DIY_EFI Digest Monday, 22 September 1997 Volume 02 : Number 330 In this issue: Re: A short intro... Re: A short intro... Re: Inline Fuel Pump Re: Upgraded drivers Re: Inline Fuel Pump PLEASE SEND ALL INFO! Re: Upgraded drivers Re: I understand Q-jets Re: Injector"spray"vs.evaporation Re: Anyone know... Re: wicked squeaks, possibly TPEFI related Re: Inline Fuel Pump Re: The 5th Injector Not really efi .......... Non EFI - Turbo + Supercharger Re: DIY_EFI Digest V2 #329 Re: I understand Q-jets Re: Question on Cold Starting See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: swagaero Date: Sun, 21 Sep 1997 05:29:22 -0700 Subject: Re: A short intro... Mark Nowakowsky wrote: > > Hi All, > > I will try this for a second time...this time to the right address... > (: > > My name is Mark Nowakowsky and I'm a 34 year old with 3 girls between > the ages of 6 & 10. I live in Edmonton Alberta Canada with my girlfriend > Pixie and I have been a licenced automotive technition for 10 years with > 12 years tune up, fuel injection, and electricle experience under my > belt... (: A big belt...but getting smaller. > > I have read this listing for a few days and some of this stuff is above > my head yet but I'm a quick learn. > > Cya Mark... (: > http://www.connect.ab.ca/~mdnowak/index.html > mdnowak@xxx.ca Welcome to to this mad list I hope you understand as much as I don't. - -- ----|------||------|---- --|------[]------|-- 0/ \0 www.flash.net/~swagaero ------------------------------ From: Mark Nowakowsky Date: Sun, 21 Sep 1997 10:10:16 -0600 Subject: Re: A short intro... Hi Garfield, Garfield wrote: > On Sun, 21 Sep 1997 07:51:04 GMT, garfield@xxx.com (Garfield) > wrote: > > >On Sat, 20 Sep 1997 23:29:30 -0600, Mark Nowakowsky > > wrote: > > > >>My name is Mark Nowakowsky and I'm a 34 year old with 3 girls between > >>the ages of 6 & 10. I live in Edmonton Alberta Canada with my girlfriend > >>Pixie and I have been a licenced automotive technition for 10 years with > >>12 years tune up, fuel injection, and electricle experience under my > >>belt... > > > >Hey Mark. > > > >Yur my kinda guy. Cain't spell technician nor electrical, but you are > >one! Hee hee. > Oops did I forget to use the spell checker... (: > > > >Welcome, make yerseff at home. 8) > > > >Garfield > > Well, I SHOULDN'T have to do this, but OH Well. Sigh. > > In these days of the 90's, when everyone is s'posed to take themselves > soooo seriously, I guess I should point out, in case Mark is *really* a > newcomer, that the above was posted by Goofy Garfield, and is meant as a > warm-hearted welcome, rather than some snide sarcastic snotty....well, > you knowadamean. > Thank you for the heartwarming welcome to the list... (: > You'll find, Mark, that folks with their nose up in the air (or up in > their you-know-where) are usually short-lived in this fine group. So > bear with a wee tad of razzing, and really, welcome. Besides, anyone > with a gal named Pixie has gotta have somethin on the ball, eh? 8) > > Garfield (: Mark ------------------------------ From: MaxBoost@xxx.com Date: Sun, 21 Sep 1997 12:26:41 -0400 (EDT) Subject: Re: Inline Fuel Pump >Go find a Nissan 300 ZX, and there's your inline pump... All 300ZX's have in tank pumps, both first and second generation 300. The 280ZX had an in line external pump. As did the earlier 280Z that was fuel injected. All of the Z pumps are not suited to real high output applications. The only Z pump that is suited to high output is the one from the second generation 300ZX turbo. But it is an in tank design. Max ------------------------------ From: TMatthe@xxx.com Date: Sun, 21 Sep 1997 13:21:51 -0400 (EDT) Subject: Re: Upgraded drivers The GM #1227730 computer. I can build circuits, but I'm clueless as to designing them... Tom > > Is there any way to upgrade the injector drivers in a GM computer to drive > the low impedence injectors? I've heard the stockers will burn out driving a > L Imp. pinjector, but they are so much cheaper than the ACCEL H Imp. > injectors. > Tom Which GM Computer?? ------------------------------ From: TMatthe@xxx.com Date: Sun, 21 Sep 1997 13:31:20 -0400 (EDT) Subject: Re: Inline Fuel Pump OOPS. I looked again in one of my books and it did say 280 ZX. It does say that it's adequate for a TPI system, but I wouldn't imagine it could handle much extra. Tom ------------------------------ From: TromBo36@xxx.com Date: Sun, 21 Sep 1997 13:48:20 -0400 (EDT) Subject: PLEASE SEND ALL INFO! I already introduced myself