delorean6584 Posted May 17, 2009 Share Posted May 17, 2009 Hi all, i finally got able to drive the car all week long to tune the megasquirt on my 280zx !! under low boost/vacuum ive been able to acheive great results, got the air/fuel to about 12-13 all the way, then 11-11.5 under all boost conditions, the thing is that i have alot of pinging over 10psi of boost wich in 4th gear is like 2500-3000 rpm, its very low so i cant imagine at WOT !!! i used the metro tables for timing and fuel, i only tweak it by 1 or 2 points under 100KPA wich the boost begins, so i know that i have enough fuel caus its about 11 to 1 when it pings and between 26 and 30 of timing...i also have about 82 degree faranhiet as intake temp i am also very confused about the psi to kpa !!! the map sensor in megasquirt is connected at the same place as my boost gauge...0 psi (say just after vaccum and before beginning to boost i have 100kpa on megasquirt....but if you convert 100kpa in psi it gives 14 psi ???? what the ? any ideas ? my setups is : stock 1982 l28et megasquirt II v3.0 stock injectors/turbo/wastegate etc... custom IC piping godpseed intercooler greddy blow-off valve custom boost controller lc-1 wideband gauge (not connected to ms2) Quote Link to comment Share on other sites More sharing options...
slown280z Posted May 17, 2009 Share Posted May 17, 2009 I think you might be running a tad too much timing. 1 range colder plugs, a 180deg thermostat, and a good coolant system go a long way with keeping ping at bay. Make sure your cooling system is up to snuff, run higher octane gas, and pull a few degrees of timing. Quote Link to comment Share on other sites More sharing options...
delorean6584 Posted May 17, 2009 Author Share Posted May 17, 2009 i have bpr6y from ngk right now... how much timing down should i go with ? the cooling system is all good, new radiator, 180 thermostat, new coolant, i also noticed that my head temp sensor is showing 212 degree faranheit in megatune...i imagine the head is hotter than the rad...do you have the same ? heres my timing map Quote Link to comment Share on other sites More sharing options...
Noddle Posted May 18, 2009 Share Posted May 18, 2009 i am also very confused about the psi to kpa !!! the map sensor in megasquirt is connected at the same place as my boost gauge...0 psi (say just after vaccum and before beginning to boost i have 100kpa on megasquirt....but if you convert 100kpa in psi it gives 14 psi ???? what the ? The standard atmosphere (symbol: atm) is a unit of pressure and is defined as being equal to 101.325 kPa.[citation needed] These other units are equivalent: 760 mmHg (torr), 29.92 inHg, 14.696 PSI, 1013.25 millibars. One standard atmosphere is standard pressure used for pneumatic fluid power (ISO R554), and in the aerospace (ISO 2533) and petroleum (ISO 5024) industries. http://en.wikipedia.org/wiki/Atmospheric_pressure Nigel Quote Link to comment Share on other sites More sharing options...
Careless Posted May 18, 2009 Share Posted May 18, 2009 if your head temp sensor is at 212 degrees when the engine is at running temperature of 180F (thermostat opens), that means it's most likely not working correctly, as most of the nissan head temp sensors are made to have a fully closed circuit at the boiling point of water (212 degrees F)... you may want to look into testing another head temp sensor. Quote Link to comment Share on other sites More sharing options...
delorean6584 Posted May 18, 2009 Author Share Posted May 18, 2009 for the head temp sensor it reaches 212 before the termostat opens, then stay like 200 or less on hard driving, i also filled the tank with high octane gas...didnt helped much... still have hard pinging over 10psi of boost, i also tweaked the table and reduced all the timing, when it begins to ping it have 24degree of advance 10psi of boost and about 3000rpm...fuel always stays in the 11 to 1...i am lost with it ? do you guys have a some ideas oh and tomorow i will get colder plugs too i now have bpr6 Quote Link to comment Share on other sites More sharing options...
