Is it a good idea to lean out the MAF maybe to 390 to get a little more HP
That will only work when the engine is running in closed loop at part throttle. When running at full throttle the ECUs go to open loop and run a fixed map ignoring the maf, O2, and temp coolant sensors.
Hello gentlemen professors, Small information, if I have a baud rate of 383 ohms and a 392 ohms will there be dysfunctional ecu on the calculations? Do you need to balance the settings? Thank you in advance for your answers
No, do not balance them unless you are monitoring the air fuel ratios while doing so. 383 ohms is only the base setting to get the car started, not an absolute specification. The actual measured resistances could vary quite a bit once the MAFs are adjusted to achieve the proper air/fuel ratios. So unless there is a specific reason for readjusting them you are probably better off leaving them alone unless you are going to use them to set the correct air/fuel ratio, in which case measured resistance will not matter anyway. Hopefully that makes sense.
Mike, what about balancing based on exhaust gas temperatures? In other words, measuring the cat temps at idle after warm-up and adjusting the MAFs from there.
Those MAFs so stoogats unless you have every little vacuum leak fixed Intake gaskets get wasted very easy, vacuum hose and a biggy is the One way valve on the header that goes to the intake. I just lost that cranky thing. All the rubber intake parts. After all of that is verified with smoke and or pressure testing then the MAF's will do a little for you. Yes wideband AFR on each bank before cats if you have them buy the way the clunky old ECUs work about @50% duty cycle. When I do the ITBs then turbo I have have a TC in each header tube, 8 of those suckers - Image Unavailable, Please Login
Kind of like treating a broken bone with a bandaid, best just set them the same read my other post One day I may do a write-up on tuning the 348 if someone does it for me and takes the pics I'm literate
I agree with Mike - setting both potentiometers to exactly the same Ohms does not really make sense. The pots are trimming the ECU-s (not the MAF-s) to achieve the same output results (AFR-s) by both ECU-s. Since everything is separate for the left and right banks, each ECU has its own separate input sensors (CTS, TPS and the MAF signals) and each runs with its own FPR and a set of injectors. Since all of these have tolerances and will likely have certain differences left to right, the potentiometers are there to trim the ECU-s so that they produce the same results (AFR-s) even though they receive slightly different input signals and may be operating the injection at slightly different fuel pressures.
It's better than adjusting both MAFs to the same resistance since instead of equalizing one of several input parameters you're equalizing the output to a degree (see what I did there? ) The problem is that unless you have data to provide a decent correlation between EGTs and AFRs on the 348 you still don't have much of an idea of what the actual AFRs are. EGTs can still provide some decent tuning data in certain situations but in this case using a WBO2 to adjust the AFRs is truly the best way to go about it. If you're only concerned with adjusting the MAFs to get the engine running to factory spec during closed loop you really only need a single WBO2 setup and those aren't all that expensive from places like Zeitronix, Innovate Motorsports, etc. Last I looked you could get a single sensor setup for well under $200 that would allow you to adjust the MAFs to factory spec (assuming the rest of the engine/intake/etc. is in good shape, as Tim points out). Now, if you were to monitor EGTs along with AFRs you could guesstimate future AFRs from your EGTs but unless you already own and have the car wired for EGT monitoring I'm not sure how useful that would be in comparison to just leaving a couple of WBO2 monitors in place all the time. WBO2 sensors last a lot longer and cost a lot less than they used to so unless you're building something wild installing semi-permanent WBO2 monitors would provide more useful info than monitoring each bank's EGTs alone. Or at least that's the way I see it. There are others here who play with this stuff more frequently than I do. Since we do have provisions for monitoring each bank's EGTs it'd be interesting info to have but if you're going that far you also want to monitor AFRs. That many displays would pretty much fill the glove box so linking the various sensors to a tablet using Bluetooth or WiFi starts looking pretty attractive. But I digress...
The potentiometer on the MAF does not adjust the MAF (the MAF signal or anything else in the MAF). It is not connected to the MAF's circuitry in any way but between one of the ECU pins and the ground. So the pot is trimming something inside the ECU causing it to produce higher or lower AFR (richer or leaner) under the circumstances, the circumstances being all the input signals (including that from the MAF) together with the given fuel pressure and the injectors' flow. The potentiometer could have ben located in the ECU but it is more convenient if placed in the MAF body.
As the reviews are to share on balancing or not the MAF, I post you my statement "Pollers Empty" http://ga68.free.fr\autre\FERRARI-348ts\348-Relevé-Pollution-16-03-2017_348TS-1993.JPG Can you tell me if it is necessary to make adjustments or not? What I want to look for: It is that I have slowed down a smell a bit strong to my taste, as well as a small black depot on the bumper type soot. - slowed to 1000 rpm / hot engine. - as mentioned above the MAF values are: ** Left 392 Ohms and right 383 Ohms. - the thermocouple is in place and functional. - No codes Errors Ecu, except "4444" The car rolls nickel, no worries of idling there from hole to acceleration. Need other elements for a good diagnosis? Thank you again for all the work of one and the other on the multiple subject. Can I be nibbling for nothing ..... I use Google Tradution (please excuse me if this is not always very clear)
My idea : When running at full throttle the ECUs go to open loop (correct) and run a fixed map (correct ) ignoring the maf (not correct) , O2 (correct), and temp coolant sensors(not correct). In open loop the ECU ignores the return signal of the Lambda sensor to adjust mixture to stochiometric (14.7/1) => Open loop regulation. All the rest is taken into account. Open loop mixture cold of warm engine is way different ! I programmend my ECU on a cosworth engine. Grts Pat
Thats correct First thing needs to be done is truly isolate each bank then tune them. This is one of the things that takes time. You can get it close with common tools but will need more advanced stuff most folks dont have. Unfortunately many folks just use a theory looking at one part of the engine not looking at the big picture. Everyone guess's what the ECU is doing but few actually has seen it run on a motes emulator or programmed it to see whats changes do what. They are 1 step up from a carb not all this exotic stuff folks read about in a modern ECU, not many maps in these old girls. Makes me chuckle some time Yes these are 2 little 4 cyl engines running side by side, think of it thgat way and you will get her running fine
I attach a file containing some very good info on the CO Screw on the MAF, including the setting procedure (all info is actually from earlier posts on this forum). Image Unavailable, Please Login
Hello, during my reading of bedside, of the magnificent Workshop Manual 348, I fell page C33 on a return of a diagnostic sheet N ° 10 with the anileas. Would any of you have this documentation? With my warmest thanks.
