So of the two wires going into the coil as i understand it, one has constant 12V and the other should provide an interupted signal from the PIP. Well, as I'm checking my no start condition I found that both wires are constant 12V KOEO and while cranking. This is the case with the old distributor and the new one. I also have no spark from the coil, but had spark yesterday. Any ideas what would cause this? Is my coil shot? I'm starting to feel like I'm chasing a ghost. Please help, I'm tired of walking to work.
91 Lx Ignition Question
- Thread starter jmast
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How the TFI ignition works in 86-93 model Mustangs:
Tools needed: DVM, noid light, safety pin.
Theory of operation:
The TFI ignition in 86-93 Mustangs has 4 main components: the ignition switch, the coil, the TFI module and the PIP sensor inside the distributor.
The ignition switch gets power from the two yellow wires that are supplied power by a fuse link located in the wiring harness that connects to the starter solenoid.
Diagram courtesy of Tmoss & Stang&2birds
The coil is mounted on the driver’s side strut tower on most EFI Mustangs. It gets power from a red/green wire and a brown/pink wire from the ignition switch. That wire from the ignition switch feeds a 20 gauge blue fuse link that connects to the red/green wire. The fuse link protects the wiring and the ignition switch, since the fuse link for the two yellow power supply wires has a much higher current rating. Without the smaller fuse link protecting the smaller wiring used in the ignition circuit, a short there would cause the red/green wire to overheat and burn up.
The TFI module is mounted on the side of the distributor and supplies the ground for the coil. Every automotive power supply circuit uses the ground as the return path to carry power back to the negative side of the battery. The TFI switches the tan/yellow wire coming from the coil to ground. It gets power from the red/green wire when the ignition switch is in the Run position. The red/lt blue wire supplies a signal to turn on more power (dwell time) when the engine is cranking. The trigger signal comes from the PIP sensor when cranking and the computer when the engine is running. The SPOUT jumper plug enables computer controlled spark advance. When the SPOUT is removed, spark advance is locked at the setting determined by the mechanical position of the distributor.
The PIP sensor is in the bottom of the distributor under the shutter wheel. It is a Hall effect magnetic sensor that senses a change in the magnetic field when one of the slots in the shutter wheel uncovers the sensor. Then it supplies a pulse that triggers the TFI module to provide a ground to the ignition coil. A bad PIP will often set code 14 in the computer and cause hot start problems. Replacing the PIP sensor requires removal of the distributor and pressing the gear off the distributor shaft to expose the sensor. For most people, a remanufactured distributor ($55-$75) is the solution, since they may not have access to a press.
Troubleshooting the ignition system – no spark or weak spark. All the tests are done with the ignition switch in the Run position unless specified otherwise. A safety pin may be used to probe the wiring connectors from the back side.
1.) Check for 12 volts at the yellow wires on the ignition switch. No 12 volts and the fuse link near the starter solenoid has open circuited.
2.) Check for 12 volts on the red/green and brown/pink wires coming out of the ignition switch. No 12 volts, replace the ignition switch.
3.) Check for 12 volts at the ignition coil. No 12 volts and the blue 20 gauge fuse link has open circuited.
4.) Check for 12 volts at the red/green wire on the TFI module. No 12 volts and you have wiring problems.
5.) Remove the small red/blue wire from the starter solenoid (looks like it is stuck on a screw). This is a safety measure to keep the engine from turning while you are making measurements. Have a helper turn the ignition switch to Start and look for 12 volts on the red/lt blue wire on the TFI module. No 12 volts and you will have starting problems, but push starting the car will work OK. No 12 volts, replace the ignition switch. Be sure to reconnect the red/blue wire to the starter when you finish.
6.) A noid light available from any auto parts store, is one way to test the PIP pulse. The computer uses the PIP signal to trigger the fuel injectors. The noid light plugs into the fuel injector harness in place of any easily accessible injector. Plug it in and it will flash if the PIP is working. No flash from the noid light and the PIP is suspect. To confirm the PIP is being the source of the non flashing noid light, look for 12 volts on the red injector wiring. Good 12 volts and no flashing noid light means the PIP has failed.
