Speed Density to Mass Air Conversion

1.) Dump the codes. Fix the ones that come up.
As boost comes on, the requirements of the ignition system increase dramatically
2.) Check the spark plug gap. You will need to reduce the gap from the stock .055 to .035
3.) Plan on replacing the distributor cap, rotor and plug wires.

Dump the codes: Codes may be present even if the Check Engine Light (CEL) isn't on.

Dumping the computer diagnostic codes on 86-95 Mustangs

Revised 26-July-2011. Added need to make sure the clutch is pressed when dumping codes.

Codes may be present even if the check engine light hasn’t come on, so be sure to check for them.

Here's the way to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.

Post the codes you get and I will post 86-93 model 5.0 Mustang specific code definitions and fixes. I do not have a complete listing for 94-95 model 5.0 Mustangs at this time.

Be sure to turn off the A/C, and put the transmission in neutral when dumping the codes. On a manual transmission car, be sure to press the clutch to the floor.
Fail to do this and you will generate a code 67 and not be able to dump the Engine Running codes.





If your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.



The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.

89 through 95 cars have a working Check Engine light. Watch it instead of using a test lamp.



The STI has a gray connector shell and a white/red wire. It comes from the same bundle of wires as the self test connector.


WARNING!!! There is a single dark brown connector with a black/orange wire. It is the 12 volt power to the under the hood light. Do not jumper it to the computer test connector. If you do, you will damage the computer.

What to expect:
You should get a code 11 (two single flashes in succession). This says that the computer's internal workings are OK, and that the wiring to put the computer into diagnostic mode is good. No code 11 and you have some wiring problems. This is crucial: the same wire that provides the ground to dump the codes provides signal ground for the TPS, EGR, ACT and Map/Baro sensors. If it fails, you will have poor performance, economy and driveablity problems

Some codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.

Dumping the Engine Running codes: The procedure is the same, you start the engine with the test jumper in place. Be sure the A/C is off, and clutch (if present) is pressed to the floor, and the transmission is in neutral. You'll get an 11, then a 4 and the engine will speed up to do the EGR test. After the engine speed decreases back to idle, it will dump the engine running codes.

Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.

Your 86-88 5.0 won't have a working Check Engine Light, so you'll need a test light.
See AutoZone Part Number: 25886 , $10




Alternate methods:
For those who are intimidated by all the wires & connections, see Actron® for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.

Or for a nicer scanner see Equus - Digital Ford Code Reader (3145) – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.

which mass air conversion did you do? If you did the re pinning method(like i did) double check to make sure everything is where it's suppose to be.

Also do you have an ignition retard box or a MSD btm box?

What did you do with the MAP?
You should leave it plugged in electrically, but you must remove vacuum from it.
Leave a short length of vacuum hose on it, but have the side formerly attached to a vacuum port open to the air.

Awsome information about the code reader: Going for the Ford Unit. Good thing to have for other issues that pop-up.

1200gt said:

Awsome information about the code reader: Going for the Ford Unit. Good thing to have for other issues that pop-up.

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IMO don't waste your money on a code reader. All you need is a paper clip and if you don't have the CEL indicator a test light.

agreed on that!

Noobz347 said:

Code readers for OBD1 are cheap. Just having the codes displayed on a screen vs. counting flashing lights, is worth the 35 bux all by itself.

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I went through 2 of them I bought on flea bay. Neither of them worked a damn. They werent the digital ones, just the ones that were audible and flashed an led light. Went back to the paper clip method thats worked for 20 years.

Maybe I'll give the digital one a try.

This one...

http://www.amazon.com/gp/aw/d/B000EW0KHW

plugs right in to the diagnostic port

mikestang63 said:

I went through 2 of them I bought on flea bay. Neither of them worked a damn. They werent the digital ones, just the ones that were audible and flashed an led light. Went back to the paper clip method thats worked for 20 years.

Maybe I'll give the digital one a try.

Click to expand...

When you're done testing the digital one could you give us some feeback on it? Thanks for the info with you experience with the audible units.

Mustang5L5 said:

That's the only one to buy.

Spring for the extension cable. You can sometimes find them bundled on eBay. That way you can do the testing from the drivers seat to hold the clutch in, start the car and blip the throttle to run the cylinder balance test.

I've had this reader for 5 years now. Use it all the time and it works great.


Sent from my iPhone 4S using Tapatalk

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Again: great info. I was gtoing to order this unit, stand alone, but the extension suggestion makes all the sense. BTW, Summit has the unit for 21.95 i believe, but I didn't look at shiping.

Thanks

Dwayne

WyattBCobra said:

Looking For Some Help. I have a 86 GT With a PowerDyne SuperCharger. As Speed Density I have no
issues with Boost. , I converted to Mass Air , Now When I hit about 3 lbs of boost the car will Pop like it is just shuting off, now once it falls below 3 lbs boost, start running OK . Am I missing something on the mass air conversion ?

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Wyatt, still following your problem. Let us know how you eventually solve it.

Thanks,

dwayne

thank you gents. I'll shop around for that tester. Not in any hurry as the paper clip is free vs. $50 for the tester and cable. I'll let you know how it works.