scottyMIz Posted July 25, 2002 Share Posted July 25, 2002 ok i think some people might have tried different things with the stock efi system on the turbo cars.So here is what i want to try, me and tony fruzza have beee thinking how to make the stock system run leaner with big injectors and he and i thought up to by pass air behind the afm and loosen the spring so it's easier to get air and easier on the spring.So i was thinking today that i'll make a tube that ties into before the afm and then again after it so it'll have a nice way to bypass the afm and it will be a constant flo of air unlike drilling holes in the afm flap that changes the weight and dynamics of the afm flap.I'll put in a 3" ring between the afm and turbo and then just weld a pipe angled around so it's a nice flo around it and loosen the spring to make up for the difference in air flo.I think that's what is making my engine choke sometimes it's not getting enuf air to match the fuel and it gets hesitation from that and the afm so hard to open(tony's thinking).Well has anyone thought of this and if so did they try it and what where the results?I have to find a way to make this system work until i can save enuf to get a good system.Plus it'll help the others who are poor like me Quote Link to comment Share on other sites More sharing options...
scottyMIz Posted July 25, 2002 Author Share Posted July 25, 2002 i'm not gonna let it lean out i'm gonna keep a good eye on it.I can't afford to rebuild it this winter cuz if i have to then i'm going to do it right and i just can't afford it right now. I plan to try it tonight if it doesn't take too much time if it is going to then i'll do it tomorrow.I'll let you know sleeper how it turns out. Quote Link to comment Share on other sites More sharing options...
fl327 Posted July 25, 2002 Share Posted July 25, 2002 have you thought of changing out the cold start injector for a full on injector for that extra umph? Quote Link to comment Share on other sites More sharing options...
scottyMIz Posted July 26, 2002 Author Share Posted July 26, 2002 i don't have a coldstart injector in my car.But it's a good idea i just need more air for the fuel my car is choking. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted July 26, 2002 Share Posted July 26, 2002 You beat me to it Scotty. That is where I was going to go when I upgraded my injectors. I think it can work, but please don't lean it out too much !!! (we want your engine to last, so you can at least find out whether the mod will work) Quote Link to comment Share on other sites More sharing options...
scottyMIz Posted July 29, 2002 Author Share Posted July 29, 2002 Ok update the by pass tube didn't work.... well it did but didn't it was very hard to tune and when i did it wouldn't run good at low rpm.Now someone prolly could make a better design but after the run i had in it with the bypass tube and the spring loosened it hauled ass but like i said it was hard to get to run at low rpm it wouldn't run smooth thru the whole range of the engine.It just showed me the potential of my engine with a good engine management system.The car pulled much harder with the bypass tube and much leaner but i couldn't have driven it on the street too much. Quote Link to comment Share on other sites More sharing options...
DAW Posted July 29, 2002 Share Posted July 29, 2002 How about a larger capacity AFM (BMW?) to increase airflow, coupled with another leaning approach for lower rpm with the big injectors: you could install a resistor in parallel (NOT series) across the cyl head temp wires in order to make the ECU think the engine is warmer than it actually is and the ECU will shorten the duration of the injector pulse accordingly (and accross the full rpm range). The problem with the bypass approach is that you are letting in unmetered air that doesn't stay at a constant relationship or proportion in flow to the flow of the changing lumen size of the AFM/flap door opening. Unmetered air has no ECU-regulated fuel flow to match up to it and you could end up with an overly lean spot under a condition that could destroy the engine. If you could get a large displacement-source AFM and map/compare then calibrate its sensor/voltage specs to a stock AFM then you could set the big AFM's door spring tension to approximate the stock unit's signal and start tuning with spring tension/mixture control from there. DAW Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted July 29, 2002 Share Posted July 29, 2002 Part of the problem with reducing the value of the temperature sensor to shorten the DC is now you can't get back to the high duty cycle with the bigger injectors, part of the reason to install them to begin with. I'm not sure that would happen, but when the ECU hits the top of it's air map, it may not go to max duty cycle (anyone confirm or deny this?) I am also thinking the air bypass may work better with the MAF sensor, since it has low restriction. The bypass flow may actually be roughly linear with airflow through the MAF. Quote Link to comment Share on other sites More sharing options...
DAW Posted July 30, 2002 Share Posted July 30, 2002 I don't think I understand about the duty cycle portion..I was thinking if a stock injector sprayed a certain volume of fuel for a given pulse signal, that a larger injector just delivers more fuel for the same pulse. If it's too rich then you can shorten the pulse, lower the pressure, or go to a smaller injector. I agree re a bypass and a MAF system because both lumens are a fixed value rather than one constant and one varying all the time. I've wondered if there is a donor for MAFs with a similar range of output values as the MAFs on the L28s that could be adapted easily. DAW Quote Link to comment Share on other sites More sharing options...
