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I have a 2002 Monte Carlo SS with 3.8l I'm DESPERATE the injectors are not pulsing I've narrowed it down to cam sensor on producing 2.55 volts from ICM. There are no codes and car runs on starting fluid these are new part ecm, cam sensor, crank sensor, and these are verified used parts replaced ignition switch, bcm, icm harness, key, I've tested everything to the best of my ability but I'm weak on wiring issues but I try I've tried 7 experts at just answer and they gave up I'm sure it SIMPLE but I cant find it please help?? I have a Autel maxisys scanner also Thanks for any help? Also no rpm while cranking. The cam magnet is still attached.
Last edit: 4 years 10 months ago by Kyle55. Reason: Add content
I have crank signal 3x and 18x while cranking and good spark runs on starting fluid and crank sensor new but no rpm while cranking per scanner and scanner shows crank position sensor presence but no cam signal present plus cam sensor is new and magnet is there
Kyle55 wrote: I've narrowed it down to cam sensor on producing 2.55 volts sent to ICM and Ecm.
Took a look at the OE wiring diagram, and attempted to decipher the troubleshooting procedure for P0341.
It appears the ICM should supply 5V to both the CMP signal wire and the PCMs CMP input. The CMP grounds the signal to sensor ground when it triggers. I'd try unplugging the N.E.W. CMP to see if that brings the voltage up. If that doesn't then unplug the PCM and see what if it does.
The following user(s) said Thank You: Noah, Paul P.
Thank u matt 4 replying anyway with both unplugged first cmp and then ecm I still have 2.55 v at cmp signal wire with good power and ground to cmp and ICM has been replaced but it is used from running vehicle so BAD ICM? both ICM's did exactly the same both no rpm both good spark both run on starting fluid. Anyway to test ICM on 3.8?
Ok here goes I tried one more ICM and guess what I have correct voltage at 5.5 volts coming from ICM and remember cam and crank sensors are new so now it should run rite? Well it doesn't now I have no. Rpm and still no cam presence on my scanner and no codes and no security light this thing is demon possessed the other ppl I talked to swore to me ICM was good if it had good spark well they were wrong so now I'm even more lost?
Let's get back to basics. You have spark, but you have no fuel. That is certain. You proved that by running on starting fluid.
Do you have fuel pressure at the injectors?
What test did you run to determine the injectors weren't firing?
Have you checked ALL powers and grounds at the ECM connector? Easiest way to check that is with a test light. There's a scannerdanner video on that. If you changed the ECM, go back to the original one unless you are sure the original one is bad.
Can you have someone help you get it running off propane long enough to see if your scan tool shows RPM? Some systems may not report RPM to the scan tool during cranking. I haven't worked on a GM of that vintage in a while so I don't know how it would behave.
I found a diagram for a 1995 GM 3800. Looks like there is a 10 amp fuse to the injectors and then each one is ground-side switched individually by the ECM -- sequential fuel injection. You need to verify power to the injectors. Connect your test light to ground and then touch it to the terminals of the fuel injector connector one at a time with the ignition switch in the run position. On one of those contacts in the connector, it should light. If not check your fuel injector fuse. If it lights, then we move towards the ECM.
Here's a video from Mr. Danner with specifics.
and please stop throwing parts at it! That's only going to make things harder.
I would also recommend trying a different alternative fuel source than starter fluid since I've heard many on here say that it has lead people to think they have spark because it seems like it wants to start but actually doesn't. Have you actually seen spark with your own eyes yet? I can't remember if you have tested for that yet with a spark tester or anything. Paul turned me on to using a test light for this check.
It doesn't sound like it, but I wanted to make sure that you were getting the 2.5v at the sensor while cranking it, since that may be accurate for a meter to show on a 5v square wave.
Keep at it and you'll get it sorted out. The help on here is as good as it gets!
50 psi fuel pressure I did test light on injector ground while cranking no pulse but Injectors have power I did voltage test and ground test on wires m, n and signal wire j at ICM and I hand cranked engine with key on to check cmp drop and it dropped to 0 from 5.5 volts but b4 it started raining on me today I only have 3.87 volts at ecm #7 with key on so that is where i will look tomorrow but the crazy thing is with bad icm i had 2.55 volt at ICM wire j and 2.55 at ecm #7 they were the same and now i have correct voltage at ICM j it drops at ecm #7 so I'm guessing that wire is bad i will check it tomorrow thanks again for the help
I've seen spark and it runs on starting fluid but I believe now my cmp signal wire to ecm is compromised I will find out tomorrow.THANK U EVERYONE FOR UR HELP SO FAR!! GOD BLESS
Well I guess this car has got In my head this is where I'm at still no injector pulse THE ICM WAS BAD EVEN THO IT HAD SPARK AND RAN ON STARTING FLUID now new ICM and still injectors wont pulse I did cmp and crank sensor diagnostics and they passed its getting 5.5 volts at cam sensor and dropping to 0 when turning engine by hand key on now the problem when testing cmp wires at ecm while cranking engine voltage is between 2-4 volts and wiring is good SO WHAT CAN MAKE VOLTAGE GO CRAZY GOING TO ECM FROM CAM, CRANK SENSORS? Review new cam,crank, sensors new ecm different bcm, SO ITS TIME 4 VODKA AND A MATCH FOR THIS DAMN CAR!!! ANY HELP GREATLY APPRECIATED!
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