No Injector Pulse, Out Of Ideas.

welndmn

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Jul 17, 2017
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#1
I know, another thread on this but I’m stumped.
It’s an 89 5.0 with MAF,
Has spark, has fuel pressure, no injector pulse.
I’ve gone though the checklist and still empty.
It will start and run on starting fluid.
TPS voltage is 0.9v
Voltage at the injectors.
I picked up a stock distributor from o Riley, no change, no saying it could not of been dead out of the box.
While swapping out the distributor I noticed with key on power (i was trying the turn the shaft to see if the injectors would fire) it sparked when I touched it to the block, checking the ground on the TFI, it did have ground there. This makes me curious is this new part was shorted out, or something else.

I tried a different PCM, no change.
With pcm Unplugged I checked the harness and had ground at pins 20,40,60.

The only codes I had were ECT and ACT out of range, but it was stone cold. (There were other emission codes, but it’s because they are missing)
Any other ideas?
It’s a swapped motor that always ran great, this am it ran for 45 seconds then stalled and this is where I’m at.
 
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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
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#2
Did the new distributor come with tfi? There are two and look similar, I know it's covered in the cranks but no start checklist, I'd go back through the list, you missed something or the distributor/tfi is defective and it will tell you
 

jrichker

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#3
Code 14 - Ignition pickup (PIP) was erratic – the Hall Effect sensor in the distributor is failing. Bad sensor, bad wiring, dirty contacts. Factory tach will sometimes read erratically.

Revised 8-Apr-2017 to correct SPOUT problem symptoms wording

The PIP is a Hall Effect magnetic sensor that triggers the TFI and injectors. There is a shutter wheel alternately covers and uncovers a fixed magnet as it rotates. The change in the magnetic field triggers the sensor. They are often heat sensitive, increasing the failure rate as the temperature increases.

PIP Sensor functionality, testing and replacement:
The PIP is a Hall Effect magnetic sensor that triggers the TFI and injectors. There is a shutter wheel alternately covers and uncovers a fixed magnet as it rotates. The change in the magnetic field triggers the sensor. A failing PIP sensor will often set code 14 in the computer. They are often heat sensitive, increasing the failure rate as the temperature increases.

Some simple checks to do before replacing the PIP sensor or distributor:
You will need a Multimeter or DVM with good batteries: test or replace them before you get started.. You may also need some extra 16-18 gauge wire to extend the length of the meter’s test leads.
Visual check first: look for chaffed or damaged wiring and loose connector pins in the TFI harness connector.
Check the IDM wiring – dark green/yellow wire from the TFI module to pin 4 on the computer. There is a 22K Ohm resistor in the wiring between the TFI and the computer. Use an ohmmeter to measure the wire resistance from the TFI to the computer. You should see 22,000 ohms +/- 10%.
Check the PIP wiring - dark blue from the TFI module to pin 56 on the computer. Use an ohmmeter to measure the wire resistance from the TFI to the computer. You should see 0.2-1.5 ohms.
Check the SPOUT wiring – yellow/lt green from the TFI module to pin 36 on the computer. Use an ohmmeter to measure the wire resistance from the TFI to the computer. You should see 0.2-1.5 ohms.
Check the black/orange wire from the TFI module to pin 16 on the computer. Use an ohmmeter to measure the wire resistance from the TFI to the computer. You should see 0.2-1.5 ohms.
Check the red/green wire; it should have a steady 12-13 volts with the ignition switch on and the engine not running.
Check the red/blue wire; it should have a steady 12-13 volts with the ignition switch in Start and the engine not running. Watch out for the fan blades when you do this test, since the engine will be cranking.
If you do not find any chaffed or broken wires, high resistance connections or loose pins in the wiring harness, replace the PIP sensor or the distributor.

The PIP sensor is mounted in the bottom of the distributor under the shutter wheel. In stock Ford distributors, you have to press the gear off the distributor shaft to get access to it to replace it. Most guys just end up replacing the distributor with a reman unit for about $75 exchange

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 to pulse the fuel injectors, but only needs to be 5.75 volts to trigger the TFI module. Hence with a weak PIP signal, and the SPOUT in, 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.
 

welndmn

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Jul 17, 2017
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#4
Thanks, I just went though again and ohm’d out the wires, they all checked out.
I got another distributor (loaded with TFI and pip) with no change.
I just sent off my spare PCM to a guy in Florida to look at it.
Still no injector pulse :(
I have a race on 3/21 that I’m scared I won’t make it will wreck my season points
 

welndmn

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Jul 17, 2017
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#5
I opened up this computer, I can’t see any burns on it.
 

welndmn

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Jul 17, 2017
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#6
Maybe 2 of the caps have a little leak, but not near as bad as ones I’ve seen in the past
 

welndmn

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Jul 17, 2017
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#7
What else can cause the injectors not to pulse?
I’m checking for pulse by putting a injector in water and compressed air on the other end while cranking.
 
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welndmn

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Jul 17, 2017
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#8
going to try this tomorrow in the Day light, posting it here so I remember.


