS system as well.

bl85c

iTrader: (2)

Neat project. This is exactly what the v6's need to run $6e without having to wire in all the extra relays and crap. If this works out you might want to let the guys on the v6 board know about it too. I'll make a mention of it on my '165 swap thread. Part # please?

bl85c

iTrader: (2)

Couple of things I wanted to bring up. First, do I have the right pinout on the maf ->

A- Power
B- Ground
C- MAF return
D- MAF signal

Second, what do I do with the MAF return? I'm not even sure what it is. 5 volt refrence maybe?

s24a

Ford MAF Sensors have the following pinouts:

A - 12V Battery Power from EEC relay
B - Power Ground
C - Sensor Return (secondary ground to EEC analog grounds in module)
D - MAF signal out

You can tie the two grounds together when you wire it, or run the Signal Return to the sam analog ground as the MAP sensor or TPS would use in a GM module

bl85c

iTrader: (2)

C is a 5 volt ground then. Great, thanks.

89onlyZ51

iTrader: (3)

Awesome - can't wait to hear of the results. The mustangers have been running re-calibrated MAF's for a while now (imagine that, buy a whole new MAF when you change injector size so you don't need to burn a new prom!).

I'm interested in running a re-cal'd ford MAF and rescaling the '165 MAF tables and injector constant to fake around the 255 gms/sec limit since I haven't gotten a difinitive answer as to the sensing range of a stock TPI MAF sensor.

bl85c

iTrader: (2)

The problem's not the maf, it's the ecm. The maf can actually 'see' higher than 255 g/sec, but because of the ecm's 8-bit calculations it's limited to 255 g/sec. Doesn't matter though, you can just use a wb O2 and tune via the wot tables to get the afr you want.

89onlyZ51

iTrader: (3)

Tuning in the PE mode won't work reliably for turbos since boost isn't a function of TPS and RPM like it would be with a supercharger.

You can get around the ECM's limit by scaling your MAF tables and your injector constant by some factor (like 0.5 or .7 or whatever headroom you need). You'll have to redo your fuel and spark tables using the new compressed scale, but a few people that have done it have had good results.

My concern is with the TPI MAF sensor itself. It can flow enough air for a mild turbo app, but I'm not sure the sensor stays accurate in the higher-flow ranges. I've never seen anyone do a flow test while monitoring the sensor's output voltage.

pandin

Something else to consider the max air flow vs rpm. WOT at 2000 rpm and 82 gps with the same maf my stock 350 and my moded 383 both hit the max table and ride all the way to 255. Tried one bosch and a wells type both read the same. I would have thought the 350 would have been lower and never hit the max table. what do you think? I am interrested to see if the ford would work.

89onlyZ51

iTrader: (3)

Interesting - MAX flow v. RPM isn't present in the $32b mask. When the weather gets a little better out here, I'll have to do some datalogging and see where mine pegs. A stock 350 shouldn't peg, and a modded 383 should peg until 4k+ rpm based on N/A air requirements.

pandin

Looking at tunerpro the 32b xdf shows the max table at 6f2 to 702.

I would not think the stock 350 would hit the max table.

Did exl graph with the max table and data logs for both engines using same maf. was testing for differances in the mafs not the engines. both engines and mafs were limited by the max table. one maf maxed at 187 gps an other at 205 gps the wells hit 255 but was reading more air flow at rpm making everything way rich.

BTW the 187 gps maf conpensates (reads less air at rpm, lean) for the 24# injectors at 50 psi.

Have a calloway but its just parts and pieces.

bl85c

iTrader: (2)

I did a quick mockup with the t-bird maf yesterday (didn't switch plugs, just pushed the wires into the plug terminals) and cranked it over. It ran- like a turd. It's overreporting airflow 5 to 1. Probably need to ground the maf return to a 5 volt ground. Don't have the time to mess with it though.

tequilaboy

I suspect you're having the same problem that I am

I'm in the process of installing a Ford slot style maf into my 88 Corvette with a 165 ecm.

Here's where I'm at as of today:

The ecm is pulling up the green signal line up to 5v. The Ford MAF output does not appear to have sufficient current to pull the signal low again.

When running, this results in a constant MAF raw input of 175 gm/sec. The signal line is in the vicinity of 4 volts.

I think it will be necessary to modify the ecm to remove the 5v pull-up. I haven't looked into the ecm hardware yet.

bl85c

iTrader: (2)

My problem's a little different. It's pulling the signal down just fine, but it's reading at a higher voltage everywhere. At idle (sort of ) it reports 16g's @ 1.5v and continues to report 5 times as much airflow as there really is. It normally idles at 3-3.5g's.

Fast355

iTrader: (2)

http://www.dainst.com/info/maf/ford_mustang_maf.html

tequilaboy

Ok, good to know.

My issues may be somewhat complicated by previously running mafless and also with the MAF dtcs (33, 34 and 36) disabled. It was running on the default airflow and the raw input was frozen at 175.

