nkx Posted September 21, 2004 Share Posted September 21, 2004 i have an auto meter air/fuel gauge, but it always reads full rich. if im WOT, the rest of the lights flicker and kinda bounce back and forth. im not sure if i have a grounding problem, (ive tried multiple spots to ground) or if this would be indicative of a bad O2 sensor. my gas milage is kinda crappy, but i dont drive it for economy. i havent yet seen a check engine light. am i overlooking something? Quote Link to comment Share on other sites More sharing options...
All_talk Posted September 21, 2004 Share Posted September 21, 2004 This is in your GL-10 Turbo right? From reading the FSM it appears that the ECU doesn’t use the O2 sensor under boost, and others have observed the same full rich reading you have, I’m guessing the fuel map is dumping extra fuel to cool the intake charge and reduce the chance of detonation (common solution in factory turbo cars). Are you are seeing full rich off boost? If so, it could be an engine or a gauge problem, if the engine is truly running rich most/all the time the plugs will show it (fuzzy black with carbon). Gary Quote Link to comment Share on other sites More sharing options...
NorthWet Posted September 21, 2004 Share Posted September 21, 2004 As far as I know, most all computer controlled fuel systems go "open-loop" (ignore feedback from O2 sensor) and default to "safe" rich maps under high-/full-power. The basic idea is to prevent the mixture from going lean under power, and I would agree that the turbos probably go even richer for a little charge cooling. (They also use default maps while cold and other conditions.) Please remember that if you're using the standard O2 sensor that they are non-linear, implying that you cannot tell much other than the mixture is where it is supposed to be or it is leaner or richer. You can't tell quantitatively how far lean/rich you are. And, if I remember right (always in doubt!), the point of accuracy for the O2 sensor is not stoichiometric mixture anyway. (Was that more than $.02 worth??? If so, keep the change.) Quote Link to comment Share on other sites More sharing options...
archemitis Posted September 21, 2004 Share Posted September 21, 2004 did i read that right, at full throttle the other lights turn on? on both subaru efi systems ,i have hooked an autometer guage up to, mpfi and spfi. they both did the same thing, as well as other cars i have driven. at part throttle, after the o2 sensor heats up, it will bounce back and forth from full rich to almost full lean, a couple times a second. then when you floor it it goes all the way to rich, 3or 4 bars on the right side of the guage. Quote Link to comment Share on other sites More sharing options...
oddcomp Posted September 21, 2004 Share Posted September 21, 2004 ok having run both suby and do it yerself fuel injectinon with o2 monitoring on both the suby system at normal cruise will bounce around... and i mean bounce around alot! when you stomp it i certainly does go rich .... i lost my data log of the stock suby ecu .. i also found it unnerving... that the stock system bounces from wayyy rich to wayyyy lean at steady state conditions i also know that under boost the suby system while still sorta rich . is still not rich enough to help control detonation reason i can say this is the fact when i did my megasquirt and edis conversion in stages under suby fuel and distributorless ignition i had to retard the timing alot to prevent detonation at full boost 10 psi when changed over to megasquirt fuel inejction control with shadows' start up fuel map he made me i was able to run a more normal ignition advance map so long sotry short.. what you see at wide open is fine what you see at part throttle is ok for non modded suby's eh ecu just barely cuts it oops gotta go Quote Link to comment Share on other sites More sharing options...
NorthWet Posted September 21, 2004 Share Posted September 21, 2004 Hey Oddcomp, how much did your A/F meter jump around with the MS? Have you been able to keep your right foot out of it enough to know if fuel mileage improved? Does the Autometer A/F thingy have a sensitivity control? If things are bouncing that wildly you are not getting much useful info. Maybe if you could set it to be less sensitive it might be more useable. In general, though, it does sound like stock ECU is pretty sad. What year was oddcomp's soob? Maybe the ol' computer world's problem of too slow a processor to keep up. (Main reason why ABS took so long to become mainstream.) Quote Link to comment Share on other sites More sharing options...
