Electrical No Injector pulse

Foxybody95

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Sep 14, 2015
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Hey guys I got a strange problem, my car wont give any injector pulse. It was benched for a few weeks because I was putting a new transmission in it and once I got the thing all together it wouldn’t start even though it ran fine before I benched it. After a bit of diagnosing I suspected it to be the pip sensor in the distributor which I then had replaced under warranty, but still no pulse. I swapped out the ECU with a known good unit as well as checked all the wiring and all the wiring is flawless and still no pulse. The injectors are getting 12v but the computer isnt grounding them for whatever reason. TFI has been replaced as well, the pip sensor is getting power and ground. There is a few volts present at the signal and I tested the signal ground with a noid light and still couldnt light it. What should I test next?
 
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jrichker

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Dump the codes....

Dump codes sticky

Look at the top of the 5.0 Tech forum where the sticky threads are posted. One of them is how to dump the computer codes. Codes may be present even if the CEL (Check Engine Light) isn’t on. You don’t need a code reader or scanner – all you need is a paper clip, or if your lady friend has a hair pin, that will do the job.
I highly suggest that you read it and follow the instructions to dump the codes. http://www.stangnet.com/mustang-forums/threads/how-to-pull-codes-from-eec4.889006/
 

Mustang5L5

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23 is throttle position I believe which shouldn’t have any effect on injector pulse

Investigate/fix it anyway.

The ECU references TPS voltage at ignition on. If you had a flooded engine, you would then floor the gas pedal which would signal the ECU to turn off injector pulse while cranking to help clear the flood condition.

This could be related so don't overlook it. Correct TPS voltage at idle is anywhere from 0.5 to 1.25 volts

https://www.stangnet.com/mustang-fo...r-tps-to-0-99x-volts-is-not-necessary.825424/
 

jrichker

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23 is throttle position I believe which shouldn’t have any effect on injector pulse

If you lose signal ground, the TPS voltage will go to max, and then the computer will shut off the injector pulse

Code 23 - Throttle sensor out of range or throttle set too high - TPS needs to be reset to below 1.2 volts at idle. Keep in mind that when you turn the idle screw to set the idle speed, you change the TPS setting.


You'll need a Digital Voltmeter (DVM) to do the job.

Wire colors & functions:
Orange/white = 5 volt VREF from the computer
Dark Green/lt green = TPS output to computer
Black/white = Signal ground from computer

Always use the Dark Green/lt green & Black/white wires to set the TPS base voltage.

Do the test with the ignition switch in the Run position without the engine running.

Use the Orange/white & Black white wires to verify the TPS has the correct 5 volts source from the computer.

When you installed the sensor make sure you place it on the peg right and then tighten it down properly. Loosen the back screw a tiny bit so the sensor can pivot and loosen the front screw enough so you can move it just a little in very small increments. I wouldn’t try to adjust it using marks. Set it at .6.v-.9 v.

1. Always adjust the TPS and Idle with the engine at operating temp. Dive it around for a bit if you can and get it nice and warm.

2. When you probe the leads of the TPS, do not use an engine ground, put the ground probe into the lead of the TPS. You should be connecting both meter probes to the TPS and not one to the TPS and the other to ground.

If setting the TPS doesn’t fix the problem, then you may have wiring problems.
With the power off, measure the resistance between the black/white wire and battery ground. You should see less than 2 ohms. Check the same black /white wire on the TPS and MAP/Baro sensor. More than 1 ohm there and the wire is probably broken in the harness between the engine and the computer. The 10 pin connectors pass the black/white wire back to the computer, and can cause problems.

See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host)

http://www.veryuseful.com/mustang/tech/engine/images/88-91eecPinout.gif

See the graphic for the 10 pin connector circuit layout.
68512.jpg


If you lose signal ground, the TPS voltage will go to max, and then the computer will shut off the injector pulse
 
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Foxybody95

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Sep 14, 2015
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Oh yeah I completely forgot about clear flood mode! Thank you for the tip i’ll try that out tomorrow!
 

Foxybody95

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So I verified the tps was faulty, I replaced it verifed the new one worked, and unplugged the battery to reset the ecu. Still no injector pulse. I ran the codes again and it just says system okay