1.4 Turbo Engine operation at low RPMs, manual transmission

[LowGearTurbo]

For best gas mileage, it is best to keep the engine RPMs low. My engine seems to run OK down to 1000 RPM (32 MPH in 6th gear), with limited power. Below 900 RPM, it seems to add throttle on its own, probably to prevent lugging (or maybe it is lugging?).

There is a YouTube video "Why You Should Never Lug Your Engine (Especially Turbos)" by Engineering Explained https://www.youtube.com/watch?v=soJea7xEt-8, with a reply by Marios EvoCy which states:

Although the above has a certain pragmatical basis, it is not always entirely the case. Most modern engines, with advanced engine ecu units and software, can detect knock, pinging and pre-ignition, through very sensitive knock sensor/s, catching it right just about it starts detonating, and thus reducing timing, and or richen afr at a specific load point/s.
By reducing timing and in combination with richer afr, the ecu manages to minimize to the greatest degree possible or eliminates detonation and pre-ignition completely. Also the above conditions, vary a lot from setup to setup, as these adverse effects depend a lot on the materials used and on the design of the internal structure of cylinder block ( i.e cooling and oiling), cylinder head and ancillaries, pistons and rings, inlet and exhaust manifolds, turbocharger and intercooler used, degree of cylinder pressures and heat produced. It's not about how early in the rev range boost is introduced, it's about how much early boost is introduced and if the rest of the setup/engine can cope with it. On some engines these effects are severe, on others, are almost non existant.
Also I do not agree with the comment about the colder range plug not working, as it does.

With the limited power at low RPMs, going up hills requires down shifting to 5th or 4th, unless you can keep your speed up so that the turbo gives enough power at full throttle. Gas mileage is best in the highest numbered gear that can be used. (I have an Ultra Gauge Classic for instantaneous MPG readout. )

How do these comments relate to your experience?

 

[66roadie]

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How do these comments relate to your experience?

It sounds like you're lugging the engine and the ecu is compensating. Not good for engine life.

 

[LowGearTurbo]

Another characteristic of this engine that I meant to mention is that if you shift into the wrong gear, so that the engine RPM is too low, the engine dies altogether, and does not even try to recover with the clutch pushed in. You have to use the starter to get it going again.

 

[skurtov]

Use 93?

 

[ScarabEpic22]

900rpm is what both the factory "stall saver" (MT only) and desired Rolling Idle are set to in the factory calibration. The ECM will try to keep the engine RPM at the target Rolling RPM (there's also a modifier based on speed), but it can only do so much. I wouldn't use this as an everyday driving tool, rather a helper when you miss a shift or if you don't downshift/clutch-in when rolling to a stop occasionally.

 

[LowGearTurbo]

Good info

900rpm is what both the factory "stall saver" (MT only) and desired Rolling Idle are set to in the factory calibration. The ECM will try to keep the engine RPM at the target Rolling RPM (there's also a modifier based on speed), but it can only do so much.

This sounds like inside information. Where are these factory calibration settings documented?
I have been using only regular 87 gasoline, usually Shell.

 

[skurtov]

This sounds like inside information. Where are these factory calibration settings documented?
I have been using only regular 87 gasoline, usually Shell.

You can pull them yourself with logging.

 

[ScarabEpic22]

This sounds like inside information. Where are these factory calibration settings documented?
I have been using only regular 87 gasoline, usually Shell.

It's easy to find in the stock tune, I just opened mine up and looked at the idle tables.

Try running a tank of premium 91+, bet you'll notice the engine idles smoother and has a hair more power. I logged mine a few year back and with 87 the ECM was pulling spark pretty much everywhere and dropping the octane scaler to bias towards the low octane table vs high = less power.

You can pull them yourself with logging.

Probably can, but it may be tough to reproduce consistently. If someone doesn't have EFILive or HPTuners to pull the tune, logging is the next best way.

 

[LowGearTurbo]

I don't have access to a tune hardware/software.
What should be monitored, and how to interpret it?
Besides the UltraGauge, I have PC software ODBwiz (obdsoftware.net), but have not used it while driving.