7.) Remove the SPOUT plug from the harness and try to start the engine. If it starts, replace the PIP. This is a common no start condition when the engine is hot.
8.) The TFI module is a go/no go item when you have a no spark/weak spark condition on a cold engine. It either works or it doesn’t.
The TFI failure mode on a running car is usually a high speed miss on a warm engine. Many auto parts stores will test your TFI module for free. Bring along a hair dryer to get it hot while testing it and run several test cycles, since it often gets weak when it heats up.
The coil is somewhat more difficult to pinpoint as a problem. A good coil will make a nice fat blue spark 3/8”-1/2” long. The problem is that one person’s perception of a fat blue spark looks like may not be accurate enough to spot a weak coil. The coil is cheap enough ($13-$16) that having a known good working spare might be a good idea.
diagram courtesy of Tmoss & Stang&2Birds
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.
Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif
Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif
Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif
Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg
HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif
TFI module differences & pinout
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif
Tools needed: DVM, noid light, safety pin.
Theory of operation:
The TFI ignition in 86-93 Mustangs has 4 main components: the ignition switch, the coil, the TFI module and the PIP sensor inside the distributor.
The ignition switch gets power from the two yellow wires that are supplied power by a fuse link located in the wiring harness that connects to the starter solenoid.
Diagram courtesy of Tmoss & Stang&2birds
The coil is mounted on the driver’s side strut tower on most EFI Mustangs. It gets power from a red/green wire and a brown/pink wire from the ignition switch. That wire from the ignition switch feeds a 20 gauge blue fuse link that connects to the red/green wire. The fuse link protects the wiring and the ignition switch, since the fuse link for the two yellow power supply wires has a much higher current rating. Without the smaller fuse link protecting the smaller wiring used in the ignition circuit, a short there would cause the red/green wire to overheat and burn up.
The TFI module is mounted on the side of the distributor and supplies the ground for the coil. Every automotive power supply circuit uses the ground as the return path to carry power back to the negative side of the battery. The TFI switches the tan/yellow wire coming from the coil to ground. It gets power from the red/green wire when the ignition switch is in the Run position. The red/lt blue wire supplies a signal to turn on more power (dwell time) when the engine is cranking. The trigger signal comes from the PIP sensor when cranking and the computer when the engine is running. The SPOUT jumper plug enables computer controlled spark advance. When the SPOUT is removed, spark advance is locked at the setting determined by the mechanical position of the distributor.
The PIP sensor is in the bottom of the distributor under the shutter wheel. It is a Hall effect magnetic sensor that senses a change in the magnetic field when one of the slots in the shutter wheel uncovers the sensor. Then it supplies a pulse that triggers the TFI module to provide a ground to the ignition coil. A bad PIP will often set code 14 in the computer and cause hot start problems. Replacing the PIP sensor requires removal of the distributor and pressing the gear off the distributor shaft to expose the sensor. For most people, a remanufactured distributor ($55-$75) is the solution, since they may not have access to a press.
Troubleshooting the ignition system – no spark or weak spark. All the tests are done with the ignition switch in the Run position unless specified otherwise. A safety pin may be used to probe the wiring connectors from the back side.
1.) Check for 12 volts at the yellow wires on the ignition switch. No 12 volts and the fuse link near the starter solenoid has open circuited.
2.) Check for 12 volts on the red/green and brown/pink wires coming out of the ignition switch. No 12 volts, replace the ignition switch.
3.) Check for 12 volts at the ignition coil. No 12 volts and the blue 20 gauge fuse link has open circuited.
4.) Check for 12 volts at the red/green wire on the TFI module. No 12 volts and you have wiring problems.
5.) Remove the small red/blue wire from the starter solenoid (looks like it is stuck on a screw). This is a safety measure to keep the engine from turning while you are making measurements. Have a helper turn the ignition switch to Start and look for 12 volts on the red/lt blue wire on the TFI module. No 12 volts and you will have starting problems, but push starting the car will work OK. No 12 volts, replace the ignition switch. Be sure to reconnect the red/blue wire to the starter when you finish.
