Doug Goodwrench Posted August 23, 2007 Report Share Posted August 23, 2007 Story is: 1993 Olds Cutlass 3.1 vin T. Car ran fine after engine swap (1993 Lumina - donor car, 286,000 miles.) *** While it was still in the garage: *** One day it decided not to run anymore, unless you spray ether in the intake. Diagnosing the system revealed: No injector signal, but had spark. (Obviously, if it ran off of ether.) Rules out crank sensor. Checked Injectors for 12v. Good. Checked wires that control injectors for continuity. Good. Where do we go from here? How does the computer get its reference pulse? (There is a High and a Low pulse) At first we though that the computer figured it out on its own. Not true. The injector reference pulse signals come from the Ignition Control Module. The computer uses the input from the ICM to control the injectors. It turned out to be that the female end of the connector was not making a good connection on the ICM. The first (or last) 2 pins on the 5 (or 6 depending on what you have got) connector are the ones that control the injector signal to the computer. These 2 wires are not bundled with the other engine wires, they come from the harness with the ground wires that attach to the bellhousing (also the O2 sensor.) Anyway, we provided a better connection to the ICM and all problems were solved. I hope this information helps someone out there. A little helpful tool that reads the reference signal from the computer through the ALDL connector would have been nice. Having that would have saved me a lot of time. Later. Quote Link to comment Share on other sites More sharing options...
Andrew Posted August 23, 2007 Report Share Posted August 23, 2007 wait? you are telling us how you fixed something?!?! does this ever happen?? cool man. contribution without whining = Winnar! Quote Link to comment Share on other sites More sharing options...
pwmin Posted August 23, 2007 Report Share Posted August 23, 2007 wait? you are telling us how you fixed something?!?! does this ever happen?? cool man. contribution without whining = Winnar! thx for the info...sticky? Quote Link to comment Share on other sites More sharing options...
Doug Goodwrench Posted August 23, 2007 Author Report Share Posted August 23, 2007 Hey, I could whine about the time that it took me to figure it out...but who would listen? Another story is how I started liking the w-body to begin with. ---If you want a sticky out of this, you better start now.--- Back on topic, I was just hoping that this information would be useful to ANY of us W-body enthusiasts. (Or anyone that uses a 60 degree v-6 that is mpfi.) Enjoy your ride...and drive it like you stole it! Quote Link to comment Share on other sites More sharing options...
Robby1870 Posted August 23, 2007 Report Share Posted August 23, 2007 Yeah, the ICM controls everything via crank sensor signal from 0 to like 400rpms, then the ECM takes over. Quote Link to comment Share on other sites More sharing options...
pwmin Posted August 23, 2007 Report Share Posted August 23, 2007 Another story is how I started liking the w-body to begin with. for some reason i gave up a 98 riviera for the 96 SPED...still not sure why, lol, but i loved it. obviously, or i def wouldnt have gotten the 91 that needed tons of work. i wouldve let luke keep it Quote Link to comment Share on other sites More sharing options...
Doug Goodwrench Posted August 23, 2007 Author Report Share Posted August 23, 2007 Yeah, the ICM controls everything via crank sensor signal from 0 to like 400rpms, then the ECM takes over. The High reference signal that the ICM sends to the PCM/ECM does what then? The ECM ALWAYS controls the injectors. The low signal for cranking and possibly idle. But I think the High reference pulse is used for anything above idle.(or a combination of both signals.) The ECM would ALWAYS need a reference signal. Remember...the crank sensor is plugged into the other connector of the ICM, making the ICM the controller of all subsequent circuits and readings. Quote Link to comment Share on other sites More sharing options...
Turbo231 Posted August 23, 2007 Report Share Posted August 23, 2007 Great work! Long story short, check your connections. Mechanics 101. Good catch. Quote Link to comment Share on other sites More sharing options...
Robby1870 Posted August 24, 2007 Report Share Posted August 24, 2007 Yeah, the ICM controls everything via crank sensor signal from 0 to like 400rpms, then the ECM takes over. The High reference signal that the ICM sends to the PCM/ECM does what then? The ECM ALWAYS controls the injectors. The low signal for cranking and possibly idle. But I think the High reference pulse is used for anything above idle.(or a combination of both signals.) The ECM would ALWAYS need a reference signal. Remember...the crank sensor is plugged into the other connector of the ICM, making the ICM the controller of all subsequent circuits and readings. I shouldn't have been so liberal with the word "everything" Quote Link to comment Share on other sites More sharing options...
Doug Goodwrench Posted August 24, 2007 Author Report Share Posted August 24, 2007 I was wondering if I could have worded my response better as to not offend anyone. If I did offend, let me apologize, Sorry. I am just here for the women. lol. Peace. Quote Link to comment Share on other sites More sharing options...
Robby1870 Posted August 24, 2007 Report Share Posted August 24, 2007 I was wondering if I could have worded my response better as to not offend anyone. If I did offend, let me apologize, Sorry. I am just here for the women. lol. Peace. No offense here, I just didn't really mean "everything" when I said that. If you're here for the ladies then, let me apologize ahead of time. Quote Link to comment Share on other sites More sharing options...
pwmin Posted August 24, 2007 Report Share Posted August 24, 2007 yeah, no ladies here, lol. nichole is the only one to stick around. im sure that was a joke, though. you wont see many people apologizing around here for coming off as rude, let alone people apologizing for being rude Quote Link to comment Share on other sites More sharing options...
Doug Goodwrench Posted August 25, 2007 Author Report Share Posted August 25, 2007 Robbie, you are right though...the crank sensor does control everything (in a manner of speaking), but the ICM divides the signals up and the ECM interpets them and sends the signals on to the injectors and back to the ICM to control spark timing. I figured that there wern't too many women on here...that was a joke. lol. I am just here to offer my experiences and help where I can. If you notice me listing NAPA part numbers...that's because I work for them. Later everyone. Quote Link to comment Share on other sites More sharing options...
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