How to safely add more timing to this map? (tuning timing vs. fuel)
 

Heard more knock on the way home from SLO tonight. :vash: I've been struggling with it for a couple of weeks now, slowly pulling more and more and more timing until I didn't hear it, and adding fuel in a couple of places as well. I thought I had it all, but I saw the oil pressure gauge wiggle back and forth in 3rd gear at around 5700rpm, so I went and added a bunch of fuel to that area and it seemed to flatten it out. I still have a tiny bit in the 4600 range, so I'll have to go back out tomorrow and see if I can't get some more fuel into that area too. I'm below 11.8 everywhere on my wideband, as low as 11.3 in the 5700rpm range. The timing map is really conservative too, even for piss-water 91 octane.

Attachment 215238

Any suggestions? I don't think the timing should have to be that conservative. Once I have a bit of spare cash, I'm going to rent some dyno time and get the spark map hashed out, but that's not going to be for a couple of months. I know there's no other proper way to do spark.

Anyone have a 1.8/GT2554R/91octane spark map they'd be willing to share for me to fiddle with?

I would only mess with spark on the dyno. I know this from experience with my last motor ;). What are your IATs up at max boost? That pressure ratio is at the point that is getting outside the efficiency of that turbo. I think that could probably account for some of the reason that timing needs to be pulled. Its getting to the point where its just blowing hot air.

112° on track at Buttonwillow, running 100 octane with a bit more advance in the upper boost ranges. I have done nothing but remove spark since I started fiddling. During tonight's tuning runs, max IAT of 73. Max boost is just over 15psi.

I don't think tuning will effect oil pressure (unless the tuning broke the motor)... The best thing would be to post a log with EXACTLY where you heard the pinging...

Siegel

Actually, on the 89-93 cars with the real pressure sender you can see bad knock in the form of rapid pressure changes. Its not perfect though, sometimes my needle will wiggle if I just hit a bump.

You sure your are not off 10 degrees in your base timing? Because I agree, that map looks very conservative but add 10 degrees and it would be VERY aggressive.

Mark

Mark, the base timing was set when Jerry tuned it. It's correct.

i would still double check the base timing, you shouldn't be knocking at all with that map. did you make sure to set fixed at 10 when you set base timing?

With my motor set at 10deg Im pulling 5 at 10psi boost from 5500 up and afr's are at 12.5 on a 1.8 with a t25/intercooled. Air is way cold up here though. Ur map looks way outta wack.

come on now, I thought you would know this :)
The early miatas use carbon resistance sensors to monitor oil pressure. Knock screws with the sensor's ability to work, and causes the OPG needle to oscillate.

"Siegel" eh?

I will check it, but unless the CAS came loose I really, really doubt it's incorrect. Jerry himself set it.

The other thing to check and I got bit on this, was ignition settings. I had the wrong settings in a Haltech once and it caused timing to be very unstable with RPM. So at idle it looked good but was madly advanced at 4500 RPM. Use a timing light to verify this... set the entire ignition map for 10 degrees and vary the RPM. The timing should stay dead nuts on...

Mark