Switched to mass air; have some problems, need help.

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Switched to mass air; have some problems, need help.

June 30, 2005, 10:14:32 PM

After switching to mass air today, I promptly got a check engine light. I scanned the computer in KOEO and got a system pass for hard fault codes, and codes 41 and 91 for intermitent. Codes 41 and 91, according to my book, tell me the oxygen sensors are constantly reading lean. I cleared the memory and started it back up.

I noticed the MAP vacuum tube I had plugged was leaking, so I plugged it better (no leaks this time). Started the engine once again, and it actually seemed to run pier. I could smell gas out the exhaust.

I shut it down and covered the side of the conical K&N that faces the alternator (I've heard that the fan could cause the MAF to bug out with a big conical filter on it that's open to the engine bay). After I properly shielded the filter, I started it once more....still running kinda py, and I still smell gas out the exhaust. This time I take it for a spin around the block. After about five minutes of driving, the check engine light comes on again. Once again, back to the garage.

I run the scanner on it and get the same scenerio....system pass, codes 41 and 91. This time I run a KOER, and get code 92 (which says the right oxygen sensor is always indicating rich).

WTF? I run a cylinder balance test, and it passes on the first time around.

This is really starting to bug me. The only things I can still think of that could be throwing the lights would be the old MAP sensor I converted to BAP. It's part number starts with E7. That or the weazing 88 lph fuel pump. I noticed at idle the pressure was only at 35 pounds, so maybe a weak pump is causing the lean issues. The oxygen sensors are brand new, as are the fuel injectors. Maybe I got a bad oxygen sensor? Of course, this A9L might just still be junk. It's the one I repaired the other day. It does run all the tests (which it didn't before), and other than throwing the codes and the engine running pily, it seems to be operating fine (the DA1 I repaired in the same way seemed to work well....better than this A9L is working anyway).

I never checked the DA1 for codes before I disconnected it, so I don't know if 41 and 91 were also thrown with the speed density setup (the check engine light never came on, but from what I understand about speed density computers, they really don't ever turn on the light anyway).

Can any of you guys help me out on this one? Could it be the MAP sensor? A set a bad oxygen sensors? The wiring seems fine on the O2's, and I believe they're grounded well, but I haven't checked that yet. Bad fuel pump? FPR? A9L still ped out? Maybe the MAF (I cleaned the MAF wires before installing)? I don't know where to start looking.

Joe

Re: Switched to mass air; have some problems, need help.

Reply #1 – June 30, 2005, 10:29:07 PM

Did you convert to a HO from the SO?
If not did you move the pins to the pins to the new locations?

Here is what I found when I did the convertion and had the same problem. Its knida long.

CONVERTING YOUR SPEED DENSITY 5.0 MUSTANG TO MASS AIR FLOW SYSTEM
Author: Mike Stowe

Mustang Mass Air Conversion

In this document, I will outline the steps to convert a speed density
mustang to the MAF system. I am generating this because I felt the
documentation I had to work with could be improved. This is based on my
own personal experience converting my 88LX convertible to MAF and the
instructions that came with the kit I bought. The color codes of the
wiring are what I saw in my car and may not be the same but probably
are. This document is for reference only and I accept no responsibility
for what you do to your car.

REQUIRED COMPONENTS: You will need to obtain a Mass Air meter, a MAF
computer and the electrical harness for the MAF meter. The meter harness
can be purchased from several manufacturers for about 50-60 dollars but
you can make your own if you wish. There are a few EEC's that can be
used depending on the car. I've heard it doesn't matter manual vs. auto
tranny but I don't know for sure so this is just some additional info
for you.

For older MAF computers, the numbers are:
Manual transmission hard top:E9ZF 12A650 AA
Manual transmission convertible:E9ZF 12A650 BA
Automatic transimission:E9ZF 12A650 CA

For later (early 90's I think) MAF computers, the numbers are:
Automatic transimission:F3ZF 12A650 BA
Manual transmission:F3ZF 12A650 AA
Universal EEC:F3ZF 12A650 DA

You can also use the 93 cobra computer:F3ZF 12A650 CA but it requires
MAF calibrated for 24# injectors.

