Tuning Wisemen Please Enter

[NJGSX96]

Usually I have tuning down pat, but this damn 1G is just a thorn in my side. Quick background... 92 AWD, 95 pistons, VPC w/ 550 chip, AFC (adjusting off of MAP), FIC 650cc, Supra pump rewired, HKS 264/264, FMIC, 3" exhaust with O2 eliminator, 1G BOV, SBR 20G with internal gate set at 20psi, and all the support mods.

VPC Gain is at 0, Response is at 3 o'clock. AFC throttle points are at 20%/80%. AFC Lo is set so that all trims read 100, -/+5 (starts at -35 at 1K niceley curving to -15 by 7K). AFC HI is set to -11 at 1K nicely curving to -8 at 7K. Base timing is set to 5° and FPR is at 43psi.

I have leaned it out 10% from here on the AFC and I have richened it up 10%. the settings I currently have seem to work best at the moment. I have moved the throttle points all over the place. No matter what I do, I cannot seem to get rid of my knock. At around 10psi it spikes to 15-20, slowly bleeding off to 10-8 count. Never goes up, always drops from the initial knock count. Timing goes from 12-16 advance... if I am lucky. No matter what settings I seem to try, I always get that initial knock at 10psi. Since it bleeds off, that tells me that their is no knock at that point but the ECU doesn't just gratuitously give back the timing, right? EGTs never go above 850° and O2s hover around .88. Everything seems OK with the logs I take, but they all consist of this damn knock. What would cause that initial knock spike? How can I tune that out?

One other thing though is that the car hauls ass still. It doesn't feel like the timing is getting retarded at all. The car feels good. I can only imaging how it would feel if there was no knock. Really has me stumped. Anyone have any ideas?

Thanks

 

[GRNDSM]

Rich,

I usually start out with VPC gain in 7-9 o'clock position and then use SAFC (off of TPS) to lean it out from that point. And I am using 550cc injectors and 550 chip. You are using 650 injectors and make it even richer by starting out at 12 o'clock. But I guess if you are comfortable with this set-up it is up to you to use it.

You are describing really strange low to mid boost level behavior, I wonder how much of it is due to your SAFC control?

Do you experience any other phantom knock symptoms? What gas were you using?

Leon
RR

 

[jw]

That symptom is pretty common on the VPC. I was seeing the same thing, it often spike knocks when I first stomp on it and then it bleeds off. I tried different tuning and it's always the same. At one point, I was so set that it's due to mechanical noise but after hitting the track with race gas, the knocks went away.

I dont know how much I can help but I am sure it's the tuning. Another thing tho, my AFC is after VPC. It goes MAP->VPC->S-AFC->ECU. That is what everyone else is doing because you actually want a final say when it comes to airflow. Going your route is tricking the VPC, why do you want to do that? The VPC does a good job in handling MAP and let it do it's job. Also, try adjust your Hi TH point lower, I have mine at around 40-45% and the car ran strong since even at 35-40% throttle

 

[NJGSX96]

I just installed the 650s this past week. I originally had the Gain at 7 o'clock and then richened it up after someone said to try setting it to 0 to see what happened. i can always lean it out which is what I may try next. I am sure once race gas goes in at the track, that knock will go away. Too bad richening it up on pump doesn't have the same affect.

Leon, what do you mean, associated with my AFC control? You think adjusting off MAP might have something to do with it? Gas is 93, usually Exxon, Amaco or Sunoco. WOuld i thelp to pick up a 660 chip and try that? I have been told by a bunch of people not to use it, but if it may help, I might just try it.

I had the AFC hooked up to adjust off of TPS before and had huge Phantom Knock problems. No tuning could get rid of them. I switched to adjust off of the MAP and ever since, no more phantom knock. Car goes great except for that damn initial spike of knock.

 

[jw]

Oh, you are saying the throttle point adjusting by the MAP. I was thinking you meant you ran the AFC before the VPC. My bad, oh well, I am running the 660 chip and if you need one, let me know.

 

[NJGSX96]

How do you like the 660 chip? Like I said, a couple people who have run it actually switched back to the 550 chip. Don't know the actual reasons why, but they didn't recommend it for some reason. I think I might have to check that out so i can rule it out or possible have it fix the problem.
I just got back from lunch. i tried to richen up the lower rpm range and richened up response too. Car seemed to respond better and the boost/timing gauge from the TMO ECU didn't seem to drop as hard as usual but I really couldn't get on it too hard thanks to this freaking rain. Plus, I didn't hjave my logger. I'll try to get some logging doner after work and see what I see.

 

[jw]

I like it. I used to run the 550 but it's sitting in the closet now. Since I have not used the 550 long enough, i wont give any comment, I am sure the 550s work because many run them. But the 660 works fine and my AFC setting is close to zero on the street than the 550s used to. If decided you need chip, PM me.

 

[silver91talon]

Try upping your LO setting to 33%
0-5V =0-3bar
0psi (1bar) = 33% =~1.7V
15psi (2bar) = ~66% =~3.4V
30psi (3bar) = ~100% = ~5V

Set your HI and LOW settings accordingly. Remember that the SAFC linearizes when the sensor is between the HI and LOW settings.

 

[KenTSIII]

The AFC will reset 100% to whatever your full boost is...

 

[NJGSX96]

I tried upping the LO to 30 and it got real shacky at 0-1psi. I put it down to 25% and all is good. I also lowered the Hi to around 60%. Then, on the advice of some friends, I then put the response on the VPC to 5 o'clock and richened up the all the settings, starting at +4 at 1K to -1 at 4K to -8 by 7K. Seems to have fixed the whole initial knock spike. I might get 1 count, but the car feels so much better. I'll have to do a little more driving around and logging, but it seems to be much much better. Thanks for the help guys.

jw, thanks for the offer. I'm gonna stick with the 550 for now.

 

[sunflashx]

Originally posted by NJGSX96
I tried upping the LO to 30 and it got real shacky at 0-1psi. I put it down to 25% and all is good. I also lowered the Hi to around 60%. Then, on the advice of some friends, I then put the response on the VPC to 5 o'clock and richened up the all the settings, starting at +4 at 1K to -1 at 4K to -8 by 7K. Seems to have fixed the whole initial knock spike. I might get 1 count, but the car feels so much better. I'll have to do a little more driving around and logging, but it seems to be much much better. Thanks for the help guys.

jw, thanks for the offer. I'm gonna stick with the 550 for now.

I mentioned it elsewhere to you, but that is about the same range (12% total) I see with 660's and my car.

I thought my settings were odd, so it's nice to see someone else having the same experience I did.

 

[NJGSX96]

Originally posted by sunflashx


I mentioned it elsewhere to you, but that is about the same range (12% total) I see with 660's and my car.

I thought my settings were odd, so it's nice to see someone else having the same experience I did.

Yes you did. Thank you! Worked like a charm. i can't wait to hit the track now.

I hear you about odd settings. My car has gone against the grain in every aspect of tuning. It is nice to see that one person has the same ballpark settings as me too. This 1G is so different than anything else. i help tune a lot of my friends cars (1G and 2G) and they all run great, all using the same ways of tuning I learned from my 2G. My 2G is so easy to tune, as are most 2Gs to me. This 1G is so different than the rest though. It always throws me for a loop and things that don't make sense, all happen to this car.

Thanks again.