archemitis Posted September 21, 2004 Share Posted September 21, 2004 i have ridden in several turbo cars, and they all bounce around. thats what fuel injection does, theres no system that holds it at stoich all the way through the throttle position. this is not a guage to be used for tuning. you need an egt. Quote Link to comment Share on other sites More sharing options...
oddcomp Posted September 21, 2004 Share Posted September 21, 2004 first off it was a 87 well still is as far as keeping my foot out of it first run with full megasquirt injection and my current runing dis ignition.. i killed the auobox in it.. oops i will go under the semi false pretense it was the increase however small it may have been that finally killed the 3at... secondly my turbo with ms has no 02 bounce... if i stomp it it goes rich.. like i want.. actually 2 rich at fulll wide open as it bogs a tiny bit i need to remap that section of the fuel map at cruise the o2 stays at around 13. something to 14.7 air fuel ratio.. i will tinker when i get a new tranny in and try and get it to lean out at cruise for economy reasons also this is all done witha bosch heated o2 sensor i had laying around also the heated o2 had less "bounce" under suby ecu controll btw it is a narrow band unit since i have not found a good doner care for a wide band o2 and yes even with a "close" fuel map mileage imporved a tiny bit i expect better once i can actually spend the time to re map it as far as full o2 bounce on the suby ecu i got .00 volts up to .9 00 being super lean "at cruise/steady state condition" and .9 volts being just below the 1 volt<if i remember right> over rich side of things i have no idea if the autometer unit has sensitivity adjustments but i have schematics to build some really nice one's that do ... as well as electronic boost gauges hehe for my a/f meter monitoring i used my megasquirt box and had it hooked up to sensors like air intake temp and o2 sensor output ect i wish i had the suby ecu logs i made to show the diffrence Quote Link to comment Share on other sites More sharing options...
archemitis Posted September 21, 2004 Share Posted September 21, 2004 i thought some new hondas are the only ones that use a wideband o2 sensor, stock from the factory. that would be the win! Quote Link to comment Share on other sites More sharing options...
rallyruss Posted September 21, 2004 Share Posted September 21, 2004 02 bounce is completely normal. All efi cars are designed to run like that. and yes it is supposed to hit what would appear to be extreme limits while bouncing. That is the sign of a good healthy motor running well. The purpous of this is to make the Cat converter work most efficiently. yes on a sube it may indicate a bad 02. here is why. subaru (along with GM, dodge,and others) send out a verry low amperage signal of aprox 5 volts on the 02 signal wire. the 02 generates the signal you would normaly see overiding the referance voltage if all is working properly. if the o2 is dead it cannot pull the signal down to the 1 volt range needed to send a good reading back to the ECM. your mixture meter is nothing more than a volt meter that reads only 0 to 1 volts. so if it sees 1 volt or above (the referance voltage) it calls it rich. if you have a volt meter you can get a better sense of what is really happening while watching the signal. to be honest mixture meters are verry dificult to use in dialing in a perfect mixture with the o2. all they really can tell you is if you are going lean under full load. this is rather important as we should all know that lean under load or boost means detonation. the check engine light should have been triggered for this problem if the o2 you are using is the same one as the ECM. that may cause you some trouble as well because it may put too much load on the sensor. its usually best to run a seperate O2 for a mixture meter or find a way to boost the signal. ah well thats about enough about 02 sensors. I just had to describe this same thing to my seinor mechanic at work the other day. Quote Link to comment Share on other sites More sharing options...
nkx Posted September 22, 2004 Author Share Posted September 22, 2004 i know what the gauge is supposed to do when it operates correctly, but my problem is that im not seeing it. the lights dont bounce between rich and lean. there is 1 light in the max rich that remains on all the time. if im really on the throttle, not necessarily in gear, i can see that the other lights faintly light up. and this is after the sensor should be hot enough to work (i think). would it be possible that my O2 sensor is bad, but i dont know it because the check engine light might have burned out? the car is 15 years old, and i dont really know much about its life before i bought it, except that the last owner had a very hairy dog. Quote Link to comment Share on other sites More sharing options...
