I need help, nobody can answer this!! Im rarely stumped!

[stang668]

ok, I bought a 98 v-6 mustang body (250.00), pulled a 97 explorer 5.0L motor and installed it in the v-6 cradle. I also pulled an 87 mustang ECU/Harness (speed density) and distributor out of an EFI/TFI 5-liter truck also installed. I have everything that I can think of attached for this to work..the car runs, but it sounds like a ______dragster! Also, its running very rich, so much so that it made the headers and Cats glow red, and if I let it run too long, it will shoot flames out the tailpipes when it backfires, if I hit the gas it studders. Ive made sure to time this at #1 TDC on compression stroke 13726548, replaced the injectors, fuel pressure regulator, throttle body and TPS, plugs..still no change. Any Ideas? Ive spoken to two ford mechanics, they have no clue. If you happen to know, Id very much appreciate!!!

 

[jrichker]

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.

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.

 

[dgollem]

I'm a little confused, you have a speed density computer/wire harness on a 97 mass air motor?

 

[stang668]

yes, speed density computer and harness on a (once) MAS motor. I no longer utilize the MAF sensor

 

[stang668]

I took all of the harnesses off the exploder motor, and replaced them from a wrecked donor 87 mustang GT. I removed the coil packs and replaced them with a distributor

 

[stang668]

here is a video of my situation

 

[jrichker]

What codes did you get?

 

[dcurtis]

where do you have vacuum hooked to your egr from?

 

[stang668]

ok, my egr gets a vaccum from the upper intake (thanks tmoss), and jrichker// I did not run the codes yet due to it being such of a freinkensein combo,,If you dont have an idea.. i understand..me neither. Ill try codes, but I dont think the computer is going to know whats going on

 

[1987stangman]

Since it's speed density do you have the baro sensor hooked to vac from the intake? I didnt see it mentioned, but I just skimmed over the thread. The baro usually vents to atmosphere on MA cars but needs to be hooked to vac on SD cars.

 

[stang668]

Yes, that sensor is mounted behind the engine on the firewall. I have all grounds connected, and still idles like it has a big cam..I saw the donor explorer, it looked stock as can be. Im starting to wonder if there isnt anything mechanically wrong inside the motor (broken valve spring/burnt piston) I did a compression check, all was good. This just doesnt make since to me. Ive built several musangs in the past, but I always used the electronics that go with the car...never a frankenstein like this one. Do you possible think that ford used a different TFI for that computer (87)?

 

[BlownFiveLiter]

Without the codes, we're going to be simply guessing and throwing parts and money at it. Pull the codes and post up the results, so we know how to proceed with helping you. The Frankenstein combo will still have codes in the EEC.

 

[1987stangman]

TFI should be the same...

You should be able to pull codes even with all the differnt parts.

Really if I had to guess without codes based on what you have told us that you have a massive vac leak or there is a timming issue esp. with the idle you desribed.

 

[dcurtis]

ok, my egr gets a vaccum from the upper intake (thanks tmoss), and jrichker// I did not run the codes yet due to it being such of a freinkensein combo,,If you dont have an idea.. i understand..me neither. Ill try codes, but I dont think the computer is going to know whats going on

Wouldn't that cause a constant vaccum to the egr, not sure about speed density cars but maf cars get vac from the tab tad solenoids on the passenger strut tower don't they? That would cause the erratic idle and temp. EGR does not need constant vaccum.

 

[stang668]

I will run the codes tomorrow.. I didnt think it would help me any, but I may be kicking myself in the a$$. As for the egr, my other 2 cobras EGR's are routed to the vaccum tree on the bottom of the upper intake..seems to be working fine. Also.. I dont think the timing is the issue, as I made sure to TDC #1 piston on the compression stroke..but the way the car runs, it doesnt even sound close! I really appreciate the help!

 

[stang668]

PROBLEM SOLVED.. I didnt realize I had a 3 wire O2 harness when I plugged the 4 wire O2 sensors (covered by chaff wrap). The O2 sensors from the 87-90 where 3 wire, and in 91 mustangs went to a 4 wire style.. The difference is, the ground wire...the 4 wire sensors are grounded in the harness, the 3 wire is grounded the car body. The 3 wire harness will fit in the 4 wire plug, but the engine will run like it has no O2 sensors at all. BTW, running the codes DID NOT tell me this

 

[jrichker]

Some basic theory to clarify how things work is in order…

EGR System theory and testing

The EGR shuts off at Wide Open Throttle (WOT), so it has minimal effect on performance. The addition of exhaust gas drops combustion temperature, increases gas mileage and reduces the tendency of the engine to ping. It can also reduce HC emissions by reducing fuel consumption. The primary result of EGR usage is a reduction in NOx emissions.

