LSX454 swapped 95 BASS burb.

[folkenheath]

That's a good point, that self-learning could skew things off at idle (especially if something else is amiss with the system). I am used to setting idle as open loop because some engines are more stable idling at 13.5-14.0 than they are under closed loop seeking 14.7:1 at all times. For reading the plugs, I would think that's more of an average over the whole operating time, vs. the few seconds the engine is dying.

Yes but if its off it can be way off at idle. Whereas at WOT a little leak isn't much compared to full flow. So I've had it before where the 02 said it was super lean but the plugs were pig rich and the learn table was doubling the fuel. Granted I don't expect that with his LSX454 cam, its only 236/246@ .050, which is pretty close to my 388 cam and it doesn't have the cubes to tame the cam.

There's an old trick to fine tune the spark table so that the desired idle speed sits in kind of a trough. When the engine tries to slow down, the increased timing pushes the PRM back up to where it should be. AFR can be similar. It's only kind of good, IMO, and I don't know if that's possible with this system. I just know that not stalling is better than stalling.

You can do that with the table, by finding where it idles on the table and make a little 2D "trough" as you say, there is a thread on that years ago on the Hollley forum from "Danny Cabral" or something close to that, but that's what the idle spark feature does automatically now, it uses timing changes so fast to try and correct the idle. But you can add that to the fuel but I don't find it usually necessary.

I think old school logic still applies, that fine-tuning the engine to achieve maximum vacuum for a given idle speed would still help. However, it may not be related to fuel or spark at all, but a weak signal or interference on CPS, MAF, etc. It's possible the system voltage is just too low and causing errors.

I agree, I have been thinking if it was here I would do exactly that, shut off self learning, and see what it likes when its warm, go back to old school and tune for maximum vacuum or RPM for both timing and fuel, which is easy with a MAP sensor. Maybe as fast as a screwdriver and a vacuum gauge with a carb, but way faster with everything else. You may have to move the butterflies and reteach the TPS a couple times, but then you would know.

I also wonder if his gigantic dual alternators and throwing more of an instant load than normal, because it sounded like it did it when the fans turned on, RPM dropped, voltage dropped, and it had to catch itself.

 

[Babaganoosh]

Shady, make a trip to Heath for a day get this thing sorted.

 

[shady]

I've contemplated just that a few times.

It's made the drive there before lol.