Project Custard - Gearbox issues

[custardavenger]

Thats what I've been doing and exactly what I was worried about. Lowest is now 11. Will have a go at getting the WOT points richer and see how that goes. I have been trying to read up on the internet about this but not found anything good.

Whats the theory on low load points and ballenced throttle. Got those points tuned to 14.5 ish which I was recommended. Have been told that when not on the power there aren't the high cylender pressures and therefore less risk of damage?

[loadswine]

For the amount of hard work and sweat you've put in on that engine Rob, I'd be straight over to somewhere like Thor and get it mapped by them. The risk of another meltdown would scare me, but I know you don't scare easy mate.  s:wink: :wink: s:wink:  
Good luck with it and for goodness sake be careful, I want a ride in this beastie at some point.  s8) s8)

[custardavenger]

It's all down to money mate. I have very little and if I spend it on mapping now the it will be wasted once I've fitted the CC and WI. I know some may be disparing at my mistakes but this is something I would really like to learn. I am taking it really slow this time. And really appreciate all the help on this. Just want to get into a no knock not too rich/lean safe map to see me throught till I can afford some Dyno time.

[custardavenger]

Isnt a 100 silly high? I get audible knock spikes at 40 when its silly hot and pushing it and crap myself and back off. Can you hear it knocking or is it noise?

You've tried going richer? You've pulled timing, how about the VVT settings? What is the value on that cell? What's the boost level at that point? Is 13000 near the max load? I've read reducing the value to create overlap helps in supercharged applications as it blows boost out and helps in spots when theres too much. Check out posts on NC by 'GoatOfRafin' as he has documented this with graphical proof

I know absoulutly nothing on how the VVTI map works so am nervous to go near that. I think I'll try and get the fueling better first It was stupidly rich and looke like I've pulled it too far the other way. Will check the values in there and post.

Give me a clue, NC?

[aaronjb]

Whats the theory on low load points and ballenced throttle. Got those points tuned to 14.5 ish which I was recommended. Have been told that when not on the power there aren't the high cylender pressures and therefore less risk of damage?

Low load, cruise, gentle acceleration can all be at stoic - that's how the stock ECU works, you have to have a reasonable amount of throttle on before it drops into open loop.

Trailing throttle should be stoic or lean (sssh, nobody mention that my overrun is ~11:1! pop.. bang.. flames.. fire.. FIRE.. FIRE!)

If you want a really safe tune I'd tune to 11:1 on WOT and then work back from there toward 12:1 - at 11:1 you shouldn't get any mixture-induced knock at your boost levels, so you can find out what timing you can run, then wind back the mixture a little and juggle mixture & timing until you find the 'sweet spot' of best power.  That's where you really need a rolling road, or a lot of time on the road and a very good butt-dyno (and someone you trust to drive, really) - I don't personally believe you can auto-tune for best power, but that's another argument for another day  s:) s:)

I'll take a screenshot of my target AFR map later - it's horrible, as really the map should have nothing but smooth transitions and mine jumps massively from 14.7 to 11.5 in some areas, but it 'does' as a 'get me around' map.

[aaronjb]

Oh.. VVTi map - I think I got all the knowledge I have from NewCelica.org - there's a very good thread on PFC tuning on there, which is the 'NC' referred to earlier  s;) s;)

[ChrisGB]

Thats what I've been doing and exactly what I was worried about. Lowest is now 11. Will have a go at getting the WOT points richer and see how that goes. I have been trying to read up on the internet about this but not found anything good.

Whats the theory on low load points and ballenced throttle. Got those points tuned to 14.5 ish which I was recommended. Have been told that when not on the power there aren't the high cylender pressures and therefore less risk of damage?

This is correct IMO, at partial load you are not generating high cylinder pressures or temperatures, so should be fine. Manufacturers aim for the magic 14.7 (stoichiometric combustion ratio) for these part throttle and closed loop operation conditions. It is not the most efficient burn, but feeds the catalytic converter what it needs.

The part load condition is less critical in many ways. Knock occurs generally when one of two things happens. Either the cylinder is filled too well (IE too much boost) and the mixture detonates by compression heating, or when the spark is too far forward for the cylinder filling, when peak pressure is reached before the piston gets to TDC. (Other things can cause it like glowing deposits igniting mixture, oil breather allowing too much oil mist in, just plain old too much boost or not enough quench).

