cygnusx1 Posted September 10, 2008 Share Posted September 10, 2008 Could someone take a look at this short datalog. At idle, the AFR will sit around 12.5-13.5 or so. All of a sudden, the RPMS will drop simultaneously with a really rich spike. I have been doing some tuning and I might have gone too sensitive with MAPdot. Although in the datalog, I don't see a correlation of MAPdot to the spikes. I am thinking it might be the influence of a MAP glitch or accel enrichment glitch. I am not touching the pedals and the A/C and fan is not on or cycling. Anyone see any "spike" signals causing this sudden idle drop and rich spike? I see a correleation on the datalog in RPM-deltaT-MAP-AFR Accel Wizard and General Lag Factors shown below datalog200809092058.zip Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted September 10, 2008 Author Share Posted September 10, 2008 OK I studied the datalog myself and see that everytime I got rich spikes was because AE was triggered by MAPdot. However, my MAPdot threshold was set to 15kpa/s and it triggered AE way below that threshold. Is MAPdot threshold working? See below AE is triggered and MAPdot is only 8mPa/s. Threshold was set to 15mPa/s. Throttle is shut. Quote Link to comment Share on other sites More sharing options...
Turbo6inKY Posted September 10, 2008 Share Posted September 10, 2008 OK I studied the datalog myself and see that everytime I got rich spikes was because AE was triggered by MAPdot. However, my MAPdot threshold was set to 15kpa/s and it triggered AE way below that threshold. Is MAPdot threshold working? I attempted MAPdot for about fifteen minutes one day, and went right back to TPSdot. It was doing what yours is doing. It's just erratic. It probably didn't help that I had big ignition problems that were causing misfires and a wild vacuum signal. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted September 10, 2008 Author Share Posted September 10, 2008 I wonder it it's X-Tau that is making the spikes? I read that X-Tau uses a separate mapDOT than the Acceleration Wizard (correct?). I haven't found the mapDOT for X-TAU yet but I could simply turn off X-TAU. Quote Link to comment Share on other sites More sharing options...
niner11 Posted September 11, 2008 Share Posted September 11, 2008 It has been a while but I had a similar problem. The mapdot would spike for what seemed like no reason so I am currently running with xtau disabled....I believe it is the source of the accel spikes. I figured it was my xtau settings rather than a problem with xtau itself. Chuck Quote Link to comment Share on other sites More sharing options...
flames_187 Posted September 11, 2008 Share Posted September 11, 2008 i had a similar problem...i was advised to turn my lamda way down ...it smoothed things right out...the way it was explained to me was that i was allowed the AFR meter to correct the A/F ratio. i had mine set to 100% and now i am at 5-10%... Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted September 12, 2008 Author Share Posted September 12, 2008 I did some re-reading of the Megamanual because it has been a long time and I have learned a lot more since I last read it. Here are the things that I found out. You can set AE to happen only at certain RPM ranges. I had mine set so it could go into AE at 1000rpms which is apparently too low. I raised it to 1200rpms and stop AE after 3500rpms. Now it won't fire the AE at idle. I also raised my threshold for the MAP and lowered the threshold for the TPS. I blend the two about 50-50. My new theory is to keep the low MAPdot's fairly rich and the high MAPdot's lean. Then do the opposite with the TPSdot's. Another thing I noticed was that the AE would go lean after an AE squirt. What I did was lengthen the AE taper time. Now it goes slightly rich when I punch the throttle and gradually fades back to the correct AFR after the AE event. Another thing I did was to disable the AE totally. I did datalog runs, followed by Megalogviewer analyzing the VE table compared to my AFR table. I ran through four datalog-tune sessions back to back until the car ran great without AE. Then I added a little AE to get the throttle response where I wanted it. I also discovered that the car does NOT like 14+:1 AF ratios pretty much anywhere. Anytime I get running in the 14+ range, it feels really weak and I get some holes in the powerband. I guess you can't have your cake and eat it too. 13.6 seems to be as close to econo-supercar as I can get. Smooth idle only exists at 11.5 - 12.5 AF ratios. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted September 12, 2008 Share Posted September 12, 2008 Another thing I did was to disable the AE totally. I did datalog runs, followed by Megalogviewer analyzing the VE table compared to my AFR table. I ran through four datalog-tune sessions back to back until the car ran great without AE. Then I added a little AE to get the throttle response where I wanted it.If you're using Megalogviewer to tune, it's tempting to just leave AE on as MLV says it ignores records where AE is active. But the WB O2 sensor delay (slider between 0 and 4) is only accurate at a particular rpm range so by definition it's a compromise and not accurate at other rpms/loads. So what you're doing here is getting your VE tables as good as possible BEFORE adding in AE. Once I adopted this approach I found I was using much less AE and things just worked better. BTW, another thing to check since it just happened to me the other day is if the processor is well-seated on the circuit board. I was trouble shooting an intermittent lead to the MAT sensor and all of a sudden was getting all sorts of triggers of AE even when the log showed that neither the MAPdot or TPSdot was triggering. Eventually I tried reseating the processor (just because I couldn't think of anything else to try) and the problem went away and hasn't come back. And what's weird is that it was physically already well seated, but I guess pulling it out and reinserting it solved whatever was causing the problem. Just something else for you to try. Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted September 14, 2008 Share Posted September 14, 2008 12.5:1 is awfully rich for idle. Even lower than that is pretty rough. That's got to wear your cylinders faster. Mine idles at stoich. It's alittle grumpy and I can tell it will idle smoother when it dips into the 13's but it should be fine. Use your base ignition map to counter some of the rpm fluctuations caused by stoich idling. IOW, set the point that is both lower in rpms and higher in pressure to a bit more timing. If it's sucking a bit hard because it's at stoich it will slide into that cell and the timing will nudge it back up. Idle is much easier to stabilize on standalones with closed loop timing control for idle. 13's are practically always better for power, but that's the tradeoff with fuel economy. FWIW, any time I tune a standalone on a car that starts with a basemap I always shut ALL enrichments off until the base fuel and timing maps are 98%. Likewise, I've yet to see many standalones that can implement a decent dMAP/dt enrichment. Basically I set mine pretty soft and use a bit of dTPS/dt enrichment for vacuum only (when that can be configured). Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted September 14, 2008 Share Posted September 14, 2008 Have you recalibrated your WBO2 sensor? On mine and a buddies car, we ran about 15:1 on cruise with no issues. My idle was almost stoic as well by cracking the TB open to lean out the mixture enough, then lowering the idle speed with timing. Mario Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted September 15, 2008 Author Share Posted September 15, 2008 I calibrate my O2 sensor about every two months or so in fresh air so it should be OK. My engine has always liked to idle that rich. If I lean it out near 13, it starts to get misses. My idle timing is already around 27btc. I understand the timing trick, Wzardblack, that's the same trick I was using with the VE table to stabilize the idle. I was building a little rich "ring" around the idle point so when it would fall out of the idle point due to a miss, it would slide back to where it was comfortable. I didn't try it with timing though. I'll give it a shot. At 12.5 it will idle rock steady all day at 1000rpms + or - about 20. Sure does stink though! Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted September 15, 2008 Share Posted September 15, 2008 I think I was running about 12-14deg at idle, and it would jump to at least 20+deg right off idle. Stock is about 20deg at idle, yet people would often move it to 24deg to get a little bit more performance. 27deg sounds like an awful lot. Other then the smell, is there any other downsides to it? For some reason I think it would affect idle water temp. Mario Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted September 15, 2008 Author Share Posted September 15, 2008 Factory spec on my 83 motor is 24deg +/- 3deg @ 700rpm Quote Link to comment Share on other sites More sharing options...
Zmanco Posted September 15, 2008 Share Posted September 15, 2008 Factory spec on my 83 motor is 24deg +/- 3deg @ 700rpmThe spec for the stock L24 is only 8 deg. Just curious what's different with the later motors that there is such a big change? I wouldn't think that switching to electronic ignition and FI would by themselves cause such a large change. BTW, I have my current L28 idling with 20 degrees and tuned more towards lean than stoich (the actual AFR varies a lot based on temp and who knows what else). It seems to recover from sudden loads like efans and AC better when lean vs. rich. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted September 15, 2008 Author Share Posted September 15, 2008 8 degrees? Is that without the vacuum advance connected? Quote Link to comment Share on other sites More sharing options...
Zmanco Posted September 15, 2008 Share Posted September 15, 2008 Yes, IIRC, it's 8 without vacuum connected. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted September 18, 2008 Author Share Posted September 18, 2008 I went out tonight and took a great running performance map and tried to "economize it". With some arm twisting, I was able to get a decent idle at about 14:1 but I had to bump my idle timing to around 28btdc and had to make the next kpa cells just off idle very rich to stabilize the idle mixture and speed. I leaned out the AFR map all over the 0-50kpa regions to around 14 except in the torque areas and ran a couple of Megalogviewer tuning iterations. It certainly smells much less now. I still need to tweak and run a few more MLV iterations but it seems to still run great and smell less. Hopefully I won't get too many air quality complaints from the wife when we go out in the car this weekend. Quote Link to comment Share on other sites More sharing options...
flames_187 Posted September 18, 2008 Share Posted September 18, 2008 when you tune that lean (14)and the low kpa ( below 50) does your car lean out on light throttle (15-16)? mine did so i tuned for 12.5 at idle and on light throttle i get into the high 13s...this is prolly cuz im not using TPS now that i think about it... :-/ Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted September 18, 2008 Author Share Posted September 18, 2008 I still haven't got it where the AFR's dont spike around a little bit during dynamic RPMs and loads. I think that would take a dyno and a weekend with a tuner sitting next to you. I know what you mean. You are driving along at light loads and roll on a little throttle at medium pace and see the AFR needle go to 17-18 for a split second and then go to 10-12 for a split second before it stabilizes. Sometimes this happens, sometimes it doesn't. I don't really notice it unless I'm watching the AFR gauge. I tried tuning it out with AE but it's kind of intermittent to begin with. It could also be a misfire throwing some raw fuel at the O2 sensor causing a lean read for a second. Under normal driving, it runs fine regardless. If you go too lean in the wrong places, you do feel a "hole" in the powerband that feels uneasy on the butt dyno. Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted September 20, 2008 Share Posted September 20, 2008 I'll have to look at my Haynes manual but 28 degrees sounds way to high. I remember looking up my '77 280 idle numbers and it was supposed to be around 10 degrees. Maybe I forget, I dunno. Be that as it is, my car idles at 13 degrees at stoich at 850 rpms. Quote Link to comment Share on other sites More sharing options...
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