PO244 and other tuning related issues. Help to understand what is happening

I have a few minor issues with my tune but I'll start with one at a time.

During my tune (dyno & road) my car drove perfectly. 2 weeks later it rains (+colder temps) and I get the PO244. I assumed it to be ambient temp and tried my best to keep boost below 21psi (not easy to do and hit the same cell code a few more times).

I noticed that the ambient temps were around 57-58* when it happend but when it rose to around 61-62* no more PO244. This led me to believe it was only temp related.

Later on the temps warm up to around 62-65* and I get it again. Now thinking that atmospheric pressure also has something to do with it. It later warms up to over 70* and for another week I never see it again and this time I cannot boost over 21.8psi (thinking everythihng is back to normal).

Just this morning I hit 21.9 and get the PO244 in 73* ambient temps.

Now I'm utterly confused as the atmospheric pressure seems less, w/less moisture in the air, warmer overall... I don't get it.

-Drew

Hey drew, here's some info about my 2 overboost codes in case it helps:

1st time was at a Track day @ Buttonwillow. 70ish temps, pretty dry day. Chevron 91oct gas in Bakersfield. 1st session of the day, 9am, I was coming out of turn 2, a tight slightly uphill 180 degree turn. As I was straightening out, I went WOT and coded right away.

2nd time was at Infineon. 50ish degrees, rainy. Random Valsomething 91oct gas. Coming out of the last pinwheel turn, again I must've hit WOT a bit too early. Another slow 3rd gear turn, I overboosted a second after going WOT on that front straight.

During logging sessions or during my commute, I've never popped P0244, clean LV's. During my last sessions @ Laguna, I added some octane booster just to make sure I didn't have any crappy gas. No problems all day.

Let's see, so what was similar between the two overboost situations: low-ish temps, 50-70 degrees. Both were in 3rd gear, coming WOT out of a slow turn. Throttle input from 30% to WOT was a pretty quick slam of the gas.

Since then I tried to be smoother on the throttle inputs, and haven't overboosted since.

You are overboosting. What boost should you be hitting? It's simply a matter of either a) boost fuel cut set too low, or b) boost targets too high, or c) boost control that still needs some work. I'm guessing it's the latter.

More than likely it is happening in higher gears and lower rpms and lower temps. Using stock boost control I have my tune set up so that I run less peak boost than lower gears. It's fun getting this set up, actually. You should post some logs. Get 2nd and 3rd 2k to 6k rpms and also get 4th and 5th to 4krpms.

Once set up you can go WOT at any time in any gear and not overboost. Stock boost control is pretty powerful.

Let's see, so what was similar between the two overboost situations: low-ish temps, 50-70 degrees. Both were in 3rd gear, coming WOT out of a slow turn. Throttle input from 30% to WOT was a pretty quick slam of the gas.

 

Since then I tried to be smoother on the throttle inputs, and haven't overboosted since.

So its a combination, and now factoring in load? If I recall I was at least in 3rd and wot.

You are overboosting. What boost should you be hitting? It's simply a matter of either a) boost fuel cut set too low, or b) boost targets too high, or c) boost control that still needs some work. I'm guessing it's the latter.

 

More than likely it is happening in higher gears and lower rpms and lower temps. Using stock boost control I have my tune set up so that I run less peak boost than lower gears. It's fun getting this set up, actually. You should post some logs. Get 2nd and 3rd 2k to 6k rpms and also get 4th and 5th to 4krpms.

 

Once set up you can go WOT at any time in any gear and not overboost. Stock boost control is pretty powerful.

I know it's overboosting, but I'd like to know why it's happening or what it is the ECU sees that triggers it. It's not simply boost (but maybe just boost+load?). I have hit 22.4 and not gotten a cell (HKS Camp2 w/boost plumbed into the BPV line).

If I remember correctly 21.8 was max. I do have a couple logs, one was showing the PO244 and the second was to represent the other issue I'm having. Which is what I think may be an open/closed loop transition issue. I'll go look for them and post it up.

BTW, Grimmspeed EBCS here.

Data logs would help a lot. See if you can re-create the problem. Even if you don't actually over-boost, the logs might shed enough light on the problem to fix it. Log these parameters:

* throttle plate angle

* target boost

* actual boost (manifold relative sea level pressure)

* initial wastegate duty

* primary wastegate duty cycle

* turbo dynamics proportional

* turbo dynamics integral

Use the 2-byte versions where possible.

Ok, my nephew was logging and after several he says he captured the two best examples. One showing the low rpm studder and the other capturing the overboost.

I just looked at them and if these are indeed it then I cannot tell which is which...

So how best to share a .csv file? I have them zipped together. I can share via e-mail. PM me an address if thats the way to go.

I think we need to log it again.

You can PDF it and post it.

What are boost targets? What is the boost cutoff set at?

You can attach .csv files to replies on this forum. Click "go advanced" below the text box, you'll get a page with more options, including attachments.

Attach each file separately.

FYI did you know that there is a delay in triggering P0244? (Probably built-in delays on triggering many CEL's for that matter.) Simply exceeding the preset limit is not enough alone to trigger the CEL. Once that threshold is surpassed, the ecu monitors it and if the condition reverts back to acceptable quick enough the ecu won't bother with the CEL. That might be why you've seen P0244 with 21's and yet have seen 22's and no CEL.