Suggest to confirm the PIP pulse is present at the correspondent ECM pin (#56)......a LED from Radio Shack will allow you to confirm this if it blinks, connect red LED wire to PIP pin/wire at the ECM connector, and the yellow (negative) LED wire to a good ground and crank the engine.....if the LED blinks, PIP is OK.... if not, check wiring
 
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welndmn

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Jul 17, 2017
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#9
What pins on the ecu Can i check to make sure all the grounds are good to chassis.
 
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jrichker

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#10
going to try this tomorrow in the Day light, posting it here so I remember.


Suggest to confirm the PIP pulse is present at the correspondent ECM pin (#56)......a LED from Radio Shack will allow you to confirm this if it blinks, connect red LED wire to PIP pin/wire at the ECM connector, and the yellow (negative) LED wire to a good ground and crank the engine.....if the LED blinks, PIP is OK.... if not, check wiring
That is not the correct way to do it.
A 12 volt led works on 12 volts because it has is a resistor to reduce the voltage down to about -1.5-2.5 volts. It may not work on the 6-7 volts pulse that the PIP sensor puts out.

A led without the resistor only needs 1.5-2.5 volts to flash - since the computer needs 6-7 volts to fire the injectors.
The led may flash even though the output voltage of the PIP is too low to trigger the computer to fire the injectors.

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.



Grounds are not likely to be your problem, but here's the info on them.

Grounds

This checklist applies to all Mustangs , not just the EFI equipped cars. Some of the wiring will be different on carb cars and carb conversions

Revised 26 –Oct -2016 to add fuel pump ground to the list.

Grounds are important to any electrical system, and especially to computer controlled engines. In an automobile, the ground is the return path for power to get back to the alternator and battery.

Make sure that all the ground places are clean and shiny bare metal: no paint, no corrosion.

1.) The main power ground is from engine block down by the oil filter to battery: it is the power ground for the starter & alternator.


2.) The secondary power ground is between the back of the intake manifold and the driver's side firewall. It is often missing or loose. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges. The clue to a bad ground here is that the temp gauge goes up as you add electrical load such as heater, lights and A/C.

Any car that has a 3G or high output current alternator needs a 4 gauge ground wire running from the block to the chassis ground where the battery pigtail ground connects. The 3G has a 130 amp capacity, so you wire the power side with 4 gauge wire. It stands to reason that the ground side handles just as much current, so it needs to be 4 gauge too.

The picture shows the common ground point for the battery , computer, & extra 3G alternator ground wire as described above in paragraph 2. A screwdriver points to the bolt that is the common ground point.

The battery common ground is a 10 gauge pigtail with the computer ground attached to it.
Picture courtesy timewarped1972
ground.jpg


Correct negative battery ground cable.
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3.) The computer's main power ground (the one that comes from the battery ground wire) uses pins 40 & 60 for all the things it controls internally: it comes off the ground pigtail on the battery ground wire. Due to its proximity to the battery, it may become corroded by acid fumes from the battery.
In 86-90 model cars, it is a black cylinder about 2 1/2" long by 1" diameter with a black/lt green wire.
In 91-95 model cars it is a black cylinder about 2 1/2" long by 1" diameter with a black/white wire.
You'll find it up next to the starter solenoid where the wire goes into the wiring harness.

All the grounds listed in items 1,2 & 3 need to bolt to clean, shiny bare metal. A wire brush or some fine sandpaper is the best thing to use to clean the ground connections.


4.) All the sensors have a common separate signal ground. This includes the TPS, ACT, EGR, BAP, & VSS sensors. This ground is inside the computer and connects pin 46 to pins 40 & 60, which are the main computer grounds. If this internal computer ground gets damaged, you won't be able to dump codes and the car will have idle/stall/ performance problems

5.) The O2 sensor heaters have their own ground (HEGO ground) coming from the computer. This is different and separate from the O2 sensor ground. It is an orange wire with a ring terminal on it. It is located in the fuel injector wiring harness and comes out under the throttle body. It gets connected to a manifold or bolt on back of the cylinder head.

6.) The TFI module has 2 grounds: one for the foil shield around the wires and another for the module itself. The TFI module ground terminates inside the computer.

7.) The computer takes the shield ground for the TFI module and runs it from pin 20 to the chassis near the computer.

8.) Fuel pump ground the fuel pump has a ground pigtail the connects to the body under the gas tank. You have to drop the gas tank to see where it bolts to the body.

attachment.php?attachmentid=49675&d=1175374071.gif


See http://assets.fluke.com/appnotes/automotive/beatbook.pdf for help troubleshooting voltage drops across connections and components. Be sure to have the maximum load on a circuit when testing voltage drops across connections. As current across a defective or weak connection, increases so does the voltage drop. A circuit or connection may check out good with no load or minimal load, but show up bad under maximum load conditions. .

Voltage drops should not exceed the following:
200 mV Wire or cable
300 mV Switch
100 mV Ground
0 mV to <50 mV Sensor Connections
0.0V bolt together connections

attachment.php?attachmentid=64167&stc=1&d=1286329941.gif


Extra grounds are like the reserve parachute for a sky diver. If the main one fails, there is always your reserve.

The best plan is to have all the grounds meet at one central spot and connect together there. That eliminates any voltage drops from grounds connected at different places. A voltage drop between the computer ground and the alternator power ground will effectively reduce the voltage available to the computer by the amount of the drop.

A
 

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