I'm also not even certain that the sensor I have is working properly. Its a used sensor from an 05+ mustang. It does seem to show some small voltage output when the signal line is open to the ecm while the maf is powered up during the fuel pump priming.

Now after disconnecting the battery again, it appears that the ecm is at least reading the MAF input now at key on prior to crank, instead of immediately using the default airflow calculation as before. I'm now seeing the MAF flow at the 23 gm/sec initial limit with a 138 gm/sec raw value. Unfortunately, my battery is now to weak to crank and fire. Its charging now.

Hopefully I'll learn something on the next restart, when the MAF input is recognized and the MAF is powered for more than a few seconds during prime.

Still getting 175 gm/sec on the MAF raw input signal with good battery voltage, which is enough to put me into the default airflow mode. If I ground the signal wire, I can pull the MAF raw input value down to 8 gm/sec or below. I'm thinking maybe a pull-down resistor to counter the 5 volt pull-up may work.

I wonder if the older Ford tonsil style maf output current is greater than the 05+ slot style (Hitachi) MAF. I could always adapt to a tonsil style if it works. Keep us posted on your results.

tequilaboy

To the OP or bl85c:

Which ecm pin are you using to input the MAF sensor signal? Are you using the normal analog MAF pin (B12) or the digital maf or vats pin (B6) for the MAF input.

In your original post, you mentioned setting the switch to analog. Were you previously running a digital MAF?

I've got the 05+ Ford MAF wired as follows:

MAF signal on B12, MAF return on A11, 12 V from the MAF power relay (purple wire), and ground on A12.

If you've done something differently, please explain.

Thanks.

tequilaboy

I think I'll try running the Ford MAF signal into the MAT input when I get a chance. I don't know if the MAT input pin is also pulled up to 5v, but I can check it.

If that results in a useable raw signal, then I'll try changing the MAF A/D reads from channel A to channel 8 in a new bin.

I experimented a bit with the MAT input.

With the return line either grounded, or shorted to the signal line, the MAT reads 5 volts or 392 F.
With the signal line open or connected to the MAF signal, the MAT reads 0 volts or -40F.

With the MAF signal connected to the MAT return with the MAT signal open, The MAT reads a steady 0.74 V, seemingly independent of airflow.

With a 1.5 volt battery inserted between the signal and return pins the MAT reads 3.47 volts (5 volts - 1.5v)

Grounding the return and applying a positive voltage to the signal line would seem to have the same effect as just grounding the return and resulting in 5 volts again.

bl85c

iTrader: (2)

The MAT pin won't do you any good, it measures resistance not voltage. Found that out when I hooked up my wb O2.

I have a v6 w/ a '165 swapped in so yes, I'm using the stock pos digital maf. When I hooked the ford maf up I just pushed the stripped wire ends into the v6 plug. The v6 plug only has 1 ground so I hooked the maf return there too.

Fast355

iTrader: (2)

You need to move the maf pin on the ECM to the Analog MAF pin @ B12.

Fast355

iTrader: (2)

I am not sure that the 05+ MAF works the same way as the older 90-93ish MAFs do.

bl85c

iTrader: (2)

Do'h! I should've known that!

tequilaboy

I tested the maf signal input line (B12) tonight.

This pin has 5 volts supplied by the ecm. By grounding or applying various resistors between this pin and ground, I was able to achieve different values on the MAF raw input as observed via TunerProRT. The MAF signal itself was limited to 23 gm/sec by the max airflow vs rpm table (0 rpm), but would display values below the limit when grounded.

I tried a couple more known resistors tonight (1k and 100k). It looks to me like a 100k digital potentiometer used as a voltage to resistance converter could work.

MAF RAW Input values vs resistance:
Note: the voltages shown were obtained from my specific MAF tables.
Signal grounded: 8 gm/sec (approx 0 volts)
1 k resistor: 66 gm/sec (approx 2.5 volts)
Resistor 1 (7.5k??): 184 gm/sec (approx 4.43 volts)
Resistor 2 (10k??): 202 gm/sec (approx 4.64 volts)
100 k resistor: 247 gm/sec (approx 5.05 volts)
Open circuit: 252 gm/sec (approx 5.09 volts)

From the voltage values, it looks like there must be an internal 1k resistor making up the other resistor in my ad-hoc voltage divider circuit that was created by grounding the signal line through various resistors.

In addition, applying 1.5 to 3 volts with respect to ground to this line via c cell batteries had no effect.

Based upon these results, it appears that the maf must act like a variable resistor rather than a 0-5 v voltage source to result in a useable signal with the 165 ecm.

Now how to make a Ford MAF act like a variable resistor (potentiometer)?

One thing I've noticed: If the MAF raw input signal happens to be a large value (greater than 140 gm/sec or so) when the ign is turned on, the ecm seems to ignore the input and the MAF raw input signal doesn't respond to additional changes for that ign cycle.

If I ground the signal wire first before keying on, the raw input will go low to 8 gm/sec and then it will respond accordingly to changes in resistance on the signal line.