NorthWet Posted September 22, 2004 Share Posted September 22, 2004 OK, so it sounds like rallyruss understood your problem and tried to address it. I haven't heard of the 5v "pull-up" signal that rallyruss was talking about, and I can't reconcile that with a voltage-producing cell like an 02 sensor, but I haven't looked at O2 sensor theory for awhile. But I DO agree with rallyruss that you should use a good ol'-fashioned analog (NOT digital) voltmeter to look at the signal. By watching the needle swing you should be able to get an idea what is happening. If it goes above 1v then russ' reference voltage may be present and his thought that the O2 sensor is bad should be considered. My personal opinion is that the A/F meter is wonky. But testing with a volt meter would help prove/disprove that, too. Just don't try to get by with your average digital volt meter. Its display rate is probably once/sec, or at best twice/sec, and you won't be able to see the signal fluctuation. (The best thing would be an oscilloscope, but oh well!) Quote Link to comment Share on other sites More sharing options...
oddcomp Posted September 22, 2004 Share Posted September 22, 2004 hmm i was under the impression<corrected since my last o2 reading impression i did in the msnedis thread thing as i have done a bit more reading now> that 1 volt was like full on way max rich .7 .8 ish are rich ect ect ect .0 being super lean or off throttle decelerating. or so my megasquirt shows things a analog or "needle" type voltmetter will show you all the dips and swings where as a digi type meter will sorta average it out unless its really expoensive Quote Link to comment Share on other sites More sharing options...
Cliptin Posted September 22, 2004 Share Posted September 22, 2004 Disconnect the O2 sensor and see if things improve. I think mine was sending out a sporadic signal. Quote Link to comment Share on other sites More sharing options...
rallyruss Posted September 22, 2004 Share Posted September 22, 2004 i know what the gauge is supposed to do when it operates correctly, but my problem is that im not seeing it. the lights dont bounce between rich and lean. there is 1 light in the max rich that remains on all the time. if im really on the throttle, not necessarily in gear, i can see that the other lights faintly light up. and this is after the sensor should be hot enough to work (i think). would it be possible that my O2 sensor is bad, but i dont know it because the check engine light might have burned out? the car is 15 years old, and i dont really know much about its life before i bought it, except that the last owner had a very hairy dog. I already gave you all the info you need. if I was not clear in my explanation I appologize. contact me on what part you do not under stand. I can assure you that the info provided is correct as this is what I do day to day. Quote Link to comment Share on other sites More sharing options...
NorthWet Posted September 22, 2004 Share Posted September 22, 2004 Hey rallyruss, if you thought that I doubted what you were saying, then I apologize. I didn't doubt it, just couldn't yet reconcile new info with what I felt that I "knew" (electronics). At first blush, I couldn't see how the O2 sensor, a voltage source, could sink the ref signal. After I pulled my head out of my nether-region, I thought of the O2 sensor as a simple battery, and the ref voltage as similar to a trickle charger (obviously not same purpose, but similar reality). An auto trickle charger can put out voltages much higher than 13.2v (I made a simple one once that could be 150v+ with no load), but the car battery acts as a load on it to reduce the voltage to near 13.2v. So, if the O2 sensor is working correctly, it will pull a 5v-but-very-low-current signal down to slightly above the voltage of the ion pump of the O2 sensor. If the sensor is dead, I can see the ref voltage going to 0v or floating to 5v ref voltage. (Not sure of fail modalities, so not sure if both are possible.) So rallyruss, if the O2 sensor has truly failed and he is seeing the 5v ref signal, our friend should be getting an error from the ECU? Can these things "soft fail", such that they will work somewhat under high load (sensor gets hotter???)? Quote Link to comment Share on other sites More sharing options...
