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| More thoughts on start up tuning. https://slantsix.org/forum/viewtopic.php?t=26413 |
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| Author: | Sam Powell [ Tue Jan 01, 2008 7:24 pm ] |
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Thanks Frank. The blessing is that you guys have hung in there and answered my dumb-dumb questions patiently, and shared what you could. I really could not have gotten this far without the Slantsix forum to bounce things off of. I have worked on other internet support groups such as this, and none of them are as cool as you guys. There is a long way to go. I do think that as a result of this patient struggle, I am slowly becoming one of the more knowledgeable amateurs trying to get the Accel system to work, at least concerning the phases of the system that I have tuned so far. It has served to keep my old head young. That was one reason I didn't just keep the carb system. That and Dart270 talked me into going EFI in the first place. Eighteen months ago I knew almost nothing, and struggled mightily to get the car to run at all. Even the so-called pros have a relatively narrow field of expertise in most cases. Most of them seem to be just simply trying to produce horsepower, and are not concerned with producing a reliable, pleasant drivng machine. I think most of the guys who can install and tune this Accel system are not giving much knowledge away. They charge for their time and knowledge. It has been a long and sometimes frustrating road. I am learning just a bite at a time. The next two bites to take are the feedback system, and maybe the anti knock system, which is not hooked up yet. I hope that this stream of consciousness reporting I am doing is laying the ground work for others here on the forum. Here is the sad thing, if I don't write about this, and do a certain amount of documentation now when my head is into it, in a few years I will no longer remember some of the more important details of setting up and tuning EFI. When I was young I could remember things for years without consulting notes, or manuals. But not any more. Thanks for the compliment, but this has indeed been a team effort so far. I will bug you with guys more dumb-dumb questions in the future. Sam |
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| Author: | Sam Powell [ Tue Jan 01, 2008 7:26 pm ] |
| Post subject: | |
Sorry, Double post. Sam |
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| Author: | Sam Powell [ Thu Jan 10, 2008 4:51 am ] |
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This engine still does not want to start when cold like an OEM system, and yet it is programed for alot of start up fuel. Maybe it still needs more. The process now is crank it once, no fire. Stop cranking, pump the throttle twice quickly for the "Faux Fuel Pump Shot", crank, and it fires. If that is all the better it gets, that is OK, because it does start now. But, I would like to understand how to make it start up with just a simple crank and ignition. The interesting thing is, I have not flooded it yet, so I am not putting in too much fuel for sure. I am wondering if the base VE figure in the start cells is still too low. Raising this would increas the fuel when warm as well, so I would have to go back in and reconfigure the warm up curve for the start fuel. It fires right up when warm. I would still appreciate someone with EFI to look into their tuning software, and see what VE numbers you have in for low vacuum at crank. Lou, Pierre, Matt? I would need to know what size injectors you have as well Sam |
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| Author: | Matt Cramer [ Thu Jan 10, 2008 7:16 am ] |
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Unfortunately I didn't get my cold start settings dialed in too well before I took the Dart off the road for the turbo upgrade. |
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| Author: | KitCarlsonEMS [ Thu Jan 10, 2008 7:49 pm ] |
| Post subject: | Starting |
Sam, Perhaps I can help with my experience with my EMS system. I think it has similar setup features, possibly less complex. I tune starting as follows: Step 1 (after warm up enrichment is correct) The initial prime pulse so the engine hits immediately with a varoom. Too little it hits but not enough to take it away from the starter, Too much it cranks hard like being flooded. Time depends on injector size... 7 to 9 mS seems to be in the range. ( prime only happens if coolant temperature is below ~35C and TPS < 75%) Step 2 The cranking fuel, in my system is adds to the normal fuel calculation. The cranking fuel changes every second, typically ~0.5mS, varies up and down with time. The idea is to clear if to rich or be richer if too lean. Too lean engine will not hit, too rich it will crank hard and smell gassy. Step 3 Just started fuel. It also is additive to normal fuel calculation. It helps with initial short term enrichment. In my system, values change every 5 seconds up to 55 seconds. Decrease values with time, initial values keep engine from stalling, later values taper to 0. There in some interplay with normal temperature enrichment. Be intuitive. A typical initial value ~0.5 - .8mS. Step 0: Temperature enrichment (coolant). In my system it is a fuel adder vs temperature numbers. You need some cold days, and experience. When this is set right everything is golden. I get something that is close, then modify values in the warm up. It is best to start rich then work down. If too lean, the stall and restart will start, again and initialize the just started fuel. Values 1mS at 0C decreasing to 0 at normal operating temperature. It does not get cold here, my experience is limited. Note: charge air temperature is another compensation that is in fuel calc. The difficult part is breaking it all down to make the adjustments at the right place! I get sensor overload by trying to watch all the sensors and EFI info. Once things are close, it becomes easier to make the small changes towards perfection. It requires repeating the process. Only adjust VE cells when at operating temperature and running long enough, that above enrichments are not in play. |
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| Author: | runvs_826 [ Thu Jan 10, 2008 8:28 pm ] |
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Hey Sam I totally feel you in the cold start problems. I got it going pretty well this week cause it was like 36 degrees. The biggest problem I had was leaning it out as soon as it fired. However, I still have problems that is takes about 4 seconds to crank, than fires up. No pumping, no problems. So the last post was dead on, don't change your VE table unless your having trouble idling after it is warmed up. I'm a little worried about doing a turbo efi cause it seems like you've had up and downs kinda things. However, I do know that you did jump in with both feet and I can feel you there. I just had to go back from the HEI to the distrubtor manual advance cause the HEI was keeping it at 10 degrees. So keep with it and get that baby running right! |
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| Author: | Sam Powell [ Fri Jan 11, 2008 5:23 am ] |
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The cranking cells and idle cells are not the same. Idle cells are highest vacuum ,and the cranking cells are lowest vacuum, or 0 KPA. They don;t effect one another. Thanks for the feedback from all involved. The 7-9 MS for start, is that cold or hot? Sam |
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| Author: | Wizard [ Fri Jan 11, 2008 8:10 am ] |
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Sam, Also forgot. The millisec times is DEPENDENT on injector's size and minimum (for ease of idle mixture control especially if too small, the injector can't pulse because it's too SLOW to pulse so small squirts especially if injector is sized way too BIG.) and maximum open times (all are 80% max open-time), size of injector determines sufficient flow at 80% PWM to "COVER" engine's max HP at WOT, fuel PSI changes the flow in small amount BUT too low streaves engine at WOT or too high PSI and injectors won't open or not too reliably. Going beyond 80% PWM risks burning out injector drivers or injectors themselves. Type of engine & whatever is wet or dry manifolds and type of manifolds design changes some of whole picture and effects the start up/after starts/warm up process. That is where you have to work this out after you have determined that injectors is right type for what you need. That's all detailed in the megasquirt manual. Cheers, Wizard |
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