When you are at WOT, the cylinder has a high density charge with lots of energy. If the spark is too far forward, the mixture will burn from too early in the compression cycle. Now to this you need to add in compression heating. This also increases the speed at which the flame travels through the mixture. So when you run boost, the system has very dense mixture, hot mixture and increased compression heating. To counter this you have two adjustments (given you don't want to back off the boost). You can retard the spark so that the burn starts later, or you can add fuel so that the fuel soaks up some of the compression heating, cooling the cylinders. In practice you do a bit of both generally.

Just a thought, have you got a TRD thermostat fitted? That might help with chamber cooling.

There are other pitfalls too. You can tune an engine so that you will have a bit too much advance (does not matter if this is WOT or part throttle. You will not get knock, you will not gain power, but you will cause A LOT of stress to the engine. The art of getting ignition timing right is to work your way up to optimum. Imagine you start at a retarded timing condition. As you gradually advance the timing, the power will gradually come up. You will get to a point where you can add more advance but the power will stay where it is. The sweet spot is that point where adding more advance will not get more power, but taking any off will drop the power. This is only possible to do if you have a rolling road and engine stethoscope. You will hear the engine getting harsher as you add advance, and you will hear it get a lot harsher before knock sets in, but the dyno will show you that you have reached the timing "shelf" (the point that you want to be on the edge of).

Now imagine you are tuning on road. You cannot tell how the power is. You may perceive an improvement in the top end that may really be a drop in the upper mid for example. You have no scope, so can only hear knock when it is gross. The engine harshness may have gone up a long way, but not yet set off the knock count. Under these conditions, you have all the ingredients that can kill an engine. You then run it hard, of have a duff tank of fuel, or the day is hot and then pop goes an engine. I don't mean this to sound harsh, but the last engine could well have been lunched because of this. I would say take it to a mapper and get it done, or just plod it around on low boost, safe mixture low knock until you can. I think you have enough experience with this to make a safe setup, but when you want to maximise output, you need the rolling road, scope and expertise of a good ECU tuner.

Regards bleeding boost off with valve overlap, that will lead to unburnt fuel going off past the exhaust valves and into the exhaust system. Not a great way to go IMO.

Chris

[Anonymous]

... I love the detail in your posts Chris!....

Regards bleeding boost off with valve overlap, that will lead to unburnt fuel going off past the exhaust valves and into the exhaust system. Not a great way to go IMO.

You can use the VVTi to retard cam timing to achieve something akin to a miller cycle. i.e. retarted intake cam timing causes some mixture to be pushed out from the cylinder into the intake manifold as intake is still open well into compression stroke - thus reducing the effective cylinder pressure and reducing potential for knock.

[ChrisGB]

... I love the detail in your posts Chris!....

Regards bleeding boost off with valve overlap, that will lead to unburnt fuel going off past the exhaust valves and into the exhaust system. Not a great way to go IMO.

You can use the VVTi to retard cam timing to achieve something akin to a miller cycle. i.e. retarted intake cam timing causes some mixture to be pushed out from the cylinder into the intake manifold as intake is still open well into compression stroke - thus reducing the effective cylinder pressure and reducing potential for knock.

There is that, it all depends on when the exhaust valve closes I guess.

EDIT: Talking of valve timing, did you find any top end advantage by increasing overlap?

Chris

[Ilogik]

what are you monitoring knock with mate? didn't think the pfc showed knock? or am i getting mixed up. What are you using to control your boost?

[DannyN]

PFC will shock you knock on the commander

[Ilogik]

PFC will shock you knock on the commander

I noticed this on the commander, but for some reason on yank forums they were telling me to buy J&S safe guard to monitor knock.

 m http://www.spyderchat.com/forums/showth ... gik&page=2 m


mixed up between pages.

[custardavenger]

Wow. ok lots of posts and lots going on.

Cheers Aaron and Chris. comments are great.

Chris I'm totally with you with what you put in your post. Indeed last engine was my fault. I've put that down to the learning process. And indeed it may actually work out better for me in the long run but I'll explain that later. In what I'm doing at the moment I am in no way looking for maximum output and totally realise that can only come from time on the dyno. I am happy running underpowered and safe for the moment, But, I'm a man driving a car with a loud pedal that is exciting so realistically there is no way I'm going to potter about, Thus this work to get a safe map. I promise to all on this site that once the CC and WI are installed then the next thing is dyno time with the best I can afford.   s:D s:D  

So on to the events of today.
I advanced the area I had previously retarded and upped the fueling. Took it for a run and a whole load better. A few tweeks on fueling and the top end is now at 11.3-.5 with 13 deg. Now giving it a power run now it has a flat spot at 5500 where the knock was, the engine light flashed but Knock measured is 19 basic 24 advanced. Question is have I run out of injector duty? Max duty was in that cell at 72. Can't see any other reason for the light to flash.