Skip Posted September 22, 2004 Share Posted September 22, 2004 Folks, all well and good info here but Subaru engineers were nice enough to equip our cars with an oxygen monitor. Why not put it to use? No voltmeter needed, no connections, no problems. The O2 sensors on our cars do produce a voltage but as has been pointed out it is either rich or lean. As pointed out by our good friend Al Savage,and proved with several articles (and up to that point unbeknowst to me) they do not show degrees of richness or leaness (real word??) To see a degree reading, or a true stoichiometric ratio, one needs a wide band 02 monitor (new Hondas have them and kits and units are available) so our the 02 monitor is just a light triggered by a close to 1 volt output. on =rich off = lean It will stobe at a freq of about once every couple of seconds when the 02 sensor is working. If no strobe it is not funtioning. Always off. They do get tired and should be replaced at about timing belt intervals (60 kmi.) Where is this mystery light - on the ECU it also funtions as the code reader light. I would disconnect the A/F meter and watch it (engine must be in closed loop i.e. warmed up) If at idle it comes on and goes off, on, off.... then reconnect the meter making sure it's wired properly. See if it changes. I have three turbo cars with A/F meters, none disturb the strobe freq. As a side note exhaust systems do have ground problems. I connect an ECU ground directly to the body of the 02 sensor with a fuel line hose clamp. Hope this helps. Quote Link to comment Share on other sites More sharing options...
archemitis Posted September 22, 2004 Share Posted September 22, 2004 that gets me thinking, my car ran like crap after i hooked up a faulty one of these. make sure your not sending 12 volts right to the computer through the o2 sensor wire, made me think my computer was fried. Quote Link to comment Share on other sites More sharing options...
rallyruss Posted September 23, 2004 Share Posted September 23, 2004 NORTHWET- yep you get it. thank you for understanding. yeah the ground is rather important and is not to good due to rust and heat related problems. I went with a three wire 02 to eliminate the bad ground and also give it a heater to kick it into action quicker. and of course Skip always has good input thank you. this may actualy turn out to be an good thread full of info. I know this should go elsewhere but does anyone have good info on the wide band 02? maby send me a PM? Quote Link to comment Share on other sites More sharing options...
nkx Posted September 23, 2004 Author Share Posted September 23, 2004 thanks all for the good info. im printing this thread right now so i can take it to the garage this weekend and see if i cant figure something out. oh, and sorry for not quite understanding you the first time around, rallyruss. Quote Link to comment Share on other sites More sharing options...
rallyruss Posted September 23, 2004 Share Posted September 23, 2004 well hopefully you can go on out there and find your problem now that we have fully discussed the workings of the 02 sensor. good luck and tell us what you find. Quote Link to comment Share on other sites More sharing options...
oddcomp Posted September 23, 2004 Share Posted September 23, 2004 for wideband info try www.msefi.com more or less the website for my injection system http://www.diy-wb.com/info.htm do it your self www.sdsefi.com not my choice for going stand alone.. but lots of usefull info Quote Link to comment Share on other sites More sharing options...
rallyruss Posted September 23, 2004 Share Posted September 23, 2004 for wideband info try www.msefi.com more or less the website for my injection system http://www.diy-wb.com/info.htm do it your self www.sdsefi.com not my choice for going stand alone.. but lots of usefull info thank since I posted I had some info fall into my lap. oh I hapen to have an old SDSEFI system in a box in the garage. It was not too bad to use only tricky part was getting good low end and idle when running big injectors. I swaped it back to a stock ECM to gain better drivability along with stock injectors. this was on a toyota 22R(E?) motor. Quote Link to comment Share on other sites More sharing options...
oddcomp Posted September 23, 2004 Share Posted September 23, 2004 yeah the sdsefi sytem.. looks lik a pain in the rump roast to tune.. since its all done on the little lcd display ... no computer port to tune it like mine crappy low end idle .. i would guess that it was keeping the injectors open 2 long so the pulse duration was to big. not sure how its done on sdsefi due to the boxer setup i found the smoothest running setup so far to be 2 squirts per revolution operating in alternatting so one bank fires twice then the other bank fires twice made it reallly smoooth .. and its not even tuned yet i killed the auto box jsut after i did my first full ms run.. oops Quote Link to comment Share on other sites More sharing options...
Myxalplyx Posted September 23, 2004 Share Posted September 23, 2004 i killed the auto box jsut after i did my first full ms run.. oopsWow! Now that's what I called tuning for low end torque. Good tuning! Quote Link to comment Share on other sites More sharing options...
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