Hi, Just looking into the best way to manually adjust your fuel mixture. Please forgive me if there is another thread on this. If so I would appreciate it if someone could point me towards this. I have not had so much of a problem with my Zed. In fact I would have to say the opposite. To be honest my problem has been mainly with the falcons and commodores running too rich. Nevertheless I do believe the principle would most likely be the same. Bar the obvious, or not, differences between systems. I understand there are several controllers on the market. Some of which are actually relatively quite cheap. However the basis for my question lies mainly in the technical aspects of fuel mixture control and the design of the systems and the sub-components required to make an adjustment. For example. I had been mainly looking into what circuits could be used to adjust the input and/or output of the oxygen sensors. AFAIK we are fortunate enough to be able to program ECU for fuel mixture with Z32. Again, the basis for my question would be how to do this manually without making an adjustment in programming. Also given that any programming changes in some cars cannot be made without physically replacing the "chip". Regards
Fooling with air/fuel ratios without properly diagnosis is the first ingredient in the reciepe for an engine rebuild. But there are many ways; I list from the cheapest and nastiest through to the correct way. - Signal intruption, by modifying the signal from either the O2 sensor or air floow meter. - Piggy back ECU or chips. - Nistune - full after market ecu Each of these should be done using diagnositic gear like an air/fuel ratio meter and knock sensor as a minimum. But, you can give it a go on the road and risk the outcome.
To be completely blunt and honest, that is a stupid idea. Get Nistune and be done with it. Fooling the O2 sensors will only work for the closed loop section of the map and be average at best.
Thanks to both for your posts. Like I said I have very little problem with my Zed in terms of fuel mixture. I would probably not go stuffing around there. Also, I would have to agree, the Nistune does look to be very good value for money. The main problems I have had are with the Fords and Holdens which are not reprogrammable without "re-chipping" AFAIK (yes some are reprogrammable but depending on engine). So why do I ask this question here? It seems a lot of you on this forum have had experience with O2 sensors etc. Yes, perhaps a question for another forum. However I am sure that I would get a better quality rather than quantity response from users of this forum. Especially given the more so technical design of our car. Point taken though. Yes, probably a stupid thing to do on a Zed. If I wanted to go "stuffing" around here. It would be best done on the commodore. And, as you point out, it does seem to be once it goes into closed loop. That it starts to run rich. Also, the engine diagnostics on the commodore, possibly with many cars, will not bring up an error with sensor if it is working. AFAIK this may be despite it not working properly. Regards
If it is running rich when it is going into closed loop. It suggests either a cracked exhaust prior to the O2 sensor or the O2 sensor is faulty. Also, other sensors might be at fault like the temp sensor, TPS and even airflow.
This forum is for Z Related - Technical, not holden or falcon questions. Your question as you have stated is probably better posed on a Holden or Falcon Froum. Although the VG30DE(tt) uses similar pricipals for engine management, they are not the same.
Hi, well I continue to learn new things every from you guys which I am very grateful. While I am sure these are common knowledge to many of you guys. I knew nothing of these really. Still not 100% but I will do some reading. gmbrezzo, the only reason I post here also, apart from what I have mentioned above. Is that AFAIK the systems are similar. In particular that of the oxygen sensors. If you could possibly refrain from locking this thread I will keep my posts as closely Z orientated as possible. Yes my problems have been mainly with those cars. But I am not posting here to get advice on how to fix them. I am posting here to hopefully get an idea of what signals and systems are required to make "analogue" adjustments in fuel mixture. And from the impression you guys have given me is this is something you don't really want to to. And I suppose neither is it something the system was designed for. Nevertheless AFAIK it can be done. If I could ask a really stupid question. What are the sensors mounted in the catalytic converters??? Are these temp sensors? I was taking them out to replace the clutch, (Makes perfect sense not!). Thinking they were the O2 sensors only to find the actual O2 up in the manifolds. Regards
Sensors after the cats are for overtemp. Light up the little light on the dash and do nothing else. Problem with fart arsing about with the sensor input into the ECU is what it does with those signals. To work out how much fuel the engine needs the nissan ecu calculates something called theoretical pulsewidth, or TP. This is calculated off various things such as AFM voltage, TPS voltage, coolant temp, fuel temp etc etc. You fool around with one it can effect other things. The coolant temp input will effect the ignition timing as well as does other things.... While this is basically how the apexi SAFC works, it is far from ideal.
