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My 924 Turbo, data logging AFRs
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CÚdric  



Joined: 27 Aug 2004
Posts: 1838
Location: Sweden

PostPosted: Mon May 20, 2019 9:14 pm    Post subject: Reply with quote

So, i had a severe misfire issue which actually almost got me halted. I really didnt have time to sort the issue so i threw in a new coil and ignition amplifier since i knew those two were older than me. It seems to run great now, so I went out to do some logging with 1 bar boost again, now without misfires.

I didnt really have a lot of time so unfortunately the data below have maybe to few runs behind it to be certain. But it looks fairly similar to what I could see in the logs and on the display (though running 1 bar limits the time you can take your eyes of road). There were a few occasions where it dipped down to AFR9,8, which really is crazy rich, im surprised it even wants to run at those AFRs, it does seem to lean out very quickly at the top end where the AFRs are actually fairly reasonable. Its interesting to see how the airflow characteristics have changed with the IC and turbo change, before AFR were flat up until redline, but even at stock boost its now have this really rich midrange. A combination of the even inlet temperatures that the IC provides compared to no IC, and the airflow characteristics of the new compressor, with the non linearity of the flap system as a tricky layer on top of all this. They were quite finely tune as std these engines, with every CIS component in tune.

My biggest issue is that I got some flickers on the knock light, not sure it its false or real knock, it could be a sensitivity with the much higher cylinder pressures. I will have to fiddle a bit and see what i can come up with. I really should put in my knock control device, I think it also have output for head phones, which would be helpful.

Not sure where to go with the WUR, i will firstly try to limit boost enrichment a bit and see how it runs, then I will lay up a plan on how to deal with it long term, there are many alternatives, from very low tech to high tech solutions

I couldnt resist anymore, ordered a set of 7x16" Fuchs replicas, just have to decide on what tyres to use for the best fit and grip. Will have a wheel clearance soon, my BBS wheels, cookie cutters and some more wheels will have to go to get some money back and more space in the garage, and maybe a set of 6"+7" D90 if I could possibly find anyone interested in those.
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CÚdric  



Joined: 27 Aug 2004
Posts: 1838
Location: Sweden

PostPosted: Tue May 21, 2019 3:50 am    Post subject: Reply with quote


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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1639
Location: MI

PostPosted: Wed May 22, 2019 2:32 am    Post subject: Reply with quote

Do you have your boost sensor pre-TB so it never sees vacuum and your chart in psia?
That would explain the very lean readings at 1.000 where your engine is actually in high vac overrun but the sensor still sees atmo pressure..

I really doubt you are actually that lean in throttle (cause it wouldn't run at all) so all that stuff in the top right looks like overrun up to the 1.143 in the 4ks might be reading that little bit of pressure at overrun from compressor surge or whatever the BOV can't get rid of fast enough on overrun..

I think this is making your logs impossible to get good data from and you should put your sensor post-TB so you get boost/vac readings so everything where you are actually in vac isn't skewing the data on your chart at 1.000 and slightly above which is probably residual intake pressure after you have closed your throttle.
Even part throttle you will see boost pre-TB when you are actually in vac post-TB therefore the data is wrong..
For example, if you are cruising at like .5-.9 Bar psia post-TB/MAP you will still read 1.xxx bar psia pre-TB because your turbo is trying to push air through your almost closed TB..

I think your data on that log chart is quite useless and you shouldn't use it to tune until you get good data.. You need to log with your pressure sensor post-TB, MAP sensor style, so you are logging what you are actually running, and not whatever pressure is in your charge piping..
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CÚdric  



Joined: 27 Aug 2004
Posts: 1838
Location: Sweden

PostPosted: Wed May 22, 2019 4:03 am    Post subject: Reply with quote

You're right about the low load stuff, I wrote about it before earlier in the thread, any low load data here is not relevant. And since it cruises around stoich there is little reason to adjust anything, i keep good track on the low loads during driving. Anything in the plot from 1.5 and above is full throttle(which is the area that im interested in) , i was either cruising or hammering for the sake of logs. Though i will move the boost sensor pretty soon as i will prepare for next run with some other fiddling on the way to lean it out a bit.
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 1639
Location: MI

PostPosted: Thu May 23, 2019 3:21 am    Post subject: Reply with quote

CÚdric wrote:
There were a few occasions where it dipped down to AFR9,8, which really is crazy rich, im surprised it even wants to run at those AFRs, it does seem to lean out very quickly at the top end where the AFRs are actually fairly reasonable.


These occasions where it dipped into the 9's are at 1.9 bar psia at 1026rpm, 2053rpm, 2395rpm, and 3079rpm..

Now, how did you possibly have almost 1 bar of boost at 1026 rpm? Or even up to 2395 rpm? Can you even build .9bar at 3079?
This data looks unrealistic and therefore is probably also caused by pressure in the charge tubes that is not in the intake, probably when you dropped your throttle and it looks like your BOV didn't open very well to fill those boxes..
I doubt you could fill those boxes at all with a good MAP reading..

CÚdric wrote:
Its interesting to see how the airflow characteristics have changed with the IC and turbo change, before AFR were flat up until redline


Few reasons I can think of..
1. when you drop your throttle you have a lot more potential energy stored in your charge tubes now because they now have MUCH more volume, and are at a higher pressure than ever so you have a huge amount more energy to get rid of because of the increased volume and pressure..

