Log it both ways and see which one runs you into knock. I'd add a bit more boost and see what that nets since more airflow is likely going to make more of a difference than a leaner tune. If you see dips in timing, back the boost down until you see a steady timing curve from the onset of WOT to the end of the gear. By they way, narrowband readings are crap. It's IDC, IPW and knock that determine a safe tuning limit.

andymoraitis said:

Log it both ways and see which one runs you into knock. I'd add a bit more boost and see what that nets since more airflow is likely going to make more of a difference than a leaner tune. If you see dips in timing, back the boost down until you see a steady timing curve from the onset of WOT to the end of the gear. By they way, narrowband readings are crap. It's IDC, IPW and knock that determine a safe tuning limit.

Click to expand...

If I could log IDC IPW and KNOCK then I would be in great shape...
But all I have is my logger and I'm a 2g...

850s, with 43 psi base pressure, fuel specific gravity of .75, and a target AFR of 11:1, will support 61 lbs/min. I maxed out a 60-1 at 62-63 lbs/min. So 850s are the bare minimum. If you are going to do some form of injector compensation, which is absolutely required as adequately covered earlier in this thread, you might as well go right to FIC 950s or similar and buy yourself some headroom. Not to mention that most poeple that go to a 60-1 eventually upgrade to some form of a 56 trim GT turbo anyway

Given the same variables stated above, 550s will cover exactly 40 lbs/min. Most 2 liters with cams can do this at roughly 20 psi, so I would suggest keeping it to 15 to be safe. I personally would not even run the car like this, all it takes is a blown off boost controller line or something to let boost get away from you. Without enough fuel system capacity to cover the turbo's max flow rate the motor is pretty much toast.

Well I got my aeromotive external FPR... fuel pump rewire...
I'm running 16 psi w/ my 550's leaned out -22 all the way high

My log shows 1.00 volts from 5.5k till redline...
timing is low and ends at 15 advance at redline...

Seems like my car is running rich ???

so lean it out more?
Or
add another psi or two of boost??

Check out this page on my site, there is a screen capture of my front O2 reading .98 volts while my WBO2 read 13.5:1

read my posts in this thread to give a brief explaination of injector to pump sizing. particularly the post on page three with the pulse to time explaination through cycles.

http://www.dsmtuners.com/forums/showthread.php?t=141667&page=3&highlight=injector+pulse

Now as I read back through I didn't see me mention a surge supressor for the fuel system. If you have one things will be a little different as it acts like a little battery.

Do not go lean!!!!!

Ok point taken... I really don't wanna blow my engine.

I also had my fuel pressure at 44psi...

So should I drop my fuel pressure back down to 42.5?
Drop Boost back down to 15 psi?

Then my car runs like a rich bich...
I'm talkin I have to go -28 on high for it to even pick up.

Also, If the o2 readings are so off on the logger what is the point in logging it??
and why does everyone stress over it?

Seems to me only timing seems to be worth anything

I can't remember if we've already covered this or not, but assuming everything is "normal," you would need -18% correction just for the 550s, then another -10-15% to get into 10.5-11:1 AFR range. The settings you mention seem to fall into this range.

Logging front o2 is worthless in most cases, but it's all 2g owners have if they don't understand timing. If airflow is not high enough to remain on the highest load map, it's tricky even for people that do understand how this all works. You have to know what the ECU's target timing is in order to know if any timing has been removed because of knock. To be honest, I don't know how I used to get by like this. Better you than me. But I can say that the highest load map has timing ramp up from 4 degrees at 3500 to 16 at 6000 (through 7500), so it should not be less than this if there is no knock. You can lose timing to high coolant temps (1 degree at 206 and 2 degrees over 220, roughly, and 1 degree lost below 35 degree intake temps or over 80, all of which can be obtained from your logger). In most cases though, yours included, timing will be higher because your airflow is not high enough to get on this map, which means the ECU pulls this value from the base timing table, and it's tough to know what it should be. Taking out airflow signal with an AFC or similar compounds the problem even further. See a recent post where I outlined how to go about sorting all this out using logged airflow (2g loggers should be able to read lb/min). It is possible to do a lot of math (or build a spreadsheet) to compare to the stock timing table, but there's no way I'm going to get into that now. I think you were talking about getting DSMlink at some point anyway, which is the best thing you could do.

May I play Devil's Advocate for a second here? Let me start off by saying that I will be the first to admit that I am no longer on the 'cutting edge' of DSM technology, as I have been away from tuning these cars for quite some time now. Just a few months ago I did the 'free mods' on a 92 AWD and it brought back a warm fuzzy.

With that being said, when did these cars get so damn complicated? My experience with DSM's (aside from the breakage associated with making big power out of 2 liters) was pretty positive, and pretty easy. I'm not knocking anyone, as I think it's great that you all are delving so deep into the fine points of fuel injection, etc. but man, it's really not neccessary. It's not rocket science, and my constructive criticism is saying that I think a lot of you should really stop making it rocket science. The more you over-analyze, the more you LOOK for issues to fix, the more you are going to CONVINCE yourself that there are issues to fix, when in reality, everything is fine.

I passed over a thread yesterday I think where a guy mentioned he got 11 counts of knock for a split second while he was logging, and worrying so much about how to fix that, etc. Sometimes it's important, but sometime's it's not. If I sat around analyzing the possible problems I could have had with my Laser, I NEVER would have done what I did. Instead, I just did it, and saw amazing results. Truth be told, I had that car on a datalogger ONE time, and that was on the dyno. And ONLY because someone there had one! I tuned that car to 423 wheel HP on a small 16g using my buttcheeks.

The point of all this is I think some of you need to take a deep breath and relax a bit. Tuning a DSM, selecting parts, and putting together a dynamite combination is a LOT easier than you all think. It really is. The more you actively LOOK for problems, the more you are going to find. I guarantee it.

Regards,

Wow... I understand where both of you come from.

I wanna be careful, but not too obsessed with perfection. ### I know I'll never get that in this car...

It just seems to me if I was running 17-18 psi @8xxcfm w/ 550cc's @44psi and my timing is seeing 0 knock... then why is that bad?

Why do I "have" to get bigger injectors w/ anything over 15?
Don't get me wrong, I want bigger injectors so I can push 21-22psi... but I'm moving to alaska in December, so I gotta save.

With that being said, the move and all, I can't blow up my engine.

So I'm in a pickle... I wanna push my car to its limits w/ what I have right now, but safely.


( anyone have a chart for fuel pressure and how it bumps the cc size of injectors? )
I wanna see what 44psi fp runs my 550's at

Well I just burned a Supra TT today w/ me running 17-18 psi on my 550's... FP @ 44psi
I'm gettin good timing and my o2 reads .97

I dunno whats up with my car, I should be lean as hell with knock but I'm not.
Its never ran so good