DAW Posted July 30, 2002 Share Posted July 30, 2002 er..AFMs on the L28s Quote Link to comment Share on other sites More sharing options...
Tony240ZT Posted July 30, 2002 Share Posted July 30, 2002 I've been getting more and more into electronics. I think by setting up the AFM so that the full range is used with your engine and then modifing the map with a piggy back computer is the way to go for those of us who have upgraded injectors. I've had such a hard time getting my car to idle well AND have good power under boost. Most of the time my car is running rich just so that if the AFM doesn't react quick enough I have some room. The reason why my AFM isn't reacting quick enough sometimes is because I have to have the thing tightened down more than it should be. I will be working on a piggy back system for myself, and hopefully evolving it to a full engine management system down the road. If my setup proves to work well you guys will be the first to know about it and I will offer it at the best price I possibly can. To keep the piggy back system cheap I'll probably limit it to only taking in inputs from the head temp, RPM, o2 sensor, and AFM posistion. If we believe that the stock timing is not a major problem, then for sake of keeping it cheap I don't think I'll play with it. The mods required would be splicing about 6 harness wires, and you would have to program it with a computer. We could share our configureations over the net, and a default setup would be included. It would cost you around $60 for what I have in mind. Let me know if this is something you guys would be interested in, and if it would be worth the money. Also, what other features would you like? I could probably setup a true closed loop setting so that fuel management is controled directly by the o2 sensor. Possibly could do data logging, but not certain on how much data could be stored. Feel free to email me directly on this, and if you are into electronics help me brain storm. Quote Link to comment Share on other sites More sharing options...
scottyMIz Posted July 30, 2002 Author Share Posted July 30, 2002 ummmmm ok you guys are over my head now but tony if you figure it out soon and i don't have my new system then i'm in. Quote Link to comment Share on other sites More sharing options...
Tony240ZT Posted July 30, 2002 Share Posted July 30, 2002 I'm thinking if I'm going as far as remapping things I might as well use a mass air flow meter. I think more people would be interested if they could convert to a commenly found MAF. I have a Z31 Turbo MAF laying around. I'm sure a non turbo one would work just as well. Part of my problem is due to the restrictive AFM, so it'd make me a lot happier. Quote Link to comment Share on other sites More sharing options...
DAW Posted July 30, 2002 Share Posted July 30, 2002 Tony, I'm thinking leaner at idle and off-load and richer at higher rpm (and boost) could be accomplished with a rising-rate fuel pressure regulator. The best piggy-back computer I can envision for need-based enrichenning would be in circuit with a G-meter...(I'm serious, I think it could be a useful parameter for performance tuning). DAW Quote Link to comment Share on other sites More sharing options...
DAW Posted July 30, 2002 Share Posted July 30, 2002 You could put the MAF in front of the AFM and hook it up separately, with the voltmeter in the car, in order to see the signal at various rpm/flows, then put a stock AFM there and do the same (both tests would be upsteam of the working AFM system). DAW Quote Link to comment Share on other sites More sharing options...
clint78z Posted July 30, 2002 Share Posted July 30, 2002 Good idea DAW you can chart everything that way. scottymlz just do this. Setup up AFM spring tension to give you maximum power under boost, O2 sensor will correct a bit at part throttle. And have an electronic solenoid off the TPS idle circuit this will allow bypass air. On the end of the solenoid have a bleeder valve that you can manually set the metered air leak around the AFM. So to set idle mixture simply adjust the little valve. Simple and easy, one relay, one solenoid, one bleeder valve. Quote Link to comment Share on other sites More sharing options...
DAW Posted July 30, 2002 Share Posted July 30, 2002 The MAF signal is voltage and the AFM is resistance, but with the MAF being less restrictive, maybe the whole system from a 300ZXT ECCS could be transfered over. V6 or inline 6; the cylinders fire at the same interval and both the L28ET and VG30ET use a crank angle sensor and thermistor sensors (in general, Bosch thermistors share the same ohms change per temp regardless of the type of car they're used in). You may have to modify the injector harness lengths to get the connectors to reach their injector, but that's easy. The ECCS doesn't know if it's hooked up to a V6, L6, or flat 6. DAW Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted July 30, 2002 Share Posted July 30, 2002 Originally posted by DAW:The MAF signal is voltage and the AFM is resistance, but with the MAF being less restrictive, maybe the whole system from a 300ZXT ECCS could be transfered over. V6 or inline 6; the cylinders fire at the same interval and both the L28ET and VG30ET use a crank angle sensor and thermistor sensors (in general, Bosch thermistors share the same ohms change per temp regardless of the type of car they're used in). You may have to modify the injector harness lengths to get the connectors to reach their injector, but that's easy. The ECCS doesn't know if it's hooked up to a V6, L6, or flat 6. DAW Not "maybe" - "yes" I've done it, and it works so much better. Quote Link to comment Share on other sites More sharing options...
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