The MAF mounting bracket and associated plumbing between the throttle
body and the air filter box will have to be acquired from a junk yard or
you can rig up your own setup. If you intend the to do the "optional"
signals mentioned later, you'll also need to obtain 3 EEC connector pins
and some wire.

NOTES: Average mechanical skills are about all that is needed. The only
special skill I suggest you have to do this conversion is soldering.
Crimp connections are unreliable and could lead to future
troubleshooting headaches which you should avoid.

1. EEC REMOVAL
Before you begin, disconnect the battery. Remove the passenger side kick
panel. There is 1 screw and a push-in fastener that secure it. Remove
the screw in the white plastic retainer that holds the EEC in place.
There was a ground wire and a relay, each one screw that I had to move
out of the way so I could get the old EEC out. You should now be able to
pull the EEC down and out. Once the EEC is out, remove the EEC harness
connector using a 10mm socket to loosen the bolt in the center of the
connector.

2. MAF HARNESS INSTALL
You'll need to run the 4 wire MAF meter harness through the fire wall on
the passenger side. I suggest you poke another hole in the large oval
grommet the existing EEC harness goes through located in the upper
corner on the passenger side of the firewall. I popped the grommet out
of the firewall with a screwdriver and used an exacto to poke a hole in
the thin section. You don't just want to blindly jam something through
there because you may cut the insulation on some of the wires and cause
future shorts. I then used a wire coat hanger as a snake, poking it
through the grommet and coming out by the EEC inside the car. I taped
the MAF meter harness to the snake (protecting the EEC pins) and pulled
it through from inside the car. Pop the grommet back into the firewall
after the harness has been pulled through. I then used some silicone to
seal the area where the new harness goes through the grommet so I didn't
get any water leaks. Remove the red "H" shaped plastic pin lock in the
EEC connector. Gently pry around the plastic pin lock with a pointed awl
or small scewdriver working it up and out of the connector. You can't
add or remove EEC pins to the connector without removing this lock.
Depending on the MAF meter you have, it may have a 4 or 5 pin connector.
Refer below for pin locations.

PIN
5-Pin connector (E4FB 14489 BA)
4-Pin connector (F078 14489 BA,E9DA 14489 BA)

A
Power (+)
Power (+)

B
No connection
Ground (-)

C
Ground (-)
Signal (-)

D
Signal (-)
Signal (+)

E
Signal (+)

a. The Power (+) wire from the MAF meter harness needs to be spliced
into the existing red wire in position #37 of the EEC connector.
b. The Ground (-) wire from the MAF meter harness needs to be spliced
into the existing black/green wire in position #40 or #60 of the EEC
connector.
c. The Signal (-) wire from the MAF meter harness needs an EEC pin which
then gets inserted into position #9 of the EEC connector.
d. The Signal (+) wire from the MAF meter harness needs an EEC pin which
then gets inserted into position #50 of the EEC connector.

The locations for pin #9 and #50 should be empty. The pin numbers are
embossed into the plastic connector on the back of it where the pins
insert. It's a little hard to see but they are there if you look closely.

Please note that the notches shown in the diagram are not the ones seen
in the picture. The ones in the diagram are actually keys that only
permit the connector to be installed into the EEC one way. Pins 20,40,
and 60 are closest to you in the picture. It should be obvious because
the pin locations for the additional signals must be empty.

3. MAF METER INSTALL
Remove the existing air filter box cover and tube leading to the
throttle body. Install the MAF to the passenger side strut tower which
should already have the holes for the bracket. Connect the duct work,
tighten the clamps and connect the meter to the MAF meter harness.

