Thread: ENGINE TUNING - EGT, Psi and Wideband AFR

Originally Posted by RRT

Should have possibly just PM'd the resident tuner Shack LOL but this rabbit hole that I heading down has implications / interest for anyone who is looking at or has had tune.

Started out whilst looking for the combined EGT Boost Gauge, the site I found also had this interesting product.

JRP-14in1-automotive-digital-oled-multi-gauge-display.jpg

- Digital Multi Gauge Systems :: JRP Auto All-In-One Gauges

Have seen a multitude of these on ebay etc. but they were always OBD2 plug in systems and hence no interest for a D2, this one not so. For basically an extra $130 over the twin gauge, rather than just two inputs, it would give 14 and I could stick the Gear display to the right hand side of the display...

one of the inclusions is the air fuel ratio (AFR) sensor, sure knew of the petrol stoichiometry 14:1 but not so much of the diesel world. So heading deeper into the rabbit hole there is the 'wideband' AFR which differs between the two and then onto what happens with high and low instances - the JRP site gives a better explanation than I can.

It also has twin volt gauges and this I thought was pretty good for the rear battery monitoring.

Do not profess to know much about the tuning of the TD5 other than the tables etc, but how to change them or the parameters to change them within, well that's why you pay someone like Shack.

So the questions I have

1. does anyone currently monitor their AFR in real time and how do they use it if they do?
2. How much control of AFR is available throughout the rev range, turbo pressures and fueling of the TD5 when programming?
3. How do the flow maps of a turbo assist if available (went searching for these for my Garret turbo at Shacks request and they are for all my effort, seemingly unavailable)?
4. Correlation of the programmed tables expectations against real time AFR monitoring?
5. Is it worth having if 4 is not strong?

1. Yes... WB02 is needed.

2. A lot of control, but mainly on the rich end, the lean end can vary a LOT.

3. Having a compressor map is crucial when looking to buy a turbo, it tells you exactly how the turbo will perform under pretty much all circumstances. And yes, nearly all aftermarket "uprated" turbos for a TD5 will come without a flow map - it costs too much to test them

4. Correlation is very tight until you run to the lean side, then it can vary significantly, as the AFR map only limits one way, different turbos will also change AFR when running lean.

5. I don't understand the question!

Cheers

Originally Posted by shack

1. Yes... WB02 is needed.

2. A lot of control, but mainly on the rich end, the lean end can vary a LOT.

3. Having a compressor map is crucial when looking to buy a turbo, it tells you exactly how the turbo will perform under pretty much all circumstances. And yes, nearly all aftermarket "uprated" turbos for a TD5 will come without a flow map - it costs too much to test them

4. Correlation is very tight until you run to the lean side, then it can vary significantly, as the AFR map only limits one way, different turbos will also change AFR when running lean.

5. I don't understand the question!

Cheers

Thanks Shack, most informative!

Question 5 related to Question 4 that if correlation wasn't tight then would the sensor be worthwhile.

So the way that I am understanding it, running leaner leads to higher EGT's (?) and as with the standard turbo, the boost rate can be controlled by manipulation of the wastegate making the AFR simpler, boost at x requires y amount of fuel to maintain the AFR. VNT more complex as the boost rate is not controlled by software control but internally and this, not necessarily linear.

Originally Posted by RRT

Thanks Shack, most informative!

Question 5 related to Question 4 that if correlation wasn't tight then would the sensor be worthwhile.

So the way that I am understanding it, running leaner leads to higher EGT's (?) and as with the standard turbo, the boost rate can be controlled by manipulation of the wastegate making the AFR simpler, boost at x requires y amount of fuel to maintain the AFR. VNT more complex as the boost rate is not controlled by software control but internally and this, not necessarily linear.

Diesel is total opposite of petrol.

Lean in a diesel is cooler - theoretically a diesel can keep taking fuel and make more power (think those black belching tractor pulls in the USA) until eventually it gets so hot in there it just melts everything!

The other catch with a standard type turbo is inefficiency at higher rpm/boost leads to heat and as you drop off the compressor curve far less performance (in a simplified nutshell)

^^

Hmmm, lots of thought here to weigh up, but as I had not read the info correctly and the diesel AFR is not included and the minimum for this is over $300 taking it to just under $700, nice but that's one expensive cigar!

This said, the importance of watching the EGT's is heightened from here on!

Originally Posted by RRT

Hmmm, lots of thought here to weigh up, but as I had not read the info correctly and the diesel AFR is not included and the minimum for this is over $300 taking it to just under $700, nice but that's one expensive cigar!

This said, the importance of watching the EGT's is heightened from here on!

EGTs are just a number haha

Originally Posted by RRT

This said, the importance of watching the EGT's is heightened from here on!

I can confirm that 100% as i was stupid enough long time ago to think that i can make a remapped chip myself without studying deeply all the implications and altered the injector durations also used a voltage clamp on the MAP sensor.and tigthened the wastegate rod to max .. . didnt have EGT gauge nor nanocom at that time, the car went like a rocket strangely not with too much black smoke(maybe due to the increased boost), after some time and more study i bought a nanocom and fitted the EGT gauge, surprise... peaked up to 900*C uphill under load not once and the average was aroud 600... binned the chip right away and refitted the original but it was already late as i discovered soon that the head was cracked and the injector balances were all over the place with figures between 5 and 25, bought a new AMC head and 5 new injectors + remap made by Alive tuning, since then the average EGT is around 300 max 350 on motorway driving and never exceeds 650 no matter how i drive... so it wasnt a cheap fun at all, donated the chip programmer to a neighbour who is IT student... lesson learned: i'll let those who really know theyr stuff with remaps to do that as i dont have the energy nor enough neurons anymore to learn well the whole thing.

The good thing is when you run 30-40psi of boost you can run plenty of fuel and still have under 850c EGTs at WOT