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Topic: Mass air conversion question (Read 10105 times) previous topic - next topic

Mass air conversion question

Hi! On my '87 we converted the car to mass air with a HO engine and 89 mustang A9P about 9 years ago. When you do the swap, what happens with the VSS or speed sensor wiring? According to the mass air wiring the VSS is used by PIN 3 and 6 on the 60 PIN EEC connector. Do you have to run the wiring from the sensor to the EEC? It seems like it should even though the speedo works. I know it's needed for the EEC to send a signal to the IAC when slow cruising or coming to a stop. What do you guys think? On my wiring there is nothing to PIN 3 or 6.
Only in America do we use the word "politics" to describe the process so well: "POLI" in latin meaning "many", "TICS" meaning "bloodsucking creatures".

Mass air conversion question

Reply #1 –
This is what I used when converting mine.

http://www.coolcats.net/modifying/massair.html

Mass air conversion question

Reply #2 –
When I did mine the Ford Racing kit was still available and that's what I used.  I did nothing with regard to the VSS.  On your 87 the stock setup pin #3 should have a dark green wire with white stripe.  Pin #6 should have an orange and yellow wire. Mine were all there so zero issue for me.

-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

Mass air conversion question

Reply #3 –
Ok, I think I'm going to clarify why I was asking this; plus I've read a bit more. I just put a new 347 engine in the car about two months ago and just started driving it this week. The engine is significantly stronger then the previous 5.0 with 1.94 aeroheads and B-cam.

The new engine has pro-comp 2.02s, 10.88 CR and a Comp xe282HR cam. Runs really good except at slow speeds and coming to a stop, the car sometimes will just stall out. So, I was reading on stangnet the other day and read where others have had the same problem with mass air converted cars that were modified. I haven't experienced this until the new engine and thought I would check this out and at the time of converting to mass air I had no idea.

 3 wires that are usually left out on the conversion is PIN 19 to the fuel pump relay for voltage monitoring, and PIN 3 and 6 for the VSS. The wire for the pump relay isn't so important (will give a code though) but I believe the VSS is! So, I started checking and was surprised not to find the wires in the 60 pin connector, I thought at least they would have to be repinned. In the Haynes manual under '86-'88 engine wiring diagram it shows PIN 3 and 6 being used for this but it's not on my car. While I had the cluster out I looked under the dash and found the two wires from the VSS (dark green with white and orange and yellow) going to a control box above the brake pedal. Tomorrow I'm going to splice into these wires and run then to the EEC and hopefully that will be the case of this slow speed/stop stall. I'll post some pics.
Only in America do we use the word "politics" to describe the process so well: "POLI" in latin meaning "many", "TICS" meaning "bloodsucking creatures".

Mass air conversion question

Reply #4 –
Ha! Ok at least I'm on the same page with you guys!! Thanks for the help!!
Only in America do we use the word "politics" to describe the process so well: "POLI" in latin meaning "many", "TICS" meaning "bloodsucking creatures".

Mass air conversion question

Reply #5 –
DId your car come originally equipped with cruise or no?
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

Mass air conversion question

Reply #6 –
Yes it did.
Only in America do we use the word "politics" to describe the process so well: "POLI" in latin meaning "many", "TICS" meaning "bloodsucking creatures".

Mass air conversion question

Reply #7 –
It should be all hooked up then.....
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

Mass air conversion question

Reply #8 –
True! I'll post some pics tomorrow of how some of this wired.
Only in America do we use the word "politics" to describe the process so well: "POLI" in latin meaning "many", "TICS" meaning "bloodsucking creatures".

Mass air conversion question

Reply #9 –
Alright, I went to the junkyard yesterday and was able to get the EEC pins out of a harness from a '91 Mustang to install in the EEC connector. I wanted the correct factory wire colors. Should be able to get that wrapped up this afternoon or tomorrow.

