Injectors pulsing when engine is OFF?!

**CDeeZ** · 02-03-2019

Tonight, the pulsing with the key off came back.... Not sure what it could be. Maybe ANOTHER flaky junkyard PCM....

I guess if it doesn't affect anything else it won't matter. Just will have to treat it like a carb and not flood the engine when it's off :)

**1project2many** · 02-03-2019

Did you mean to say key off? The original report was key on, engine off.

**CDeeZ** · 02-03-2019

Whoops sorry. I meant to say key ON but engine off.

**1project2many** · 02-04-2019

lol...

And you thought no one was paying attention. ;)

**steveo** · 02-05-2019

fundamentally, injectors wont pulse unless it thinks the RPM is >0.

so whatever you're using for primary positional reference during cranking (cam sensor, crank sensor, distributor base) is signalling falsely (interference? defective sensor?)

key on engine off, you still have datalogging ability. lets see a log of when it's doing it, key on engine off. does RPM stay at zero the whole log?

also, does the ECM actually pulse the injectors (does your BPW increase)?

**CDeeZ** · 02-05-2019

Originally Posted by 1project2many

lol...

And you thought no one was paying attention. ;)

Originally Posted by steveo

fundamentally, injectors wont pulse unless it thinks the RPM is >0.

so whatever you're using for primary positional reference during cranking (cam sensor, crank sensor, distributor base) is signalling falsely (interference? defective sensor?)

key on engine off, you still have datalogging ability. lets see a log of when it's doing it, key on engine off. does RPM stay at zero the whole log?

also, does the ECM actually pulse the injectors (does your BPW increase)?

Well it's a TBI setup using the stock sensors so no cam or crank sensors. You guys have a better working knowledge of OBD1 stuff than I do, so correct me if I'm wrong here but the positional reference in this case will be from the DRP right????

The funny thing is, there is no repeatable or predictable pattern to when it does this. So, I haven't been able to catch it on a log yet. I will try to do that though.

Again, you guys have a better working knowledge of OBD1 than I... But if the injectors are making a noise and actually spraying fuel then they are being pulsed by the PCM right??