Serious 50 Trim tuning questions

[aves911]

Okay, first off this is my setup

AFPR, bfp set at 32psi
720cc
255lph pump
-6AN lines

PTE 50 Trim
Ported O2, and manifold
2.75" turbo back

All honeycombs removed from MAS (except the big center one)

3" Intake pipe
Dejon FMIC with 2.5" piping
6-bolt swap

Now my questions

I just went out and logged my car to try and start tuning it. Second gear pull 26psi. O2's across the board at 0.94v. My EGT's hit 1600 at 7000 in second. But im not getting full spool until over 4K rpm. My timing doesnt drop to 10 degrees until 5100 rpm. From there it jumps to 17 at 6000 and only climbs to 18 at redline. Rich knock is my best guess there and mabey high EGT's from running to rich as well. Only problem is my AFC is already set to -35% from 3000 until 7000rpm. That seams really really lean to me, plus I have the fuel pressure dialed back and the MAS is hacked.

Any pointers as the what I should do next would be great. I'd like to reduce my lag so full boost hits at 3800, and to do this I need to figure out how to get my timing to drop sooner. The best I can figure is that the AFC is set so low that it sends such a low airflow signal to the ECU that the computer doesnt realize the car is under boost until the higher rpm range. On top of that, I can't richen it up anymore or I get rich misfires. But leaning it out to -40% on a 50 Trim at 26psi seams really really lean to me.

Any help is appriciated.

 

[brads]

Your timing should start levelling off and rising again after you reach full boost. The 2 reasons why this wouldnt occur, is that you have excessive knock, or that your airflow per engine revolution keeps going up after you reach full boost. The airflow/rev is what the ECU uses to figure timing out. It normally tracks boost pressure fairly closely.

The first thing I would check for, is to see if you have any boost leaks, using a boost leak tester. Between your hacked MAF, -35% on the AFC, and around -14% from the lowered base pressure, your car should be pretty lean. That it isnt could indicate leaks. Which would be consistent with the slower spool. If you find a big leak, fatten your fuel mixture back up before you run it again.

Also, have you considered trying to find your problems at a lower boost level? Maybe turn it down to 20 or lower, and start tuning from there?

Brad

 

[kpt4321]

Agreed, tune at a lower boost level, especially when you have nothing to go by.

How do your fuel trims look? What are your corrections on the lo throttle table? That can help you to decide if you are rich or lean.

If you really think you're getting rich knock (which I am skeptical even exists) then why not just lean it out and see if it goes away?

....Kyle T.
93 TSi AWD "TURBO4"
14b - 12.8 @ 108

 

[aves911]

The weird thing is...my HI throttle settings are lower than my LO throttle settings on the AFC. I tried using a boost leak tester, but when i put it on the turbo inlet and pressurized the system. I just lost pressure out through the valve cover. I don't burn any oil or anything so I know my valve seals aren't bad (I just put new ones in a thousand miles ago). I think I might have a leak somewhere. But how do you build and use a good leak tester. Mine was just a piece of PVC with a valve stem in it and I used the air compressor at a gas station. I would put air in, but it never registered any positive pressure.

I did turn it down to 20 pounds and I am trying to get this stuff dialed in right.

Thanks,
-Jacob

 

[kpt4321]

Wheee, boost leaks!

Do you mean that the air was coming out of the valve cover vent? If that is the case, then your PCV is done. You can either replace it with a new (Mitsu) one, or do the PCV elimination procedure (http://home.attbi.com/~tarryo/kyle/pcv.html).

Once you get that leak fixed, then you should try to pressure test again.

When the hi throttle settings are lower than the lo throttle settings, that is very indicative of a boost leak.

HTH!

....Kyle T.
93 TSi AWD "TURBO4"

 

[aves911]

Wow thanks,

I'll try that and then see how it goes. Thanks for the tip.

-Jacob

 

[hostile]

Shouldnt your base fuel pressure be 43 instead of 35?

 

[kpt4321]

His base fuel pressure can be whatever he wants.

...Kyle T.