With this in mind, I may have to go back and retest with the Ford MAF in the loop and the engine running making sure to initially ground the signal line to be sure the ecm is really reading the signal and not just retaining a historic high value...

Inspired by bl85c and his WB input idea, I've got something new to try.

Next attempt will be to run the Ford MAF signal into the Fuel Pump Voltage pin (B2) and correct the MAF A/D reads from A/D channel A to A/D channel 6 in the bin. I think this will work.

tequilaboy

Update:

I tried the 05+ Ford slot style MAF output on the fuel pump input pin (B2) along with a bin reprogram to read A/D channel 6 for the MAF instead of channel A. Its sort-of working.

I can see the voltage varying at the fuel pump, and the resulting MAF unlimited airflow value and filtered values are responding to the changing voltage.

Unfortunately, the conversion from volts to airflow is off by a factor of 5. A/D channel 6 must behave differently than A/D channel A. There must be a voltage divider upsteam of the D/A on channel 6 to extend the range to 25.5 volts.

When I applied 11 volts to B2 for a test, the MAF raw (unlimited airflow) signal read 47 gm/sec. This is the reading that should occur at 2.2 volts with my bin.

I've created a new bin that multiplies the A/D value by 5, but I'm out of blank eproms and don't have an eraser on hand. Its going to have to wait until tomorrow for further testing. Amplifying the MAF sensor output may be a better solution to avoid losing resolution. As it is now there will only be 50 steps available between 0 and 5 volts.



The car starts, but stalls quickly since its running pretty lean.

I think this is going to work.

tequilaboy

Another approach:

After a little more digging, I think using the unused A/D channel 0 on pin D8 (MAP2) will be the easiest input for the Ford MAF since there is no pull-up or voltage divider on this input. A/D channel 3 on pin C11 (MAP1) could also work since it is a similar circuit.

This appears to be the common method for inputting W/B O2 signals.

I should be able to test these ideas tonight.

tequilaboy

pandin

Congrads! Hard that pays off is better than hard work that doesn't. But you learn more when things don't work well then when they do. Enjoy the fruit of your labor.

bl85c

iTrader: (2)

Messed with my setup a little today, still no luck. I repinned the signal to B12 and grounded the maf return at the 5 volt return but the ecm's still ignoring the maf.

bl85c

iTrader: (2)

Alright, this thing's sat on my desk long enough. Works as a paperweight but not a maf, LOL. Need some more input on what's not working here. I've got the maf pinned as follows-

Maf A- 12v power
Maf B- ground (via digital maf ground wire)
Maf C- ground (same as B)
Maf D- ecm pin B12

ECM's reprogrammed to ford maf table and scalars adjusted accordingly, analog bit checked... unless I've got 2 bad Maf's in a row I'm not sure what else could be wrong?

tequilaboy

You need to re-pin into one of the MAP sensor inputs. MAP1 or MAP2 and correct the A/D channel reads in the eprom for the appropriate channel. If you get that far, you will also likely need to increase the MAF filtering by reducing the multiplier for the sliding filter.

If you go back and read through my posts in this thread, it should become clear what needs to be done to get it to work.

bl85c

iTrader: (2)

Not being assembly code literate how do I go about that?

tequilaboy

I've got an updated $32B xdf to make it easy to change the MAF A/D channel reads, etc. I haven't gotten around to making an equivalent $6E xdf, but its not a big deal to do so.

Which mask are you using?

bl85c

iTrader: (2)

$32B right now, but I'm going to $6E soon as I confirm this works.

tequilaboy

PM me with an email address and I can send an xdf.

bl85c

iTrader: (2)

Ah, pretty simple. I don't have acess to a fully commented hac of $32B so I can't find the A/D read locations myself. When I get a chance I'll test it out.

tequilaboy

On the A/D reads, be sure right click so you can see the raw hex values when editing.

I forgot to update the output type to Hex Digits in the xdf item info, othewise, you will see the floating the point values. You can correct this in the xdf yourself also by simply changing the output type to hex, so that you will always see the hex values directly.

You want to set the raw hex values to those that I've indicated, either 00 or 30 depending upon the input pin choice.

bl85c

iTrader: (2)

Already done. I ended up adding those constants to my own version of $32B I made up for the v6's. Got it all plugged up and reprogrammed and still no luck. Tried pin D8 first and got the same response as before, tried C11 and got a maf low code (34). Won't have acess to my laptop for a while so I can't see what's going on so I may need to postpone this project a while longer.

bl85c

iTrader: (2)

Well I don't know what changed but it's working perfect now. Must have had something hooked up wrong last time.

tequilaboy

Glad its working. Welcome to the Ford MAF club.

bl85c

iTrader: (2)

By the way, what's the maf/burnoff a/d read locations for $6E?

tequilaboy

For $6E:

MAF Burnoff A/D channel read: 2BF8
MAF Signal A/D channel read: 38FC

Note: Addresses are shown as they would appear in the xdf.