Fuel Injector Problems

[optronix]

Since it's been about two weeks and you're still posting here clearly without a resolution I'll spell it out for you- this is a forum for owners of the 2024 Acura Integra Type S. It shares literally nothing in common with your car, which in fairness has an engine from an Integra but one from literally 30 years ago. So people on this forum are probably not going to be familiar with your situation, and thus probably not be very helpful. As I would hope you've discovered by now.

Try https://honda-tech.com/, maybe you'll get farther.

 

[jayy_swish]

The plugs were not getting fuel so I removed the injectors with the fuel rail attached and attached a nine volt battery to the injectors and they fire. The injector ground is attached to the ECU and the hot wire to the battery. The ECU ground pulse tells the injectors to fire. When I connect a Noid light to the injector harness it flashes like it's getting a signal so they should be firing but they are not. Their must be an answer but I can't figure it out. Any thoughts?

I’d prefer you to see with an oscilloscope, but try double check with a multimeter at each injector while cranking the engine to see what voltage it is actually getting. I’ve seen a similar situation in a Lancer where yes it lit the noid light, but dimly. It had a dying ground driver in the ECU. Ending up replacing the ECU and it corrected the issue. Similar to your situation, injectors were fine.. lit up the noid light, but under load on the injector was not enough to fire the injector.

 

[creaturemachine]

I’d prefer you to see with an oscilloscope, but try double check with a multimeter at each injector while cranking the engine to see what voltage it is actually getting. I’ve seen a similar situation in a Lancer where yes it lit the noid light, but dimly. It had a dying ground driver in the ECU. Ending up replacing the ECU and it corrected the issue. Similar to your situation, injectors were fine.. lit up the noid light, but under load on the injector was not enough to fire the injector.

Just curious, but what would you see on the scope, a square wave as the injector fires? The last time I saw a scope used I was in high school in a job placement at a shop, diagnosing some pre-obd ecu which turned out to be faulty.

 

[jayy_swish]

Just curious, but what would you see on the scope, a square wave as the injector fires? The last time I saw a scope used I was in high school in a job placement at a shop, diagnosing some pre-obd ecu which turned out to be faulty.

I didn’t have an example on my phone unfortunately, but I did find a waveform image on google that not only shows it but explains the waveform. You’ll see the battery voltage, the drop in voltage as the injector’s pulse time, the magnetic voltage spike that is created to begin the activation of the injector, the fall of the spike as the magnetic field collapses, and a small “hump” on the collapse spike where the injector is actually mechanically fired and back to battery voltage. I believe in his case as mentioned above, he has battery voltage on his hot wire side, but under load it is not enough to activate & fire the injector

 

[BillsVETEC]

Thanks. How many volts do you think at the injectors are needed to make them fire while cranking?

 

[jayy_swish]

Thanks. How many volts do you think at the injectors are needed to make them fire while cranking?

So you’ll need to either pierce the wire or back probe the injector which ever is easiest for you. You’ll have battery voltage with the key is on which is normal, during cranking there should be a slight drop in voltage cause the starter is engaging. So you should be 9v+ at the injectors when firing. The issue is the refresh rate with multimeters might not be the fast to see/capture the voltage changes

 

[BillsVETEC]

Got it. Thanks.

 

[RamVA]

Dumb question, but you're confident the battery is good?

Beyond that, if you have fuel and you have fire, I'd check the timing, all the way around (but cam in particular).

I assume from your post you have crank but no start, but forgive me if I misunderstand.

That car will be fire when you get it going, good luck.