but i'll do it again. My name is Joel Banyai and I need to design and build an EFI system from the ground up for a 4cycle turbocharged bike motor. i need any and all info, specifically : which sensors are required behavior of those sensors behavior of fuel injectors how to design/build the EFI computer. PLEASE! SEND ME ALL INFO POSSIBLE! thank you. ------------------------------ From: Sandy Date: Sun, 21 Sep 1997 15:47:01 -0700 Subject: Re: Upgraded drivers At 12:23 AM 9/20/97 -0400, you wrote: >Is there any way to upgrade the injector drivers in a GM computer to drive >the low impedence injectors? I've heard the stockers will burn out driving a >L Imp. pinjector, but they are so much cheaper than the ACCEL H Imp. >injectors. >Tom > This seems odd, as most peak and hold injectors are more expensive as they are for race or high output applications (except some of the older bosch stuff). Check summit or other retail hot rod places for discounts on regular high-impedance injectors. Sandy ------------------------------ From: Paul Tholey Date: Sun, 21 Sep 1997 22:41:42 GMT Subject: Re: I understand Q-jets >If the mechanical fuel pump can't keep one bowl filled, how can it >keep 2 bowls filled (assuming same rate of consumption & still only >one fuel pump)? The problem is with your acceptance of one mechanical fuel pump being enough. The pump runs off the cam. Therefore the pump is working to feed 8 cylinders at only 25% of the time, The other 75% of the time it is idle. The Holley allows you to run more pressure and at the same time more volume while not blowing past the needle valve, as would the problem be with the Q-jet. Paul > >> To be more correct the reason the Holley carb is used over a Q-jet >> is because the Q-jet has a single fuel bowl in the center to feed both the >> primaries and secondaries. Mechanical fuel pumps cannot keep this bowl >> filled, and electric fuel pumps that can keep an average carb filled run at >> a pressure that will blow past the Q-jet needle and seat, wich are only good >> to 7 lbs. >> The Holley has two fuel bowls, one on each end, which can be >> extended to hold even more fuel. Their needle and seats also hold 9 lbs. >> and can be replaced with ones that hold up to 12 lbs. >> I am not trying to start an argument, but there are people who >> subscribe to this list that run Holleys, and it is not because we can't >> figure out a Q-jet. >> >> Paul Tholey >> pft101@xxx.edu >> > > >-- >Daniel Grambihler >danielg@xxx.com >'87 328 GTS '95 D90 #3064 '96 900SS/CR > > ------------------------------ From: Frederic Breitwieser Date: Thu, 18 Sep 1997 16:33:32 -0400 Subject: Re: Injector"spray"vs.evaporation > The "secret" part was how he kept the thing from detonating its guts >all over the road. It's still a secret, as far as I know. Personally I >think it was a hoax. I happen to agree with you Dave - I've glanced through several of his "how to make power" books, while evaluating automotive books for my collection... but all his books seem to be what I would consider somewhat of "common knowledge". Not a slam to Smokey Y or anything, but the concept of using a bigger Holley and increasing the fuel flow to balance is not rocket science. Me, I'm more interested in the "formula" for the Duttwieller dual turbo Buick V6 setup :) Its real, it exists, but its expensive LOL. Frederic Breitwieser Homebrew Automotive Mailing List Bridgeport, CT 06606 http://www.geocities.com/MotorCity/Downs/4605/index.html 1989 AG Hummer 4-Door 1993 Supercharged Lincoln Continental 2000 Mid-Engine Sports Car - --- ------------------------------ From: Frederic Breitwieser Date: Wed, 17 Sep 1997 15:18:03 -0400 Subject: Re: Anyone know... >...If the engine in the Ford Probe GT (93-97) is the same basic engine as >whats in the Contour and Mystique now? I am pretty sure that the engine is >the same, but the intake manifolds and the ECUs are different. I know the The blocks are of the same origin, however I ::think:: they have been bored to different displacements, but I'm not completely sure. my friend's girlfriend recently bought a Mystique and when I see them tomorrow, I'll poke my nose under the hood. >have the same engine? I was interested in the extra 10 horsepower and in >the 196hp of the SVT (versus 164 for the Probe :( ) and thinking about >adapting the Contour's sytem to the Probe... If you are looking for additional performance out of your Probe - you have several choices to go. First, is to find a Ford 3.0L Taurus SHO engine, as