6.) A noid light available from any auto parts store, is one way to test the PIP pulse. The computer uses the PIP signal to trigger the fuel injectors. The noid light plugs into the fuel injector harness in place of any easily accessible injector. Plug it in and it will flash if the PIP is working. No flash from the noid light and the PIP is suspect. To confirm the PIP is being the source of the non flashing noid light, look for 12 volts on the red injector wiring. Good 12 volts and no flashing noid light means the PIP has failed.
7.) Remove the SPOUT plug from the harness and try to start the engine. If it starts, replace the PIP. This is a common no start condition when the engine is hot.
8.) The TFI module is a go/no go item when you have a no spark/weak spark condition on a cold engine. It either works or it doesn’t.
The TFI failure mode on a running car is usually a high speed miss on a warm engine. Many auto parts stores will test your TFI module for free. Bring along a hair dryer to get it hot while testing it and run several test cycles, since it often gets weak when it heats up.
The coil is somewhat more difficult to pinpoint as a problem. A good coil will make a nice fat blue spark 3/8”-1/2” long. The problem is that one person’s perception of a fat blue spark looks like may not be accurate enough to spot a weak coil. The coil is cheap enough ($13-$16) that having a known good working spare might be a good idea.
diagram courtesy of Tmoss & Stang&2Birds
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.
Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif
Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif
Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif
Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg
HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif
TFI module differences & pinout
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif
Ok, ran all the test I could, dont have access to a noid light or really anything to make one (any suggestions?) everything checked as it should. The only discrepancy I found was testing the pip wire at the tfi connector. It says while cranking should read 3-6 V. Mine read 8V??? The only thing that is not new is the computer and it's relay. I just have no spark from the coil. I also checked my grounds, checked out fine.
Replacement parts are Billet ready to run distributor from summit, MSD TFI coil, new wires, and the ignition switch is less than a year old.
I ran a test for codes. KOEO showed 11 (Ok?), CM code was 14 (PIP, which I suspected before and replaced). I tried to start the engine and of course wouldn't start, let the key go and got code 67? The one thing I cannot determine for sure is the signal coming from the dist. I have a test light and a multimeter. Is there another way to check this signal without a noid light?
One other note of importance, and where I think this current problem lies. When I put the new dist in and tried to start the car, something popped I think near the coil and everything went dead. Unhooked the battery, hooked it back up, and everything was good, except no spark. But I cannot find what might have blown, and all the power seems to be in the right place. This happened with the old coil on the car BTW.
Could I have possibly recieved a bad part? My frustration level is so high I'm about to break down and buy a freakin Daewoo...somebody stop me!
Replacement parts are Billet ready to run distributor from summit, MSD TFI coil, new wires, and the ignition switch is less than a year old.
I ran a test for codes. KOEO showed 11 (Ok?), CM code was 14 (PIP, which I suspected before and replaced). I tried to start the engine and of course wouldn't start, let the key go and got code 67? The one thing I cannot determine for sure is the signal coming from the dist. I have a test light and a multimeter. Is there another way to check this signal without a noid light?
One other note of importance, and where I think this current problem lies. When I put the new dist in and tried to start the car, something popped I think near the coil and everything went dead. Unhooked the battery, hooked it back up, and everything was good, except no spark. But I cannot find what might have blown, and all the power seems to be in the right place. This happened with the old coil on the car BTW.
Could I have possibly recieved a bad part? My frustration level is so high I'm about to break down and buy a freakin Daewoo...somebody stop me!
No noid light, you have no way of telling if the distributor is putting out a PIP pulse. I suggest you quit trying to do without the diagnostic tools you need and spend the $12-$29 to buy a set at Advance Auto Parts. You only need 1 noid light to see if the PIP is sending the computer a pulse.
