Poor Timing Advance at WOT

[latvianrkey]

I have a few problems if anyone can give me some insight it would be much appreciated.
I recently did a FMIC install with 680cc injectors on my '97 GSX. My mods are:
Built 6-bolt swap, Big16G set at 18psi on 93 octane, 255HP pump, NO AFPR. I have all other supporting mods.
When I datalog a 3rd gear pull, my timing maxs out at about 10 or 11 degrees max. I have my throttle points set at 30 and 75. If I change the HI point to 80, i get 12 degrees of timing, but I throw a P300 code (Random Cylinder Misfire) I have new plugs and wires gapped at 0.028. If I set it to 75, I do not have the misfire, and my timing only goes to 10 or 11 max.

About my AFC settings:
Currenty, I have my hi throttle settings at about -35 accross the board give or take 2%. My EGT's are hitting about 1550 F at the top of the pull. My O2's are at about 0.94 to 0.96. I am curious if anyone else is running 680cc injectors and I am way too rich compared to their settings. I think that that may be the case. I also tend to think this because i am getting a misfire that I never use to get before, so I do not think it is the 6-bolt swap causing that. The EGT's may be high because of running too rich also. Please give me some insight, because the timing not advancing to the high teens low 20's is killing my performance!!!!

 

[Blk_99gst]

Hmm, I'm pretty stumped. I have a very similar setup; big16g, greddy big fmic, 660cc denso, 255 walbro, no afpr, safc, and I just got a gm maf so I no longer us my safc.

But before the gm maf, my high settings on the safc were around -33% to -34%, with 30% and 70% throttle switch over points. I ran about 19psi on 93oct, and I have always gotten pretty good timing advance, drop to 8 then up to 17 or 18 at the top of 3rd. You say you put new plugs in, did you go one range colder? If not then you should. .94 or .96 on the logger my say your a little rich, but not very; egt's sound normal.

It could be a lack of fuel; changed your fuel filter in a while? Spark plug wires? I don't know, I'm really reaching here. I've always had tuning problems too, the pocketlogger is only O.K. So I just sucked it up and bought a wideband, so now I can know easily tune the car. Maybe go to a dyno and have them air/fuel log your car. I know it would be expensive but it would tell you for sure if you're too rich.

 

[latvianrkey]

Well, your input on your setup helps a lot!! Now at least I know that I can leave my switch points at 30 and 70 and still get good timing, so at least that takes out one more variable. I was starting to think that the switch point directly reflectd on timing advance.
Since you were at -35 plus or minus, I can assume now that I am at least in the ball park with -35 plus or minus on my 680's.
I am actually running BPR6ES plugs. My theory was that I was getting a missfire because the plugs were not reaching the self cleaning temp, and I have a HUGE front mount, so I was not too worried about detonation.
The fuel filter was changed out approx. 12,000 miles ago, so I think that would be fine for a while longer.
Im thinking of getting as cloase as I can, and putting a little race fuel in and seeing if I get timing advance. Maybe I'm running just too much boost, but I think 18psi on 93 octane would be easy......

Thanks for the input.....keep it coming!!!

 

[2g6boltTsi]

Are you running a potentiometer inline with the barometric pressure sensor to prevent the ecu from detecting a false misfire?

if not this could be your problem, some 2g ecu's get confused by the cam sensor signal and throw a misfire code, which makes trhe comp go into limp mode.

 

[latvianrkey]

I am currently dong a little better. I turned the fuel up to -25% accross the board, and I now get 17* of timing at 6500 rpm. I set the switch points to 30 and 75. If I put it on anything other than 75, I get a Random Cylinder Misfire at about 6000 rpm. So I'm guessing I was just running too lean for 18~19 psi.

Now if I could only get a radiator fan that didn't melt....

 

[drillo99]

I run the pte 680's with a large front mount, afpr set at 43 lbs and a fp bigt28 at 20 psi, my safc settings are at -35 with about 60 degree weather and i see 19 degrees of advance at 7000 rpms, have you checked for a boost leak? I have also heard that the pte680 injectors are over rated and somtimes flow less then 625cc when tested at 43 lbs which could lead you to belive you should be rich when your really lean, guess we should get a wide band 02 to be sure

 

[latvianrkey]

I will be installing a potentiometer within the next week or so. Will see if this helps at all with the misfires. Probably will from what I've heard.

 

[TimG]

The rule of thumb when using a SAFC is, when you decrease the airflow signal the ECU, you increase your timing.

So the only way your timing would be pulled is if you have a constant 5-9 counts of knock throughout your rpm band or high knock at higher rpms under WOT.

Quite baffling. Keep us informed.

 

[kpt4321]

He was at -35%, and his timing has low. He went to -25%, and the advance increases. That means he must have been knocking.

 

[latvianrkey]

Prior to realizing that the misfire may actually be electronic rather than mechanical; a result of 6-bolt swap rather than of actual misfire, I removed fuel thinking that the misfire was induced by a "too rich" condition. I believe this to be the cause of my poor ignition advance. I plan to install the potentiometer and effectively eliminate the "phantom misfire." Once this is addressed (hopefully) I can tune without the false pretense that the misfire is due to having too much fuel and I can start to add fuel where timing is being effected by knock.

