Boy, wouldn't it be something for the whole works to have been down to a flaky keyswitch!
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| Starting fuel calculation question? https://www.slantsix.org/forum/viewtopic.php?t=26040 |
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| Author: | emsvitil [ Sat Dec 01, 2007 5:20 am ] |
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If I'm understanding that right, it varies the timing during starting looking for a successful ignition event........... |
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| Author: | Sam Powell [ Sat Dec 01, 2007 5:31 am ] |
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I think that is right. It seems like it might be a way to go. Man, what are you doing up so early? What, is it 5:30 AM there. Sam |
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| Author: | emsvitil [ Sat Dec 01, 2007 6:09 am ] |
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Quote: I think that is right. It seems like it might be a way to go.
Haven't gone to bed yet.......
Man, what are you doing up so early? What, is it 5:30 AM there. Sam |
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| Author: | Sam Powell [ Sat Dec 01, 2007 6:51 am ] |
| Post subject: | More success! |
OK, I got it started after a long attempt on a 33 degree morning. I decided to keep the garage door closed while cranking, and because the door was closed, I could smell gas from the exhaust pipe. I got out of the car and sniffed the pipe to make sure that was where it was coming from, and sure enough. It was flooding big time. I watched the tuning screen and saw that the RPM count was working,(ignition count there), and then checked the read out for the injection time, which was reading 6-7 ms. I then went to the VE table, and watched which cell it was in during cold crank. For some odd reason, it was cranking in the cell for 107KPA, which had a VE number of 615! That would mean the engine was cranking at 615% of volumentric efficiency, which is rediculous. It idles at about 50%. So that is where all the fuel was coming from. I set that cell for 190, and set the ones around it low as well, since it averages from the cells around it. Then I went to the start up VE coffient table, which multiplies the base VE table by a selected figure to compensate for different ECT temperatures. It was at about 180% for 40 degrees. So I ran this all the way down to 110% and began cranking. AFter a long crank, it sputtered once, and died. I clicked up the coefficient a click. And it sputtered and died. Progress. I clicked it up two clicks, and it fired and stayed running. Hurray! I then proceded to stop, and start it a few times more, dialing in the start up coefficient to start with the first rev. I did this over and over as the engine got warmer, finding the sweet spot each time. I finally quit at 80 ECT to get ready for work. (Yes I work on Saturday.) I will not drive it to work until I have this cold start thing convincingly dialed in. I don;t want to get stuck there in the cold and dark, alone with a car that won;t start reliably in the cold. So far, I have cut the start up fuel by more than half. For start up, the injectors were firing at about 3 ms when I left it. I still have colder temps to do. And of course, until I can repeat this success, I won't feel like I am there. This is hard, but not impossible. Stick with it. You must be patient, and thoughtful in your approach. If it is not working, look at all the variables, and see what you can change, and give it a try. I am sharing this in the hopes that those of you who are doing EFI slants will be helped by my experience. |
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| Author: | SlantSixDan [ Sat Dec 01, 2007 6:59 am ] |
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Good sleuthing (door-closed cranking) and good progress! Onward and upward. I have no experience dialing-in a port fuel injection system like yours, but 3ms sounds like a great deal of fuel to me. |
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| Author: | Sam Powell [ Sat Dec 01, 2007 11:39 am ] |
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You know Dan, at the end there it was starting so fast that I could not tell prciesly what time the injectors were on. I will give more complete information once I have that really down. The comments this group has made int he last week were an essential part of what success I have had so far. Thanks. Sam |
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| Author: | Sam Powell [ Sat Dec 01, 2007 11:40 am ] |
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You know Dan, at the end there it was starting so fast that I could not tell precisely what time the injectors were on. The math would suggest that the actual time is lower. I will give more complete information once I have that really down. The comments this group has made in the last week were an essential part of what success I have had so far. Thanks. Sam |
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| Author: | Sam Powell [ Mon Dec 03, 2007 7:22 pm ] |
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Dead cold starts are still a problem when it is below 45 outside. It is about 35 F. now. AFter I fiddle with the cold start ratio a bit, it starts, but honestly it seems as if the changes I am making are not what makes it start, because almost any direction I go with the ratio, up or down, and it eventually fires over. It is almost as if just cranking on it for awhile makes it start up. Fuel pressure is fine. It is not that. Ignition count is fine, it is not ignition, apparently. Almost at any temperature, it is a little flakey. It will start right up one time, and then take two tries the next time. And when it takes two tries, it seems as if letting up on the ignition switch, and then immediately turning the key, bang it fires right up. Now that I am writing this, it occurs to me that the MSD box is powered by the ignition switch, and maybe the crank voltage is not reliable. Maybe the cold is affecting the switch in some way. I think I will run the MSD to the same toggle that turns on the ECU. My '70 Dart had this random condition where the crank voltage would not work once in a blue moon. It would crank for a bit, and then back fire through the tail pipe as it roared to life. . I wired in a toggle on that car to by pass the ignition switch only if I needed to. I will keep you posted. Sam |
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| Author: | SlantSixDan [ Mon Dec 03, 2007 7:40 pm ] |
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Boy, wouldn't it be something for the whole works to have been down to a flaky keyswitch!
