MAF wired wrong, any damage from this? - Ford Mustang Forums : Corral.net Mustang Forum
 
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post #1 of 21 Old 11-09-2018, 10:07 PM Thread Starter
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MAF wired wrong, any damage from this?

Short Story: Got half-way through a new build and then ended up relocating. Project sat for a few years and I just got it to fire up. Although it fired, it was running unbelievably rich in the 9:1 range. I started to go over the wiring by ohming out wire runs all the way back to the ECU harness connector. I discovered that the MAF connector was wired backwards by me many moons ago.

Assuming that the correct wiring is as follows:
A=PWR-37
B=GND-40 or 60
C=Signal RTN-9
D=SIGNAL-50

Mine was wired as follows:
A=SIGNAL-50
B=Signal RTN-9
C=GND-40 or 60
D=PWR-37

Can I just correct this and be on my way or did I cause some other unforeseen damage?

Thanks


'01 GT:
YSI, 20lbs
89 LX:
347 stock
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post #2 of 21 Old 11-10-2018, 10:05 AM
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test it by taking a voltage reading at idle

back probe the pins

0.7-0.9volts is a usual signal voltage

battery voltage to power

less than 125mV on the grounds


89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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post #3 of 21 Old 11-10-2018, 12:22 PM Thread Starter
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Thanks, that is helpful.

I am optimistic that I can get it to idle now, so I should be able to back probe.

Any chance that my wiring screw up could have ruined the meter or the EEC? Would this error have caused the absurd rich condition?

'01 GT:
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post #4 of 21 Old 11-10-2018, 01:27 PM
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anything is possible, but its unlikely in your case, unless there is something you are not saying

the eec will ignore the maf, if its signal is out of range

yours would def be out of range

if your ecm is programmed for the actual injector you are using

limp mode should have correct fueling

if your ecm is NOT, limp mode may not work correctly

the above test will verify maf integrity

89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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post #5 of 21 Old 11-10-2018, 01:28 PM
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this is just another reason, for correct tuning

and not using a 'calibrated' maf

fords dont use them

89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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post #6 of 21 Old 11-10-2018, 04:05 PM Thread Starter
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I hear ya on the correct tuning and agree with that. This car does have a chip in it, but I have no idea what is actually tuned on the chip. So with the car having 30lb injectors, a screwed up C&L MAF, and a possible ECM not tuned for the injectors it would result in a pretty rich/rough running car.

Just because there is a "tune" doesn't mean the ECM was corrected for the injectors, correct? A "tune" can still rely on the calibrated MAF signal for the injector compensation if the tuner is lazy I suppose.

Next time I start the car I will do so on the A9L alone, 30lb injectors, and calibrated C&L MAF as I should be able to get it to run under those conditions.

'01 GT:
YSI, 20lbs
89 LX:
347 stock
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post #7 of 21 Old 11-10-2018, 06:02 PM
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if the chip is done correctly, limp mode should be correct

when you say running rich, i hope you are using lambse from a log

if it is from smell, or plug examination, that is not reliable

89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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post #8 of 21 Old 11-10-2018, 09:58 PM Thread Starter
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I am saying running rich based on my wideband, plugs, and smell.

'01 GT:
YSI, 20lbs
89 LX:
347 stock
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post #9 of 21 Old 11-11-2018, 01:33 AM
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was the 02 voltage at?

89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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post #10 of 21 Old 11-11-2018, 12:23 PM Thread Starter
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not sure as I have not probed it yet. With as little run time as this car has had, I am assuming that the wideband is accurate. However, a voltage check as you suggested will support that assumption.

I am making a list of things to check if the cars gets running as I need it to run well enough for me to exit the driver's seat.

MAF voltage first
Fuel pressure adjustment second if needed
Timing adjustment third, should be pretty close to 10 now, but will need more if the MAF fixed the previous issue. Timing adjustments with the screwed up MAF wiring really had no impact in the 0-20 BTDC adjustment range.
Narrow Band O2 sensor fourth
Wide Band O2 sensor fifth

I picked up some T-pins from a craft store yesterday so I can back probe the aforementioned items later today if the car will run on its own.

Thanks for the feedback thus far!


