Mellon Racing

iTrader: (38)

Entirely too lean during spoolup it's likely ruining the entire pull. I would fatten that up quite a bit. Once that's in check, I think you'll find some torque.

AutoXer

iTrader: (1)

In an effort to try to minimize my amount of time going "over the speed limit" on the street, what AFR should I shoot for? I realize that there is no magic number, but I'd like to get it close before I start tweaking for knock reduction.

BTW, this knock went away when I ran straight 100 octane unleaded a few weeks ago. So, it is real knock.

I try not to run gas from shady looking stations, but my car has 73,000 on the odo. What are the signs of injectors going south(clogged, bad spray pattern, ect.)? Will it show in the AFRs at WOT? It may be a good time to upgrade just to eliminate the worry. Perhaps this should be in it's own thread.

Mellon Racing

iTrader: (38)

I would start by trying to get the afr in the low 12's range when you go WOT and get it closer to low 11's by the time you reach peak boost.

you're exactly right, if you added race gas and the knock went away, it's real

You might consider pulling the plugs and see if the color of the tip matches in each cylinder. I'm sure there are some tutorials online that explain the colors but in a nutshell, you want a nice cardboard brown color. Darker means it's rich and lighter means it's lean. Keep in mind that leaded fuels like some race gas will turn the plugs white as well.

Mad_SB

iTrader: (8)

While you are at it, look at the piston tops through the plug hole with a bright flash light and make sure that all the tops are uniform in color, if one is lighter than the rest you may have a bad / weak injector.

TouringBubble

iTrader: (2)

If it helps, I'm running at 11.2:1 on 93 at about 22psi (~245 load) with 4* of advance at peak ramping up to 13* over 7000 rpm. AFR starts at about 13:1 during spool up and levels out at 11.2:1 @ around 3650 rpm. I get 1 knock count randomly in the 4000 - 5000 range.

It is a IX though ... not sure how much that matters.

nothere

iTrader: (23)

I'd suggest disabling lean spool and richening the 13s you see in the low rpms. Kill lean spool first, log and see what you have, work from there.

Even in moderate load you may find it hard to run as much timing as you have.
You also have to consider the advice you get, take it with a grain of salt. Each of us has a personal method that works in our own case, but may not be best for anyone else.
In my case I would do low twelves on spool up and mid elevens the rest of the way, maybe fall to the low elevens up top. And as I said, timing seems a bit high.
I seem to need, two, threes, and fours where you have fives and sevens (3000 rpm through 5000. (as low as 180 load)
I even needed to lower the low load areas that may have been tainted by a mail in flash. Some 17s and 23 had to drop down a bit too. (around 100, 120 load)

At any rate flashing is relatively harmless, oh oh bad choice of words, what I mean is try lowering the timing and try lowering the afr, see what happens and go from there.

your question about the injectors may be spot on, might be wise for anyone with that mileage to think about having the injectors flow tested/cleaned. still your logs should/could be a simple matter of needing some adjustments.

nj1266

iTrader: (6)

It matters a great deal. The IX has better cooling in the cylinder head and is therefore more knock resistant than the 8. It is hard to run the numbers you are running on an 8 and not get knock.

Mad_SB

iTrader: (8)

not to mention the difference in cam timing / overlap with mivec.

Mellon Racing

iTrader: (38)

his timing at peak boost isn't alarmingly high, the problem is the fuel more than anything. He may still need to shave off a few degrees but he won't know until he gets the fuel dialed in.

iTune

iTrader: (3)

HAHA....thats funny.. Really, it is. VERY ignorant comment. After looking at his timing maps, it's more than obvious that my hunch was correct. Of course he's running a bit lean at peak torque...... but, his timing is making things a lot worse.

Just because i choose not to sell anything on these boards and am not a vendor, does not mean i'm not qualified.... i would work you in my qualifications. You have no idea who i am man....no idea.

NOW....back on topic

CJ

AutoXer

iTrader: (1)

4 or 5 degrees at 4750RPM(where the knock jumps up) is too much?

Please.

Evo_Jay

iTrader: (17)

It matters, but an VIII can run more ignition timing then a IX. IX usually run around 13-15* up top and VIII usually run 17-22 up top.

iTune

iTrader: (3)

The timing before that seems a bit high. Every engine is different and will have different needs while tuning. It is true, when knock gets going, the cylinder temps and pressures raise and can get worse as the run continues, even if ignition timing is reduced and/or AFRs are richened up.

Reduce timing in your 3000-4000rpm range(peak torque) to about 3 degs...... slowly increase ignition timing to about 13* at revlimiter.... Of course, how fast you advance the timing as RPMs increase will be trial and error. Don't increase the timing too much, too soon. Richen AFR's up in the 3000-4000rpm range to 11.5:1 and keep it there until you get to about 6000rpm, then slowely taper the AFR down to 11.1:1.

PLease, remember that timing adjustments will effect AFR. As you retard ignition timing your AFRs will go richer....if you advance ignition timing, they will leaner.

The MAIN reason why i asked to see your timing maps is because of this. If you retarded your ignition timing a little, the fueling changes would not be as much as you think. Like I suggested, reduce your timing and see were your AFRs are..... If they are still a little lean in these areas, tune like i stated above. You won't have a problem.

Also, very important....when making your runs for tuning...do it in 3rd gear ONLY(this will ensure you won't run too lean in 1-2nd gear or too rich in 4th-5th gear onced tuned). After you get fuel and timing like i stated.....advance timing 1 deg at a time throuhout the pull and see what happens. If you run into knock, retard ignition timing 2 degs in that area then advance ignition timing everywhere else 1 deg.....do another pull....but pay very close attention to AFRs. Keep doing this until you can't go any further, then retard ignition timing 1 deg accross the rev range for safety. Remember, as you advance ignition timing, your AFR will go leaner. So pay close attention to what your timing changes did to your AFRs. Adjust fueling accordingly to keep your target AFR.

with that said, i doubt very seriously you will be able to get more than a few degs over the timing i stated, throughout the pull, with no knock.....with AFRs where i suggested.

Of course, vendors arent going to give you this information. i'm giving you information that will help you now, and won't cost you anything. The best way to tune ignition timing is on the dyno, but the methode i stated above is best if you have no choice but to street tune. The stock EVO knock sensor and it's protocols are very effective in hearing knock before it's audible to the ear, which makes it very safe. Stay 1-2deg behind the knock sensor for safety.

Good luck!

CJ

JohnBradley

iTrader: (30)

Up top is a far cry from peak torque and therefore peak cylinder pressure however. I know E85 guys (running an VIII) that have a hard time duplicating the timing a IX can run at almost the same boost on pump. 28psi spike 0* on E85 vs. 4* at 25 on Shell 92. BIG DIFFERENCE.

C6C6CH3vo

iTrader: (9)

Confusing, I'm lost