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First real post. Been lurking around for a year shortly after I picked up my first turbo. I since put an exhaust and a tune (among a list of other mods) to compliment it, then recently started data logging via Durametric.
Looks like my ignition timing is being pulled (or decreased) when heading towards redline, in the 5-10 degree range. Starts to drop right around 3k RPM when boost is starting to build up. Is this normal? I've done some searching, and under the impression that ignition timing should advance (or increase) when RPM rises. Was hoping someone with more experience can take a look. Screen shot below, datazap link here. https://datazap.me/u/cjoy/3rd-gear-pulls-2?log=0&data=1
Are you running the stock intercoolers? My guess is yes as your intake temps rise super quick during your pull. Once you get over 50C, I've always heard the engine will start to pull timing. You didn't log knock, so we dont know if that could be a source of the timing retard.
One of the things I found out when logging with the Durametric long ago was that the knock data really didnt tell you much other that it was non-zero. When I datalogged with it I would get huge positive and negative numbers, which didn't really translate to anything. Unfortunately it may be a limitation of the Durametric software, as I never was able to get it to show true knock data. My UMW logger will show degrees of timing retard for each cylinder, which is helpful..
In California with crappy 91 octane. Tune was from Sharkwerks, and they use the EVOMS tune. Car does have the stock intercoolers. I changed my plugs less than 10k miles ago (right when tune was done).
I've also read that timing gets pulled when reaching over 50C, but based on the data log, it does not reach 50C until redline (6000+ RPM). But, the timing does start pulling back exactly when intake temps start to rise. Graph below has intake temps showing.
So I went to a gas station not too far from my place, and they carry race fuel, 101 octane. Loaded her up near empty (less than an eighth of a tank left of regular 91 pump fuel). Unfortunately, same result. Timing is being pulled starting around 3k RPM's. Screenshot below, datazap link here: https://datazap.me/u/cjoy/mission-hi...zoom=5081-5166
Depending on your tuner, if your tune is for 91 octane then adding race gas might not help much.. OTS tunes are pretty conservative as to protect the engine.
I had forgotten how crappy the stock intercoolers are, it's amazing to see how fast those temps rise.. even when you are not on boost the delta during cruise is huge in some cases.. You need to upgrade those..
In my time datalogging over the years, I have been surprised at the difference of just a 10C of IAT will make on the timing and knock curves..
I have the GT2RS coolers and they are good value option for a street driven, non-track car. Lots of opinions here, you can do some searches and have hours of fun reading material.
Do you see garbage data in Durametric for the knock values?
Yes, my next step is to get in touch with my tuner to see if it was intentionally set up conservatively, especially for being in CA with 91 octane.
I agree that the stock intercoolers are crappy. It is on my to do list. The reason why I picked up a Durametric to data log is to check on intake air temps to see if it was pulling timing so I had a baseline before I upgraded. Unfortunately, it looks like my car is pulling timing for other reasons than intake air temps.
I agree, there are a lot of threads about intercoolers and I have done a bit of reading. I'm looking at the do88 'small' intercooler upgrade, not the big pack. I think it is still slightly bigger than the 997.1 oem intercoolers, maybe about the same size as your gt2rs's (or the 997.2's). Reason I'm going for this set up is cost, $1k vs $4k for a bigger setup, my personal opinion is it's not worth it. Maybe worth it if I had bigger turbos. Another reason is lag, read on a thread that someone reported a slight increase with bigger volume intercoolers. Lastly, I'm planning on doing a meth/water injection kit which will address the crappy octane and help intake air temps overall.
I haven't recorded the knock values. Before I did the data logging last night, I tried searching Durametric software for the knock sensor, but couldn't find it. Do you know what the name of the sensor in the Durametric software?
Did you ever log with the stock tune? I suppose you could flash back to stock to see what it's doing in stock form.. this may help to determine if it's tune related or environmental.. The tune can be a major factor in how your map looks, i.e. aggressive timing that kicks back at any knock, vs. a more conservative tune with less aggressive timing.
What version of Durametric are you using? I have the enthusiast version and v6.3.2.5 of the software.
Looking at some of my old logs, I see values called "Retardation cylinder x" for each cylinder. As I said, the range of values are all over the place, so you can't really determine the severity. However, if it's non-zero, it should indicate that some knock is being detected.
Another thing about the Durametric is the sample rate.. depending on how many variables you are logging, the sample rate is only 6 per sec., at least back when I was doing it. Looking at your logs, that's about what you are getting, too. Just something to be aware of.
You may have seen before, but since you seem to be interested in this kind of stuff, here's a thread I did a while back about some of the data I saw, as well as a dyno thread with some additional data in it..
saabin, thanks for sharing your data logs. Looks like your data logs also show lower ignition angles (~6-8) in the same higher RPM range, especially when there is a lot more engine load. The way you graphed your data has an extra dimension on it (engine load), if plotted just against RPM at full throttle, it may look like it starts to pull timing around the 3k-4k range like mine. Do you have the raw data you can share that I can compare with? Not feeling so concerned now after seeing your datalog. Looks like ignition angle decreases as RPM increases, too.