4. THERMACTOR PUMP PIN MOVES
You will need to move the 2 signals for the thermactor pump to different
locations in the EEC connector. The EEC pins are held in place by a hook
shaped retainer that snaps into a groove in the EEC pin. To remove you
must pry the hook back from the EEC side of the connector and either
push on the pin or pull on the wire from the back. I used a paper clip
and flattened one end but a small jewelers screwdriver would work also.
The wire currently in position 51 tan/red needs to be moved to position
38. The wire currently in position 11 green/black must be moved to
position 32. If there is not enough slack for this to reach the new
location, you'll have to splice in some extra wire. Mine reached without
doing this.

The next 2 steps some consider optional but will generate error codes in
the EEC. Others have reported stalling problems without the VSS signals.
In my opinion it's worth doing if only for piece of mind and no bogus
error codes. In preparation for these signals, remove the driver's seat
and the driver's side kick panel. There are 3 wires that will need to be
added for these signals with EEC pins on one end. I suggest you tie them
all together and route them as one cable over to the EEC on the
passenger side. I took this opportunity to change the carpet at the same
time so I had most of the interior out which made this fairly simple.

5. FUEL PUMP MONITOR SIGNAL
This signal called FPM2 is used to monitor the voltage going to the fuel
pump. It will generate an error code in the EEC if it's not connected
but "shouldn't" cause a problem. Splice into one of the 2 pink/black
wires going to the relay located under the driver's seat and insert the
other end into position 19 of the EEC connector. Refer to figure 1.
Figure 1 (Relay under driver's seat)

6. VEHICLE SPEED SENSOR SIGNALS
These signals are required for cruise control and as stated earlier,
some have reported stalling problems on cars not equipped with cruise so
avoid the head-ache and just do it. These will also generate an error
code in the EEC if not installed. These signals come from a sensor that
plugs into the transmission. The easiest place to tap into them is
behind the driver's side kick panel. There is an 8 pin connector cable
which runs back to the driver's seat, across the floor under the seat
then back towards the front of the car and then goes through the
transmission hump to the sensor. You will need to splice into the
orange/yellow wire. The other end of this signal needs an EEC pin
attached and this gets inserted into the EEC connector into position 6.
You need to splice into the dark green/white wire for the other
connection. The other end of this signal needs an EEC pin attached and
this gets inserted into the EEC connector into position 3. Refer to
figure 2.

Figure 2 (VSS signals behind driver's kick panel)

7. COMPUTER INSTALL
Put the red H shaped pin lock back into the EEC connector. Bolt the
connector to the new MAF EEC and slide the EEC back up in place. Install
the bolt for the EEC retaining bracket and any other relays/grounds you
may have removed to get the old EEC out.

8. MAP SENSOR
The manifold absolute pressure (MAP) sensor is located on the firewall
next to the vacuum tree. Disconnect the vacuum line from the sensor
going to the intake and plug the line going to the intake so you don't
have a vacuum leak. Leave the port on the sensor open and DO NOT
disconnect the electrical connection to the sensor.

MAP Sensor on firewall

Congratulations! You should now be done with your MAF conversion. I
suggest you re-check all your wiring changes at this point before you
re-connect the battery to avoid a smoke show of a different sort. Once
you are happy that everything is correct, re-connect the battery and
start the car. The car may idle a bit rough for a while until it
relearns, but severe idle or drivability problems may indicate a real
problem.

