gman
Boosting 10 psi
Posts: 35
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Misfire
Feb 11, 2016 14:58:33 GMT -5
Post by gman on Feb 11, 2016 14:58:33 GMT -5
Attached are copies of my tune and two logs of pulls for my 1987 TC. I fixed my loose distributor, replaced wires and plugs. I have an MS2 with spark table switching, using table 3 in premium, running 93 octane. I have a cold air intake, with no VAM. The rest of the intake/exhaust/heads are bone stock. I've been auto tuning fuel for a while on my wideband, and believe that it is setup fairly well, as I've been driving for a while and very little changes occur.
Today, I applied boost > 5# (134 KPa) and cut back spark 2* whenever I heard detonation, then wash rinse repeat for a few runs. I think I have things dialed in pretty well between 5-10# (169 KPa) and even occasional boost up to 15#. However, as you will see in the earlier log, I get an occasional misfire (at 714497.438). The later log looks fine, and I included it for comparative purposes.
I have no idea why the misfire occurs. It would also happen on the stock LA3 with VAM. I note that the inj. duty cycle at about 15# (see 714501.500) is above 100% (109.4% to be exact), although the misfire occurred around 3800 rpm at half throttle and about 8# (155 KPa) of boost.
I'm wondering how to proceed. Should I have the injectors cleaned? Anything else I should look at? The AFR looks nice and rich (12.8), so I'm doubting that I need to check fuel pressure/pump?
Rob
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Misfire
Feb 11, 2016 15:34:21 GMT -5
Post by Stinger on Feb 11, 2016 15:34:21 GMT -5
Where did your original timing tables come from? Right now, even though you've dialed it back some, you've got "blow my engine up" timing values in certain areas and not nearly enough timing in other areas. You're running 10+ degrees more than you should in some areas where 2-3 degrees too much can damage the engine and running half of what you should in other places (like idle).
Are you running two timing tables for regular fuel and premium fuel? If you are then why is advance table 1 set to "blow my engine up" timing where it's running 2-3 times as much timing under boost as the "premium" table 3? I guess I just can't figure out what you're trying to accomplish with the two tables.
Why is your idle timing 10 degrees? It should be 20-23 degrees or so. 10 degrees will build a TON of heat at idle.
12.8:1 under boost is not "nice and rich", that's lean. Anything over 12.5 is lean and we actually target 11.5:1 at 15+psi and 11.8-12.0 at lower boost as it doesn't hurt power but is safer. I actually see it's in the high 13's at 7.5psi which is WAY lean. It's at 13.2 at 12psi which is "melt pistons" lean. Even at idle it's around 16:1 when it should be 14.7. That won't damage parts (because it's idle) but it will create extra heat and make it idle poorly.
Changing the AFR target table to proper values and then running VE Analyze in MegaLogViewer quickly showed that your fuel table values over 100 kPa are 10-15% too low (which is why it's lean). For example, it's 115 when it should be 130. None of this matters if you don't have enough injector to give it more fuel though.
I'd suggest you take a real good look at the tuning guides I posted in this section of this forum. It explains all of this, gives a sample "safe" timing table, etc. No point in my trying to explain it all here when it's outlined very concisely in the tuning guide titled "Megasquirt Tuning Basics - Timing" at the top of this forum section.
More than 100% duty cycle means you are out of injector (or out of fuel flow somewhere in the system, though your fuel table appears to show it's injector flow, not pump flow, that is the limiting factor here. Cleaning them won't help, they need to be larger. If you have no plans to run more than 15psi, you can bump up fuel pressure to get you by but if you plan more than that, you're going to have to purchase larger injectors. We have a good selection available.
The misfire is caused by the erroneous RPM reading of 23704 which triggered the rev limiter to engage for a split second.
