Adjusting Power Enrichment

I have tuned my VE tables on my 94 K1500 and have gotten them pretty close, all within 122-130 (though a couple of cells seem to have strayed a little on this run). Anyhow, I've re-enabled PE, hooked up my WB02 and made a new datalog and started researching how to adjust PE. I'm a little confused...with the PE AFR vs RPM table set to a predetermined AFR (12.1 - 12.6) , why would my truck be running as rich as it does under WOT (as rich as 10.3)? Do I just go back into the VE table and adjust it to bring PE where I want it? Also, I read varying opinions on PE AFR and what it should be adjusted to. Is this more of a preference or feel for what the engine likes? Last, the TPS for PE vs RPM tables are still stock vortec settings, would you guys leave these alone? Any help or opinions to get me going in the right direction is appreciated. Thanks.

Timing can also have an effect on your PE AFR. What does your timing look like? If you adjust your VE table till you read your commanded PE AFR then your tune would be correct. You could fudge the the PE AFR table around to get what you are wanting to see on your wide band, but that would be the "wrong" way of doing it.

My timing is still a work in progress but right now not very aggressive (see below). I'm getting some knock retard in 5 or 6 cells at WOT so I will need to dial that back a little I guess. I was hoping fine tuning my PE would help that but I was thinking it was going to run leaner at WOT than what it actually is once I turned PE back on. I will adjust the VE table to fine tune the PE...thank you

So what PE AFR did you tune to on your 94 Blazer? I read on a different forum..."A good PE AFR for a truck would depend on the TPS for PE vs. RPM. Low TPS for PE you would want to have leaner AFR's, like 13.5:1 up until about 2600rpm where as High TPS for PE would want around 12.0:1." This concept makes sense to me (less air entering the engine at lower RPM's, slightly leaner PE AFR required) but i wasn't sure if this was a common practice.

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Originally Posted by dispoejoe95

My timing is still a work in progress but right now not very aggressive (see below). I'm getting some knock retard in 5 or 6 cells at WOT so I will need to dial that back a little I guess. I was hoping fine tuning my PE would help that but I was thinking it was going to run leaner at WOT than what it actually is once I turned PE back on. I will adjust the VE table to fine tune the PE...thank you

So what PE AFR did you tune to on your 94 Blazer? I read on a different forum..."A good PE AFR for a truck would depend on the TPS for PE vs. RPM. Low TPS for PE you would want to have leaner AFR's, like 13.5:1 up until about 2600rpm where as High TPS for PE would want around 12.0:1." This concept makes sense to me (less air entering the engine at lower RPM's, slightly leaner PE AFR required) but i wasn't sure if this was a common practice.

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Yes I did. Its Turbo Charged now, so its a whole different animal.

Turbo on your Blazer...nice!

So...has anyone else tried using different PE AFR's for different RPM ranges like suggested below?

"A good PE AFR for a truck would depend on the TPS for PE vs. RPM. Low TPS for PE you would want to have leaner AFR's, like 13.5:1 up until about 2600rpm where as High TPS for PE would want around 12.0:1.

Back to your original question. You probably didn't do much tuning of the VE table in the same area you're now running when in PE mode.

As for the ranges, you can do that and it often works. The AFR required can vary as the rpm varies. I think I've read to go richer until the torque peak and then lean it out again. I tend to somewhat follow the factory curve or just go flat.

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Originally Posted by lionelhutz

Back to your original question. You probably didn't do much tuning of the VE table in the same area you're now running when in PE mode.

As for the ranges, you can do that and it often works. The AFR required can vary as the rpm varies. I think I've read to go richer until the torque peak and then lean it out again. I tend to somewhat follow the factory curve or just go flat.

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Thanks...I think I am going to do the same as you and stay with the factory curve, at least for now. Maybe later once I have a better feel for what i am doing I'll experiment with varying PE AFR's to see if there are any gains to be had.

I'm dealing with almost the same issues with my truck in regards to the pe/ae stuff, so this thread interests me.

I'm curious though, when you are accelerating and the engine is being given extra gas since more air is being allowed to enter, and, your spark is being advanced to whatever the table calls for, wouldn't the wideband show a stoich value if the mixture being commanded is correct for the spark timing at that point?

When PE is active it will command an AFR that is equal to your TPS for PE vs RPM table. Mine ranges from 12.1 to 12.6.