Careless Posted May 18, 2009 Share Posted May 18, 2009 i don't think the sensor should be hitting 212F before the thermostat opens... definitely sounds like something is wrong there, if you ask me. on my z31 which uses a coolant temp sensor as well, when i changed mine, my computer started to advance timing because it was now working (fried mine by accident by over volting... it's a 12 volt thermistor)... my distributor was maxed out for timing and i was struggling to keep it into the proper 15 BTDC timing mark... but after i changed the sensor it started to advance MORE so i backed the distributor off until it was in the middle of it's rotation-range, and it is now at a solid BTDC and the sensor is now working. I find it tough to believe that the coolant temp sensor being so close to the thermostat (or somewhat close) could be 35 degrees apart... that doesn't make sense to me as a functioning cooling system. it sounds like partway through your driving the sensor kicks on and off and is advancing timing and causing detonation. have you checked, as per FSM, what the values on the connections should be back to the ecu? Quote Link to comment Share on other sites More sharing options...
delorean6584 Posted May 18, 2009 Author Share Posted May 18, 2009 hi, the connections for the ecu are good i made the wiring and i have magasquirt, for the head temp sensor it find that weird too, when the coolant is cold its accurate so i beleived that it was also accurate when hot....i have another one laying around form a known working car (values when cold are the same...) but it will replace it right now, as for the timing goes, megasquirt decide of the timing all values are now maximum 24degree so it shouldnt be detonate ?? Quote Link to comment Share on other sites More sharing options...
dexter72 Posted May 18, 2009 Share Posted May 18, 2009 From what I have read on this forum you need to reduce timing more when you up the boost. Try reducing the timing another 8 degrees and see if it still pings. If it stops, then increase timing 2 degress at a time until it pings again. Try the colder spark plugs and reducing the spark plug gap also. Quote Link to comment Share on other sites More sharing options...
delorean6584 Posted May 18, 2009 Author Share Posted May 18, 2009 hi all, did some testes today, i reduce all the timings, now pings occurs after 13psi of boost, but still like at 22degree of timing wich for me seems low enough....i replaced my head temps sensor but realized that it is not a coolant sensor, no coolant in there, so i am sure it is normal to have more heat on the head than on coolant i am now on my way to replace the plugs for colder ones Quote Link to comment Share on other sites More sharing options...
hughdogz Posted May 18, 2009 Share Posted May 18, 2009 i am also very confused about the psi to kpa !!! the map sensor in megasquirt is connected at the same place as my boost gauge...0 psi (say just after vaccum and before beginning to boost i have 100kpa on megasquirt....but if you convert 100kpa in psi it gives 14 psi ???? what the ? That's because your boost gage reads in gage pressure, and the MAP (manifold absolute pressure) sensor measures absolute pressure. The absolute pressure scale starts at a total vacuum (zero psi), and the gage scale starts at negative atmospheric pressure (-14.696 psi). In other words, gage pressure plus atmospheric pressure equals absolute pressure. As Nigel stated, 1 atmosphere = 101.3125 kPa = 14.696 psi absolute = 0 psi gage. To convert kPa to psi gage, divide the kPa reading by 101.3 (this will give the % of atmospheric pressure). Then multiply that percentage by 14.7 (this will give the absolute pressure in psi). Finally, subtract that number from 14.7 and make it negative (this will give the gage pressure). To convert psi gage to kPa absolute, add 14.7 (this will give absolute pressure psi). Divide that number by 14.7 (giving percentage of atmospheric). Multiply that number by 101.3 to get absolute pressure kPa. My boost / vacuum gage reads vacuum in millimeters mercury (Hg), but the boost is in psi. You can also measure pressure by inches Hg, etc. Hope this helped clear things up a bit... Quote Link to comment Share on other sites More sharing options...
delorean6584 Posted May 18, 2009 Author Share Posted May 18, 2009 thanks for clearing that up ! but now i am tottaly out of ideas !!! i put colder plugs on the engine, put high octane gas in the tank, tried to lower the advance by 10degree, wich gives pinging at 9degree of advance ????, i also tried to up the fuel to 9:1 air/fuel and i still have pinging issues depending on the gears it begins to ping from 7 to 13 psi(boost gauge) cooling system is all new, head temp and intake air temps is good too... i just can't figure it out... Quote Link to comment Share on other sites More sharing options...