If you don't have that kind of money and want to experiment, try Radio Shack® 12V/20mA 4mm Red LED with Holder
Model: 276-270(A) | Catalog #: 276-270 $2.19
It may work, I have not tried it. The red wire goes to the red wire in the fuel injector harness connector and the black wire goes to the other wire in fuel injector harness connector .
If you don't have that kind of money and want to experiment, try Radio Shack® 12V/20mA 4mm Red LED with Holder
Model: 276-270(A) | Catalog #: 276-270 $2.19
It may work, I have not tried it. The red wire goes to the red wire in the fuel injector harness connector and the black wire goes to the other wire in fuel injector harness connector .
I'd love to have the diagnostic tool but they are kind of hard to come by in Korea. No autozone on the corner and all. I've looked for an led and can't find that, not even on base. I'm goin to have these things sent to me,but it takes a couple of weeks, and in the meantime I'm on foot 6 miles a day. That's why I'm lookin for the alternative. Thanks for the info.
jmast you could try and see if your computer has any stored codes in it....also its worth the wait for you to get the correct trouble shooting tools as you will save a lot of money this way as opposed to throwing new parts at it to try and fix it....do you have access to a donor distributor to try in your car? good luck and have fun....
I agree, I definitely dont want to throw parts at it, especially with the cost of shipping. Unfortunately mustang parts are in very low demand out here, so I'm trying to be real careful with what I order. The stored code I have is 14, PIP sensor. This along with the troubleshooting I did led me to by a distributor. The new distributor did not fix the problem. I'm wondering if the dist is not getting the right signal from the eec, would that cause a no spark? I hope summit didn't send me a bad part. The car has been down for a month, and it's looking like another month after waiting for tools, ordering new parts, waiting for new parts...etc. Just trying to find out if there is anything else I could do in the meantime. Walking sucks. Thanks for the replies, any advice is greatly appreciated!
Have you tried removing the SPOUT jumper and spraying starting ether in the intake? If the car fires off briefly then, you have a bad PIP sensor.
What branch of the military are you serving? There may be some on base resources that you haven't thought about to help with the LED/noid light substitute problem.
What branch of the military are you serving? There may be some on base resources that you haven't thought about to help with the LED/noid light substitute problem.
Yes sir, i ran that test as well but it did not fire. I'm in the Air Force and actually work in vehicle maintenance. I do have some resources, but unbelievably we do not have a noid light. Alot of my mechanic friends have looked at this as well and have left scratching there heads. I do have a dvom and have done alot of diagnostics already based on the info you gave. It all seems to point to no signal, but i'm not a 100% sure without that noid light. I tried looking for a pulse with a test light and the dvom but am not seeing anything. I was wanting to troubleshoot the connection between the PIP and the computer while I wait on the noid light, just not sure how to go about it. Also, someone mentioned the EEC relay, but if that was bad, wouldn't I be lacking fuel pump oeration too? I waited two weeks for that distributor, I really hate to think they sent me a junk part, if that turns out to be the case.
lesson learned today...never accept the first offer. After being told we had no noid lights, i decided to go on the hunt. Low and behold, in an old Vidmar in the back of the storage room, sat a noid light set, looking like it's never been used. So, game on. I re-ran the checklist and hit paydirt at the injector pulse. I have 12V at the red wire but no pulse. I tested two diferent lights on two different injectors with the same outcome. My battery is low with all the diagnosing, but it still cranks. Could a low battery cause the lack of pulse or is it time to call Summit? I can charge it and try again. I also check my eec relay for the hell of it and all is good there and the computer is giving codes (KOEO 11 system pass, CM 14 PIP. Kinda looks like I got stiffed. Any final advice? Thanks for all the help I recieved thus far. I appreciate it more than you know.
If it cranks, there is enough voltage to run the ignition and computer. Occasionally you will get a bad part right out of the box, and it seems that is what has happened to you.
