DIY_EFI Digest Thursday, August 5 1999 Volume 04 : Number 450 In this issue: Re: DIY_EFI Digest V4 #449 [none] Re: DIY_EFI Digest V4 #449 Re: TBI to Port Injection RE: Ecu 6 More Questions on cranking Injector flow rates needed. See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Wed, 04 Aug 1999 15:45:23 -0400 From: Frederic Breitwieser Subject: Re: DIY_EFI Digest V4 #449 > Wiring said that I was headed for a big problem. The speed sensor in the > Sub runs the speedometer and something to do with the brakes. He said the Does your Suburban have rear anti-lock brakes? If so, you will lose this feature if you rewire the truck, and depending on your preference, this may or may not be an issue (I hate antilock on trucks, cars its cool). > this work. I called Edelbrock and they do not sell this chip separately, > only with the full EFI set up. This is how they make their money, I imagine - selling complete, integrated systems. > The Edelbrock system was a possibility until; 1) the tech said that his > system is not big enough to feed the 400 SBC I have ready to go in the Okay, you have a 400cid SBC, and TPI stuff of what? A 305 or 350? You should be able to use a 350ECM and be in the ballpark to get things started, and up the injector size one size to get the right flow - the GM systems are somewhat adaptive and with the MAP will "learn" your engine to some degree. Others here can correct me if they think I'm way off base... Longer runners on the TPI system are good for low/mid RPM towing... about 4k or less, above that, they tend to choke the engine, unless you port them as well as the intake (or replace with Accel runners, either way). > Some where in the box with the TPI stuff is a harness adapter that is > suppose to convert the TBI injector harness to an eight injector harness for > the TPI. Another option, which you may or may not like, is this. What did you take the 90 TPI setup from? You might be able to get that harness if its out of a junkyard car, and go through the agrevation of merging harnesses. I've done this a few times, and its not impossible, or really that bad. Hope you can determine wire color better than I can ::grin::, but its doable, and a LOT cheaper than a painless wiring setup, as good as painless is. - -- Frederic Breitwieser Xephic Technology 769 Sylvan Ave #9 Bridgeport CT 06606 Tele: (203) 372-2707 Fax: (603) 372-1147 Web: http://xephic.dynip.com/ ------------------------------ Date: Wed, 4 Aug 1999 16:08:28 -0400 (EDT) From: Pat Ford Subject: [none] Hi All; This comming weekend I'm building an intake for the LandRover. I have a few questions. 1) is there any use in trying to tune the intake ( like what was posted for header tuning? 2) I want to do tbi first then add tpi ( to make the tbi a redundant system) is there any problem laying a tbi on it's side?? Has anyone done a redundant efi system? Thanks I look forward to your Ideas - -- Pat Ford email: pford@xxx.com QNX Software Systems, Ltd. WWW: http://www.qnx.com (613) 591-0931 (voice) mail: 175 Terrence Matthews (613) 591-3579 (fax) Kanata, Ontario, Canada K2M 1W8 ------------------------------ Date: Wed, 4 Aug 1999 19:58:23 EDT From: A70Duster@xxx.com Subject: Re: DIY_EFI Digest V4 #449 250 ft-lb of torque and only 111 hp at 6000 rpm? That doesn't seem right. >> Torque * RPM / 5252 = HP So, 250 * 6000 / 5252 = 286 ------------------------------ Date: Wed, 04 Aug 1999 20:45:46 -0400 From: Shannen Durphey Subject: Re: TBI to Port Injection > Date: Tue, 03 Aug 1999 14:12:45 PDT > From: "David Sagers" > Subject: TBI to Port Injection > > I ran into a brick wall with my DIY EFI project this morning. Ouch! Can you fix it? I'm > converting a '92 Suburban TBI to a '90 TPI MAP system. I have about all the > parts including the TPI system, brackets, cables, etc... > > Called this morning to buy the wiring harness and the tech at Painless > Wiring said that I was headed for a big problem. Ohh... LOL >The speed sensor in the > Sub runs the speedometer and something to do with the brakes. Yes, that something is called ABS, or RWAL (Rear Wheel AntiLock, a cousin of ABS) He said the > problem is that the TPI ECM uses a different speed sensor than the TBI uses. > And they are vastly different in the signals they produce, are not > interchangeable, nor