there is a small but loyal aftermarket following for this engine, which is rated 220HP by Ford. A neat thing is that it bolts directly to the Probe's transaxle, assuming both vehicles are stick rather than Auto. I would ::think:: that if both vehicles have an automatic, the compatibility would be there as well. But, like above, I'm not completely sure. Another option, though its not immediately obvious to me if it would work, proved successful on my 1993 Lincoln Continental, which is a front-wheel drive 4000lb sailboat, with a 3.8L Ford engine. I increased the size of the injectors slightly, and fabricated brackets for an existing Paxton supercharger that I had, and attached it to the vehicle on the passenger side of the engine, since its transverse. Very crowded. However boost, at low levels (under six PSI) yield a decent increase in performance without blowing the rings. I have just about 75k miles on the car, about 62-63K of which were supercharged. So far, I've not been plagued with any engine problems, and the compression as of a month ago is equal among the cylinders and quite strong. Of course, I use 93 Octane gasoline. If you aren't into the Supercharge thing, and I have to admit it was a real pain in the ass to find space as well as fabricate the necessary brackets, you might consider a turbo. Its much easier to install as it goes behind the engine towards the firewall, however then you have interesting intake-hose routing problems. Either way its a pain, but I wish I went the turbo route. I lucked out and didn't have to change the ECM, any prom chips (if that's even doable), or wiring for the supercharger. Lock and load. I think the car "adapted" to the additional pressure then compensated with the larger injectors I installed. I did all of the above under the direction and supervision of a more knowledgable friend who assisted me in the upgrade. Hope I added some other choices to your list :) Frederic Breitwieser Homebrew Automotive Mailing List Bridgeport, CT 06606 http://www.geocities.com/MotorCity/Downs/4605/index.html 1989 AG Hummer 4-Door 1993 Supercharged Lincoln Continental 2000 Mid-Engine Sports Car - --- ------------------------------ From: Frederic Breitwieser Date: Wed, 17 Sep 1997 13:03:04 -0400 Subject: Re: wicked squeaks, possibly TPEFI related >What ever is causing the squeak is definitly vacumme related. I checked >PVC vales, clean as a wistle and free. The evidence suggest that there is >ported vacuume leak from the manifold to the crankcase and that the While it might be EGR related, I would first put the vehicle in park with the emergency brake on, and while its squeeking, pull the vaccuum hose off your power brake booster. Its very possible that the EGR fibulation (if it is that) can be caused by a leaking power brake vaccuum resevior. Also, on most GM vehicles, there is a vaccuum canister that "stores" vaccuum, which can result in the same thing. The squeeking, if it is the EGR valve itself, is unlikely to be a fibulation, or modulation of the valve, but rather vaccuum leaking past, or causing a partial open.close condition. On my 69 Ford Convertible, which has the old cast iron 390, the vaccuum canister (which was a 1/2 gallon Dole Peaches Can, so it seemed) leaked and caused all sorts of funny noises. After replacing the can, all the whistling noises went away. Whistling, not squeeling. Good luck :) Frederic ------------------------------ From: Simon Quested Date: Mon, 22 Sep 1997 12:47:42 +1200 Subject: Re: Inline Fuel Pump Hi Stephen and All > my old messages and someone said that pre-85 Nissan's (200SX?) had an > in-line type, but the guy at the parts store say's nope. Does anyone know > of another doner vehicle or where else to get one? I got a Nissan Silvia/Gazel in line pump it's located near the rear wheel arch under the car Cheers Simon +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Simon Quested (E-mail questeds@xxx.nz) Computer Technician, Silicon Graphics & Windows NT Support Centre for Computing and Biometrics LINCOLN UNIVERSITY OF NEW ZEALAND Phone (64)(03) 3252811 Ext. 8087 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ http://www.lincoln.ac.nz/ccb/techs/simon/default.htm +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Some people can tell what time it is by looking at the sun. But I have never been able to make out the numbers. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ------------------------------ From: Simon Quested Date: Mon, 22 Sep 1997 12:09:02 +1200 Subject: Re: The 5th Injector Hi All > I can't acces your doc file Sorry my link is dead if you want the circuit mail me. > Anyway , between the moment you inject fuel using the 5th injector and > the moment you have some readings from the O2 sensor it's arround 0.5 > sec ( on my car ) . If the O2 sensor control the PW without delay ( > hysteresis ??? ) your system will go in a sort of oscillation . The O2 sensor is only there for an on condition, the injector will only come on if the O2 output is below the set voltage. The map sensor controls the the pulse width. Cheers Simon +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Simon Quested (E-mail questeds@xxx.nz) Computer Technician, Silicon Graphics & Windows NT Support Centre for Computing and Biometrics LINCOLN UNIVERSITY OF NEW ZEALAND Phone (64)(03) 3252811 Ext. 8087 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ http://www.lincoln.ac.nz/ccb/techs/simon/default.htm +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Some people can tell what time it is by looking at the sun. But I have never been able to make out the numbers. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ------------------------------ From: Simon Quested Date: Mon, 22 Sep 1997 14:11:41 +1200 Subject: Not really efi .......... Hi all Nothing to do with efi .....but I had to share this with you all. This story was related by Pat Routledge of Winnepeg, Ontario about a repair call he handled while living in England. It's common practice in England to ring a telephone by signaling extra voltage across one side of the two wire circuit and ground (earth in England). When the subscriber answers the phone, it switches to the two wire circuit for the conversation. his method allows two parties on the same line to be signaled without disturbing each other. Anyway, an elderly lady with several pets called to say that her telephone often failed to ring when her friends called; and that on the few occasions when it did ring her dog always barked first. Pat proceeded to the scene, curious to see this psychic dog. He climbed a nearby telephone pole, hooked in his test set, and dialled the subscriber's house. The phone didn't ring. He tried again. The dog barked loudly, followed by a ringing telephone. Climbing down from the pole, Pat found: a. The telephone system's ground was disconnected from the ground post and used to restrain the dog via an iron chain and collar. b. The dog was receiving 90 volts of signaling current. c. After several such jolts, the dog would start barking and urinating on the ground. d. The wet ground now completed the circuit and the phone would ring. Unfortunate but very funny =-) Cheers Simon +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Simon Quested (E-mail questeds@xxx.nz) Computer Technician, Silicon Graphics & Windows NT Support Centre for Computing and Biometrics LINCOLN UNIVERSITY OF NEW ZEALAND Phone (64)(03) 3252811 Ext. 8087 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ http://www.lincoln.ac.nz/ccb/techs/simon/default.htm +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Some people can tell what time it is by looking at the sun. But I have never been able to make out the numbers. +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ------------------------------ From: "alex nicu" Date: Sun, 21 Sep 1997 19:18:27 PDT Subject: Non EFI - Turbo + Supercharger Any kind of informations on engines with turbo and supercharger ? Who it's first , the turbine or supercharger ? Alex ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com ------------------------------ From: Jake Date: Mon, 22 Sep 1997 00:29:54 -0500 (CDT) Subject: Re: DIY_EFI Digest V2 #329 > Hi Jake > Don't think of injectors, particularly low impedance injectors, as operating > on a voltage. Think of them as operating on a current. Their impedance (the > DC part plus the AC part) varies dramatically with the position of the > armature in the injector. What this tells us is to drive them with a current > generator for maximum speed & predictability under varying environmental > conditions. For a current generator to work properly you need a relatively > high supply voltage (compliance voltage) to guarantee that you can force the > required current thru the coil under all conditions. The simplest of current > generators is a ON NPN transistor with the base held at a controlled > voltage, a resistor in the emitter to set current and the injector in the > collector. A typical base voltage