[pthornton]

How does the min injector pulsewidth figure into the final pulsewidth @ WOT in the 94+ EEC? Anyone know any specifics on this?

Randy

[sailorbob]

IIRC the MIN_INJECTOR_PULSEWIDTH time is converted to MIN_INJECTOR_PULSEWIDTH_TICKS and if the calculated injector pulsewidth (in ticks) is less than the minimum value then the injector pulsewidth (ticks) is clamped to the minimum value. I wouldn't expect you would see the value being clamped at WOT.

[2Shaker]

I wouldn't expect you would see the value being clamped at WOT.

I followed you until you made this point. It seems obvious you would never have minimum PW at WOT. But as has happened to me in the past a point was made where I thought it was obovious only to learn about some other condition I wasn't thinking about.

[sailorbob]

My last sentence was conjecture because of the original question, just a case of trying to find out if there was some reason for thinking that the MIN_INJECTOR_PULSEWIDTH may (does?) affect the final figure.

[rockin_rick]

I don't believe that it is any part of the total PW. Just a min clamp value - so if calculated PW is > min PW scalar, then commanded PW = calculated PW, but if calculated PW < min PW scalar, then commanded PW = min PW scalar.

However, fuel shutoff on decel mode doesn't use this, and in that condition PW = 0 (less than the min).

Rick

[pthornton]

This was my original thinking also. But I'm beginning to wonder. I recently lowered my minimum pulse with and it threw off the whole bottom end of my MAF curve by 10%. I didn't expect this large a change and I didn't expect to see it at such high MAF voltages. I'll get the wideband out sometime soon and see if I see any difference at WOT. The weather has been too nasty and I'm in the process of replacing my heater core right now. Fun job.

Randy

[sailorbob]

I recently lowered my minimum pulse with and it threw off the whole bottom end of my MAF curve by 10%.

What do you mean by this :? Injector pulsewidth shouldn't affect your MAF curve.

[pthornton]

I recently lowered my minimum pulse with and it threw off the whole bottom end of my MAF curve by 10%.

What do you mean by this :? Injector pulsewidth shouldn't affect your MAF curve.

The KARMF went from ~1.02 to ~1.16 across the entire bottom of the curve. So, it actually changed by more than 10%. The min pulse width is the only change.

[sailorbob]

Ah right, I understand it now.

KAMRF isn't your MAF curve, it's the adaptive fuel trim correction stored in the KAM. By lowering your MIN_INJECTOR_PULSEWIDTH the calculated pw is less than is required for a stoichiometric AF ratio at idle and therefore the hego feedback is signalling that the AF ratio is lean and this results in your KAMRF value being increased to compensate.

[pthornton]

Ah right, I understand it now.

KAMRF isn't your MAF curve, it's the adaptive fuel trim correction stored in the KAM. By lowering your MIN_INJECTOR_PULSEWIDTH the calculated pw is less than is required for a stoichiometric AF ratio at idle and therefore the hego feedback is signalling that the AF ratio is lean and this results in your KAMRF value being increased to compensate.

Thanks for the obvious. Got anything specific as far as calculations on minimum injector pulsewidths?

[craig429]

You don't want the Minimum injector pulsewidth to be used and therefore effect KAMRF's, It was more for a safe guard. I selected .0003 Seconds for use with 42# injectors. During deceleration, the EEC would command the lowest injector pulse widths.

The problem you had was that the Mininum injector pulsewidth clamp value was reached even though the EEC calculated a lower PW using the current MAF curve so it had to command the higher Mininum pulsewidth value to the injector. Therefore the lower part of the curve was not really being used. Now when you lowered the Mininum injector pulse width, the EEC is now able to command a lower injector pulse width as determined by the MAF curve but the current MAF curve was lean in the lower values so the KAMRF have to compensate by being larger to keep the AFR at 14.7. The MAF curve was actually being used.