can you run a dual sensor system. Now the dual sensor comment is untrue. With a competent machinist and enough money, anything's possible. ; ) > Ok, let's get that pained salesman straightened out. The computer is looking for a 2k or 4k pulse per mile speed signal input. The VSS in a 90 suburban outputs 40 pulses per driveshaft revolution. Now without knowing your tire size, gear ratio, or driving habits I can definitely say that this is not compatible. However... Have you seen the term DRAC mentioned on the list? Maybe in the archives? (hint, hint) Well, the DRAC's job is to take that 40 pulse/rev ac signal and turn it into 2k and 4k (and 128k) pulse/mile square wave output. Are things looking better? Now you'll need to locate one. Well, if you remove your glovebox and reach into the dash toward the driver's side, you should find a small white box about 3" X 2 1/2" taped or velcroed in. This is the beast you need. So what to do next? You'll need some wiring diagrams to connect it to the ecm. The schematic for the 747 and the 727 are in "incoming", and there may be a 730 pinout there also. Now that I've gotten around to it, you'll also find a file called dracnfo.zip which has unconfirmed drac pinouts, some pictures, and some instructions for using the DRAC with non-original configurations. For anyone who may have a version of this that's about 2 Meg, this one's a "lite" version, with some small corrections in the conversion instructions. > I remember seeing in a Jegs catalogue that Edelbrock sells a multi-port > system that uses the the TBI computer but requires Edelbrock's chip to make > this work. I called Edelbrock and they do not sell this chip separately, > only with the full EFI set up. Edelbrock does very little to their "conversion" chips. I'm sure a few other folks can back this up. > I've already paid for all the TPI stuff and really like the long runners on > the TPI, not sure I can really afford to shell out another $1000 for > Edelbrock system. > > Some where in the box with the TPI stuff is a harness adapter that is > suppose to convert the TBI injector harness to an eight injector harness for > the TPI. Really? I'd like a description of that. > > But the big question. Does anyone know of a chip maker that makes a chip > that will allow my TBI computer run a TPI system? You should stay with your TPI and TPI ECM. Shannen ------------------------------ Date: Wed, 4 Aug 1999 19:34:57 -0700 From: "Al Lipper" Subject: RE: Ecu 6 Tom, My appology for the confusion. I am offering to sell people BLANK PC boards for $37. They include no components. I only wish it were that cheap to make thes things! Perhaps some background will help. Having PC boards made in small quantities is extremely expensive. I got a special discount on the last batch for ECU6 - it cost me $160 for 4 boards (with plated through-holes, but no silkscreen or solder mask). The estimate on the ECU7 boards is about $100 per pair. The components were purchased from 3 or 4 different sources, but probably cost less than $100 for all of them (in single quantities). The board then took 3 or 4 hours to assemble, and even more time to get the software loaded the first time. To date I have built only one ECU6 board (that was about a year ago...it still works fine). I hope this helps. Al > -----Original Message----- > From: RSRACE@xxx.com] > Sent: Wednesday, August 04, 1999 9:23 AM > To: efi@xxx.org > Subject: Re: Ecu 6 > > > One more question to ask. Does the board come with all the components > soldered on like the pictures you have on the web site? If so > all I have to > do is make a box to house the unit and run the wiring. I know > have to get > all the related sensors. It's looking good so far > > Thanks Again > Tom > > ------------------------------ Date: Wed, 4 Aug 1999 20:45:05 -0700 From: "John Dammeyer" Subject: More Questions on cranking > >Date: Thu, 05 Aug 1999 03:31:24 +1000 >From: Phil Lamovie >Subject: More Questions on cranking > >Hi All, > >John wrote :- > >>I thought one of the injector's jobs was to atomize the fuel though. > >atomize = very small drops vapor = molecules > >Petrol drops burn like a candle. They have essentially two layers of >combustion the ratio of which is controlled by chaos. As the drop >surface vaporizes >there are instants of both rich and lean combustion in very pretty >patterns. The resultant gases are all bad news. Keep in mind the >surface area/volume ratio. Got it! >Don't even look at the Map sensor during cranking the signal from the >sensor >is useless as the engine is "cogging" and slowly to boot. The signal >has both positive and negative excursions. For a high class test fit a >vacuum gauge, and turn the engine over on the starter without fuel >or spark. Don't borrow a gauge you can't afford to replace. > >Pick an appropriate amount say 7 ms and just squirt. If the engine >fires it may go >from 0 vacuum to 70 kPa and 600 rpm in 5 or 6 revolution. Good point. My starting algo. has a pulse width from 10ms with MAP == Ambient to 4.5ms at 8". So The cranking gives it a couple of shots of rich mixture and once the engine accelerates the mixture leans out to my cold running value. Hot starts are even more efficient and start with only a tiny puff of black smoke. > >If this aircraft is flying above 5000 ft you would be well advised to >reconnect the throttle body water supply. This will prevent freezing >as the aluminum will out shrink the brass and lock it solid. This will >make landings difficult and/or messy. I'm not sure the throttle body water supply actually warms the throttle body. What happens as far as I can see is this: Bi-metal strip inside assembly when cold allows a certain amount of air to bypass the throttle plate. As the engine warms up the coolent warms the strip which slowly closes (or reduces the opening anyway) and in essence reduces the idle speed. Connected to this interesting assembly is the idle air bypass motor which doesn't allow air past the throttle plate but allows warm water past the bi-metal strip which opens and allows air past the throttle plate. Convoluted? Yes. > >Check your default for O2 sensor failure in closed loop and make sure >it's not lean. >Aircraft engines have a habit of operating under much higher average >loads than cars. >Thus a 70% load is not unusual. In most cars the average engine load >is 10-15% >This is not an appropriate load for 14.7:1 A/F in closed loop. If you >have a broad band sensor then you will be able to target 12.5 - 13.0:1 >A/F ratio. > >Under no circumstance should the engine boost at A/F of more than 13:1 >it will >simply melt after a few minutes. Imagine under what circumstance you >would keep the throttle of a turbo car at 3/4 for 3 or 4 hours in >closed loop. Boy you've got that right. I mades sure that the engine ran slightly rich (1100 degree EGT readings) open loop. Then when I enabled the O2 closed loop, the mixture leans out and I reached 1350 degrees. I'm told they like to run the engines at 70% to 80% at about 1450 degrees so I have some room for tweeking. The ambient air pressure sensor should handle changes in altitude to ensure that the mixture doesn't go lean or rich with changes in altitude or weather. > >I know that auto makers are "dumb" but they have read the Bosch Blue >Book. Bosch Blue Book???? > >And the cost of the hoses was less important than a throttle stuck >after a long run on the highway in freezing conditions. Remember that >partial vacuum = cooling just as increased pressure = heating Good point. I know there is warm water in the intake manifold, I'll check into how far that heat goes. > >By the way how did you determine the injection amount vs map points >for rpm vs load at 50, 100, 150 etc. rpm ? > I worked backwards. Not knowing the size of the stock Honda Injectors I made assumptions on Honda's HP and Torque ratings along with displacement and RPM. Then calculated, based on what I figured the injectors should be, and installed a series of percent values into a VE table indexed by RPM. I have an initial mixture based on RPM; cranking(9%), idle(14.5%), running(14.7%) and accelerating(?). MAP/Ambient modfies the mixture. The VE value also modifies this mixture. There is also a cold enrichment based on engine temperature that decreases as the engine warms up. Once the engine is warm the O2 loop closes. If acceleration occurs (TPS change), the O2 loop is broken until either n strokes or m milliseconds. Haven't got the Accel quite right yet; engine stumbles a bit under really quick throttle increase. Also my O2 loop