Tuning With Turbotuner On A Built 850R

[JCviggen]

Yeah you can run without an o2 sensor, runs pretty well actually. But if you live in a place that sees big temperature swings you'll run into large AFR differences in cruise.

Tuning it without an o2 and then reconnect it is pointless because it WILL then apply correction factors anyway putting you back at square one.

[Über855R]

Tuning it without an o2 and then reconnect it is pointless because it WILL then apply correction factors anyway putting you back at square one.

Your point is well taken. I am curious though if you don't mind indulging me, wouldn't those corrections be better if the base map is more accurate without corrections? Essentially leaving a smaller margin of error to correct for.

On a related note, I have been tuning primarily at night and am getting close to 11.3 AFR everywhere that I have been testing. Usually under 6k rpm. During the day I am seeing basically 12.0 AFR with the exact same settings. I'm guessing this is due to ecu corrections for ambient temp based on MAF readings of air density. This seems like a wide variation of AFR conditions, is that normal/acceptable?

Also, I'm reasonably certain that my continued AFR spikes are due to not enough timing advance. Greg Banish says to lower EGT you advance spark and if knock becomes a problem adding fuel is the best method to combat the knock. Only retard timing as a last resort. He recommends smooth rolling maps where the timing map is essentially an inverse of the fueling map while allowing for timing pull at high load for the same rpm. Another tip he had was to tune at relatively fixed rpm points for perfect AFR and timing via EGT then smooth the maps between those fixed points for a smooth transition. This method should yield very close results to what will be required in the transition rpm's. Allowing for extra fuel at higher load and similar rpm's to account for sudden throttle plate opening causing higher load for the same rpm.

He also threw out a tip about advancing timing to slow turbo sloop speed, lowering the EGT values will give the turbo slower spool and make a nice transition between boost and NA parts of the motor. The converse can be employed as well, retarding ignition advance can make higher EGT values and as a result done properly can get the turbo to spool more quickly if so desired. It could be my quick spool characteristics are a result of my retarded timing map. Or similarly George you might just need to retard timing a bit to get quicker spool.

[lookforjoe]

I think you can run much more timing than you have. No reason for the 0, 6% load values to be so low, esp over 1200rpm. Low timing values can induce higher load/boost onset, but the tradeoff can contribute to higher EGT's as you have experienced. I think you can run much closer to my map.

[EricF]

Reading about all of this datalogging and thinking about EGT/AFR and how everything relates makes me miss that blue 244. Tuned Megasquirt just by feel, never even had O2 feedback. Good enough for 100+ mph traps and cross-state drive-ability. Man, anyone want to buy the 850 so I can get another 240?

Glad to hear things progressing, and that it is helping other people refine their setups. Mine still sits in the garage

[Über855R]

I think you can run much more timing than you have. No reason for the 0, 6% load values to be so low, esp over 1200rpm. Low timing values can induce higher load/boost onset, but the tradeoff can contribute to higher EGT's as you have experienced. I think you can run much closer to my map.

You are so right. I went out tonight armed with a very close AFR map and a little info on timing and wow did things get better. Where the timing was previously 11* it is now up to 23* with everything earlier shifted up as well. It still spools before 3k and I am able to hold 10psi prolonged now without topping 1400*F. I haven't gotten to tuning above 5k rpm yet but below that mark is shaping up nicely at 10 psi. After my tuning I did a little freeway pull up a hill and where before I had EGT skyrocket now it held firm. Also had a new Audi chasing me and could pull away easily. Couldn't tell what kind because it was so far away. I think that timing map I was using would be better for like 20 psi. At 10 psi I can run a lot more timing.

Can someone help me out here, I remember something about more boost equals less timing. Is there a rule of thumb for how much timing to pull per psi boost raised?

[JCviggen]

Your point is well taken. I am curious though if you don't mind indulging me, wouldn't those corrections be better if the base map is more accurate without corrections? Essentially leaving a smaller margin of error to correct for.

Maybe, but you'd have to make considerable changes still...

The way I used to do it was simply to get the main fuel map "somewhere in the ballpark" to the point that at least it wouldn't give me a CEL.

I would then drive for a while until I was sure that the ECU had made the necessary corrections, and after that I would adjust only the WOT fuel sliders to give me the right full load AFR.

I never encountered big swings in AFR when tuning this way, at least until I had to disconnect the battery again.

Greg Banish says to lower EGT you advance spark and if knock becomes a problem adding fuel is the best method to combat the knock. Only retard timing as a last resort.

The best map I ever ran was for the most part tuned by a friend of mine who ran a sophisticated knock detection unit. His results were that at least on our volvo engines, it made more sense to tune for 12AFR, conservative timing but lots of boost (big turbo obviously)

He told me that to gain a single degree of timing he had to add a ton of fuel and that robs more power than you gain. It was much easier for him to add boost than to add timing without running into knock. And I must agree, my engine always felt best around 11.8-12 AFR but really not much more than that. When I first flashed to his timing map it felt slower than what I was running but the GPS timers didn't lie and it was actually well quicker...just more smooth than the aggressive map I had.

Afterwards I fine-tuned it on the dyno and the only place where it really needed more advance was at 6500-7000+ rpm. Below 6K you really need to go quite easy on the timing, in fact the base rica 'tuned' map supplied with TT is very close to being spot on, only needs extra rpm points at the high end with timing quickly ramping up above redline.

[Über855R]

The best map I ever ran was for the most part tuned by a friend of mine who ran a sophisticated knock detection unit.

What type of knock detection? I was reading about measuring cylinder pressure while the motor is running to determine the knock limits, is that what he used? Thanks again for the input.

Could you post the timing map for that tune so I can compare the basic layout?

I'm pretty sure the maps I had been using had timing setup for 18-20 psi and that's why the timing was so retarded. I could probably turn up boost and get good results but for the low boost it seems like the motor wants a lot more timing. I have thought of using gps to time pulls also now that I found a nice, straight, flat, deserted, road to play on.

[Martijn_B]

Simply started the day with an old map, pressed +5% like five times, and it gave me a perfect AFR at idle between 14.7-15.1.

Then went for a drive, and it was actually pretty good but will need some fine tuning.

AFR readings:

Cruising: 14,6~15,0

Part throttle: +-13,5

WOT: 11.6

Might be a little leaner in some areas, but not too bad for 5 minute-tuning. The car kept working throughout yesterday and today, so no weird changes anymore.

My timing map looks like this, which I think is similar to the RICA tune that Jan mentioned:

You can clearly see that it retards timing at the 3200 RPM area, probably due to the max torque peak for the Mitsubishi turbo's. My Garrett wont hit full boost < 4400 RPM, so I am wondering whether the table should look different in the WOT area for me.

[JCviggen]

What type of knock detection?

http://www.phormula.co.uk/KnockMonitor-KS-4.aspx

Could you post the timing map for that tune so I can compare the basic layout?

Unfortunately the tuning laptop is 2000 miles from where I'm at. But I would say the base "tuned" map is about right for standard T-5 compression...you're in uncharted territory with yours.

[Martijn_B]

I am going to start with a det-can next week. Just as a basic solution to see whether I can hear something.