Another thing I didn't think about is how AFR can potentially effect ignition angle. Based on your data log, there is less ignition angle on higher engine loads. I read that engine load is a function of RPM and air (not sure of the details). If this is true, I'm guessing AFR (air fuel ratio) can influence ignition angle since engine load is a function of air?
^ Each tuner can adust the timing profile at a particular engine load. I'm not sure in my case if it's more of a timing "pull" vs. limit setpoint so as to protect the motor in high-torque situation. Around 4300 is peak torque at around 585lb/ft (as per my dyno thread data)
Those plots were done a while back so I'll dig up the raw files.
Also, the ignition angle (timing) increases as RPM increases at WOT.. The load is decreasing a bit, but the data shows it increases to about 16Deg at 6800 RPM, although the load is lower.
I also noticed that the links I posted are both the same.. I edited my original post to correct that..
My current car had the ots evoms tune on it when I first bought it. I noticed not only pulling timing but also dumping fuel (with constant CELs), and this was with normal driving. I swapped to a custom fvd tune, (not easy to remove the 2009 evoms tune, had to send the ecu to Germany), problem solved. I think the evoms tunes are overly aggressive and is the root of your problem. I'd recommend custom FVD or UMW only on these cars.
These cars never run very much timing on 91oct, 8-10deg through the midrange is about as much as you see on a healthy car. This car is pulling a bit more timing than that so something is going on, but it's always going to be low for this fuel and these mods. Doing further modifications or running better fuel pretty much allows you to run more aggressive boost and timing until you get back to that bare minimum timing level.
First thing I would start is checking your MAF sensors. With the key on, engine off, check MAF voltage. It should be under 1.100v, if it's over that replace both sensors. I would also do a cursory check for intake/boost/vacuum leaks. The injection time is a bit high for the air:fuel and mass air flow, check the vacuum line at the FPR to make sure it hasn't blown off, and see if the fuel filter has been replaced in the last 5-6 years. Any of these three are super common issues for 997TTs that will all cause them to knock a bit, and since the car didn't respond to better fuel I would look into these issues first before changing the tune.
My current car had the ots evoms tune on it when I first bought it. I noticed not only pulling timing but also dumping fuel (with constant CELs), and this was with normal driving. I swapped to a custom fvd tune, (not easy to remove the 2009 evoms tune, had to send the ecu to Germany), problem solved. I think the evoms tunes are overly aggressive and is the root of your problem. I'd recommend custom FVD or UMW only on these cars.
Hey Surgeon. My car hasn't thrown any CELs so may not be the same problem you are experiencing. I should probably clarify in my original post about pulling timing. Meant to really just ask in general if the lower ignition angle in the upper RPM range is normal or not. I referred to it as pulling timing because of my understanding at the time (i don't think it's true anymore) that ignition angle should increase as RPM's increase. It doesn't seem that is the case especially after seeing saabin's data too.
These cars never run very much timing on 91oct, 8-10deg through the midrange is about as much as you see on a healthy car. This car is pulling a bit more timing than that so something is going on, but it's always going to be low for this fuel and these mods. Doing further modifications or running better fuel pretty much allows you to run more aggressive boost and timing until you get back to that bare minimum timing level.
First thing I would start is checking your MAF sensors. With the key on, engine off, check MAF voltage. It should be under 1.100v, if it's over that replace both sensors. I would also do a cursory check for intake/boost/vacuum leaks. The injection time is a bit high for the air:fuel and mass air flow, check the vacuum line at the FPR to make sure it hasn't blown off, and see if the fuel filter has been replaced in the last 5-6 years. Any of these three are super common issues for 997TTs that will all cause them to knock a bit, and since the car didn't respond to better fuel I would look into these issues first before changing the tune.
EVOMS, thanks for chiming in, didn't know that you guys roam this forum these days. Thanks for the suggestions, if the ignition angles I'm reporting are lower than expected, will check the things you listed. I had the fuel filter replaced about a year ago when I first got the car, so I'll scratch that one from the list for now.
Once solved, does EVOMS have a 100 octane map I can use? If so, are the gains significant? I did contact Sam and he did mention that EVOMS had tune files specifically for 100 octane, but never heard back from him. If gains are significant, I would like to purchase/download it.
So I did the following and didn't really find anything unusual:
Checked voltage on MAF, one read 1.016V, the other 1.005V
I used the needle trick from a search I did to take the reading
Checked FPR to see if vacuum hose popped off, but was okay
Checked the MAF reading from cold start and idle until it warmed up to 85-90C, it read about 19.5 kg/s, datalog here
I did a few more 3rd gear pulls tonight and still seeing the ignition angle dropping as far as 1! Data log here. Again, not sure if something is actually wrong with car or if the OTS tune is doing something funny.
more 3rd gear pulls, ignition angle as low as 1
cold start MAF reading, idling until temps reached ~85C
07-01-2018, 10:28 PM
My Datalog - Timing Question