ktm Posted May 18, 2009 Share Posted May 18, 2009 What do you mean you used high octane gas? If you used 100 octane, you should not be pinging at ALL with that timing table assuming your fuel map is correct You have an Innovate LC-1. Are you recording your AFRs with Logworks? If not, you should and then post them here. I have an LC-1 and LMA-3 auxbox (with built in RPM converter) that I use to tune with. I have a feeling that you are going lean in places on your map. Your wideband is not hooked up to MS, therefore you must be looking at your gauge to determine your AFRs. I am not familiar enough with MS, but I believe that a large part of your problem may be attributable to not having your wideband hooked up to MS. MS is unable to determine your AFRs and therefore not use them in any calculations if you are trying to use its autotune features. You keep saying you adjusting your AFRs, how? By modifying the AFR table? This is useless if you do not have your wideband hooked up. Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted May 19, 2009 Share Posted May 19, 2009 Are you sure it's detonation that you're hearing? Quote Link to comment Share on other sites More sharing options...
delorean6584 Posted May 19, 2009 Author Share Posted May 19, 2009 hi all ! i drove the car to one of my friends who work on turbo cars and said that its definatly not pinging, so i am really sorry for all that confusuion (i guess we learn each day!!) for tuning up the maps i use the map table wich isnt useless cause it is not automatic i use the afr gauge though for readings, so the fuel map is good along with the spark map the sound is very strange though, its like a whisling but very hard and loud a very loud squealing more like a bypass or something similar, i just dont know what, maybe tomorow i will try to remove the egr valve and install a block-off plate instead again sorry for searching with a false symptom, but atleast i have learn how to tweak megatune tables and the engine have no damage as for the sound maybe someone already got something similar ?? yan Quote Link to comment Share on other sites More sharing options...
Careless Posted May 19, 2009 Share Posted May 19, 2009 Check your wastegate spring or actuator line/vacuum line. I think your waste gate is venting (whistle type sound) and it's closing too quickly (clacking sound). does your wastegate dump back into the exhaust or is it dumped to atmosphere below the car? when I had the waste gate on my turbo fixed (someone shoved a carb jet in my actuator line to increase boost), i started to notice a wh0000000000000000 sound like a coyote howling at the moon or something... depending on how close your waste gate is to your cylinder ports, it may sound really fierce if it's just dumped to atmosphere. EDIT: I just noticed you have a stock turbo/wastegate... perhaps you have misfire up there (but not detonation or pre-ignition) in the RPM range or when you're boosting that's causing you to hear weird sounds when the waste gate is open? Quote Link to comment Share on other sites More sharing options...
Careless Posted May 19, 2009 Share Posted May 19, 2009 hi all, did some testes today, i reduce all the timings, now pings occurs after 13psi of boost, but still like at 22degree of timing wich for me seems low enough....i replaced my head temps sensor but realized that it is not a coolant sensor, no coolant in there, so i am sure it is normal to have more heat on the head than on coolant i am now on my way to replace the plugs for colder ones It is called the Coolant Head Temperature Sensor because it reads the head temperature based on the coolant surrounding the jackets that are very thin close to where it is screwed in. This makes changing it easier so it doesn't spew coolant everywhere... it still does affect nissan ecu's fairly heavily, so i'm curious to know why it's acting weird with MS. is it a factory nissan sensor? you could plumb a GM sensor into a coolant hose with a large adapter... Not sure if it will do anything though, since you checked the wiring anyhow... Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted May 19, 2009 Share Posted May 19, 2009 Leaking exhaust gasket or head gasket? A whislte sound crossed with a ping sound might very well describe the above. Ask me how I know... Quote Link to comment Share on other sites More sharing options...
delorean6584 Posted May 19, 2009 Author Share Posted May 19, 2009 thanks for the hints, the best description of the sound is a howling as stated above, a HUGE howling, i have the stock setup for the wastegate, but maybe something could be bad in there cause the sounds is in relation wih the boost, i raised the boost with a manual boost controller, but does the same sound when i didnt have it, i removed the stock safety valve that opens at 11psi as for the head temp sensor, it doesnt act funky in MS it is just hotter than the coolant by 10 degree wich i attribute to the fact that head is a little hotter than coolant, and cylindre 5 is far from the t-stat housing... Quote Link to comment Share on other sites More sharing options...
Careless Posted May 19, 2009 Share Posted May 19, 2009 could be a cracked exhaust manifold too! but really, make sure your exhaust is tight everywhere! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.