Some more information to look into if you have time:
PIP problems & diagnostic info
Spark with the SPOUT out, but not with the SPOUT in suggests a PIP problem. The PIP signal level needs to be above 6.5 volts to trigger the computer, but only needs to be 5.75 volts to trigger the TFI module. Hence with a weak PIP signal, you could get spark but no injector pulse. You will need an oscilloscope or graphing DVM to measure the output voltage since it is not a straight DC voltage.
See http://www.wellsmfgcorp.com/pdf/counterp_v8_i2_2004.pdf and http://www.wellsmfgcorp.com/pdf/counterp_v8_i3_2004.pdf for verification of this little detail from Wells, a manufacturer of TFI modules and ignition system products.
Some more information to look into if you have time:
PIP problems & diagnostic info
Spark with the SPOUT out, but not with the SPOUT in suggests a PIP problem. The PIP signal level needs to be above 6.5 volts to trigger the computer, but only needs to be 5.75 volts to trigger the TFI module. Hence with a weak PIP signal, you could get spark but no injector pulse. You will need an oscilloscope or graphing DVM to measure the output voltage since it is not a straight DC voltage.
See http://www.wellsmfgcorp.com/pdf/counterp_v8_i2_2004.pdf and http://www.wellsmfgcorp.com/pdf/counterp_v8_i3_2004.pdf for verification of this little detail from Wells, a manufacturer of TFI modules and ignition system products.
I'll check those out before I make the call. I definitely want to be sure before I hassle with getting another one sent out here. I took a look inside at the PIP and it looks like it is seperating from the base. Not sure if this is normal or makes a difference. Surely doesn't look right. Again, thanks
finally got it running. I had someone send me a new PIP and put it in my stock distributor and it's good to go. So looks like the billet dist I got from summit had a bad PIP. Time to get my money back. Still not out of the woods yet, she's idleing around 1500 and throwing a code 18 KOEO and 13 KOER. Gonna check out and try to clean the IAC then reset base idle. Thanks one more time for all your help.
Disconnect the battery negative cable from the battery and turn on the headlights for about 5 minutes. See if that clears the code 18. if it doesn't, you still have more work to do...
Code 18 - SPOUT out or wiring fault - look for short to ground in SPOUT wiring going
back to the computer. Possible bad TFI or defective 22 K resistor in the IDM wiring
This code can disable spark advance and reduce power and fuel economy.
Remove the passenger side kick panel and disconnect the computer connector.
There is a 10 MM bolt that holds it in place.
Disconnect the TFI module connector from the TFI and the measure the resistance between the yellow/lt green wire and ground.
You should see greater than 100 K (100000) ohms.
Check the resistance from Pin 4 on the computer connector (dark green/yellow) and the dark green/yellow wire on the TFI connector. You should see 20-24 K Ohms (20,000-24,0000 ohms). The resistor is located in the wiring harness about 6” from the connector. You will need solder and heat shrink to replace the resistor if it is bad.
Next measure the resistance between the yellow/lt green wire on the TFI module connector and
Pin 36 on the computer connector. With the SPOUT plug in place, you should see less than 2 ohms.
The following is a view from the computer side of the computer connector.
This diagram is the wire side of the computer connector.
Diagram courtesy of Tmoss & Stang&2birds
Code 13 - Key on Engine off - ISC did not respond properly (extends to touch throttle then retracts for KOEO) – ISC
Key on Engine running - Idle Speed Control motor or Air Bypass not controlling idle properly (generally idle too high)
If your idle is above 725 RPM, the computer will set this code. Normal idle speed is 650-725 RPM. Higher than that means that someone has mechanically set the idle speed by use of the idle speed screw, and has effectively disabled to computer’s ability to control idle speed.
