gman
Boosting 10 psi
Posts: 35
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Post by gman on Dec 14, 2015 13:43:16 GMT -5
I've been lurking here and TurboFord. You guys seem to have a really good handle on this stuff! I have read your articles on this board, but I have a few theoretical questions about tuning:
1. Let's say I'm using VE live to tune fuel properly. But assume that I pull the SPOUT connector, so I'm at fixed 10* BTDC timing. Would putting the SPOUT back in (so that the squirt can now advance timing) significantly change the optimal values for the VE table? I know fixing timing at 10* BTDC will significantly decrease performance, but I'm guessing that whether the mix is lean/rich would not be affected by the timing of when it is lighted? Seems like this strategy would be advantageous to safely tune fuel during boost without having to worry about detonation, but I'd like to know others thoughts. 2. Let's say I've used VE live to tune fuel properly while burning 93 octane, and I have a good VE table. Now suppose I switch to regular 87 gasoline (limit my boost to 10#) and switch to a second VE table. Would the second VE table differ markedly from the good VE table, in the regions where the engine is operated? Wouldn't the proper amount of fuel depend upon the heat content of the fuel? Since I would not expect the heat content of 87 octane to be much different from 93 octane, I'm guessing the VE table should be about the same. 3. Same scenario as 2 above, but also assume that I've dyno tested the engine while on 93 octane, and have a good ignition timing table. Now suppose I switch to regular 87 gasoline (limit my boost to 10#) and switch to a second ignition timing table. Obviously, we could dyno the engine again on 87 octane, but suppose we don't. How much should each cell be retarded from the 93 octane ignition timing table to make up the second ignition table?
Thanks for reading,
Rob
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Post by Stinger on Dec 14, 2015 14:46:34 GMT -5
1) You never drive around with the spout removed, ever. Too little timing can be just as destructive as too much. Matter of fact, you never remove the spout at all (even when setting base timing) with an MS system, except for diagnosis of a suspected ECU failure.
2) VE table is the same regardless of the fuel (unless you go from gasoline to E85, or to an oxygenated race fuel). Octane doesn't matter. If you're creating two tables for different octanes (which is only necessary if you want to run the same boost pressure with both fuels) then you'd make it switch timing tables, not fuel/ve tables.
3) If you're dropping octane by 6 points but also dropping boost, you've got two variables at play which makes this more difficult, especially since your timing table is probably only dialed in on the dyno at peak boost, not at 10 psi. Regardless, if it were dialed in to be "on the edge" on 93 octane, you'd need around 6 degrees less timing on 87 octane under the same conditions. This is another place where you can run into a "too little timing" situation that can create a ton of heat (trying to run too much timing on low octane fuel requires crazy low timing values to not detonate).
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gman
Boosting 10 psi
Posts: 35
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Post by gman on Dec 15, 2015 16:13:58 GMT -5
First, thank you for getting back to me so quickly. I really admire your experience/knowledge/professionalism. Re 1) I set base timing to 10* BTDC with the SPOUT removed at idle, as per manufacturer's specs (e.g., to provide limp-home in the event of TFI failure). My boost is currently limited to 10# because I have disabled the BCS for the time being. But WHOOPS, I unintentionally open circuited the SPOUT signal, because I missed/failed to hook up the SPOUT wire in a replacement wiring harness, and I didn't loop check it. D'oh! I did not realize that it happened until after several VE live tuning sessions. The car felt weak, but my data log includes KS, which showed no real detonation, nor could I hear any. I didn't drive it that far, maybe 10-20 miles or so in this condition. Fortunately, I don't think any engine damage occurred. It won't happen again sir, I promise But it is an interesting experience/test, lol. Do you think I need to repeat tuning my VE table? I probably will do so, and I'll report back whether anything changed significantly. My guess is NO, because timing should not affect volumetric efficiency, right? Re 2) Thank you very much for confirming that -- it's what I suspected. I'm pretty sure that heat content is the reason why it would be needed between gasoline and other fuels such as E85 or oxygenated race fuel. At least that's been my experience when switching between JP5 and natural gas on a 160,000 HP stationary turbine, lol, and figured that experience translates properly into these otto fuel engines. Re 3) Got it! I should make separate dyno pull session on 87 octane, just to be safe then. Thanks again for furthering my understanding.
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Post by Stinger on Dec 15, 2015 21:01:50 GMT -5
Once you ditch the manufacturer's ECU, their recommendations go out the window. 10 degrees will melt stuff down in a "limp home event". MS doesn't have a "limp home" mode though so that doesn't really apply either. The key thing with MS is to make sure commanded timing = actual measured timing on a timing light. If you don't do this, you're timing advance table will never match what the engine is actually getting for timing advance. You can't check this with the spout removed as removing the spout removes the ECU's control of timing.
