a quick question for the ECU tuning folk (or those in the know)..... keeping EGT's in mind and the fact that EGT will increase with retarded timing, what would be the safest or lowest that you would retard timing?? I'm talking about area's in the map of about 42 degree's ignition timing under cruise or light throttle conditions... would 30 degree's be too much retard (12 degree's retard)... also, I know elevated EGT's are not desirable, but what damage can the increase temp in exhaust gas do?? Is this more of a concern for turbo charged cars that have a turbo waiting to receive this hot gas, or are there dangers for NA cars as well.... in my mind, it cant be as bad as detonation, but would like to know more.... Cheers
Jedi-77 has been having issues with pinging for a long while, that's why he is asking about retarding timing. Mark, when I made my 91RON tune, I had retarded some of those areas you are talking about by 8 degress and no issues. Pretty sure I explained a while back it would be better to take timing out rather than add fuel?
correct... Yes Karl you did.... and it seems you were right... using my romulator, I did some recent testing and it seems that the addition of fuel in those light throttle / cruise area's does not alleviate the pinging on hot days.. Bugger.... The annoying thing is I can drive the car fine in the heat as long as I dont turn the aircon on.... The aircon must put some extra load on the motor, and in 30+ heat, the little man with his hammer starts tapping away inside my motor..... I really dont like the little man.... the only way I can kill the little man is by using some octane booster.... anyway, I'm now back to playing with timing.... I currently have the timing in that area at 37 degrees (its normally 42 degree's)... I'll try and take it down further and see if it helps... without an EGT guage, I'm just nervous about the exhaust temps.... and what they may do.... how low can I safely go do you think? remember this will be in a part of the map where the car is normally crusing or at part throttle..... as soon as I blip the throttle for moderate acceleration, we are out of those cells and the pinging is gone... the annoying thing is, its in such a small area of the map...... but it just happens to be the area that you spend most of the time in when cruising of accelerating lightly.... Cheers
no... advanced timing causes combustion temps to go up, but egt to go down as the fuel / air mix is burnt before the exhaust valves open.... with retarded timing, the mix is ignited later, so essentially you get some of the ignited mix leaving the combustion chamber as the exhaust valves open, causing the EGTs to increase.... I'm just wondering what this does to an NA which does not have a turbo charger..... I guess the CATs could overheat..... Cheers
to make a point so you see what happends: if you retard timing so much that most of the combustion happends in the exhaust system. what happens to the exhaust temp then? gets HOT. actually the coolest exhaust temp appears when your timing is set so that the engine makes the most power it can. (when the peak cylinder pressure hits about 15-20 degrees AFTER top dead center. if it hits later, say 30 degrees ATDC the exhaust gets hotter and power goes down) EDIT: seems jedi beat me to it... JEDI: what plugs do you use?
plugs.... i'm currently using NGK iritops, 7 heat range.... which is one range cooler than what NA's should be using.... Have been using them for a couple of years now since my hot weather pinging drama's started, and they appear fine by visual inspection at least..... no fouling..... Cheers
Mark, Apart from the hip pocket, What effect does running a 98 octane fuel (eg BP Ultimate) have on your setup?
Suggest using an EGT gauge...... because retarding the timing will escalate the EGT's rapidly. Every zed is going to be different so asking for a "one size fits all" timing figure is playing russian roulette with your motor. NA's don't have inconel exhaust valves like the TT, so EGT's are more critical. I seem to remember an absolute max EGT of 850deg C for a TT but I don't know if that figure applies to an NA as well Excessive EGT's will melt your motor so it's hard to say if detonation is a better or worse alternative
Are your coils working ok ? why dont you try the SPLITFIRE SUPER DIRECT IGNITION COILS or even a ignition booster also is your air flow meter working ok ? and what is your compression like ?
answers... yes coils are working fine.... I have checked them and they are all within specs... air flow meter is also fine as I clean the hotwire every 5000km when I do the service...I have also tried 2 other airflow meters and the pinging remains with all of them... Last comp check was about 1 year ago, and at that time comp in all cylinders was 170+.... Cheers
yes, I have no EGR... and I beleive that is the cause of my detonation problem..... I at least thank you guys for at least believing that the lack of EGR could be the cause of the problem... everytime I suggest this on this forum, no one believes me...... but these problems started about 3 months (at least I noticed it about 3 months) after my headers were installed.... and the installation of the headers means you say bye bye to your EGR.... also being an NA, we have a higher compression at those light throttle positions compared to you TT guys, so maybe that along with the hot ambient temps is enough to throw it over the edge.... Now, I cant reinstall the EGR as it has been completely removed along with the solenoids... I now have to find a way to deal with the light throttle detonation... I was hoping timing would be the answer... Maybe I just have to accept the fact that every summer, I should just stock up the garage with some octane booster... or not use my aircon which sucks (pinging is much worse with aircon on).... Cheers
other causes blocked exhaust or blocked cat are also possibles, anyway of exhaust gas staying in the combusion chamber. Also what AFR are you looking at during the conditions when it pings
Back in the days when i used to tune old style carby and dizzy setups i used to tune a motor so that under a max load (2 gear take off ,wot)the motor would ping for no more than 2sec s , it seemed like a good comprimise and always resulted in lots of power as well. keep knocking back ur advance till it does. if its pinging on light throtle load u got way way too much advance. give it a try and c how it goes. keep ur afr's in the normal range. Regards, Trev
well... i'm pretty sure that the exhaust and CATS are fine, but I'll check them next time Im under the car.... as for the A/F.... well when the car pings, its in closed loop so its using the O2 sensors for feedback.... at this time, the A/F is around the 14.7:1 which is where it should be for economy...... and the O2 sensors are working fine as far as Datascan is concerned... Cheers
yeah so the AFR is where it should be. As they have mentioned you could back the advance off, i dont think the EGT's will be too high unless you go down to less than 30deg total advance. Buis this just masking the problem? Maybe. Id like to know the real reason
