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Does anyone know the highest AFR that the 2.5l runs? I run the car lean at cruising speed, but until I get an EGT gauge, I keep it at about 18:1 AFR, only at low vacuum (Idle, Deceleration, and at 67mph, on flat road). The dial gauge goes to just above 18:1, but MegaTune will go as high as needed.

your (high quality) wideband will read decently up to a lambda of 25.

An EGT is the way to go.

The stock AFR will always target a lambda of 1 (14.7:1) at running temp under normal conditions and never aim more lean than that.

Unless its unusual, but that is usual.

I had read that it goes up 16:1 AFR, under low vacuum. I read it on PT, so it could be right on, or not right at all. My AFR setup is DynoJet (pretty good one), and the gauge just goes to 18:1. Good news; I thought it was running a little weak because iof the bad tune, but it turns out that my #1 spark plug wire was broken at the disty terminal elbow. I fixed it, and now it runs more smoothly.

The real test would be to install a WBO2 on a healthy stock engine and monitor it.

The people who decode and write EPROMs don't necessarily decode the tables they write, they just copy the KL31 tables. I actually seriously doubt someone got real lambda info from the PROM itself.

I got some Lambda at my Prom
It would run hot (temp gauge), if it were running too hot in the heads, wouldn't it?

fowljesse wrote:I got some Lambda at my Prom
It would run hot (temp gauge), if it were running too hot in the heads, wouldn't it?

it probably would but i think the intensity of it running too lean could cause damage before the coolant needle had enough time to react. its not necessarily the temperature of the engine thats the problem with running lean, its the temperature in the combustion chamber that if left unchecked would actually weld the pistons to the cylinder walls. your best bet in monitoring the system would be a wide band o2 and an exhaust temp gauge mounted infront of the cat.

I've have a DynoJet wideband. That's how I know how lean it's running. It has a bad tune, which will be fixed tomorrow. I'm researching more about running lean. From what I can tell, an engine can run up to about 20:1 under light load, on average.

by light load they mean little to now throttle, as in little to no airflow, which means there is less, albeit more intense, heat generated.

The problem with running lean is burning holes in pistons and exhaust valves.

Don't play with it too much, Jesse, until you get a proper EGT sensor.