Injector Offset Correction
Thread Starter
Melting Slicks
Joined: Mar 2008
Posts: 2,141
Likes: 76
From: Santa Maria, CA
Injector Offset Correction
I decided to do an injector experiment. I originally used 42# injectors on my 85 396 Super Ram build. The idle has always been somewhat rich which is problematic when trying to pass smog. I recently upgraded my ECM to a 165 with an ARAP 6E bin in the hope that the additional tuning parameters would give me a little more control over the idle mixture. I was able to get everything but the idle where I wanted it. So I can't help but wonder if this is due to the injector size.
Then I discovered a coolant leak in the intake gasket. So the intake had to come off. So I got this bright idea to swap back to some 24# Bosch IIIs I had on the shelf. I adjusted the tune for the smaller injectors and did some data logging. The engine is running lean between 8 and 35 gms/sec of air flow. At higher RPMs and air flow the tune looks pretty good. There's no leaning out at WOT. So I think these injectors are big enough. The problem is that I am unable to adjust MAF tables 1 and 2 to enrich the mixture. I'm hitting the maximum values (23 on MAF 1) and still have BLMs around 133-135. My BPW is around 2.0-2.5. Is there a way to increase BPW in that range? The Low Pulse Width Injector Offset vs. BPW doesn't make sense to me.
Then I discovered a coolant leak in the intake gasket. So the intake had to come off. So I got this bright idea to swap back to some 24# Bosch IIIs I had on the shelf. I adjusted the tune for the smaller injectors and did some data logging. The engine is running lean between 8 and 35 gms/sec of air flow. At higher RPMs and air flow the tune looks pretty good. There's no leaning out at WOT. So I think these injectors are big enough. The problem is that I am unable to adjust MAF tables 1 and 2 to enrich the mixture. I'm hitting the maximum values (23 on MAF 1) and still have BLMs around 133-135. My BPW is around 2.0-2.5. Is there a way to increase BPW in that range? The Low Pulse Width Injector Offset vs. BPW doesn't make sense to me.
Safety Car
Joined: Sep 2001
Posts: 4,157
Likes: 554
From: Glenbeulah Wi
You can do what Mr. ****** suggested, be aware that it will make the entire tune richer. You can also change the low pulse width injector offset vs. BPW to be richer at 2.0ms and 2.5ms to add in additional fuel. This is a pulse width adder that takes into account the injector response time to add in additional pulse width when the injectors are being pulsed for short times. If you need more fuel and at 2.0 ms and your blm is 135 then 135/128 is a 5% additional fuel correction. Adding 100 micro seconds to that table at 2.0ms should correct your problem and it will not richen up the upper RPM range.