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gman
Boosting 10 psi
Posts: 35
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Misfire
Feb 12, 2016 8:09:39 GMT -5
Post by gman on Feb 12, 2016 8:09:39 GMT -5
>Where did your original timing tables come from? I used this tool to generate initial timing tables: www.useasydocs.com/theory/spktable.htm, and then cut them back from there. >Are you running two timing tables for regular fuel and premium fuel? Yes, table 1 is regular, which I have never used. Table 3 is premium. I was planning to get table 3 squared away, and then import that to table 1, and cut everything by a few degrees, which is why table 1 looks bad. I will look at your guides. You mention that I should "chang[e] the AFR target table to proper values" -- I will look for that table in your guides, and then report back.
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gman
Boosting 10 psi
Posts: 35
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Misfire
Feb 12, 2016 9:27:38 GMT -5
Post by gman on Feb 12, 2016 9:27:38 GMT -5
Hi Stinger, Thank you for the explanations in your guides. They are very helpful. I profess almost no experience with this, so I really value your experience. I looked at my original spark table, copied here: Attachment DeletedI have updated Spark Table 3 and target AFR: Attachment DeletedAttachment DeletedI will upload these to the MS2, adjust fuel at idle, and make some tuning runs today, then will report back how it feels and maybe post another log. I haven't attempted WOT, and won't do so unless all seems right and I'm not going lean on the wideband. A fuel filter replacement might be in order . . . Thanks again, Rob
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Misfire
Feb 12, 2016 11:11:19 GMT -5
Post by Stinger on Feb 12, 2016 11:11:19 GMT -5
That table generator seems very dangerous.
I'd suggest using the "VE Analyze" feature in MegaLogViewer to make initial fuel table changes (using this new tune with the updated tables) before going for a drive. It works just like VE Analyze in Tunerstudio only it does it using a log rather than live data from driving.
Load the new timing table to table 1 as well and then pull 3 degrees from everything above 90% fuel load.
You will need larger injectors than you have so I'd suggest turning the boost down to 12-13 psi until you can get larger injectors.
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gman
Boosting 10 psi
Posts: 35
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Misfire
Feb 12, 2016 11:46:12 GMT -5
Post by gman on Feb 12, 2016 11:46:12 GMT -5
Thank you, I've done those changes and I'll take it for a spin then report back.
I'm kinda surprised that merely changing to a CAI and deleting the VAM would max out the injectors. I'm going to replace the fuel filter and see if that helps. What size injectors would you recommend?
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gman
Boosting 10 psi
Posts: 35
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Misfire
Feb 12, 2016 13:53:49 GMT -5
Post by gman on Feb 12, 2016 13:53:49 GMT -5
Well that made a world of difference. I'm attaching copies of my current tune and last two logs. I'm still getting some knock between 5-10# when in 4th gear between 2000-3000 rpm. I took a couple of degrees of timing out in that range (about 3*), but it seems persistent. I'll drive the car more with Tune Analyze Live! and see if that issue improves.
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gman
Boosting 10 psi
Posts: 35
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Misfire
Feb 28, 2016 10:01:17 GMT -5
Post by gman on Feb 28, 2016 10:01:17 GMT -5
Hi Stinger, Background: I started the car yesterday to adjust warm-up enrichment some. My closed loop cold start idle speed is 1500 rpm when cold, and then drops down to 1000 rpm at 150 degrees. As CLT warmed up, and rpm started down, the rpms became unstable. I made an adjustment to VE table to dampen that out. Next time I'll take a screen shot, but it was 10 in the 1400rpm/35 load box, and I increased it to 15 to match the 15 I had in the 800&1200 rpm/35&40 load boxes. AFR was now close to 14.7. The car then happily heated up. I took the car for a 20 minute ride and towards the end of the ride, I logged two minutes with VE Analyze live turned on. Issues/Questions: 1. I'm still getting some detonation at throttle (see rpm deviations at 2342s and 2350s in attached graph). Which should I use to help solve this problem -- VE analyze live or VE Analyze in megalog viewer? What should I do -- adjust fuel, retard timing, or both? 2. When I parked at idle after the drive, the car was now running richer than before (11-12). So I lowered fuel to 13/12 in the 800&1200 rpm/35&40 load boxes. I'm thinking that I may be chasing my tail a bit here, because if I lower it further, then the car runs like crap when I first start it. It seems like something is changing that affects the fuel such that it idles better with less fuel after more operation. Attachment Deleted
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Misfire
Feb 28, 2016 15:28:41 GMT -5
Post by Stinger on Feb 28, 2016 15:28:41 GMT -5
An RPM spike is not detonation, I don't know where you got that impression. The spike isn't tune related so fuel or timing adjustments won't change that.