Here is a pic of the 60 pin connector, notice there are no wires in location 3 and 6. The VSS wires do run to a control module under the dash on the drivers side above the brake pedal, must be because of the digital cluster; i'll spice into those.
Only in America do we use the word "politics" to describe the process so well: "POLI" in latin meaning "many", "TICS" meaning "bloodsucking creatures".

Mass air conversion question

Reply #10 –
The pic on the left..... The black wire w/orange stripe.....should't that be location #41?  I'm trying to figure out the orientation of what you have there, but many things don't seem to match up.  I can make out pin #30 (brown wire w/white stripe right next to the main hold down bolt).

EDIT*  Ah OK I see the orientation now.  Threw me for a loop.  The pic goes right to left....

I keep coming back to a sentence from your first post: 
Quote
Do you have to run the wiring from the sensor to the EEC? It seems like it should even though the speedo works. I know it's needed for the EEC to send a signal to the IAC when slow cruising or coming to a stop.

This would be true for a stock EEC-IV speed density setup as well (Same IAC valve).  Is it getting the signal by some other means then?  Seems like yours left the factory this way so.....
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

Mass air conversion question

Reply #11 –
I wonder if the dash cluster has its own processor / circuitry necessary to turn the VSS signal into speedometer movement. Might be a really simple execution electrically. I would definitely expect the full digi-dash to have its own CPU.

My black cougar DOES idle high until the moment I come to a stop. Now, I wouldn't want to intentionally cause a stalling like described....but dammit I want to DISconnect this feature on my car...I hate high idling in neutral as I'm coasting...it hides the cam chop :rollin:. Especially with my cutouts open. When it settles down to 800 RPM or so, it's the perfect shake rattle 'n' roll.
1987 20th Anniversary Cougar, 302 "5.0" GT-40 heads (F3ZE '93 Cobra) and TMoss Ported H.O. intake, H.O. camshaft
2.5" Duals, no cats, Flowmaster 40s, Richmond 3.73s w/ Trac-Lok, maxed out Baumann shift kit, 3000 RPM Dirty Dog non-lock TC
Aside from the Mustang crinkle headers, still looks like it's only 150 HP...
1988 Black XR7 Trick Flow top end, Tremec 3550
1988 Black XR7 Procharger P600B intercooled, Edelbrock Performer non-RPM heads, GT40 intake AOD, 13 PSI @5000 RPM. 93 octane

Mass air conversion question

Reply #12 –
I found the following:

http://www.auto-diagnostics.info/pdf/ford_eectec10.pdf

Quote
To hook up the VSS:
VSS + must be hooked up to Pin #3 on EEC
VSS - must be hooked up to pin #6 on EEC
you can get the VSS signal right from the VSS or tap it off the speed control
amplifier which is located near the dead pedal
Its the yellowish box in the corner there..
The DG/W wire is VSS+ and the black wire is VSS

Also:  Looking at a wiring diagram for a 1986 Mustang shows NOTHING with regards to pin 3 & 6.  They are not listed.....



Remember the average MAF conversion is written with a speed density type Mustang in mind.
I do wonder how the IAC would get a signal in in a Speed Density car without these wires...... 

http://eectuning.org/forums/viewtopic.php?p=33217

I wonder if Speed Density relies solely on TPS input for the deceleration strategy in the ECU....
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

Mass air conversion question

Reply #13 –
Well......  Seeing as I did my conversion many moons ago I did the only sensible thing.

I pulled back the kick panel on the passenger side, pulled the harness from my ECU and took a look...... :hick:
Guess what I don't have? 





BTW -- Full digi dash here as well.

The EVTM would be much more correct (the diagrams I posted are basic for most configurations).  Guess I'll study mine to see if in fact the box under the dash somehow ties into the ECU harness....

You know what really  me off?  WRT to moving pin 51 to 38 and 11 to 32 for emissions as well as this?  Ford Racing NEVER mentioned it in their directions that came with the Mass Air Conversion kit.  I still have the instructions.  I remember printing out the repin info from the Coolcats website for reference.  The VSS info I knew of, but I figured I was in the clear since this car came with cruise and a digi dash.  I've never really had an unsolvable stalling issue and my car was unmolested wiring wise when I purchased it.