Recommended procedure for cleaning the IAC/IAB:
Conventional cleaning methods like throttle body cleaner aren’t very effective. The best method is a soak type cleaner used for carburetors. If you are into fixing motorcycles, jet skis, snowmobiles or anything else with a small carburetor, you probably have used the one gallon soak cleaners like Gunk or Berryman. One of the two should be available at your local auto parts store for $22-$29. Take the solenoid off the body and set it aside: the carb cleaner will damages some types of plastic parts. Soak the metal body in the carb cleaner overnight. There is a basket to set the parts in while they are soaking. When you finish soaking overnight, twist the stem of the IAB/IAC that sticks out while the blocker valve is seated. This removes any leftover deposits from the blocker valve seat. Rinse the part off with water and blow it dry with compressed air. The IAC/IAB should seal up nicely now. Once it has dried, try blowing through the bottom hole and it should block the air flow. Reassemble and reinstall to check it out.
Gunk Dip type carb & parts soaker:
Setting the base idle speed:
First of all, the idle needs to be adjusted to where the speed is at or below 600 RPM with the IAC disconnected. Then the electrical signal through the IAC can vary the airflow through it under computer control. Remember that the IAC can only add air to increase the base idle speed set by the mechanical adjustment. The 600 RPM base idle speed is what you have after the mechanical adjustment. The IAC increases that speed by supplying more air under computer control to raise the RPM’s to 650-725 RPM’s
Remember that changing the mechanical idle speed adjustment changes the TPS setting too.
This isn't the method Ford uses, but it does work. Do not attempt to set the idle speed until you have fixed all the codes and are sure that there are no vacuum leaks.
Disconnect the battery negative terminal and turn the headlights on. Leave the battery negative terminal disconnected for 5 minutes or so. Then turn the headlights off and reconnect the battery. This erases the computer settings that may affect idle performance.
Warm the engine up to operating temperature, place the transmission in neutral, and set the parking brake. Turn off lights, A/C, all unnecessary electrical loads. Disconnect the IAC electrical connector. Remove the SPOUT plug. This will lock the ignition timing so that the computer won't change the spark advance, which changes the idle speed. Note the engine RPM: use the mechanical adjustment screw under the throttle body to raise or lower the RPM until you get the 600 RPM mark +/- 25 RPM. Changing the mechanical adjustment changes the TPS, so you will need to set it.
When you are satisfied with the results, turn off the engine, and re-install the SPOUT and reconnect the IAC. The engine should idle with the range of 650-750 RPM without the A/C on or extra electrical loads.
Code 18 - SPOUT out or wiring fault - look for short to ground in SPOUT wiring going
back to the computer. Possible bad TFI or defective 22 K resistor in the IDM wiring
This code can disable spark advance and reduce power and fuel economy.
Remove the passenger side kick panel and disconnect the computer connector.
There is a 10 MM bolt that holds it in place.
Disconnect the TFI module connector from the TFI and the measure the resistance between the yellow/lt green wire and ground.
You should see greater than 100 K (100000) ohms.
Check the resistance from Pin 4 on the computer connector (dark green/yellow) and the dark green/yellow wire on the TFI connector. You should see 20-24 K Ohms (20,000-24,0000 ohms). The resistor is located in the wiring harness about 6” from the connector. You will need solder and heat shrink to replace the resistor if it is bad.
Next measure the resistance between the yellow/lt green wire on the TFI module connector and
Pin 36 on the computer connector. With the SPOUT plug in place, you should see less than 2 ohms.
The following is a view from the computer side of the computer connector.
This diagram is the wire side of the computer connector.
Diagram courtesy of Tmoss & Stang&2birds
Code 13 - Key on Engine off - ISC did not respond properly (extends to touch throttle then retracts for KOEO) – ISC
Key on Engine running - Idle Speed Control motor or Air Bypass not controlling idle properly (generally idle too high)
If your idle is above 725 RPM, the computer will set this code. Normal idle speed is 650-725 RPM. Higher than that means that someone has mechanically set the idle speed by use of the idle speed screw, and has effectively disabled to computer’s ability to control idle speed.