 

[Stock Josh]

Well, you should put the honeycombs back in the mas. And 720s are way too much fuel for a 50 trim. You are going to have to pull out a lot of signal, which will lead to alot of timing, which will make it hard to keep from detonating on pump gas, which will result in pulled timing, which makes for a slow car. 02 voltage tuning is worthless by the way, and unfortunately, so is EGT tuning.

Stock Josh

 

[aves911]

Well, I did a leak test and found one leaky I/C coupling, and the PCV valve was shot so I blocked it off. Boost builds much quicker now, but my AFC settings are still really lean with HI settings leaner than the LO. I might have missed some of the leaks the first time because the air nozzle I used was hissing pretty loudly.

But, in any event, I went out today and did some runs, logged them and tried to get somesort of fuel curve built. I adjusted AFC settings at 6 and 7K anywhere from -25% to +5%. At 5% I had crazy misfires because that was too rich but anywhere from -25% up to 0% my EGT's were still skyrocketing. I hit 1600 degrees in third at 4800. I kept adjusting the whole fuel curve up and down trying to control my EGT's but nothing did anything. As far as timing, I hit 19 degrees at the top of second. Which I am comfortable with right now. I don't know what else to try. Does anyone else think 720's are too big? I don't understand why I can't control my EGT's.

 

[loreak]

660's would have been a better choice

 

[supereclipse]

For a 2g the base fuel pressure shouel be 43 not 35 true he can have it whatever he wants but he shouldnt get on here and ask what his problem is if doesnt want the correct answers. U should turn the boost down to the bare minuim to tune then turn the boost up as u get it tuned better and better.

 

[Kevin Jewer]

WHen I used to runa hacked 2g mas, I never saw more than a couple percent difference in airflow at high rpm/flow, despite idle being off by 35-40 percent. So considreing -35 is what I run for my global with 660s, you may be richer than you think Dont go by what you "think" is rich, but by what your knock sensor tells you.

Also, you should put all the honey combs back in. The limit of the stock 2g mas is 380-400 grams per second airflow. If you do the math, thats 50 pounds per minute, or the maximum a 50 trim will typically flow. SinceI read on another forum you run 25 psi, you are most likely in the mid 40s. This doesnt account for restriction, but its not worth the tuning headaches hacked mas will give you.

The correct way to do a leak test is to pressureize the system up to the boost level you run, then take the hose off. Watch how fast the boost guage falls to see how big the leak is, and it will be quiet enough that you should be able to hear any leaks. Once you get rid of the big ones, you'll need soapy water to find the little ones.

I think 720s are fine for a non DSMlink 2g, you just have to be prepared to lean out a lot to get it to run well, and forget about race gas with only 50% range

Hope that helps...

 

[aves911]

Well,

I put the honeycombs back in the MAS, leaned the mix WAY out turned the boost back down again (after i fixed one of my leaks i got 3 psi back) and the car if finally starting to run better. Unfortunately, my HI AFC settings are still leaner than my LO settings. Guess I got more boost leaks to look for But I just wanted to thank everyone so far for their advice, it was a huge help.

-Jacob

 

[44pirate]

Originally posted by aves911
Well,

I put the honeycombs back in the MAS, leaned the mix WAY out turned the boost back down again (after i fixed one of my leaks i got 3 psi back) and the car if finally starting to run better. Unfortunately, my HI AFC settings are still leaner than my LO settings. Guess I got more boost leaks to look for But I just wanted to thank everyone so far for their advice, it was a huge help.

-Jacob

YOur HI settings should be leaner then your LO
My HI are -24% across the board. My Lo are -20% across the board.

 

[Kevin Jewer]

I agree. And I'll try to offer a quick expalnation. On the low settings you are simply trying to emulate stock fuel system, which gives you 0 trims. If you carry the same "stock" settings over to the high map, you should also get stock AF ratios at high TPS, and the ECU shoots for about 9.5:1 at WOT when you are flowing over 2.1 grams per rev, which you should easily be. Now for pump gas power, you want to be rich, but 9.5:1 should be alittle too rich. I typically run in the high 9s low 10s. That is where the 4% discrepancy comes in for the guy above. Typically if your high is leaner than you low, you are on the right track, but only the datalogger knows. Hope that helps.