1st Gen Haltech ECU Discussion

You can use a stepper output (they can function like a DPO) but you have to make sure it is set to low side control in the wiring screen. If it is set to high side it won't hurt anything but it just won't work either.

 

If I had my laptop with me, I could take a look. I think it is low side. However, the Passenger OCV just makes an occasional loud fast rattle/clicking noise, but very little if any phase change.

 

Sounds like part failure (could be the solenoid or the actual phaser unit, I know some toyota phase units leak internally when they go bad), but always worth verifying the wiring and setup first. Maybe it has bad continuity on the +12v side or something.

 

The phaser itself is brand new OEM. I just installed last weekend basically. The OCV could be culprit. Since it is off of a used engine of mine.

 

Anyone been doing anything fun?

I havefta not mess with the Taco too much for a few weeks since it'll be my DD once the turbo kit for my Golf comes in.

 

Been playing around with blending speed density and MAF fueling. No real reason, just kinda tinkering right now. At idle it’s 100% SD. As load increases it starts blending more and more input from the MAF, and then at high load it’s 100% MAF.

That’s just for the calculation of how much air the engine is consuming. AFR targets are still set off of MAP vs RPM.

 

Odd... What's the benefit?

 

More precise air metering via the MAF than with SD. MAF is measuring the air consumption is real time while SD is calculations based on your VE table to infer how much air the engine is consuming. And engine mods (opening up exhaust more, etc.) throw off the VE table needing a re-tune. MAF tuning isn't as sensitive to VE changes or elevation changes as SD since it's measuring the airflow directly. MAF-only tuning took a lot of smoothing of the MAF signal due to how choppy of a signal it is. But now it can run SD, MAF, or a blend of the two. Really I wanted to get the engine running on both strategies, and when I did I decided to play around with blending them. SD isn't really affected by any small vacuum leaks, as the MAP picks up the change in manifold pressure and adjusts accordingly. With MAF-only that vacuum leak is is bypassing the MAF throwing off fueling completely. Kinda sucked when I was on the stock ECU (that's MAF-only) and I blew off a vacuum hose on the freeway, and was running real lean in downtown traffic stop-n-go traffic. By playing around with blending I figured I'd see if I could get the best of both worlds. Dunno if I'll keep it this way or not yet, just playing with it.

I also finally got around to wiring up my flex fuel sensor that I've had plumbed into the fuel return line. So going to start playing with E85 too.

 

In my experience, both can have issues when running low airflow. It just comes with the territory of less room for error, more noise.

I guess if you're planning on doing a lot of changes still it makes sense, but VE is simply a calculation of fuel error at a given RPM (velocity) and manifold pressure (together they make mass with a known density), so they're basically doing the same thing. MAF is just the absolute reading, hence why we still use fuel trims for both. As you say, SD is impervious to leaks pre-throttle, and I've already gained the benefit of that myself when the intake tube blew off in the middle of a drive.

Idk, I've argued the benefit of a MAF system for modern vehicles, but it takes a completely different premise which is that they use torque request via an e-throttle pedal and have tables for what MAF will result in that request. To know that, you have to map out the turbo flow rate: pressure (compressor map), what duty cycle the wastegate needs at each point to reach the desired flow, and some other ancillaries. The MAF is a lot more important in this circumstance because it's ultimately the failsafe check that everything else is running as expected. But you get the benefit of mapping your foot to actual torque instead of a % throttle at the end.

 

VE is a measure of how well the engine fills the cylinders with air, compared to its theoretical max. VE changes as the engine ages and wears, or like many drivers, due to lack of maintenance. VE then decreases. Conversely, VE changes if say you install a freer flowing exhaust or get heads that flow better. Then VE increases. Speed density relies on having an accurate VE table so that it can accurately calculate how much air is being consumed. MAF doesn’t rely on VE table.

Pros and cons to both, and I’m not married to either. I had the MAF in place already from when the stock ECU was controlling things, so I figured I’d give it a go. It runs fine on either fueling strategy.

 

Recently took a 1500mile road trip and got the best gas mileage I've ever seen at a whopping 17.3mpg while going through Yosemite. Average for the entire trip was right at about 16

 

This is part of the reason ITB setups (even ones with a plenum ahead of the ITBs) often run alpha-n in idle and super low load. It's a common enough issue that HP academy and Haltech have articles for tuning stock RB26s that still have their ITBs in place. If it is just causing trims to move a bit at idle but the driving/idling behavior is okay you probably don't need to employ a second metering strategy through. It is when the engine is modified (usually cams) that they can behave pretty poorly and you need to intervene with a second metering strategy.