SleeperZ Posted June 4, 2003 Share Posted June 4, 2003 I've asked the question in various threads, and no one seems to know the answer...I just thought I'd make it a thread and see if I can get any feedback. I'm running mine at the stock initial timing, 20* BTDC. It has always worked well, but I just don't know where I'm going to be with total advance at (what?) RPM. As I increase the boost, I'm unsure whether to retard the timing, or advance it or leave it alone...I'd like to keep running my local pump gas - 91 is the best commonly available. So far 15 psi boost, stock timing, intercooled and fueled is running great. I was running very cold EGTs, about 1400F peak at the top of fourth gear, so I dropped the fuel pressure 1 psi - 1-1/2 psi, and it seems more lively, but my EGT quit working (again). I'm getting a new gauge, and I will get to a dyno with a wideband just to see where my mixture is across the band. Any comments or suggestions? I'd like to find out what the ignition curve of the ECU is so I can optimize the ignition advance either using stock initial timing, or if I can't get it where I need, I can invest in an MSD that can add some retard with high boost. Thanks in advance. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted June 4, 2003 Share Posted June 4, 2003 I want to know this too. Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted June 4, 2003 Share Posted June 4, 2003 I'm running mine at the stock initial timing, 20* BTDC. It has always worked well, but I just don't know where I'm going to be with total advance at (what?) RPM. As I increase the boost, I'm unsure whether to retard the timing, or advance it or leave it alone...I'd like to keep running my local pump gas - 91 is the best commonly available. So far 15 psi boost, stock timing, intercooled and fueled is running great. I was running very cold EGTs, about 1400F peak at the top of fourth gear, so I dropped the fuel pressure 1 psi - 1-1/2 psi, and it seems more lively, but my EGT quit working (again). I'm getting a new gauge, and I will get to a dyno with a wideband just to see where my mixture is across the band. Any comments or suggestions? I'd like to find out what the ignition curve of the ECU is so I can optimize the ignition advance either using stock initial timing, or if I can't get it where I need, I can invest in an MSD that can add some retard with high boost. Thanks in advance. Let me take a stab at this based on my experience when I was tuning my stock L28ET with SDS. DISCLAIMER: this is by no means gospel, just what worked for me and the same philosophy I follow today. I once had a copy of the L28ET timing curve that was published by someone but it was on paper and long lost. Anyone remember paper? Even better joke if you are a "Waterworld" fan :D Full advance was in at 3000 and what I found to be a good starting point for tuning for pump gas (the quality could make a BIG difference) was a total of about 22-24* @ 15psi boost. If you follow a simple, linear map to retard 1* per 1psi boost, then you would want the full advance to be about 37-38* to have 22-23* total at 15psi boost (38* advance - 15* retard = 23* total). So, with an initial of 20*, you can then build a linear map to ramp the timing up to 38* advance at 3000. Since you are not likely to have 15psi boost below 3000, it should be perfect. All the maps are linear in the example and that can be refined later when fine tuning if you feel the need to ramp differently on the way to full advance. You can also get more aggresive with the timing if there is no detonation. However, I fully believe more boost and less timing nets more power than less boost and more timing, as long as you are not detonating. Also, if you are not detonating and the EGTs are low (rich) you have the option to run more timing, turn down the FP or turn up the boost. Hmm, tough choice Hope that did not muddy the waters and I know I did not specifically tell you what the stock ignition timing map is, but I feel you can confidently assume what I suggest to match it since mine was based on it. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted June 4, 2003 Author Share Posted June 4, 2003 That's good stuff, Scottie. I am assuming the stock turbo ECU has some bit of timing retard based on load (don't know if that's a good assumption or not). Obviously since there is no MAP sensor, the ECU has to assume stock boost, and there may not be enough retard at higher boost -- especially since I've slid down the load scale by scaling the MAF in a larger intake and adding larger injectors. In that case, I might be able to get a more tailorable ignition curve by using a N/A ECU and a MSD BTM, or by simply getting a fully programmable ignition, and not using the ECU to control timing at all. Quote Link to comment Share on other sites More sharing options...
Doug71zt Posted June 5, 2003 Share Posted June 5, 2003 Thanks to SleeperZ, got my first Z31 Eccs project working last night. Set the initial to 20 deg. Ran it up through the rpm range with my timing light on it. It advances to 36 deg total and then at 4000 rpm, it takes 2 deg out to 34 deg. I'm a little confused as to how it takes timing out under boost as there is no MAP sensor. I guess the RPM vs airflow could give you a rough boost # for a stock engine, but if you increase airflow through cams or porting, this would change everything. Not a very good way to control timing, IMO. I will see what the timing comes out to if we get this thing on the dyno sometime. Cheers Doug Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted June 5, 2003 Author Share Posted June 5, 2003 I'm sure the ECCS will take some timing out based on airflow - airflow vs. rpm will give a very clear picture of load to the ECU. Quote Link to comment Share on other sites More sharing options...
Len Posted June 5, 2003 Share Posted June 5, 2003 Just with my caveman setup (stock 83 turbo electronics) I've found at 24 degrees btdc (stock timing) wasen't enough. She ran alot better around 30 to 32 degrees running 12/13 psi boost. Nice to have confirmation of my experience! Len Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted June 6, 2003 Share Posted June 6, 2003 I've found at 24 degrees btdc (stock timing) wasen't enough. She ran alot better around 30 to 32 degrees running 12/13 psi boost. Is that intial, full advance or total? How are you verifying timing at 12psi boost? Quote Link to comment Share on other sites More sharing options...
Bernardd Posted June 6, 2003 Share Posted June 6, 2003 Guys, go here to find Romeditor http://imflame.ricetek.net/~darkhalf (or email me) and for a vg30et binfile. You also want to download the rb30 address file. This is for the 86 turbo ecu. Update on ecu: I can reprogram for larger injectors now, but I can only do it by modifying the vq (maf) table. Probably not the best way of doing it as timing is effected as well, but so far that's it. Haven't had time to play with the timing yet or fuel maps much. Bernard Quote Link to comment Share on other sites More sharing options...
Len Posted June 6, 2003 Share Posted June 6, 2003 Scottie that is initial. Before all the upgrades 24 degrees was ok. after increasing the boost noticed dead spots along with bad idle. Until I retarded my timing around 30 (could have even been 34 degrees inital). I'd have to check to be sure. Quote Link to comment Share on other sites More sharing options...
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