Hi!
I have seen other posts here on forum and elsewhere on internet regarding tuning for better economy and better low rpm response, but still in doubt what is the proper way to tune my JTD EDC15C7.

Firstly, I woud like to know more about boost pressure:

Someone says to lower boost pressure in low IQ to reduce back pressure. But as I see in my original boost maps, in IQ < 24 mm^3 there is only about 1000-1200 of boost pressure (absolutely values) under 2000 rpm, which should be my preffered rpm driving range. That is acctualy 0 to 0,2 bar higher than atmosferic pressure, so is there any sense to lowering this? At least, turbo should be producing some little pressure to be prepare for increasing pressure if I need to accelerate.

Other says to increase boost pressure in low rpms, because higher pressure with same IQ produces more pressure to piston...

So, who is right and who is wrong? Does higher pressure in cylinder (that also means more air) produces more power with same IQ?

2. In my maps I can se two boost maps; one have x axis up to 64 mm^3 and other up to only 55 mm^3. When I increase boost by 0,1 to 0,4 bar to all values in this second map, I can feel that car is pulling better in low rpm and as car accelerates I actually lowers accelerator pedal. But still don't know is this improving fuel economy or not. I assume that this map up to 55 mm^3 is used when cruising and other map (up to 64 mm^3) with dynamic driving style? Is it true or I'm wrong?

3. Turbo vanes - should they be touched or not?

4. As I understand, SOI is a big factor for fuel economy and ecology. So advancing SOI should improve fuel economy. I'm thinking about 10% advancing in range 1250 - 3250 RPM and IQ < 30 mm^3.
Is this OK or to little? If I advance more, than in higher RPMs and higher IQ there will be lower SOI than in this lower range, what does not make sense to me.


I would try to lower my consumption in everyday driving to work and back.
My path looks like this: Firstly, I have 4 km donwhill, from 200m to 50m altitude; then I have about 10 km uphill to about 200m altitude and than lowering to 0m altitude in next 15 km. And vice versa when going back home. My driving speed is between 50 and 90 km/h in 4th or 5th gear. My board computer shows low to 3,8 l/100km when going to work, and about 1l more when going back. This isn't accurate, because my cars actual consumption is about 5,5 to 5,8 l/100km. I think that most of fuel is consumed when going home, because I have to drive almoust 15 km uphill instantly when I start my car...so engine is not warm enough.

I have attached my idea of tuning for economy and power...does it make sense?

Hey, Like You said before someone says lowering boost improves economy, someone that raising boost is better, someone that raising rail pressure helps, someone that lowering... :crazy: So how it is in reality??? I think there are many factors and relations which determines fuel economy. Unfortunetely I dont know ultimate solution to achieve best effieciency :( About lowering boost remember - too much is not good for turbocharger. About SOI changing, I think the best is to do that with calculation of injection end (EOI). This gives you better information about where you are standing. It is important because SOI affects engine work very much and bad values have high negative effects on the car parts. There is a very useful EOI calculator in the forum. The best SOI adjustments could be done on dyno.
I m joining to this topic and hope that pros will share a little bit their experiences ;) .

Well, by using EOI builder from eoi-builder-t1441/page20 I can see that original EOI is up to 5 degree ATD in range 1250-2000 rpm and under IQ of 30 mm^3. That's look preety retard for me.
I have noticed one interesting thing; I was driving about 600 km with different remap where boost pressure was higher by 0,1 to 0,3 bar in map 0x77E4C in range 1250 - 1500 RPM and IQ < 32 mm^3 and my board computer shows lower average consumption than stock (but BC in Alfa 156 is not smartest and accurate one...it lies very much and it have very strange calculations). Then, I change map and lower that boost, but still higher than stock, and by BC now is consumption increased. Yesterday I uploaded new remap to car, with SOI values a little advanced (by only 10%, I thing that remap I uploaded here) and don't see much difference by BC than previous remap. I know that I cannot trust BC so I have to see what is actual consumption by visiting gas station :)

However, with this new remap, I also change torque map characteristics so now car pulls all way up to 4500 RPMs...like gasoline car :)

Back to economy...I suppose that every engine have different characteristics, so something that works on one engine, maybe does not work on other. But, I think that general guidance can be in common for any engine. Like increasing power - every engine needs more fuel and air to increase power; how to achieve this...that is another question and differs form one to another approach. You can increase fuel pressure or increase duration...or both...to achieve desired fuel quantity. For more air...only thing that I know is to increase boost.. Like that, what is general guidances to increase fuel economy (of course, we are talking about turbo diesels)?
As I understand, there are two possible approach: first, increase torque in low RPMs so you can change driving style to shift in higher gear with lower RPM and driving with lower RPMs. Also, when accelerating, accelerate sharp and in short time, than try to achieve same speed with low accelerator pedal as you can. So with this approach, I think that more torque means more fuel economy, which is produced by increasing IQ and boost at low RPM-s. BUT, this is not healthy for engine, gearbox and clutch, because low RPMs produce more vibrations, higher torque in low RPMs produce more forces on shafts, clutch, bearings and so on. Also, fuel consumption could be actually higher if not paying attention for driving style.
Other approach could be lowering fuel consumption at low RPMs and low load conditions by producing more pressure on piston without increasing fuel quantity. That means adjusting SOI, and what about boost? Stock, little increase, big increase or lower?
Or maybe increasing fuel pressure, so with higher pressure there is better fuel atomization so possibly better fuel efficiency (and also duration will be shorter, so SOI will be automaticaly advanced)? But with increased fuel pressure, does any other map should be modified, so other values will be correct calculated by ECU?