will be maybe 3 volts. With a 1 ohm > emitter resistor the "constant current" thru the injector will be > 3.0-0.7/1=2.3 amps. This will hold as things vary around, like battery > voltage. Motorola has some good stuff on this in their App notes for their > injector drivers. > > Lotsa Luck Eric > 85 GTI with VR6 power hmm.. well, I understand about the current regulation rather than voltage regulation, and I understand why. The problem is, i still have NO CLUE as to how i should go about doing this. What's an "ON NPN" and which part number would you personally suggest? I only need to drive one injector, a 16 ohm style as the example. I assume i would need one current generating transistor for each injector in my system, since the injectors can fire one at a time or multiple at once? Also, would 12VDC be a good "compliance voltage"? I know i'm asking to be walked through this application, but this is how I learn new things.. i fully intend to understand the concepts and parts involved once I have a working injector on my soldering bench. If you have a good example schematic, or a part number/web site I should start with, that would be great.. if you can think of radio shack parts that would do the trick for beginners, that would be good too. This injector will be triggered by a 555 timer, in one-shot mode (triggered by a pulse). Thanks for your help in advance. (this goes for everyone) > All you have to do is use sandys LM1949 injector board > and drive it with the gm ecm.. > > L8tr:peter where can I find out more about this board? it sounds useful. > Hi again > As a more practical answer to answering your original question, just build > an interface box between the ECU that supports high voltage injectors and > the kind (low impedance bosch) you want to use. This would be as simple as > two sets of connectors and 8 Mot, Siemans or SGS drivers and a few discrete > parts. > > Lotsa Luck Eric > 85 GTI with VR6 power wow.. that was fast. Got an example design yet? I'm new to EFI. > Ok, finally time for me to plunk down the money for an inline fuel pump > for my EFI proj (have been running for short periods of time w/ an in-tank > type sitting in a big coffee can of gas;) Anyway, I looked through all of > my old messages and someone said that pre-85 Nissan's (200SX?) had an > in-line type, but the guy at the parts store say's nope. Does anyone know > of another doner vehicle or where else to get one? All of the high > pressure types in the Summit catalog are $200+. Too rich for my blood (and > I don't want to double the value of my jeep;) > > Stephen any volvo 1975-present with FI (mechanical or electronic). their fuel pumps can exceed 120 PSI easily.. they're designed for 45-80 PSI constant flow (regulator with return line) so for lower PSI you might want to use a ballast resistor. > Just wondering if anyone out there has a simple answer to this question. > Not exactly EFI, but heading that way. If I want to use the hall effect > pickup from a Chrysler 2.2 distributor to fire a simple ignition system > how do I do it? I understand one of the three wires on the hall effect > is ground, one is Vcc, and the other is a current sinking output. Does > it sink current when the vane is in proximity to the sensor, or when it > is not? What would it take to interface the hall effect switch to a HEI > ignition module? Is there a cheaper, more readily available, and/or > better module to use for this purpose. I want it small and light, and > reliable. Will be firing single coil, waste fire system. TIA my standard universal answer: volvo. Many mid 80s volvos (740 and 760 series) used a chryseler ignition with a bosch ignitor box which probably has the same connector as your distributor (round three pin plug? square? i dont know.) and this would be your simplest choice, since the spark on those volvos is completely non-computer controlled. The box very simply connects to: ground, +12V, tach (coil -), and the hall-effect pickup. On normal volvos with the bosch distributor, the pickup coil has two wires and measures around 1300 ohms.. these spark boxes are the most common, and can be found in ANY volvo 240.. grab the wiring for it too, it's not very long, and these spark boxes last FOREVER. most setups used a resistor on the positive side of the coil, which was bypassed during cranking for full-strength spark. grab that and the coil, it's high quality high spark-energy stuff. The spark box is located just rear of the battery (usually) and is black