Recommended procedure for cleaning the IAC/IAB:
Conventional cleaning methods like throttle body cleaner aren’t very effective. The best method is a soak type cleaner used for carburetors. If you are into fixing motorcycles, jet skis, snowmobiles or anything else with a small carburetor, you probably have used the one gallon soak cleaners like Gunk or Berryman. One of the two should be available at your local auto parts store for $22-$29. Take the solenoid off the body and set it aside: the carb cleaner will damages some types of plastic parts. Soak the metal body in the carb cleaner overnight. There is a basket to set the parts in while they are soaking. When you finish soaking overnight, twist the stem of the IAB/IAC that sticks out while the blocker valve is seated. This removes any leftover deposits from the blocker valve seat. Rinse the part off with water and blow it dry with compressed air. The IAC/IAB should seal up nicely now. Once it has dried, try blowing through the bottom hole and it should block the air flow. Reassemble and reinstall to check it out.
Gunk Dip type carb & parts soaker:
Setting the base idle speed:
First of all, the idle needs to be adjusted to where the speed is at or below 600 RPM with the IAC disconnected. Then the electrical signal through the IAC can vary the airflow through it under computer control. Remember that the IAC can only add air to increase the base idle speed set by the mechanical adjustment. The 600 RPM base idle speed is what you have after the mechanical adjustment. The IAC increases that speed by supplying more air under computer control to raise the RPM’s to 650-725 RPM’s
Remember that changing the mechanical idle speed adjustment changes the TPS setting too.
This isn't the method Ford uses, but it does work. Do not attempt to set the idle speed until you have fixed all the codes and are sure that there are no vacuum leaks.
Disconnect the battery negative terminal and turn the headlights on. Leave the battery negative terminal disconnected for 5 minutes or so. Then turn the headlights off and reconnect the battery. This erases the computer settings that may affect idle performance.
Warm the engine up to operating temperature, place the transmission in neutral, and set the parking brake. Turn off lights, A/C, all unnecessary electrical loads. Disconnect the IAC electrical connector. Remove the SPOUT plug. This will lock the ignition timing so that the computer won't change the spark advance, which changes the idle speed. Note the engine RPM: use the mechanical adjustment screw under the throttle body to raise or lower the RPM until you get the 600 RPM mark +/- 25 RPM. Changing the mechanical adjustment changes the TPS, so you will need to set it.
When you are satisfied with the results, turn off the engine, and re-install the SPOUT and reconnect the IAC. The engine should idle with the range of 650-750 RPM without the A/C on or extra electrical loads.
So me and a friend went to grab the car and limp it back to base to be able to do some proper troubleshooting. Half way in it starts backfiring and popping, then I get smoke in the cab and egine compartment around the firewall. Looking at the checklist you sent I'm wondering if the faulty dist jacked my s*** up. Goin to do the resistance checks, but this resistor, is it 6" away from the connector at the TFI or the computer? First turn of the key with the "new" dist and pop. Something shorted. Didn't have this problem before the dist.
First off, I hope I'm not wearing you out with this. I did the test suggested above, 2 of the 3 tests passed. 22K resistor checked out fine as well as the resistance to pin 36. Could not get a reading on yl/lt gr wire to ground, (mine is pink-ish, 93 drivetrain). My DVOM is cheap, no contact read 1., so i'm guessing that's it's infinite symbol. Tested the SPOUT wire to several grounds and reading did not change, (stayed at 1.). What does no ground at the spout wire indicate? I have a feeling I should start at the beginning and troubleshoot the current problem (irratic/searching idle). Thoughts?
There is supposed to be an open circuit between the SPOUT and ground with the wiring disconnected. If you got a reading to ground of less than 100,000 ohms, you have a problem.
So all the checks passed. I pulled codes again and still got 18, both off and running, 21 (ECT), 12 and 46. I found your surging idle checklist and I'm goin to do the first step recommend. Fix the codes. I cleaned the IAC, just have to put it back on. Luckily I have a new ect, so I'll throw that on as well. Since the tests I'm running are checking out ok, I feel like i'm looking in the wrong area. As much as this sucks, I have to admit I am learning a metric a$$ ton about this car. I did find also that my PCV valve is not connected to the lower intake and the grommet is missing. Also the fuel line between rails is in the way so i'll have to re-position it to get the PCV seated. How much would this affect performance?
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