What injectors exactly are you running? Your VE numbers should be 3-4 times higher than they are. They should be in the 40's at least. This is most likely because your injector dead time is incorrect but I can't say for sure until I know what injectors they are. If this is the case, it's also the cause of the varying idle AFR.
IF they are stock injectors, and IF your MS2 injector drivers are set up as peak and hold, the dead time should be 0.6, not 1.1 like you have it.
What MS2 is this?
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gman
Boosting 10 psi
Posts: 35
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Post by gman on Mar 1, 2016 8:47:35 GMT -5
It is a version 3.0 board MS2. They are stock brown-top injectors, and yes, I believe the drivers are set up as peak and hold (since the stock injectors are low impedance -- anything I should check to confirm that?). I will change the dead time to 0.6 -- does that mean I will have to retune the VE table from scratch?
I got the impression that it was detonation from hearing the typical knock rattle in the engine at that rpm during that pull, and then seeing the variation in RPM on the graph that correlated with when I heard it. It may be something else besides detonation, but I can hear it.
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Misfire
Mar 1, 2016 11:37:37 GMT -5
Post by Stinger on Mar 1, 2016 11:37:37 GMT -5
You may be detonating but it's not the rpm spike. They may be happening around the same time but detonation doesn't show up as an RPM spike. The RPM signal is just what the distributor is reading. Detonation doesn't change the distributor's RPM reading.
Changing the dead time will throw off the VE table at lower rpm's. You don't have to tune it from scratch but it should change it significantly down low since it's "incorrect" now.
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gman
Boosting 10 psi
Posts: 35
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Misfire
Mar 2, 2016 22:18:17 GMT -5
Post by gman on Mar 2, 2016 22:18:17 GMT -5
Stinger, could the rpm swings we're seeing be caused by a worn timing belt, perhaps in combination with a disturbance such as detonation? The car has 130K on the odo, and I have no idea whether any PO replace the belt.
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Misfire
Mar 2, 2016 23:15:58 GMT -5
Post by Stinger on Mar 2, 2016 23:15:58 GMT -5
No, not likely. The spikes may be able to be filtered out using the filter settings in the software, though I'm not positive.
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Post by wesk on Mar 4, 2016 9:07:11 GMT -5
Did you build the ecu? I see you have low z injectors, did you do #16 here: www.megamanual.com/ms2/V3trouble.htmHow is everything grounded? What ignition input circuit are you using? Is this "stock" tfi (coil too)?
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gman
Boosting 10 psi
Posts: 35
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Misfire
Mar 8, 2016 19:55:17 GMT -5
Post by gman on Mar 8, 2016 19:55:17 GMT -5
Hi Wes, Yes, I built the ECU from a kit I bought from DIYAutoTune. I cut the trace per the PDF reference in #16 when I was having battery spike issues, and then ran it out EEC IV pin 37 (versus +12V supply pin 57). Those two wires join together at the S542 junction. That didn't fix my battery spike problem, but putting a 220 uF cap on the H1 boot header did. natomessageboard.com/ubbthreads.php?ubb=showflat&Number=249592#Post249592Ground wires are run to EEC IV pins 40 and 60. I have a stock TFI coil & did the TFI ignition control mod. I'm beginning to believe that the rattling noise I hear between 2K and 3K rpm at 10# boost may be valve noise, although I'm really not sure what is going on.
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