Injectors pulse when cranking. Stop pulsing when engine fires and starts.
08-17-2018, 12:24 PM
#1
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Injectors pulse when cranking. Stop pulsing when engine fires and starts.
Well after chasing my tail all summer. I finally found my issue. Car will fire up in one or two cranks (a healthy start) then die. The injectors pulse when cranking, but not when the engine starts. I'd say 20% of the time the car fires up, and idles fine. 80% of the time it will fire and die. But if you keep trying (might take 6-9 times) it will fire and stay running.
Grounds are fine. I went over them all I believe. They're all hooked up and clean. When I put the new motor in 5 years ago, they were in great shape, but cleaned them up anyway when reinstalling.
All the injector plugs have 12v with the key forward.
In realize the ECM needs to see DRP's from the pickup coil to fire the injectors. I replaced the pickup coil already. And also, the fuel pump primes with key forward (40+lbs). It runs when cranking (40+lbs). And when the engine fires and dies, there is still 40+lbs at the rail. When the motor stalls out, I hear the fuel pump still running for a few seconds, then turn off and I hear the relay click. From what I understand, if the ECM isn't getting DRP's, the fuel pump will not run.
Therefore I am thinking the injector driver in the ECM is taking a dump. Any other suggestions before I purchase a new ECM? Thanks!
Grounds are fine. I went over them all I believe. They're all hooked up and clean. When I put the new motor in 5 years ago, they were in great shape, but cleaned them up anyway when reinstalling.
All the injector plugs have 12v with the key forward.
In realize the ECM needs to see DRP's from the pickup coil to fire the injectors. I replaced the pickup coil already. And also, the fuel pump primes with key forward (40+lbs). It runs when cranking (40+lbs). And when the engine fires and dies, there is still 40+lbs at the rail. When the motor stalls out, I hear the fuel pump still running for a few seconds, then turn off and I hear the relay click. From what I understand, if the ECM isn't getting DRP's, the fuel pump will not run.
Therefore I am thinking the injector driver in the ECM is taking a dump. Any other suggestions before I purchase a new ECM? Thanks!
08-17-2018, 12:38 PM
#3
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Thread Starter
Re: Injectors pulse when cranking. Stop pulsing when engine fires and starts.
Yes sir. I put in a brand new AC delco ICM. And that didn't help. When I ordered a new pickup coil from MSD, it came with a new ICM already permanently soldered on. So I installed them both. Didn't help. I'm an idiot, should have gotten a noid light earlier. I figured if it's firing, clearly it's getting fuel and the injectors are pulsing. But clearly that's not the case, doh.
08-17-2018, 12:50 PM
#5
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Thread Starter
Re: Injectors pulse when cranking. Stop pulsing when engine fires and starts.
If I pull the connector out from the ECM, is it labeled b5? Never did it before. Am I looking for 12v? Just key forward or cranking? Or am I just checking to make sure it's not loose? Thanks for the responses!
08-17-2018, 12:57 PM
#7
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Thread Starter
Re: Injectors pulse when cranking. Stop pulsing when engine fires and starts.
You are seriously a saint! Thank you for the direction. I have to replace the wife's sticking caliper today 
. But when I get done, I'll check that for sure!!
. But when I get done, I'll check that for sure!! Trending Topics
08-17-2018, 12:59 PM
#8
Re: Injectors pulse when cranking. Stop pulsing when engine fires and starts.
If that looks ok. I think your on the right track thinking it’s the ecm.
as for the caliper I have had the flex hose cause issues with the caliper sticking best of luck with that project.
as for the caliper I have had the flex hose cause issues with the caliper sticking best of luck with that project.
08-23-2018, 03:07 PM
#9
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Thread Starter
Re: Injectors pulse when cranking. Stop pulsing when engine fires and starts.
Well the wifes car turned into new calipers, rotors, brake pads, and a new ball joint. Ball joint was not fun, ha. I ohm'ed B5 and B3 for the heck of it. Both ohm'ed out fine. No corrosion on any connectors. Just waiting on a new ECM now.
09-04-2018, 02:09 PM
#10
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Thread Starter
Re: Injectors pulse when cranking. Stop pulsing when engine fires and starts.
Well the new ECM is installed. And the car has fired up 5 days in a row. It has not done this for the last 3 months. It would start one day, then start and stall for the next 3-4 days...etc So I'm considering it fixed (hopefully). Again, THANK YOU very much Tuned Performance. And thank you for taking time out of your day to look at my datalogs too. Your help was very much appreciated.
Last edited by IROCThe5.7L; 09-04-2018 at 04:36 PM.
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