 

[1LE]

Must be knocking. As a point of comparison, with my 2g 6-bolt at a safe 1 kg/cm2 with 550's on a VPC (does same thing to airflow as a AFC), when it's not knocking I see 21 degrees at 7000rpm and 27 degrees by 8000rpm. With bigger injectors, you could potentially see even MORE timing increase...

 

[sp00ln]

post your log.

 

[latvianrkey]

I'll post a log tonight. Im getting confused. I am running a base setting of 580cc injectors on the MAFT blow through, Idle is set at "8" and everything else is zero'd out. I set it there because with these settings I get 0 on my STFT with no lo-throttle corrections on the AFC. I have my SAFC set at about -35% from 5000 on up. curving out to -15% at 1000 and 2000 RPM. If I do not give it more fuel at low rpm's, the car hesitates like crazy. I am getting some pretty steady timing increases, but it is only maxing out at 14-16 degrees of timing at 7000 RPM. I am running 21 psi on a big 16G with 680 cc injectors and a 255LPH pump. (in case you forgot or don't want to look at the top of this post.) Odd thing is, the other night i saw 22 degrees of timing at 7000 rpm with the same settings, but it would not do it again. I also recently did the potentiometer mod to get rid of misfires on my 6 bolt swap. after i did this, my car became a lot harder to tune. ( i think) or else I am just imagining it. What do you guys think?

 

[slickster]

Big28,blowthru-maft,680ccPTE,safc,

Just listening in.

 

[latvianrkey]

here is my log. I tried richening it up where there were dips in the timing and it did not help. I made about 6 runs slowly increasing fuel where the timing was dipping and ended up at -24 and way too rich.....still no timing above 12 or 13 degrees. Im getting frustrated, please tell me something i am doing wrong.

 

[sp00ln]

Im sorry, I dont know how having a MAF air effects your tuning, but couln't you bump up the MAF a little bit to be set at 650? Then you can run near 0 on your AFC (+ or - ofcourse) and go from there? Also, you're probably running WAY too lean because I run near your settings and I have the stock mas, not a blow through that can adjust for my larger injectors. Start from -10/15 or so and work from there.

 

[latvianrkey]

yeah, im not too sure what's going on with the MAFT being set at 580 instead of 680, but 580 is the only place i can set it and the car will even start. Also, at that setting, my low fuel trims are zero'd out on the afc and working just fine, so for whatever reason, i think that is best. Maybe I got 550's instead of 680cc injectors. no way to really tell the difference from my perspective. But the car has run like crap ever since the install of the injectors. Maybe i will try one run with the hi settings at zero. I know o2 voltage is crap anyway, but isn't .94 pretty close? if I go any richer, the voltage goes to 1.0+. That can't be good. and right now, EGT is hitting 1550 at 7000 RPM. Keep the ideas coming....I'll try anything once. On another note, I recently changed plugs and they were not white at all, so I'm assuming i'm not too lean...

 

[1LE]

If you set the MAFT to 680 and try to start the car, are the plugs wet or dry after it fails to start?

 

[latvianrkey]

not sure. I guess I can go check later tonight when I get home from work. If i set it any leaner, when i go WOT in neutral, the rpm's just sit at 2000 and pop, won't go any higher, so I was guessing not enough fuel. could i be wrong?

Thanks for the inquiry, but if i can get the short term fuel trims at 0% when I am cruising and at an idle, doesn't that indicate a good baseline for the MAFT settings? Then if that is the case, why am I having to lean out my hi settings so much just to see ballpark o2 readings?

 

[1LE]

Dunno. Interesting. I completely ignore my O2 values because I know they're so far off. At .92 my car spews HUGE clouds of black smoke. At .86 it still is a little smoky, but I can't lean it out anymore without hurting timing... Sooo, I'm WAY off from what most people see...

 

[latvianrkey]

So, if i completely ignore my o2 readings and just look at timing, i would have to say that I am lean. Because the MAFT is correcting out about 10-20% richer from stock, and I am running 21 lbs of boost, with AFC settings in the -30's. I like the idea of putting my settings at -15% accross the board and doing one run and seeing what happens. Anyone else have any suggestions?

 

[1LE]

Can you have somebody follow you while you make a run or 2? To let you know how much (if any) smoke you're making? If you get to the point of making huge clouds, then you'll know without a doubt that you're too rich (Mine was so rich that I could see the clouds from my car with the rearview mirror)

 

[latvianrkey]

will being too rich cause knock in a similiar way that being too lean does?

 

[saw wave analog]

they are a bit expensive, but it sounds like a wideband o2 would help you out a lot in working the bugs out. might be worth it.

 

[sp00ln]

not sure. I guess I can go check later tonight when I get home from work. If i set it any leaner, when i go WOT in neutral, the rpm's just sit at 2000 and pop, won't go any higher, so I was guessing not enough fuel. could i be wrong?

That sounds like TOO much fuel to me. You're drenching it.