Thanks. So I am wondering why I am getting open connection from this cat-overheat light sender box, and finally open the box to check the sensors. I think one of the sensors is not working. One sensor is 10K, hot or not. The other was 3.3 ohm cold and 100 ohm hot/warm. Despite this, Does anyone knew whether some kind of variable flow/resistance injector would be feasible and/or if it has been done before? Would this have the desired effect of being able to "adjust" the fuel mixture and/or be a better option than attempting to alter sensor voltages? http://www.zdriver.com/forum/300zx-z32-forums-7/bad-fuel-injector-32225/
Or easier still perhaps. Using a single variable/selectable resistance on the +ve rail of the injectors rather the than -ve of each injector. So if you started with a higher flow injector, for example. And had 3 settings for fuel mixture to make it easy. Say Power, Normal and Economy. Having a different resistance for each setting to drop the +ve voltage to each injector???
Injectors are solenoids. Do not work off varied voltage. Won't work. What sort of engineer are you Just get Nistune or don't screw with it.
lol, I better stay out of this thread, already got a warning in the other one Seriously, just get Nistune, period.
Yeah yeah lol lol friggen lol. Computer Systems. Now I wouldn't ask the question if I knew the answer. I know very little to nothing about injectors. But just because an injector uses a solenoid does not tell me why this would not work. AFAIK by altering the resistance of a particular circuit at fixed voltage, you are altering the current of which the solenoid is going to operate. Here is resistor circuit they use in Hondas so the ECU doesn't blow up. I am not denying that you are correct. Just I would prefer to understand why. Also here's another thing they reckon they're getting different flow at different voltage???
lol I don't understand why you insist on trying to make things so difficult. Why reinvent the wheel with an inferior wheel? If you want to get creative, find a problem that hasn't yet been solved.
I think its a good idea. Put in a resistor for your injectors and let us know how you go. Make sure to do a few power runs.
This dude wants to trim fuelling by exploiting injector latency........... what a dick! You kight be able to make some very fine adjustmets at very low injector opening times but the effect diminishes as injector dwell time increases. Injector latency, (dead time) is already accounted for in the ECU with a latency/voltage table. these tables will account for voltage drops down to below cranking voltage and well above ordinary running voltage. So altering the voltage/current supply to the injectors on the +ive side will just be accounted for by the ECU and it will just laugh at you along with the rest of us!!! Dude, try to let the old school thinking go will you.... and get with the programme.. or fit a 500cfm Holley and youll feel right at home. better still, what about a pair of 2" SU's replacing each throttle body!!!! Might run like shit when cold but would sure look cool!!! E
But is this not partially how the ECU "adjusts fuel mixture" to start with? Actually my question of adding load to the circuit was not one of increasing latency. It was one of reducing the amount of power to the injectors. However I do agree it would effect the latency. Also I think you mean as dwell decreases as RPM increases. So if you attempt to decrease fuel mixture by adding load to +ve rail: 1. Before the ECUs reference voltage (In this case pin 58), and 2. Before the +ve rail to the injectors. Then you are wasting your time and I agree. However at the same time you are you not saying: Dropping voltage to the injectors should trim fuel because this is how the ECU works??? Ie, The ECU will attempt to maintain the signal to injectors irrespective of fluctuations in battery voltage. Otherwise at high battery voltage you will use more fuel and vice versa. If you did do this on the +ve side, without dropping the +ve voltage to the injectors. Ie. 1. Dropping the reference voltage to the ECU at pin 58, whilst 2. Maintaining the +ve voltage to the injectors. Are you not going to increase the fuel mixture? I think it would depend on whether or not the ECU also uses "its" other +ve voltage sources to reference fuel injection voltage. Ie Pins 49, 59 & 109. Yes, I will probably be getting Nistune which sounds awesome. However, AFAIK, with neither system, Nistune or carburettor. Can change my fuel mixture with the flick of a switch while I'm driving. For those interested Jaycar have an O2 fuel controller kit. It is in the wrong section (Audio Kits) so I have emailed them. They may or may not move it >>> http://www.jaycar.com.au/productView.asp?ID=KC5486 Other Jaycar Automotive Kits>>> http://www.jaycar.com.au/productResults.asp?MID=11&SSUBID=620&SUBCATID=965&keyform=CAT2#11 Regards
BTW, I post this here because I enjoy (most of the time) working with electronics. And would like to learn more about EFI systems. Not because I want to argue for/against the point of being able to "adjust" fuel mixture by any particular method. Regards
*long, slow exhale of breath thru partly pursed lips and ballooned checks...NOT Pff* This banter is bordering on the preposterous. For what you are seeking (and you need to stay away from Holden and Ford and the like forums) do some serious research on the principles and operation of how an automotive EFI ecu decides what it does, under what conditions and how it deals with variable operating conditions. This will save this interminable, almost automatic game-saying of whatever statement the other person makes.