'01 GT:
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89 LX:
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post #11 of 21 Old 11-11-2018, 12:42 PM
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i recommend piercing adapters as well, T-pins sometimes are tough to use

fuel pressure adjustments will throw off fueling

set it to injector spec once, and never again

in fact i recommend non adjustable reg

I would not trust WB readings, too many variables

until you can verify they are following NB and lambse

tuning fuel is the first thing you do with a tuner when the engine is nice and hot

89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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post #12 of 21 Old 11-11-2018, 06:20 PM Thread Starter
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just to double check, are you saying that I should see 0.7-0.9 volts at idle when I connect the red meter lead to the wire D (MAF Signal) and the black meter lead to the wire C (MAF Signal Return)?.

This voltage should then increase with throttle application

'01 GT:
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89 LX:
347 stock
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post #13 of 21 Old 11-11-2018, 07:22 PM
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one lead at battery negative

probe each wire, while running with the other lead

that way you check all current carrying conductors

89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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post #14 of 21 Old 11-11-2018, 08:01 PM Thread Starter
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Thanks.
I got the MAF rewired today and will start it up sometime this week to check everything and post results.

'01 GT:
YSI, 20lbs
89 LX:
347 stock
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post #15 of 21 Old 11-14-2018, 06:32 PM
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Leave the base timing at 10 BTDC.
C&L MAF should not need more timing.
MAF location & orientation are more important.
"L" from C&L walked through it all with me when I had the A9L, 30lb injectors & the purple calibration tube. He said to change to green tube for blow-thru.

The C&L website text can still be found here:
https://web.archive.org/web/20150225...php?section=15

1988 GT, 57k mi, Orig Owner
ProCharger P600B, FRPP Headers, Flowmaster F2, 3G Alt, Mk8 Fan/DCC, 3.55's, Prog Springs, ST Brace, G/Trac Bar, Subfrms, UCA, LCA, FCA, Tokico 5-ways, C/C Plates, CSA 16x8, Bridgestone RE760 Sport 225/50R16, Megasquirt DIYPNPF60, LC2 WBO2, C&L76mm MAF w/LU47's
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post #16 of 21 Old 01-28-2019, 08:41 PM Thread Starter
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Just to update this thread, I ended up correct my wiring mistake and I went ahead and put a Pro-M Maf for the 30lb injectors.
Car will start up and I can get the rpms to hold steady around 1000rpm with my foot barely on the throttle and A/F looks good. I have not been able to get it to idle on its own just yet, but it seems I am moving in the right direction.

'01 GT:
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89 LX:
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post #17 of 21 Old 01-28-2019, 09:56 PM
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cold start a/f is what?

89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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post #18 of 21 Old 01-29-2019, 08:20 PM Thread Starter
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It was a little rich in the 13.5-13.9 range.
I didn't run it too long as I noticed an oil leak at the back of the manifold, so I still got some tinkering to do to fix that leak and play around with the timing.

Will I ever be able to get it to idle without throttle on the stock ECM with the 4R70W behind it? First time with a combo like this and I was assuming that I would need a slightly higher idle to compensate for the drag of converter/trans. Is this true or did I just make this up?

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post #19 of 21 Old 01-29-2019, 09:59 PM
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cold start requires more fuel and air

without seeing what is being commanded you will never know if it is rich or lean

but, that a/f is pretty good for cold start

your idle issue is not from the trans, its has do with you fooling the eec with a skewed maf and probably an incorrect throttle blade position

if your maf is reading less air than is really entering, that is what a skewed maf does,

do you expect load to be higher or lower than it should be at idle?

89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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post #20 of 21 Old 01-30-2019, 08:19 PM Thread Starter
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I would expect the load to be higher at idle due to the drag of the converter/auto combo.
Is that an incorrect assumption?

As far as the throttle blade position can I offset it by simply re-aligning the IAC position sensor? I did open it up some as I was trying to get the RPMS up, but quickly realized that was a bonehead mistake. I got it set back to original position now as I was smart enough to take a starting picture of the set screw. I was hoping that I could open up the throttle body a tad and then readjust the position sensor to get the rpms up.

'01 GT:
YSI, 20lbs
89 LX:
347 stock
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post #21 of 21 Old 01-31-2019, 05:46 PM
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if the meter is artificially telling the ecm the air flow is really less than it is

the ecm will calculate less load, then actual

the throttle blade must allow a specific amount when closed, it has to be close to what is programmed in the ecm

89 GT gr-40, KB2200(10psi), tweecer R/T,LC-1, 22gal cell, w/tailpipes.
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