As an example, about 15 years ago I had a stock ECU/ignition failure that caused me to lose timing advance and it almost overheated going down the highway. When I stopped the manifold/turbo/dowpipe was bright orange so hot that I could see the color reflecting off the ground before I even lifted the hood. To get home safely, I advanced the timing to about 30 degrees, then made sure to avoid boost. Temp went back to normal and no more glowing exhaust components.
Too little timing won't cause detonation, or trigger the knock sensor. It just builds a TON of heat and heat likes to kill turbos and melt down engines under prolong driving conditions.
It's not the heat content of the fuel, it's the stoichiometric ratios of different fuels. Gasoline is 14.7:1, E85 is around 9.7:1, Pure Methanol is 6.5:1, and nitromethane is 1.7:1. This means you need 14.7 parts air for every 1 part of gasoline for "perfect" combustion. As these values change, you have to change this value in the required fuel equation to the VE table doesn't have to change. If you didn't change the required fuel value, you'd have to re-tune the VE table completely for each different fuel type (not octane rating, just fuel type).
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gman
Boosting 10 psi
Posts: 35
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Post by gman on Dec 30, 2015 16:46:18 GMT -5
Thank you again for that explanation.
After wiring in the wideband O2 sensor (AEM) and a few tuning runs, I took a log of a pull today. I noticed that the RPMs were slightly unstable during the pull (see attached graph). I have replaced the plugs/wiring, but the car is old (130Kmi). The compression is good and even all four cylinders about 150#. I'm not sure what the problem is, but I suspect either the TFI, or the injectors. Is there any way to tell from the logs? I would have uploaded the log, but it's 5 MB -- much to large for the limit on this board. I have attached the .msq.
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Post by Stinger on Dec 30, 2015 20:20:45 GMT -5
What's the jagged yellow "%" trace showing?
What sort of RPM jump/drop are we seeing in this screen capture? In other words, how far away from norm is it going? Looks like maybe 300 rpm or so?
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gman
Boosting 10 psi
Posts: 35
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Post by gman on Dec 31, 2015 8:37:41 GMT -5
What's the jagged yellow "%" trace showing? What sort of RPM jump/drop are we seeing in this screen capture? In other words, how far away from norm is it going? Looks like maybe 300 rpm or so? The jagged yellow trace is the raw KS (knock sensor) signal from the engine. The RPM (green trace) jumped two times, and then dropped once during the pull. At either side of the cursor, the RPM was 5320/5330 RPM, and the indication dropped to 4681, so about 650 RPM spike down from the norm. Before that, the RPM was 4724-4746, with a spike to 5068. The one before that was 4588-4591 with a spike to 4958. If there is a way to snip out a portion of the .msl, I'd be happy to attach it. But I don't seem to be able to find that feature in MegalogViewer.
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Post by Stinger on Jan 3, 2016 14:11:29 GMT -5
How many sync losses are in the log?
How is the KS signal piped into the ECU?
What ECU is this? I originally thought this was an MS based ECU but now I'm thinking it may be a stock ECU.
Is this a completely stock type ignition or are there any deviations from stock 2.3T?
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gman
Boosting 10 psi
Posts: 35
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Post by gman on Jan 4, 2016 7:06:59 GMT -5
Hi Stinger, There are no sync losses recorded in the log. The KS signal (page 64 of the EVTM) is piped into the MS2 ECU with a 3.0 board via an analog input circuit on channel IAC2B/JS5 per section 3.4.9.1 of the MSExtra Hardware Manual. The ignition is completely stock.
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gman
Boosting 10 psi
Posts: 35
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Post by gman on Jan 7, 2016 8:39:38 GMT -5
Is this a completely stock type ignition or are there any deviations from stock 2.3T? It's stock. So are you thinking it's the TFI? That's what I'm thinking, but I'm not sure how to tell whether that's the problem, or whether it is one of the injectors.
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Post by Stinger on Jan 7, 2016 11:24:41 GMT -5
I'm not sure what it is yet. Not necessarily thinking it's the TFI but I'm certain it's not the injectors. Injectors don't effect the RPM reading at all.
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gman
Boosting 10 psi
Posts: 35
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Post by gman on Jan 12, 2016 16:01:13 GMT -5
I'm thinking its the PIP, and maybe I should just change out the dizzy w/TFI for a reman.
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Post by Stinger on Jan 12, 2016 18:18:10 GMT -5
If you do, be sure to swap the old gear into the reman. They are a matched set.
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gman
Boosting 10 psi
Posts: 35
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Post by gman on Jan 12, 2016 19:22:54 GMT -5
I guess that means I'd be better off buying a new distributor pickup coil and ICM (TFI) and rebuilding rather than buying a reman, since I have to reuse the old gear anyway?
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Post by Stinger on Jan 12, 2016 20:04:31 GMT -5
Depends on the condition of your current distributor bearings and such. I wouldn't personally do the PIP and TFI both at the same time though. The problem isn't both of them.
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