In low gears you go thru the rpms so quickly that unless the overboost is really excessive, it's not going to trigger the CEL. (The ecu will be tolerant of exceeding the boost cut limit if it is temporary enough). In high gears you can't whip thru the rpms as quickly and if you start overboosting and your TD isn't set up well enough or more likely you have inappropriately high boost targets you will continue to overboost and trigger the CEL.

TD does the work to correct overboosting. For me, the key has always been to set good targets under 3rd gear peak boost. I'll plot my targets the same shape as a 3rd gear plot at 50F or so and simply move the targets to the left 100-200rpms or so. That way lower gear spooling is never hampered but high gears aren't allowed to go unchecked for so long.

My hunch is that your TD might be fine but you simply have crazy high boost targets under 35000rpms.

Ok, log files but... to my untrained eye they look like both were an attempt to showcase the low rpm studder and not so much the overboost, but I can't be certain.

If they are both useless I can do it again this weekend using the AP. If so, log the same parameters as listed above?

romraiderlog_20101229_122013.csv

romraiderlog_20101229_122110.csv

You can PDF it and post it.

 

What are boost targets? What is the boost cutoff set at?

I didn't think to ask at the time and Shawn is very difficult to get ahold of.

You have an '08. There should be IAT compensation for WGDC as well as proportional and integral turbo dynamics. I would start by trying to adjust the compensation tables first and leaving everything else alone.

hold on...I would say to leave those tables alone and get boost right.

You always need to compensate for the weather and Subaru OEM does a good job of this. I left mine alone and never had an issue :shrug:

hold on...i would say to leave those tables alone and get boost right.

+1

It all comes down to the whole workflow. If boost was behaving correctly in one weather condition and only gets messed up as weather changes, then the compensation tables are the way to go. Otherwise by going back to all the main WGDC tabels you could end up chasing your tail by having to retune a bunch of stuff over again. When spring comes around the problem could be underboosting instead.

However if the boost was indeed never right in the first place then changing a bunch of compensation tables won't solve the problem. It takes some experience and good judgment to figure out which way to go.

Remember though that the compensation tables are optimized for a factory unmodified engine. A few tweaks can be helpful once you start changing exhaust for example.

My guess would be the tuner already messed with this table and that's the issue.

Weather in Chicago ranges from <0 to >100 and I have never had an issue using the stock table.

It all comes down to the whole workflow. If boost was behaving correctly in one weather condition and only gets messed up as weather changes, then the compensation tables are the way to go. Otherwise by going back to all the main WGDC tabels you could end up chasing your tail by having to retune a bunch of stuff over again. When spring comes around the problem could be underboosting instead.

 

However if the boost was indeed never right in the first place then changing a bunch of compensation tables won't solve the problem. It takes some experience and good judgment to figure out which way to go.

 

Remember though that the compensation tables are optimized for a factory unmodified engine. A few tweaks can be helpful once you start changing exhaust for example.

Ok now you have me thinking...how/why editing the compensation table would mater depending on a TBE?

Maybe if you had a CAI I could see changing these.

NSFW's parameters would be great. Throttle plate angle isn't necessary but wouldn't hurt. Those logs you already have don't help. Drew are you going to be able to edit and flash your tune? Should be an easy fix.

No I don't.

Silly me, I have always gone with Shamar but it was inconvenient and he was too far away (no wb02).

On a reccomendation and some research Shawn Church seemed competant and gave him a shot.

Since I had a good "Infamous1" map just prior to my built motor with only the pistons changing things I asked him to adjust that tune after he moves and gets somewhat settled in. So that's probably the weekend of the 15th or 22nd. Oh and another $100...what a $ pit.

Weather is warmer today (76*+) and I pulled a PO244 this morning.

I'll come back to that...

On this tune I can avoid this while in Sport mode. Also, when it chooses not to pull the cell I can nail the throttle at anytime and it pulls nice and smooth to redline without issue. I dare say it feels perfect.

So I realize it's a minor adjustment but this is frustrating the hell out of me.

With the talk above, you guys are getting me excited to go open source and give this a shot. Especially with support like this!

Finally got ahold of Shawn and he claimed to have e-mail issues.

Anyway, I'm logging tomorrow morning and then over to his shop around 2pm so he can fix it.

I'd like to get the logs to you long before I go there.

I'm also very interested in any advice you would offer him as I don't know enough to advise him as he attempts to do his thing. Quick example, what should my target boost be etc?... 21.5 on Cali 91? or can I get away with a little more?

I'll get the logs up first... Thanks for the help!

Drew I've got mine peaking around 22.5-23 from 3500-5000rpms then taper to 17 at redline. Same turbo as you, but my E85 and elevation both make a big difference. And you have a FMIC to my TMIC. All that comes close to cancelling out, I'd surmise.. and I'd say you ought to be running about 0.5-1psi less than me. You could be knock limited... Your tuner should find the sweet spot. Is/was this a dyno tune? I'm sure infamous would know about where you should be. It doesn't sound far off anyhow.

Find out what your boost targets are under 3500rpms.. still my hunch that high targets at low rpms is part of the problem.