Pin #
Wire Color
Connections for a 88-93 5.0L HO Mustang
Value at Idle

01
YEL
+12 Battery Voltage
12-14 volts

03
GRY/BLK
VSS + / Vehicle Speed Sensor Positive
55MPH = 125hz

04
TAN/YEL
IDM / Ignition Diagnostic Monitor (TFI)
20-31hz

06
PNK/ORG
VSS - / Vehicle Speed Sensor Negative
55MPH = 125hz

07
LGRN/RED
ECT / Engine Coolant Temp Sensor
3 volts = 70*F

09
TAN/BLU
MAF RTN / Mass Air Flow Return
< 0.1volts (open to ground)

12
BRN/YEL
Fuel Injector 3
4.9-5.2ms duty cycle

13
BRN/BLU
Fuel Injector 4
4.9-5.2ms duty cycle

14
TAN/ORG
Fuel Injector 5
4.9-5.2ms duty cycle

15
LGRN/ORG
Fuel Injector 6
4.9-5.2ms duty cycle

16
ORG/RED
Ignition Ground (TFI)
< 0.1volts (open to ground)

17
PNK/LGRN
MIL / Engine Light & STO / Self-Test Output
On=<1volt / Off=12-14volts

19
DGRN/YEL
FPM / Fuel Pump Monitor
Pump on = 12-14volts

20
BLK
Case Ground
< 0.1volts (open to ground)

21
WHT/BLK
IAB / Idle Air Bypass
3.0 - 12.0 volts

22
BLU/ORG
FPR / Fuel Pump Relay
On=<1volt / Off=12-14volts

25
GRY
ACT / Air Charge Temp Sensor
3 volts = 70*F

26
BRN/WHT
Voltage Reference
4.9-5.1 volts

29
GRY/BLU
® HEGO
0.0-1.0 volts

30
BLU/YEL
Transmission Neutral Interface
0.0 volts in neutral

36
PNK
SPOUT / SPark angle OUT
6.93 volts

37
RED
+12 volts
12-14 volts

40
BLK/WHT
Ground
< 0.1volts (open to ground)

42
TAN/RED
Fuel Injector 7
4.9-5.2ms duty cycle

43
RED/BLK
(L) HEGO
0.0-1.0 volts

45
LGRN/BLK
BP / Barometric Pressure Sensor
159hz = sea level

46
GRY/RED
Signal Return
< 0.1volts

47
GRY/WHT
TPS / Throttle Position Sensor
1.25 volts

48
WHT/PUR
STI / Self-Test Input
< 0.1volts

49
ORG
HEGO Ground
< 0.1volts (open to ground)

50
LBLU/RED
MAF / Mass Air Flow Sensor
0.8 volts

52
LBLU
Fuel Injector 8
4.9-5.2ms duty cycle

56
GRY/ORG
PIP / Profile Ignition Pickup (TFI)
6.93 volts

57
RED
+12 volts
12-14 volts

58
TAN
Fuel Injector 1
4.9-5.2ms duty cycle

59
WHT
Fuel Injector 2
4.9-5.2ms duty cycle

60
BLK/WHT
Ground
< 0.1volts (open to ground)
signal return voltage reference ground +12 battery voltage +12 run

Original Harness
Moved EEC Pins

INJ 1
pin 58
INJ 1
pin 58

INJ 2
pin 59
INJ 2
pin 59

INJ 3
pin 12
INJ 3
pin 14

INJ 4
pin 13
INJ 4
pin 42

INJ 5
pin 14
INJ 5
pin 12

INJ 6
pin 15
INJ 6
pin 15

INJ 7
pin 42
INJ 7
pin 13

INJ 8
pin 52
INJ 8
pin 52

Re: Switched to mass air; have some problems, need help.

Reply #2 – June 30, 2005, 10:44:34 PM

Ya, it's a completely rebuilt 5.0 HO out of an 88 GT. It's all stock, except for the stock cam being advanced 2 degress and the engine being bored .030 over with hyper pistons. Currently there's 700 miles on the engine. It's ran well with the speed density, but it had leans issues at 1400 rpm with that setup. I was hoping the switch to mass air would take care of that. I used the same instructions you just posted, off of Stangnet. I switched around the thermactor pins and added the fuel pump moniter wire. The 88 Bird 5.0 harness I'm using already had the vss wires in their proper locations. I've triple checked my installation, and I believe it's correct. All connections were soldered and heat shrinked, no crimp connections anywhere. I'm using the stock MAF, btw.