The EGR system has a vacuum source (line from the intake manifold) that goes to the EVR, computer operated electronic vacuum regulator. The EVR is located on the back of the passenger side shock strut tower. The computer uses RPM, Load. and some other factors to tell the EVR to pass vacuum to open the EGR valve. The EGR valve and the passages in the heads and intake manifold route exhaust gas to the EGR spacer (throttle body spacer). The EGR sensor tells the computer how far the EGR valve is open. Then computer adjusts the signal sent to the EVR to hold, increase or decrease the vacuum. The computer adds spark advance to compensate for the recirculated gases and the slower rate they burn at.

Troubleshooting:
There should be no vacuum at the EGR valve when at idle. If there is, the EVR (electronic vacuum regulator) mounted on the backside of the passenger side wheelwell is suspect. Check the vacuum line plumbing to make sure the previous owner didn’t cross the vacuum lines.

Diagram courtesy of Tmoss & Stang&2birds. (the diagram says 88 GT, but the EGR part is the same for 86-93 Mustangs)

The EGR sensor is basically a variable resistor, like the volume control on a radio. One end is 5 volt VREF power from the computer (red/orange wire). One end is computer signal ground (black/white), and the middle wire (brown/lt green) is the signal output from the EGR sensor. It is designed to always have some small voltage output from it anytime the ignition switch is the Run position. That way the computer knows the sensor & the wiring is OK. No voltage on computer pin 27 (brown/lt green wire) and the computer thinks the sensor is bad or the wire is broken and sets code 31. The voltage output can range from approximately .6-.85 volt.

The EVR regulates vacuum to the EGR valve to maintain the correct amount of vacuum. The solenoid coil should measure 20-70 Ohms resistance. The regulator has a vacuum feed on the bottom which draws from the intake manifold. The other vacuum line is regulated vacuum going to the EGR valve. One side of the EVR electrical circuit is +12 volts anytime the ignition switch is in the run position. The other side of the electrical circuit is the ground path and is controlled by the computer. The computer switches the ground on and off to control the regulator solenoid.



EGR test procedure courtesy of cjones

EGR test procedure courtesy of cjones

to check the EGR valve:
bring the engine to normal temp.

connect a vacuum pump to the EGR Valve or see the EGR test jig drawing below. Connnect the test jig or to directly to manifold vacuum.

Do not connect the EGR test jig to the EVR (Electronic Vacuum Regulator).

apply 5in vacuum to the valve. Using the test jig, use your finger to vary the vacuum

if engine stumbled or died then EGR Valve and passage(there is a passageway through the heads and intake) are good.

if engine did NOT stumble or die then either the EGR Valve is bad and/or the passage is blocked.

if engine stumbled, connect EGR test jig to the hose coming off of the EGR Valve.
Use your finger to cap the open port on the vacuum tee.
snap throttle to 2500 RPM (remember snap the throttle don't hold it there).
did the vacuum gauge show about 2-5 in vacuum?
if not the EVR has failed

EGR test jig

To test the computer and wiring to the computer, you can use a test light across the EVR wiring connectors and dump the codes. When you dump the codes, the computer does a self test that toggles every relay/actuator/solenoid on and off. When this happens, the test light will flicker. If the test light remains on the computer or the wiring is suspect.

To check the EVR to computer wiring, disconnect the EVR connector and connect one end of the Ohmmeter to the dark green wire EVR wiring. Remove the passenger side kick panel and use a 10 MM socket to remove the computer connector from the computer. Set the Ohmmeter to high range and connect the other ohmmeter lead to ground. You should see an infinite open circuit indication or a reading greater than 1 Meg Ohm. If you see less than 200 Ohms, the dark green wire has shorted to ground somewhere.

Late Model Restoration may still have the Ford Racing M-12071-N302 kit with the EGR valve & sensor along with the ACT & ECT sensors for $45. See http://www.latemodelrestoration.com/iwwida.pvx?;item?item_no=M12071N302 1&comp=LRS for more details