High Load at idle?

[SecondhandSnake]

I thought I had a bad revision that wanted to run way too rich at idle, especially first startup, around 10 AFR. Looking at the logs I noticed the STFTs were just below 1. I went and looked at the load and sure enough...readings as high as 1.5 on initial startup/high idle! Throttle was closed. Looking at the corresponding part on the fueling table and sure enough, that AFR is what it wants for that region. Not only that, I know in other logs I've seen load as high as 1.2 just releasing the clutch.

But at warm idle, down around 750 RPM, and driving around load is where you would expect, around 0.1, and even getting on it I've seldom seen load exceed 1.5, so I know I don't necessarily need to scale due to running out of room at high flows.

Has anyone else seen anything like this?

It doesn't so much seem an issue as an oddity, possibly due to the Eaton or compound setup where it just wants to move a lot of air, even at low RPM with minimal throttle. It isn't causing any issues per se, just means it runs richer and with less timing than you would expect normally. If it really is seeing that high load, it would be the right thing I suppose.

 

[cj428mach]

Load is usually under .20 for a stock motor at idle. With AC it can get to .20 or a little above, a built motor is going to require more.

If your load is over 1.0 you have a major problem.

 

[SecondhandSnake]

Like I said, once it's warmed up and comes down from initial high idle it's fine, down around 0.1. It's just that initial cold startup with the initial idle adder (up to around 1600 IIRC) that it's crazy high, as well as releasing the clutch. When it warms up, and when the clutch is out, it's down between 0.1-0.2.

I also failed to mention it's a built, cammed engine, ported M112, twin 66mm turbos. It's got a lot of capability of ramming air into the engine, so it doesn't seem entirely implausible. This seems especially true at low RPM where 100% load doesn't represent a lot of air to begin with.

Doing some math, assuming stock displacement and air density of 0.075 lb/ft3 @ 70 F/ 1atm, it looks like 100% load equates to 4.55 lb/min @ 750 RPM, and 9.72 lb/min @1600 RPM. My airflow at 1600 RPM is nowhere near that. This may be more or less a fluke calculation on the ECU's part.

 

[homestead_us]

Im not sure about the 4.6 engines but i know the 5.4's had the wrong displacement in the value file. You can try loading the correct displacement value file, that will lower your load at idle if its off. This is for SCT pro racer.

 

[decipha]

the ecu isnt calculating it wrong, only possible cause is that your datalogger is pulling the wrong value, the cranking airmass function in your tune is jacked way up, or your logging perload instead and fn035 is jacked

 

[SecondhandSnake]

Im not sure about the 4.6 engines but i know the 5.4's had the wrong displacement in the value file. You can try loading the correct displacement value file, that will lower your load at idle if its off. This is for SCT pro racer.

I verified the displacement was correct for a 4.6.

the ecu isnt calculating it wrong, only possible cause is that your datalogger is pulling the wrong value, the cranking airmass function in your tune is jacked way up, or your logging perload instead and fn035 is jacked

Is cranking airmass used once the engine is running? I usually don't have the logger up and running until 20-30 seconds after start.

Like I said, aside from that small instance, you would never notice it, both from behavior or the logs. It runs just fine, just looks strange in the logs if you capture that short time.