Thanks for the info about the pinouts. It will come in handy when I go to trouble shoot the HEGOS.

Re: Switched to mass air; have some problems, need help.

Reply #3 – June 30, 2005, 11:06:50 PM

Be sure to take the maf sensor off the meter and clean the two metal probe wires. Use some rubbing alcohol and a q-tip being careful not to break them. Chances are you can't see if they are dirty or not without removing the sensor.
You may have already done this but if not it's something that should definately be done if you're using a used sensor/meter.

Re: Switched to mass air; have some problems, need help.

Reply #4 – June 30, 2005, 11:19:10 PM

I doubt its the MAP/BAP, I used one for years that was from a '87 5.0 SO engine. Tried one from a TC that was a true BAP, no difference.

I suspect a junk A9L, Ronnie had a problem with his going really lean for a few seconds and then being OK. After he checked everything, another computer fixed it.

Anyway its easy enough to switch back to the SD setup to see if the codes are there. Just reconnect the vac to the MAP and swap computers, none of the other changes will have any bearing on the SD oper.

Re: Switched to mass air; have some problems, need help.

Reply #5 – July 01, 2005, 01:51:31 AM

Fred: ya, I already cleaned the MAF before I installed it. The MAF wires looked clean when I finished, and intact. It still could be a py MAF though.

Tom, I was thinking the same thing. Tomorrow I'll swap 'em around and see what happens. I think if I look around the place I may have a BAP off an 88 turbo T-bird. I may give that a try as well.

Joe

Re: Switched to mass air; have some problems, need help.

Reply #6 – July 01, 2005, 12:31:39 PM

Did you use the stock injectors for the H.O. motor? They should have orange tops (19lbs injectors for H.O.). Or do they have the grey tops? (14lbs injectors for S.O.) Also when you did the mass air change did you relocate the pins in the EEC plug for the injectors for H.O. firing order. 13726548, or are they still setup for stock firing order 15426378?
(Not sure what setup you went from, S.O. to H.O. or 4 or 6 to 8 swap?)

Re: Switched to mass air; have some problems, need help.

Reply #7 – July 01, 2005, 01:27:01 PM

Quote from: blownbirds

Also when you did the mass air change did you relocate the pins in the EEC plug for the injectors for H.O. firing order. 13726548, or are they still setup for stock firing order 15426378?
(

When are we gonna learn it is NOT necessary the change wiring for the injectors????? The EEC fires the injectors in the correct order, harness does NOT need any pins moved for the injectors...

Basically if you re-pin the harness,you have just switched the injector order to the SO 5.0 sequence....

Re: Switched to mass air; have some problems, need help.

Reply #8 – July 01, 2005, 02:59:38 PM

I noticed you said:

"I noticed the MAP vacuum tube I had plugged was leaking, so I plugged it better (no leaks this time). Started the engine once again, and it actually seemed to run pier. I could smell gas out the exhaust."

If you're talking about the tube on the MAP sensor unplug it. When you convert to MAF the tube needs to be open to the atmosphere to read BP (barometric pressure). If the sensor is plugged the EEC-IV computer will think the sensor is seeing zero pressure instead of normal atmospheric presure. This will cause your car to run really py.

If you're talking about the vacuum from the intake then disrgard everything I said :)

Re: Switched to mass air; have some problems, need help.

Reply #9 – July 01, 2005, 04:22:12 PM

Dogcharmer: I'm talking about the vacuum line from the intake. I didn't plug it that well the first time around. The MAP is open to the atmosphere.

