Electronics Need help wiring something up? Thinking of adding an electrical component to your car? Need help troubleshooting that wiring glitch?

no injector pulse

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Old Apr 4, 2010 | 09:00 PM
  #1  
db1989iroc's Avatar
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no injector pulse

I have a 89 5.7 tpi iroc. I have a no start situation. The fuel pump primes. 42 psi at the rail. I have spark. Compression is good in all cylinders. The injectors are at 14.6-14.7 ohms. I have a brand new ECM. I tested ECM terminals D15 and D16 (injector driver circuit) for short to ground then short to voltage, no problem there.Key in run position the TPS is at .47 volts and injector plug ins are at 12.6 volts. I try cranking the car and probing the plug ins with a test light and I get a steady light. Im at a loss. The car will crank and fire up for a split second and die. I pull the plugs and they're dry. It will do this every time. Please help me, I m a new member.Thanks
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Old Apr 4, 2010 | 10:00 PM
  #2  
86ttopbird's Avatar
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From: Manchester,PA
Car: 86 Firebird SE
Engine: 2.8L
Re: no injector pulse

Might be a VATS problem. With that being an 89 and all. If the ECM doesnt receive the go signal from the VATS module, it will not fire the injectors.
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Old Apr 5, 2010 | 05:42 PM
  #3  
db1989iroc's Avatar
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Re: no injector pulse

oh crap, buried beneath the dash right?
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Old Apr 5, 2010 | 09:41 PM
  #4  
86ttopbird's Avatar
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From: Manchester,PA
Car: 86 Firebird SE
Engine: 2.8L
Re: no injector pulse

I believe the VATS module is on the steering column somewhere.
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Old Apr 6, 2010 | 01:52 AM
  #5  
Theking's Avatar
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From: Sweden
Car: 1989 IROC-Z
Engine: 350 TPI
Transmission: Th700R4
Axle/Gears: 3.27
Re: no injector pulse

Does your SECUTIRY light stay on or do it turn off after som seconds (with ignition on) if the security lights shuts down , the ECM and VATS have comfirmed the correct key and we can prolly say its working.

But have all your wiring checked, you have 2 connections near the battery (looks like this):


Check so both are connected and not loose (one of them go to Tuned Port Innjection)

also have your cables checked at distributor (2 signalcables) check so those are connected and not loose (can cause all strange problems..)

You have fuelpressure ? have you checked what pressure ?
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Old Apr 6, 2010 | 05:26 PM
  #6  
db1989iroc's Avatar
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Re: no injector pulse

The security light goes out in a couple seconds after I turn the key forward. I checked the wires for breaks at the distributor module using a voltmeter and they had continuity. However, that black fusible link in your picture I had to bypass because the wire going into it was broken. Could that cause a problem?
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Old Apr 9, 2010 | 11:07 AM
  #7  
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Re: no injector pulse

you probably have a bad crank sensor
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Old Apr 13, 2010 | 06:44 PM
  #8  
db1989iroc's Avatar
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Re: no injector pulse

I got it!. It was a bad mass airflow sensor. The car fired up when I unplugged it. I didnt think about it because it was 18 months old. I exchanged it at Advance Auto and it runs now. Thanks for the suggestions guys.
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