Many questions, many opinions...but what is correct way to go? Or just...try, measure, correct, try, measure...until find optimal parameters?

About boost: closing vanes to raise boost causes higher backpressure. It increases pumping losses. On the other hand it causes cleaner combustion, so raises efficiency. Up to 30 mg/str there is usually more than enough air inducted with no boost, so lowering boost (actually opening vanes fully) under 30 mg/str can affect consumption a bit.

Same about FRP: more pressure causes more mechanical losses - more torque consumed by high pressure pump. On the other hand, higher pressure can cause better fuel atomising, so cleaner combustion with higher efficiency can be achieved.

SOI (EOI) is best to be tuned on a dyno and set to max torque for each particular IQ (using different torque limiter setups) through a whole rpm range. Maybe I'd set it a half degree retarded - only for safety.

Well, that make sense for sure. Lowering boost and FRP automatically lowers mechanical losses so less fuel is needed to engine running at some RPMs. But as you also said: increasing boost causes cleaner combustion and raises efficiency. The same is with higher FRP. So, if we goes with boost and FRP in one or other direction there is always positive and negative effect of that. So question is in what direction to go, where are positive effects higher than negative?
Unfortunally, to use dyno it takes much time and money...so there is no use of it; money that you have to pay someone to tune SOI/EOI, your time, trip to the nearest dyno will overcome savings that can be maybe achieved by lowering consumption by 0,2 or 0,3 l/100km

...or 0.6 l/100 km (mondeo mk3 2.2 tdci):

I have lovered boost from 5-15% in lover area to better consuption - result: Žilina - Bratislava before 5.8 140kmh tempomat Bratislava - Žilina it goes to 6.2. Now ZA - BA 5.2 and BA - ZA 140kmh 5.6. I try it 4x. It is 220km to BA.

(received as private message on another tuning forum)

10% less - well, that is something worth trying. :)

I decidedc to try. But had 2 black bmws 5 up my ass when driving from work to home, so had to quit testing my economy and give them something to think about. :lol: :lol: :lol:

:D

Well, I have done some changes to maps and I will see how will reflect to consumption. I was also test drive car and done logging data, and I can see that turbo pressure is higher than I want in maps, it is even higher than in stock map.

What I've done is lowers boost until 2750 RPMs and under 24 mm^3 of fuel (just a little bit, 1-7%). I've also decrease fuel pressure between 1500 and 2000 RPMs, also very little drop...1-4% and advance injection between 1000 - 3250 RPMs and under 30 mm^3 for 5-20%. What do you think...is this values to small? I don't want to go with bigger values yet..I think that messing with SOI and duration can be dangerous if not tuned on dyno or some other instruments.

EOI is now about 0,4 to 0,8 degrees advanced (earlier) than stock.

Here is screenshoot:


And this is measured data (on cruise controll):


and without cruise controll:


Fuel pressure is as expected, but turbo boost is about 0,4 bar above desired in boost maps...it is even bigger than stock. How can that be? Is there some boost correction maps related with engine load? If so..how it looks like?

Any recomendations?

Pressure turbine is regulated map N75. A map is limited only by the maximum pressure, for example up to 2200mlbar. In your first case at ~ 75km/h flow rate ~ 4,9l / 100km.
I with such speed and revs ~ 3,9l / 100km (15c7 Marea Weekend, I do not have a cruise, off egr). But I reduced pressure turbine card N75 IQ <20mlgr and at such a rate was ~ 1100-1200mlbar.

mod

Deman wrote:Pressure turbine is regulated map N75. A map is limited only by the maximum pressure, for example up to 2200mlbar. In your first case at ~ 75km/h flow rate ~ 4,9l / 100km.
I with such speed and revs ~ 3,9l / 100km (15c7 Marea Weekend, I do not have a cruise, off egr). But I reduced pressure turbine card N75 IQ <20mlgr and at such a rate was ~ 1100-1200mlbar.

This case at 75 km/h was on very easy uphill...even not noticeable with human eye, but when driving you can feel difference (in one direction have to go with much more accelerator pedal pressed than in another, same speed and gear). I think that there should be some correction map due to engine load...but I can't find it.