Well, it just went from bad to worse. Today I swapped in the BAP from an 88 Turbo, no difference what so ever. The car is running even poorer than before. Now once it switches out of open loop, it runs so bad I can barely drive it. It has a low choppy idle at around 600-700 rpm, where before it stayed around 750-800. When ever I'm driving in closed loop it bucks and jerks terribly at 1400 rpm and 2000 rpm. If I give it more throttle, it seems to fall on it's face and backfire out the exhaust (or it's detonating, I can't tell for sure). It seems like the timing advance isn't working, or the fuel is just really lean. I put the speed density computer back in and hooked up the MAP vacuum, and I got absolutely NO CHANGE! I then undid all the wiring changes (pulled out all the MAF wires and the fuel pump signal wire, and swapped the air management wires back to there original locations....still no change. I even swapped out the intake tubes for the speed density system and put on the stock airbox....no change. Now I'm exactly the way it was before I did the mass air conversion, using the good DA1 out of the Mustang, and it's still running like absolute . :disappoin

I'm afraid I'll have to really start trouble-shooting this thing now. The Speed density system has given me no codes as of yet. Perhaps I haven't driven it around long enough for it to throw out any codes, but the way it's running makes it hard for me to drive it anywhere! :mad: GOD DAMMIT PIECE OF !!!!!!!!!

Looks like I'm back to square one.

Joe

Re: Switched to mass air; have some problems, need help.

Reply #10 – July 01, 2005, 04:28:56 PM

This engine harness is out of an 88 5.0 Bird. My car was originally a V6. Now it's the 5.0 HO and the 5-speed behind it. I did not change the injector wiring b/c it is not necessary, as Tom said. It's all plug ang play for a speed density HO swap. The only changes to the engine harness were those that are necessary for a mass air conversion. I have now converted back to the original configuration.

Joe

Re: Switched to mass air; have some problems, need help.

Reply #11 – July 01, 2005, 04:47:07 PM

Joe have you checked to be sure the fuel pressure regulator isn't leaking??? I had one out in front of the house one day, started running really bad as I turned into the driveway...

Do you have catalitic converters??? Possibly pluging up??

Otherwise, I'd check the fuel pressure and maybe try another distributor...

Re: Switched to mass air; have some problems, need help.

Reply #12 – July 01, 2005, 05:23:08 PM

Tom, I checked the FPR. I pulled the vacuum hose off it while the car was idling and didn't see any fuel come out. With the vacuum on, it has 35 psi of pressure at idle, vacuum off it jumps to 41 psi. The fuel pump is making death sounds though.

I don't have any cats, just 2.5 inch o/r h-pipe going into turbo lers and dumps. I'm using the stock mustang headers.

I took all the computers and opened them up. The two I repaired looked the same, and the DA1 out of the SSP looked perfect (no burnt circuit on pin 36), so I'm thinking that the Mustang computer is still good. Now I'm down to ignition (could be the TFI module?) and fuel. I'll have to check the O2's to make sure they're grounded and connected well. This morning I disconnected them and shot some electrical contact cleaner on the connectors....didn't seem to help any. I'm gonna take my dmm to the engine harness to see if I fubar'd anything during the MAF conversion (tugging on 17 yr old wires might have done something).

I started up the car with the oil filler cap off and didn't feel any blowby, so I'm thinking that mechanically, the engine is still sound. It still starts up easily, unlike that last time when I lost all compression due to a coolant leak.

This distributor has worked well for the last 500 miles, but I could at least check it out. I'm probably gonna pull the plugs and replace them; it's a cheap guess.

Joe

Re: Switched to mass air; have some problems, need help.

Reply #13 – July 01, 2005, 06:55:51 PM

what color are the injector tops? Also check the voltage at the maf , 5v is max and the meter should stay well below that.

Re: Switched to mass air; have some problems, need help.

Reply #14 – July 01, 2005, 09:33:06 PM

I checked all the obvious eec power and ground wires and they all check out. Here's the good ones so far:

pin1: keep alive memory
pin 6: vss ground
pin 16: ignition ground
pin 20: case ground
pin 37: vehicle power
pin 40: power ground
pin4: 02 ground
pin 57: vehicle power
pin 60: power ground

everything else can be tested once I install a computer. I guess it's onto individual sensor tests...