Friday, 19 March 2010

useful 2.0 TFSI APR EGT comment

posted by Keith@APR on

Here is what I can help with and please understand that ECU Upgrades and Calibration Philosophies are always evolving as new technology is introduced and new ecu mapping and coding is continually implemented by the OEM.

Meaning, what I am about to say may not be 100% accurate to all OEM and APR calibrations across 06 and 07 style FSI engines and TSI engines in Mk5's vs. Mk6's etc.

OEM EGT Logs = Accurate
APR Stage 1 EGT Logs = Accurate
APR Stage 2 or any higher level = Inaccurate

Here's why:

EGT's are collected by the oxygen sensor which is not pre-turbine and there are models or calculations inside the ecu that know that x temp at the 02 = y temp at pre-turbine and that there is a direct relationship between the 2 as long as all hardware that affects EGT's is the same as the model is designed to allow.

This means OEM EGT logs and Stage 1 EGT logs should be perfectly accurate.

When you move to a Stage 2 ecu you are getting a calibration that was made and tested with actual EGT's that differ from the modeled EGT's as reported by datalogging the ECU. This is so because when you change the downpipe, this greatly effects the EGT model accuracy in the ECU. So, you have to insert an EGT probe and measure the EGT's some other way than the ECU. Greatly btw, is relative to your perspective. Some tuners don't consider this a major change, however, APR does. Also, there is no longer a direct relationship to ecu logged EGT's and actual EGT's due to the hardware change. It simply doesn't work that way in such a dynamic system. Lot's of EGT model mapping and coding would have to be adjusted for the new downpipe. We know by simply looking at EGT models inside the ECU of say a GTi vs. an ED30 GTi or TT-S, or even a TSI vs. a FSI. The models are drastically different. True, other hardware is different than just a downpipe between those models but a change is a change and the EGT model is very complex.

We've talked about the maximum peak EGT spec and the maximum sustained EGT spec.

ECU datalogging reads up to 999c. This is below the actual EGT spec of the turbocharger and other components. That being said, I've seen some Stage 1 ECU's knock on the 999c door and maybe hit it for a couple of data points but then it comes back down quickly as hardware protection mapping kicks in.

What concerns us is when the 999c report from the ECU stays pegged for a period of time that is too long. This usually means that the EGT's are continuing to rise way above the 999c that the ecu is able to measure.

If they hit 999c for only a few data points, you can assume the EGT's are around 1010c at maximum. However, if they hit 999c for several data points, you can only imagine how high they are climbing before settling back below the 999c.

This is what we look for in customer datalogs. There is no exact recipe but we use our experience of what our calibrations reach via an actual pre-turbine EGT probe if Stage 2 or more compared to the amount of time it reaches and exceeds 999c in the ecu logs.

If the EGT's flatline at maximum reading and never come back down during the pull, its safe to assume you have an EGT problem and the hardware protection mapping isn't doing its job. This can happen if the tuner you use turns off hardware protection mapping and runs too lean or too much boost or if they calibrate the hardware protection mapping to the same requested AFR as their too lean primary fueling surface (some tuners claim they don't disable EGT protection mapping when they use this recalibration method but they are essentially doing the same thing as turning it off) or if your wastegate is not oem like its been tweaked or replaced with one that doesn't integrate into the OEM EMS (like those with different w/g tensions than OEM). This can also happen if so much hardware has been changed that the EGT model is completely and totally useless. We've only experienced this at Stage 3 calibrations and higher. With Stage 2, we can still look at the amount of time its at 999c and based on our previous actual EGT testing via a probe pre-turbine, can estimate if this is an issue for our clients or not.

Will we give the general public our exact EGT standards at all Staged ECU Upgrade levels for your own diagnosis? Sure, if that was all it would be used for. Unfortunately, since we've started talk of this EGT stuff, other tuners have paid attention as well and have improved their product.

That's good for the community so we share what we can but helping other companies is not good for business and I like my job.

I hope this helps.

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