plastic, and about 5"x5"x2". Its the only box on the car fitting that description. The spark coil ballast (resistor) is by the passenger side hood hinge, in the corner of the engine bay. Jake ------------------------------ From: Daniel Grambihler Date: Sun, 21 Sep 1997 22:41:28 -0700 (MST) Subject: Re: I understand Q-jets Paul: My mistake. When you were referring to the Q-junk & the Helly below I thought that you brought up the 1 bowl vs 2 bowl as part of the reason for having one over another. Are there any needle/seat kits avail for the qj which will handle higher pressure? I have a couple of used quads which I need to build into one for a s/b bowtie. While I'm in there.... Thanks - Daniel > > > >If the mechanical fuel pump can't keep one bowl filled, how can it > >keep 2 bowls filled (assuming same rate of consumption & still only > >one fuel pump)? > The problem is with your acceptance of one mechanical fuel pump > being enough. The pump runs off the cam. Therefore the pump is working to > feed 8 cylinders at only 25% of the time, The other 75% of the time it is > idle. The Holley allows you to run more pressure and at the same time more > volume while not blowing past the needle valve, as would the problem be with > the Q-jet. > > >> To be more correct the reason the Holley carb is used over a Q-jet > >> is because the Q-jet has a single fuel bowl in the center to feed both the > >> primaries and secondaries. Mechanical fuel pumps cannot keep this bowl > >> filled, and electric fuel pumps that can keep an average carb filled run at > >> a pressure that will blow past the Q-jet needle and seat, wich are only good > >> to 7 lbs. > >> The Holley has two fuel bowls, one on each end, which can be > >> extended to hold even more fuel. Their needle and seats also hold 9 lbs. > >> and can be replaced with ones that hold up to 12 lbs. > >> I am not trying to start an argument, but there are people who > >> subscribe to this list that run Holleys, and it is not because we can't > >> figure out a Q-jet. > >> > >> Paul Tholey > >> pft101@xxx.edu > >> > > > > > >-- > >Daniel Grambihler > >danielg@xxx.com > >'87 328 GTS '95 D90 #3064 '96 900SS/CR > > > > > - -- Daniel Grambihler danielg@xxx.com '87 328 GTS '95 D90 #3064 '96 900SS/CR ------------------------------ From: jon hanson Date: Mon, 22 Sep 1997 09:24:32 +0100 Subject: Re: Question on Cold Starting At 01:06 21/09/97 GMT, you wrote: >>>when cold, first ignition pulse triggers a "prime " pulse on all injectors. >>>This is a common setup, used by GM and others. Easy enough to implement, I >>>would think, even as an addon.just a oneshot triggered by the ignition >>>pulse, and not retriggerable. >> >>Any guess as to the pulse duration at 20 degrees C? >> >>Ric Rainbolt >> >> >Nope - try about double the standard idle pulse, for starters > > I have an after market efi system on a 1587 cc 4 cylinder engine When the ignition is turned on and the temp is below a user specified temp (60 deg C in my case) all 4 injectors are given a priming squirt the length of which is dep on another user specified number. here's the trick part. the no which works out to a pulse length can be between 0 and 255. When I first got the car, it was pretty cold here around 0-5 deg C in the morning. I gave it a no of 240, figuring too much was better than too little. the car would start after some cranking and throttle juggling. One day as an experiment I set the no to 100 and waited till the next morning (thats the problem with these temp related problems you do a lot of waiting). Engine fired at the first turn of the key, problem solved. to quantify the above engine capacity is 1587 cc / 4 cylinder my injectors flow around 21 lbs/hour a value of 240 gives a 4.7 ms pulse ( the formula is in the owners manual) a value of 100 gives a 2.2 ms pulse be careful of the above figures, the system I use pulses all 4 injectors 4 times for every 720 deg of crank rotation, from what I've read most batch fire systems fire all the injectors 2 times for every 720 deg of crank rotation so you would have to double the above pulse durations to 9.4 ms and 4.4 ms respectively To clarify matters their is also a warm up enrichment table which is active and reduces as the engine warms up, the above is a totally separate priming pulse (a simple form of cranking enrichment). Regards Jon Hanson. ------------------------------ End of DIY_EFI Digest V2 #330 ***************************** 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".