DFI and ECMDiscuss all aspects of DFI (Digital Fuel Injection), ECMs (Electronic Control Module), scanners, and diagnostic equipment. Fine tune your Third Gen computer system for top performance.
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Other day at track, 3rd pass car lost all power just shy of 1320... Got home, assumed that I had lunched another dissy gear as car had before, or MSD had gone bad - to my surprise I have spark and at right time.. So I squirted fuel in intake, car fired.. After checking all power and grounds to ECM and all were good, I assumed that ECM had gone bad, brought home new today and nothing.. What causes injectors to fire, is it signaled from magnetic pick-up on dis?
Any thoughts? Yes its getting fuel, second thing I checked - does not even attempt to fire...
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76 Vega 498 BBC, AFR 325 heads, and a few other goodies.9.02 @ 151
93 Firebird, 7730 ECM, most other 3rd gen running gear, 406 afr's, T56, 11.0 N/A, 10.41 W/150 Shot.
Last edited by 87_TA; 09-19-2009 at 08:47 PM.
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The ECM needs to have the REF+ and REF- signal from the distributor ignition module. Note that REF- is basically ground. With REF+ being the actual signal.
Quick check for this is to use a scan tool and start a data log. They spray some fuel into the TB and have it fire up. If an RPM value shows up then the DRP's are getting to the ECM.
The ECM needs to have the REF+ and REF- signal from the distributor ignition module. Note that REF- is basically ground. With REF+ being the actual signal.
Quick check for this is to use a scan tool and start a data log. They spray some fuel into the TB and have it fire up. If an RPM value shows up then the DRP's are getting to the ECM.
RBob.
I will, thanks..
I was just going down to make sure Laptop will show sensor Data.. Will fire tomorrow in daylight.. I was suspect of module, but figured I would not have spark.. Thanks Rob.. Can I check signal at ecm with tester?
The DRP signal (ref+/-) out of the ignition module to the ECM is a 5 volt square wave.
I just recalled an easier test to see if the ECM is getting a DRP. This works when the ECM is controlling the fuel pump relay. I mention that as you may have wired the fuel pump differently.
Key-on, engine-off. Fuel pump will run for 2-seconds then stop. Now tap the key for a short crank and check if the fuel pump runs again for 2-seconds. Can continue to do quick taps of cranking and check for the fuel pump.
The ECM upon receiving DRPs will activate the fuel pump relay. And deactivate the fuel pump relay 2-seconds after the last DRP is received.
The DRP signal (ref+/-) out of the ignition module to the ECM is a 5 volt square wave.
I just recalled an easier test to see if the ECM is getting a DRP. This works when the ECM is controlling the fuel pump relay. I mention that as you may have wired the fuel pump differently.
Key-on, engine-off. Fuel pump will run for 2-seconds then stop. Now tap the key for a short crank and check if the fuel pump runs again for 2-seconds. Can continue to do quick taps of cranking and check for the fuel pump.
The ECM upon receiving DRPs will activate the fuel pump relay. And deactivate the fuel pump relay 2-seconds after the last DRP is received.
RBob.
Thanks RBob!
Got it, tested as suggested earlier and no RPM signal to ecm.. So if you may or not remember I am running 4th gen shell which requires me to drop engine to remove DIS cap . Upon doing so I was able to see that connector had come off Module, it has been cracked for a while but weather seal would keep in place. So since it was down I changed module to the new MSD, and going to test now.
Little hisory on that, bought MSD DIS years ago, car would not rev past 3000under load, changed module in the new DIS back to stocker and car ran fine.. Returned to MSD, they sent me another and same thing.. So after years I decided to persue issue again being I had to send my 6AL back for repairs, they sent me one from a new supplier. I am going to test now, if it does not rev past 3000 I will be highly upset being engine has to be dropped again to change back. Luckily its not that hard.
Thanks for help, really is appreciated!
__________________ [/size][/color]
76 Vega 498 BBC, AFR 325 heads, and a few other goodies.9.02 @ 151
93 Firebird, 7730 ECM, most other 3rd gen running gear, 406 afr's, T56, 11.0 N/A, 10.41 W/150 Shot.
Thanks RBob!
Got it, tested as suggested earlier and no RPM signal to ecm.. So if you may or not remember I am running 4th gen shell which requires me to drop engine to remove DIS cap . Upon doing so I was able to see that connector had come off Module, it has been cracked for a while but weather seal would keep in place. So since it was down I changed module to the new MSD, and going to test now.
Little hisory on that, bought MSD DIS years ago, car would not rev past 3000under load, changed module in the new DIS back to stocker and car ran fine.. Returned to MSD, they sent me another and same thing.. So after years I decided to persue issue again being I had to send my 6AL back for repairs, they sent me one from a new supplier. I am going to test now, if it does not rev past 3000 I will be highly upset being engine has to be dropped again to change back. Luckily its not that hard.
Thanks for help, really is appreciated!
i dont know if this has been discussed already but i cant read right now. This is my understanding, and please correct me if im wrong, ill just read it later,
TPI is batch fire so you cant have just one injector not fire unless it is a faulty injector. They fire in batches, driver bank then passenger bank in a pulse of signals, twice per side per revolution. If you have just one injector that isn't firing (test with a stethoscope or similar (wooden dowel)), its not the ecm because that whole bank wouldnt be firing because all 4 on that side are wired in parallel to the same driver in the ecm...
The TPI systems are batch fire. That is all 8 injectors fire together. This is either double fire, once per engine revolution. Or single fire, once per every two engine revolutions.
The '86 - '92 TPI ECMs have one injector driver for all eight injectors.
. Upon doing so I was able to see that connector had come off Module, it has been cracked for a while but weather seal would keep in place. So since it was down I changed module to the new MSD, and going to test now. 