*Edit*

http://sbftech.com/index.php?topic=29819.0

Quote
VSS Code 29 Troubleshooting

Codes Definitions:

29 - Insufficient Input From Vehicle Speed Sensor -To 1992 (CM), Insufficient Input From Programmable Speedometer/Odometer Module -From 1993 (CM)

Ever since the speed density systems came out, the VSS input signal was mistakenly given the Quote-Unquote "non-important/you can live w/out" tag. The only importance mentioned was always related to the use of the Cruise-Control system by mistake. The VSS signal was added to all Mass Air EEC-IV system EEC's and its input does have an effect for:

Engine idle control. The EEC uses the 6 MPH value threshold to activate idle dashpot strategy and prevent engine stalls coming to a stop and tip in when shifting.
VSS input is also an engine load determiner along with other inputs (TPS, MAF, etc).
Having a code 29 logged in the system can cause engine stalls in configurations with a manual transmission.
Its cruise control use has not changed.
Since VSS input is used to activate the dashpot function, it is normal to have a higher idle when transmission is shifted to neutral and the vehicle is above the 6 MPH threshold value. This is NOT an idle control problem (as it is erroneously tagged)... the system was designed to work as explained.


I've NEVER EVER EVER EVER EVER EVER logged a code 29 in my car......  :confused:
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

Mass air conversion question

Reply #14 –
Quote from: ZondaC12;439670
I wonder if the dash cluster has its own processor / circuitry necessary to turn the VSS signal into speedometer movement. Might be a really simple execution electrically. I would definitely expect the full digi-dash to have its own CPU.

My black cougar DOES idle high until the moment I come to a stop. Now, I wouldn't want to intentionally cause a stalling like described....but dammit I want to DISconnect this feature on my car...I hate high idling in neutral as I'm coasting...it hides the cam chop :rollin:. Especially with my cutouts open. When it settles down to 800 RPM or so, it's the perfect shake rattle 'n' roll.


Ha! I have a friend who had a pretty radical 347 in his '92 LX. He had #30 injectors and matching MAF and the car ran really good! At a stop though the idle would slightly hunt not much but it wouldn't go under 1k, at 800 rpm the cam sounded really good. We found that if you unplugged the MAF the idle would stay steady at around 800, plug it back in and it would speed up. Well, he too wanted that slow cammed sound at cruises and at the fast food drive through. What he ended up doing was wiring in switch that cut power to the MAF. So, come to a stop and cut the power, the car would idle steady and good, light turn green he'd flip the MAF back on for driving!:giggle: Of course the check engine light would pop on.

Quote from: V8Demon;439672
Well......  Seeing as I did my conversion many moons ago I did the only sensible thing.

I pulled back the kick panel on the passenger side, pulled the harness from my ECU and took a look...... :hick:
Guess what I don't have? 





BTW -- Full digi dash here as well.

The EVTM would be much more correct (the diagrams I posted are basic for most configurations).  Guess I'll study mine to see if in fact the box under the dash somehow ties into the ECU harness....

You know what really  me off?  WRT to moving pin 51 to 38 and 11 to 32 for emissions as well as this?  Ford Racing NEVER mentioned it in their directions that came with the Mass Air Conversion kit.  I still have the instructions.  I remember printing out the repin info from the Coolcats website for reference.  The VSS info I knew of, but I figured I was in the clear since this car came with cruise and a digi dash.  I've never really had an unsolvable stalling issue and my car was unmolested wiring wise when I purchased it.

*Edit*

http://sbftech.com/index.php?topic=29819.0



I've NEVER EVER EVER EVER EVER EVER logged a code 29 in my car......  :confused:


That's crazy! I did have the code 29 a couple times after driving, but it wouldn't pull it always. Here is a diagram I have used:
Only in America do we use the word "politics" to describe the process so well: "POLI" in latin meaning "many", "TICS" meaning "bloodsucking creatures".