Anyway I'm happy Knock is under control and I've spent many hours cruising on the motorway getting cruise to stoic and I would say it's 90% there and I'm getting very stable AFR readings. Also noticed the exhast note is sounding better and throttle response too.

Ilogic
I'm monitoring my Knock via datalogging the PFC with a laptop, I don't currently have a Commander installed (being modified) but that would show me knock too. As for boost control I have a supercharger which being linked mechanicaly to the engine will produce the a given boost for a given rpm. There is no controller like you would use with a turbo.
And finally I've read good things about the knockguard, though I think the guys that make it have hit the wall.

[aaronjb]

PFC will shock you knock on the commander

I noticed this on the commander, but for some reason on yank forums they were telling me to buy J&S safe guard to monitor knock.

 m http://www.spyderchat.com/forums/showth ... gik&page=2 m


mixed up between pages.

The PFC will show you knock. But it won't take any action on that value - if you see high knock you better get off the throttle before it does any damage, because the PFC will carry on doing just what the maps are telling it to do regardless, until the engine grenades.

The stock ECU, on the other hand, will dynamically retard the timing as it 'hears' more knock, thus preventing any bad things from happening if you happen to get a bad tank of gas, or it's a hot day, or there's a full moon.. etc.

The J&S sits between the PFC and your ignition harness and listens to the knock sensor, it performs the function that the stock ECU would do - retarding the ignition it response to knock and preventing large bills should it all turn to rats for some reason.

I don't have a J&S because I like to think I know what I'm doing - on the other hand, should I get a bad tank of gas one day and hole a piston, I will really sorely regret not getting one.  If I were you, I would buy a J&S - it gives you 'fit & forget' like the stock ECU, and you don't have to worry that the '100' knock spike you just saw has punched out a ring land.

[Ilogik]

cheers for the reply, will look into that then as i dont want to blow up my engine with this new turbo.

[Anonymous]

Copilot?

[custardavenger]

I think you'll find J&S is no longer available.

So can anyone answer my question on inj duty?

The only thing I can think to do if thats the case is to try and run it at 12 and hope I have enough duty to get to max rpm. Then I guess I'd be saving for larger injectors.

[muffdan]

are you running stock injectors?

[custardavenger]

No. 550's I think, I haven't got the info with me but I'm sure they are 500 and something. They are light blue.

[Star_69]

Is it a quick flash or a pulse? You're not maxing your injectors if duty is 72%. Have you tried adding fuel at that point in the map and checking its making it richer with the wideband? If the light flashed quickly its because you changed the Knock Threshold on the Settings 1 tab to a lower value

[custardavenger]

Cheers Star

Thats what I needed to know. Wasn't sure what max duty would be?
It was a flash. I'm sure it's definately rich at that point. Logged afr is 11.2. I'm just amazed that the datalogit didn't log any knock. I didn't think you could change the knock level? I can't see anything in settings 1 to do that.

[Anonymous]

2ZZ-GE Power FC lets you set the knock level that will trigger a CEL, 1ZZ-FE just uses 60 for knock threshold.

90% inj duty will cause a flash, too.   Some other Power FCs (not 1ZZ or 2ZZ) give you a threshold control over that, too.  Some even give a threshold for MAF voltage.

[custardavenger]

Well those of you watching will be glad to know I passed on the Dyno run. The car is off the road for a couple of weeks while I put some miles on the volvo so will have to wait for me to sort out these mapping problems.
Thanks for the help so far guys

[inert2k3]

 s:shock: :shock: s:shock:  I have no idea what most people are talking about on this thread at the moment, but Rob, hope your car is sorted out and running smoothly ASAP mate   s:D s:D

[custardavenger]

well I'm totally skint this month but the otherside of this is exciting parcels arive at my door. Just got a MAF bracket from PPE and a Odyssey 680 battery from Tayna.co.uk (top guys).

I have started drawing up the battery tray and will get one made soon. The reason for the battery is I wanted more clearance for the CC, I could have gone one smaller and got much more room but was worried about reliability.

Also I now have a rivnut gun. This will make ataching things much easier.

Woo Hoo.