Nettlez Posted October 6, 2016 Report Share Posted October 6, 2016 (edited) So the car went for MOT (E30 M50 2.8 0.140mls) and did well other than failing on emissions. The results were CO 8 limit is 3.5 and HC 1894 limit is 1200. The car is just running the E36 plugin base map and is booked in for mapping on the 20th, problem is the car is going via transporter to be mapped and I want to drive it back once its done so really I want to get it passed before it goes. I believe as the car was registered Feb 1991 it only has to pass an emissions test at idle speed? So I have been tying to get it running a bit better at idle. I know when the car went for MOT it was running around 10 AFR and I can now get it to run 12-13 ish AFR but I doubt this will be good enough to pass still? Its running open loop idle control and I have idle ignition control on but when I try and tweak the fuel any more the idle starts to hunt. Any tips on getting it a little better would be great. MAP attached, just about to go take a log, will post that too. Thanksmot idle edit was running 13 or 14 sfr.pclrHere is the log, typically it wasn't hunting now. It was running 13 afr on this, surely I should be able to get it to 14.7?2.llg Edited October 7, 2016 by Nettlez delete files Quote Link to comment Share on other sites More sharing options...
jonnyt80 Posted October 6, 2016 Report Share Posted October 6, 2016 You should be able to getting to run 14.7 or close to it.The MOT as you say should be 3.5 max in a Lambda test it will be between 0.97+1.03Cant you get a wideband setup through the ecu and use quicktune to stabilise your idle fuelling? Quote Link to comment Share on other sites More sharing options...
Nettlez Posted October 6, 2016 Author Report Share Posted October 6, 2016 You should be able to getting to run 14.7 or close to it.The MOT as you say should be 3.5 max in a Lambda test it will be between 0.97+1.03Cant you get a wideband setup through the ecu and use quicktune to stabilise your idle fuelling?I tried turning the wideband on and using quick tune just and it adjusted the fuel cell from 38.6 to 30 then the engine started hunting loads, is this because it needs more air with the reduced fuel? As I'm running open loop idle do I need to start with the idle higher than 1000rpm? Quote Link to comment Share on other sites More sharing options...
Adamw Posted October 6, 2016 Report Share Posted October 6, 2016 What are your injectors? Your pulsewidth at idle is only 1.5ms, most injectors wont behave linear with such a low pulse width. This is why you are getting the hunting effect. So unless you can get "short pulsewidth adder" info from the injector supplier, then I would suggest in the meantime the easiest fix is to lower your fuel pressure (try around 30psi). You will need to tweak the master fuel again to get it to run but then your idle pulsewidths will be in a region where the injector will work predictably. The tuner can then increase it again later before he starts mapping. Quote Link to comment Share on other sites More sharing options...
Nettlez Posted October 7, 2016 Author Report Share Posted October 7, 2016 What are your injectors? Your pulsewidth at idle is only 1.5ms, most injectors wont behave linear with such a low pulse width. This is why you are getting the hunting effect. So unless you can get "short pulsewidth adder" info from the injector supplier, then I would suggest in the meantime the easiest fix is to lower your fuel pressure (try around 30psi). You will need to tweak the master fuel again to get it to run but then your idle pulsewidths will be in a region where the injector will work predictably. The tuner can then increase it again later before he starts mapping. I am running seimens 107-961 injectors. Had a quick Google and can't seem to see this short pulse width added info. What sort of pulse width do I want to see? Quote Link to comment Share on other sites More sharing options...
Scott Posted October 7, 2016 Report Share Posted October 7, 2016 Hi Nettlez,If you can not find any short pulse width data for your injectors then you are best to have a value of 0.000 everywhere in the short pulse width adder table.Some larger injectors can have high minimum effective pulse-widths, what this means is that the ECU is unable to reduce the pulse-width (fueling) to achieve the desired AFR/Lambda. Adam's suggestion of lowering the fuel pressure will mean the ECU needs to use a longer pulse-width under the same engine conditions to achieve the same AFR/Lambda. This means the pulsewidth can then be reduced to lean out the AFR/Lambda.It is hard to know for certain this is what is happening in your situation, but could be worth a go.If this is not possible can you look at uplaoding a PClog and matching base-map where you have the idle oscillating due to the reduced fuel table number?Scott Quote Link to comment Share on other sites More sharing options...
