90 Lx 306 Gt40 Build Just Bought, Picking Up Loose Ends

discount5.0 · Nov 1, 2014

I have been looking at this forum and just finally joined. Seems like a good bunch. I just bought a 1990 lx and here is what I know.
stock block to car, cobra rims, lowered, stock brakes.
306, forged pistons, gt40p heads, e 303 cam, not sure of valvetrane, can see aftermarket rockers, explorer intake, BBK 70mm throttle body if I remember right, underdrive pulleys, ac delete , electric fan, high volume fuel pump, shorty headers, bassani x pipe w cats, smog pump still pumped into cats. rebuilt rear end w 4.10s

The car is in decent shape, the motor was just built, I paid $`1200. Dude ran out of $ and time and needed $.
It had an AOD in it that I sold for $500.
Just now finishing putting a rebuilt t5 in it, spec flywheel and stage 1 clutch.

I am chasing some loose ends. The motor runs strong, idles well, obviously fresh.
The car still has EGR on it but coolant lines are not hooked up, EGR is plugged in.... Should I unplug?

There is a vacuum harness down near lower passenger inner fender well. Nothing is hooked up to this and the harness is all to atmosphere. Plug? diagram? need any of this?

Ran the part # on the MAF and it looks to be stock 55mm? mustang. Too small correct?

I have 19lb ford explorer injectors. Should go bigger correct? 24lb?

My plans for this car is to make a fast ugly cheap sleeper. Thanks for the suggestions!

Micheal Nadeau · Nov 3, 2014

Is it vacuum or is it the fuel tank vent line from the tank to the charcoal canister? 19 lb injectors will work fine for your set up, along with the MAF. Leave the EGR plugged in.

jrichker · Nov 4, 2014

Diagrams courtesy of Tmoss & Stang&2birds

Vacuum diagram 89-93 Mustangs

Inexpensive MAF swap:
94-95 Mustang GT MAF - $40-$100. It is 70 MM instead of the stock 55 MM on regular stangs built prior to 94. It uses a slip on duct on the side that goes to the throttle body and a 4 bolt flange on the other. You need a flange adapter to fit the stock slip on air ducting that goes to the air box. Wiring plugs right in with no changes. *1 *2

*1.) Metal flange adapter http://www.kustomz.com/components.html Buy the TR70 for $40. Or spend some time on eBay looking for one that may fit.

*2.) MAF & sensor interchange
The 94-95 Mustang 5.0 MAF & sensor is also found on:
1995-94 Mustang 3.8L F2VF-12B579-A2A,
1994-92 Crown Victoria 4.6L F2VF-12B579-A2A,
1995-94 Mustang, Mustang Cobra 5.0L F2VF-12B579-A2A,

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

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

2000xp8 · Nov 7, 2014

You should use a bigger mass air meter, but not bigger injectors. Buy a 75mm pro m with 19lb calibration, that should be good and only cost about $100 used. If your setup gets better in the future you can sell it for no loss.

Since the car has cats, IMO, you might as well make the emission systems complete and full functional.

Since the guy was runny out of money i'd make sure the E fan was done correctly.

As for the sleeper, it's tough to fool anyone when you have an e cam.

discount5.0 · Nov 16, 2014

Thanks for the info guys. I tore in and fixed the heater core last weekend. Got the vacuum situation line out and everything running. As a side note on the heater core, this can be gone way quicker without fully removing dash like a lot of people recommend. Drop the column, suspend w zip ties and move dash just enough to access heater box and slip core out the top. Also, while I had the car all torn apart I ported and polished my upper and lower intake. Took a lot of metal out of the lower runners and knocked those knees down on the front two runner big time. It takes a little patience but I did the whole project with a $15 NF burr from tacoma screw and a $22 cone sanding kit from harbor freight, couple other NF grinder bits for my little Pneumatic dentist tool. Turned out pretty damn good. Lots more room in there now.

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