is only using the P of a PID algo. I'd actually like to change that to a fuzzy logic algo. I also used a number of different articles from Bruce Bowling, Al Grippo, Ed Lansinger as the starting point. > >If you were firing the injector for 12 ms at 6000 rpm you were >probably >in another dimension. Lets see 6000 rpm = 100 rps or 1 revolution >every >10 ms. I think you were missing injection cycles because you can't >start the >new event until you finish the old. OH! I get it. This is why you suggested injecting during the exhaust cycle; you inject once every revolution. It brings up an interesting question too. When an injector is rated at 80% duty cycle to avoid overheating I've often wondered: 80% of what. 80 minutes on for every 100 minutes.... silly. I'm running a 720 degree engine cycle. At 6000 rpm this is 3000 CAM RPM which is 20ms per revolution and 12/20 is 60% duty cycle. My run log for this afternoon shows 6200RPM and 12.49ms duty cycle which is about 65%. O2 sensor was at exactly 0.5V and this stayed steady for about 2 minutes. No EGT sensors available for this run. We were turning a propellor of undetermined origins but the injector pulse width suggests that we were not at the maximum horsepower compared to our Dyno runs. I would have richened up the mixture at 6200 RPM had the muffler not fallen off and melted through the fuel pump wiring. sigh...... second time today. For the next test we've added bailing wire. ;-) Tomorrow we will finish installing the ducted fan used in the hovercrafts. With Allison Throttle Bodies or SU carburators we've achieved 125HP but the SUs aren't really good for airplanes and the Allisons are expensive and require the pilot to adjust mixture at altitude. My barometric pressure sensor should dispense with that problem. >Why not use a single hall and a chopper with a differential width for >the TDC >indicator. Start a timer with the rising edge and stop it with the >falling edge. >The short one is TDC. We ran into a physical size problem for mounting the sensors etc. My first proto. used a slotted wheel exactly as you described for initial board and algo testing on the electric motor drive. Our reduction drive is at the Flywheel end of the engine and that's where the distributor used to be. We now have an end plate over the hole. By switching to small magnets and latching hall sensors we were able to use our older model ignition with mechanical fuel injection (allison throttle body) (or SU carb) by only changing the position of the magnets. I then don't have to try and figure out by checking timers for short verses long on edges etc. as to where TDC is. My sensors are configured as a 2 bit Grey Code absolute position encoder. Interrupting on the edges therefore tells me TDC for each cyl. i.e. the two sensor values translate directly into a 2 bit integer representing the cyclinder #. > >If you leave out the units you won't pick the core issue Understood. > >The smoothest idle has the smallest cycle to cycle variation in >combustion and that is hard to control if your target A/F is stoic. If >you vary even a little say 15% leaner you will get a miss fire. This >will decrease the vacuum level and cause the fragile chain to break. >The rich tolerance for a "cold" engine is probably in the 100% range. When we are cold the engine runs a little rough. I probably haven't got the mixture perfect for warmup. But, once warm, soooo smooth. Lack of any intake/exhaust valve overlap up to 4000RPM probably has a lot to do with that and then, at 4000RPM when the CAM profile changes... wow! the engine just wants to go and go it does. I'll keep you informed. Regards, John ------------------------------ Date: Thu, 05 Aug 1999 15:15:48 +1000 From: Richard Wakeling Subject: Injector flow rates needed. Hi All, Does anyone know the flow rate of these injectors? 1) 0 280 150 973 Its impedence is 12 ohms It is out of the VT Holden Commodore V8 Sequential engine. 2) 0 280 150 775 3) 0 280 150 960 Thanks in advance. Cheers Richard ------------------------------ End of DIY_EFI Digest V4 #450 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. A non-digest (direct mail) version of this list is also available; to subscribe to that instead, replace "diy_efi-digest" in the command above with "diy_efi".