Nettlez Posted October 7, 2016 Author Report Share Posted October 7, 2016 Hi Scott,Yeah I have had a good look and cant find the info, all I can find is that Summit Racing do a DVD for $250 that has it. So think I will go down the route Adam said later and see how I get on with that, although I am running bosch 044 fuel pump and I'm not sure I will be able to get it as low as 30psi. If that's no good I will post the log with it hunting as you said. I will report back later, Thanks Quote Link to comment Share on other sites More sharing options...
Steve Posted October 7, 2016 Report Share Posted October 7, 2016 Could be a timing problem you are having. To much timing at idle tend to bump the revs and you end up with hunting. A log will show this. Quote Link to comment Share on other sites More sharing options...
Nettlez Posted October 7, 2016 Author Report Share Posted October 7, 2016 (edited) So to update I have had another go. I did what Adam said but the lowest I could get it to go was 40psi (engine not running), so at tick over its now about 30psi, I adjusted the dead times accordingly. I managed to get it to idle at around 14.5 once it was properly hot but as soon as I touch the accelerator it doesn't want to idle again unless I turn it off and start it again. Have attached the map and log of it doing this. Im thinking it might be to do with timing not catching the revs falling well enough then when it does catch it it over shoots? ran 14.5 at 104ect and 42iat.pclrrunning 14.5 then tough throttle and hunts.llg Edited October 7, 2016 by Nettlez delete files Quote Link to comment Share on other sites More sharing options...
Steve Posted October 7, 2016 Report Share Posted October 7, 2016 Try this one on for size. Just adjusted the timing map a little and did some changes to the idle ignition map. ran 14.5 at 104ect and 42iat Fudged on by Steve.pclr Quote Link to comment Share on other sites More sharing options...
Nettlez Posted October 7, 2016 Author Report Share Posted October 7, 2016 Thanks Steve, just gave it a try and its definitely better, i like what you did with the idle ignition map. Just gave it a try and it was definitely better, although it did end up doing its hunt business after touching the throttle, but managed to get it better by altering the figures in the idle ignition table. I recon this might get me through the mot now, so long as it is just at idle. I altered the fuel map by 0.2 at a time in a block around idle rpm till it was near 14afr then tried the throttle then altered the idle ignition map. I would upload the log and map but it wont let me, says it cant be bigger than 542kb but its only 160kb? Quote Link to comment Share on other sites More sharing options...
Steve Posted October 7, 2016 Report Share Posted October 7, 2016 Yes you will probably need to fudge it around a bit to get it right. I was just guessing on the numbers as i dont really know the engine.You also probably need to alter the idle solenoids dutycycle so it doesnt let to much or to little air by. It is a balancing act this.You should really try to turn OFF the idle ignition map and get it to idle as good as you can with the main ignition+fuel map and ISC dutycycle first. THEN turn on the idle ignition map as an aid.The main problem is that when it is hunting it goes in and out of idle state. Switching between your idle ign map and the main ign map. When there is a large difference between them this is what happens. You could also try to lower the numbers in the main ign map that is reached when it hunts to try to stabilise it that way. Quote Link to comment Share on other sites More sharing options...
Nettlez Posted October 7, 2016 Author Report Share Posted October 7, 2016 Deleted the old files now, here's the new ones steve 3.llg ran 14.5 at 104ect and 42iat Fudged on by Steve 3.pclr Quote Link to comment Share on other sites More sharing options...
Nettlez Posted October 7, 2016 Author Report Share Posted October 7, 2016 Yes you will probably need to fudge it around a bit to get it right. I was just guessing on the numbers as i dont really know the engine.You also probably need to alter the idle solenoids dutycycle so it doesnt let to much or to little air by. It is a balancing act this.You should really try to turn OFF the idle ignition map and get it to idle as good as you can with the main ignition+fuel map and ISC dutycycle first. THEN turn on the idle ignition map as an aid.The main problem is that when it is hunting it goes in and out of idle state. Switching between your idle ign map and the main ign map. When there is a large difference between them this is what happens. You could also try to lower the numbers in the main ign map that is reached when it hunts to try to stabilise it that way. Ah right I see. I was just fiddling with the idle and turned the idle ignition on and it went really stable so just used in since then. Now im a little more educated I will try turning it off and seeing if I can get it to idle at 14afr without it. Thanks again Quote Link to comment Share on other sites More sharing options...
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