Tuning For Maximum Economy, And Leanest Safe Afr

[Busky2k]

If the fuel map is too far away from 14.7, PowerFC's closed loop wont work. It has a 'narrow window' of correction I've found.

I've used 14.7:1 even up to a few psi of boost. I dont see why you have to go richer there. Even factory its set up that way.

[V-Spec]

ahah guys, put a block of wood behind the accelerator so you floor it and it accellerates very slowly, that will save you money ahahha

[Cubes]

I've used 14.7:1 even up to a few psi of boost. I dont see why you have to go richer there. Even factory its set up that way.

Did you find the ign had to be adjusted to prevent ping with such an afr?

I don't appear to have issues with det, light load 0 vacuum will take any ign value you throw at it. (obviously silly as more ign. timing doesn't necessarily = more torque)

Although, run 91ron fuel and its a different story.

[N I B]

If you start to lose power and torque by going lean then the car will start to use more fuel,In RBs its about 15-1.

The Wolf is easy find out the best AFR for cruz fueling, look at your O2 sensor voltage then go to sensor setup and put that value in,Typical example

is 0.60center

0.58lower

0.62upper

In order in the Wolf menu.

[Guilt-Toy]

If you start to lose power and torque by going lean then the car will start to use more fuel,In RBs its about 15-1.

The Wolf is easy find out the best AFR for cruz fueling, look at your O2 sensor voltage then go to sensor setup and put that value in,Typical example

is 0.60center

0.58lower

0.62upper

In order in the Wolf menu.

Is it bad for your engine to run it too lean on crooze ??? I think mine is running at about 17:1 will this burn a hole in the pistons or something ???

[Cubes]

Guilt-Toy.

No... You will simply develop an incomplete burn hence lean miss and begin using MORE fuel.

The exhaust gas temperature peaks at 14.7-15:1. Should you go leaner the exhaust gas becomes cooler, should you go richer the exhaust gas becomes cooler.

Run 14.7:1 at full throttle and you will most definitely burn a hole in a piston if you don't smash it to pieces by detonation first.

[paulr33]

17 sounds too lean

before i did mine i did some reading up on tuning with a wideband sensor from google. i found a few good arictiles which covered general safe limits for na and turbo motors and general guidelines and principals

[Busky2k]

17:1 is definitely too lean. The car would start to misfire at that AFR anyway...

[Busky2k]

Did you find the ign had to be adjusted to prevent ping with such an afr?

I don't appear to have issues with det, light load 0 vacuum will take any ign value you throw at it. (obviously silly as more ign. timing doesn't necessarily = more torque)

Although, run 91ron fuel and its a different story.

Nope, don't have to touch the ignition timing whatsoever. Just like you, you can wind in almost any timing but you start to know when to stop when there is no gain in throttle response and the car might actually not be as smooth.

[Guilt-Toy]

I might run it at 0.830 instead of 0.769 and see if what happens.. il also chuck in 5deg on the way home.

[Warpspeed]

Yeah, 14.7 is the best figure to run. You can run it leaner than that, but then you will need to open the throttle just a little bit more to maintain constant speed. The result is you end up using the same amount of fuel, but more air passes through the engine.

Exhaust gas temperatures will be higher, and you gain nothing. Leaning it off even further can cause a lean misfire, as others have already said and actually reduce economy.

If you can get and maintain 14.7 at light loads and cruise you are doing o/k. The next thing to do is start working on cold enrichment. A lot more fuel can be used than is necessary when the engine is warming up and still below correct operating temperature. If you do a lot of short trips around the suburbs, this can kill economy, even if you drive like a granny. If you can lean it off when cold, and it still drives o/k, that is one way to get something for nothing.

I have an Autronic which has a lot more features than some other ECUs and have been fiddling for quite a while. It is possible to get small improvements in economy, but if the factory system is running properly, small improvements are all you are going to get.

[N I B]

I did the same with my Wolf playing with water and air temp tables for both fuel and timing trims.The news said fuel may hit $2 in 6 months so fuel really is an issue now.My GTRs torque and HP start to fall at 14.85afr and the emissions get dirty.My multi gas analiser shows 14.8 as the cleanest afr and 44deg total timing at cruise gives me the best economy.Stock cams.

[Warpspeed]

What sort of exhaust gas analyzer do you use ?

I have an Autronic that uses the usual Bosch wideband sensor.

[Guilt-Toy]

What sort of exhaust gas analyzer do you use ?

I have an Autronic that uses the usual Bosch wideband sensor.

I have only used the Autronic with Bosh sensor too. I dont have access to it atm though

[Guilt-Toy]

I did the same with my Wolf playing with water and air temp tables for both fuel and timing trims.The news said fuel may hit $2 in 6 months so fuel really is an issue now.My GTRs torque and HP start to fall at 14.85afr and the emissions get dirty.My multi gas analiser shows 14.8 as the cleanest afr and 44deg total timing at cruise gives me the best economy.Stock cams.

$2 in 6 months? You cant be serious ?

[Cubes]

With regards to the cold enrichment.

I've grabbed the table from an R34 GTR.

Within the PFC the R32 RB20DET right up to the R33 GTR all run the same cold enrichment, which is richer than the R34 GTR.

So its...

The R34 GTR table does offer better cold drivability even though its leaner, driving immediately after starting still tends to bog a little when coolant temps are below 25degree's. It most definitely feels like a rich bog, now the cold weather is well and truley in I'm going to start tweaking it.

Running the std pfc cold enrichment I find the car tends to bog a little on light throttle. The leaner table feels much nicer to drive, gives the car a warm feeling if that makes sense.

[N I B]

$2 is serious.

I use the Autronic analyzer that comes with Dyno dynamic Dynos and a Bear gas bench.

[paulr33]

my car is tops on cold start and cold run driving

but mine is leaned out a fair bit on the INJ map

[paulr33]

my INJ map

[Cubes]

Here's mine..

Its running 34 GTR injectors that flowed 480cc @ 40psi.

The injectors are trimmed @ 58.5% (260cc / 444cc * 100).

Its running the R33 rb25det map reference, airflow curve, inj map (tuned) and ign map (only wot touched).

Boost starts to be made around load point 12, prior to that its under vacuum. WOT hits load point 16-17.

After the tune there was a noticable improvement in off boost acceleration, especially in the vacuum area's *only just* prior to boost being made.