2. Not only have you created more work for your BOV to equalize this pressure, due to the new higher pressure and volume, now you have a much smaller and less efficient BOV. The original BOV was huge overkill for it's job and superior to the new one with an even harder job.

3. You have a bigger turbo compressor now too.. You get that thing spooled up and it is also going to have more energy stored than your older smaller compressor due to momentum. So when you drop your throttle you are asking your BOV to equalize even more air now that that compressor is still pumping until it spins down..

The things that would skew the data on your charts are greatly amplified with your new system..

Is 2.0 bar psia as high as your chart/sensor/logging setup will go? If you are actually running at 2.0 I bet you have spikes higher than that when you drop throttle off full boost.. It just has to..
Your data is going to include pressure spikes from throttle drops all the way up to and through 2.0 and corresponding decel coming back down through them in decel, so your entire chart is tainted..

I would contend that all your data at higher pressure than 1.5 and below 3k rpm is false readings, unrealistic data, likely all overrun, you probably can't even build that boost there if you tried, which especially includes all of your 9.xx AFRs you are concerned about..
(your chart is upside down, if I say "below 3krpm" it's actually UP on your chart, or if I say "above 1.5 psia" it is actually down on your chart.. So it's hard to choose words to describe it correctly)
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CÚdric  



Joined: 27 Aug 2004
Posts: 1838
Location: Sweden

PostPosted: Thu May 23, 2019 5:23 am    Post subject: Reply with quote

Relax , i have a pretty good feeling of how the logs look like, this is just a quick summary of several runs. I do look at the transient logs aswell, the 9,60-10 AFR comes just as i hit max boost at low rpms, then it jumps back up to 10,2 something a couple of rpms later, It was repeatable.

I had quite some signal issues this time, thats why you see some outliers, obviously i dont have boost at those rpms. Theres very little boost spike when i let of the gas, almost impossible to see in the logs actually, so the BOV does what it should. The boost controller also works ver well, theres almost no data at all above 2, so didnt mind taking that in.


Not sure why i dont get as good speed signal, it works well for a while and then drops out and then resumes a second later., or freezes I didnt have that with the old ignition parts when they were working. Maybe its something in the ignition system that still isnt working 100%. Could not feel anything in the car though, or maybe the innovate is on its way out

I wished i could filter out points where it only have like 1 or two data points, but i can at least mark them with colours, red is almost no data, green is alot of data. Here it is but for several sessions added. Wish there was more customization properties in the software in general.



For next time out the line is already moved post TB as I rerouted everything to include a pressure regulator to the WUR, to control boost that it receives, which will be interesting to see how easy it is to limit boost enrichment. But i will mostly go for full boost only so wont make big of a difference in the interesting range.
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CÚdric  



Joined: 27 Aug 2004
Posts: 1838
Location: Sweden

PostPosted: Wed May 29, 2019 4:28 am    Post subject: Reply with quote

It seems that i adjusted the boost enrochement limiting knob the wrong way, hence didn't see anything different.so last time logging was a bit wasteful, even though accelerating on country roads is fun anyway. Its pretty quick at 1 bar! It also seems like i roasted my o2 sensor, i hope its wiring issues

Got my maxilite fuchs aswell, though two of them had some paint issues,so they sent out new ones and a courrier to pick the old ones up. Great customer service. It will be tricky to get a good fit, much harder than the cookies due to the added diameter. Well see what tyres i can find to make i work.

Same as last time, my rpm signal is on the way out, it was even more shaky this tim. Green and blue cells have pretty good data. Its so rich my o2 sensor and tailpipe looks like it from an ancient diesel, all covered in carbon :/ really need to lean it out..



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CÚdric  



Joined: 27 Aug 2004
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Location: Sweden

PostPosted: Sat Jun 01, 2019 11:23 pm    Post subject: Reply with quote

Went for a ride with my oldest boy today (4,5 years), he loves numbers and maths, so he gave me constant info on the AFR numbers, very practical I forgot to hook up the boost line to the WUR, which also happened to solve all my problems(the engine overfueling), the AFR curve is now nice and good. I would like a tad more at max power, instead but its a good compromise. So maybe im finished with fuel tuning now. To bad my O2 sensor went out again, changed earth point aswell, but that didnt cure the rpm drop outs

Power comes on pretty hard now when i leaned it out, 225 toyo T1Rs in the rear have no chance in 2nd gear when you push out of the corners. Might explore that further next time when Im without kids in the car

It wasnt the most obvious solution, but did solve my problems. To bad my O2 sensor is failing on me, need just some more verification to be sure it works at longer pulls etc.


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CÚdric  



Joined: 27 Aug 2004
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Location: Sweden

PostPosted: Wed Jun 05, 2019 5:26 am    Post subject: Reply with quote

New r comp track tyres are in, a tad wide for 8 inch wheels, but ive seen it work well on a 944 s2, so should work well on my car aswell. Even though it wont utilize the 245 fully it will be a big step up from my 205s, will be needed to put the new power down I got them for a nice price, otherwise i would have bought 225s.


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