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| Author: | Sam Powell [ Mon Dec 03, 2007 7:45 pm ] |
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Let's hope. And of course if the MSD box is not getting fed at crank, it could flood big time. Sam |
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| Author: | SlantSixDan [ Mon Dec 03, 2007 9:44 pm ] |
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Quote: Let's hope. And of course if the MSD box is not getting fed at crank, it could flood big time.
It may yet be worth following up on this idea...
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| Author: | Sam Powell [ Tue Dec 04, 2007 4:12 am ] |
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It's hard to test these kinds of things alone. I could rig cables and check it remotely. It took two of us to discover whey the '70 Dart would not fire cold. One cranked, and the other checked the voltage at various places. The act of touching the coil with the volt meter somehow or other bridged the gap through the meter, and it fired right off. The guy holding the meter had to go change his underpants at that point. I will keep that post in mind, and refer back to it. For now, I am going to trace out all the wiring, and make sure the flakey one isn;t me. My plan is to make the under-the-hood 12v switched voltage fuse block comes right from the BATT fuse block via a relay. I don;t know how big this relay has to be. A number of things get run from there. Cooling fans, are the biggest. The ECU also is powered from this block, as is the fuel pump. I really should take the time to redo this entire part of the car. It still has the cluedgey, add-on, add on, add on fuse blocks I have been putting in for years. Do you see any reason not to take the MSD box power right from the ECU relay? Sam |
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| Author: | LUCKY13 [ Wed Dec 05, 2007 10:35 am ] |
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Sam are you talking about the big red power wire for the MSD. If so that should be going stright to the battery with no switch inbetween. Jess |
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| Author: | emsvitil [ Wed Dec 05, 2007 2:18 pm ] |
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I don't like running things unfused..... Normally the MSD is run directly to the battery (unfused). It evidently has internal relay So I talked to them and they said use a 20 amp fuse... So take that into consideration on the power requirements...... If the ECU relay isn't big enough, have it trip another bigger relay (fused of course) |
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| Author: | SlantSixDan [ Wed Dec 05, 2007 2:36 pm ] |
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Quote: It's hard to test these kinds of things alone. I could rig cables and check it remotely.
That'd work.Quote: make the under-the-hood 12v switched voltage fuse block comes right from the BATT fuse block via a relay.
Or via its own fuse (or manual-reset circuit breaker) directly from battery positive, at least for testing purposes.Quote: I don;t know how big this relay has to be.
Well, there are heavy-duty (70A) relays, and also you can subdivide the deman and put various groups of electrical devices on various relays, if need be.Quote: A number of things get run from there. Cooling fans, are the biggest. The ECU also is powered from this block, as is the fuel pump.
I would want to see the cooling fans on their own relay, but I wouldn't have a problem powering the ECU + fuel pump off a common relay.Quote: Do you see any reason not to take the MSD box power right from the ECU relay?
None, though as has been mentioned, the input to each device ought to be fused.
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