Air/fuel Ratio's And Good Old Knock!

[Chris32]

A good read this thread...

Whats everyone's thoughts on igntion timing and AFR's?

I had my cars tune touched up on friday and it feels like a dog now, but makes more power peak.

It previously was tuned to around 11 to 1 AFR's midrange and around 11.5 up top, and my tuner leaned it off pretty much everywhere as he thought it was costing power. In doing this, he had to reduce timing (obviously) otherwise it was detonating

So on the dyno, it seemed ok, it picked up about 10rwkw peak

On the road, the car is a dog

The lean AFR's in the midrange and decreased timing has knocked the punch that it used to have right out of it

Before, it would light up 2nd no probs, and feel quite punchy, now it feels like it bogs down and doesn't even chirp the wheels

It will be getting re-tuned, but how do others prefer there cars

I know I would rather it a bit richer and more timing than lean with no timing!

[Beer Baron]

yeah, i quite like the more timing more fuel approach too. but it obviously needs to be approached senisbly as more fuel is only worthwhile to a point, as is more timing. but for sure to generalise i'd rather have a little more timing, and a richer mixture than less timing and leaner mixture.

[Cubes]

I vaguely remember Tim telling me around 3years ago that the rb's like a slightly richer mixture through the mid range. 11.5 helps torque he said.

Edited October 17, 2005 by Cubes

[Busky2k]

Who'd you get it tuned by Chris32? I suggest you take it back and tell the tuner that the midrange needs more work. You paid for a better tune, not just neccesarily a better peak power figure..

[Chris32]

Who'd you get it tuned by Chris32? I suggest you take it back and tell the tuner that the midrange needs more work. You paid for a better tune, not just neccesarily a better peak power figure..

<{POST_SNAPBACK}>

Shaun tuned it at Boostworx

my fault, as i'd been playing with the fuel map and made it quite rich! So i asked for fuel to be taken out, and thats what I got! It did make more peak power everywhere in 4th, but in 1st, 2nd and 3rd it felt flat because fuel was taken out in some of the load area's

Already spoken to Shaun about it, going to get it back in on thursday and fix it up. In all fairness it was done in a rush on friday night after work, it was just supposed to be a tidy up! but had to redo allot of it!

[yogi000]

chris,

How are your knock readings after the tune?

cheers

[Chris32]

Funny, as I just got of the phone with Shaun

He tuned to the knock light this time, which is why he took a fair bit of timing out of it - hence why its feels flat now! Last time he turned it of, as it was faulty

I thought i'd made some progress in that area with the lag timing etc, and turned it back on. I think it did help in regards to acutal knock, but the light/sensor is still playing up! Bastard! Well, booked in for thursday arvo, will be tuned ignoring the dodgy sensor and see where it ends up

Ignoring the knock light from now on, will eventually get to the bottom of that problem. What about yours, is it still playing up?

Will be going a bit richer again and a bit more timing to keep the response up. Nothing worse than a laggy feeling car with not enough top end due to smallish turbo!

Edited October 18, 2005 by Chris32

[R31Heaven]

Call me stupid but why are they tuned to 12.1:1 when stioch is 14.7 isnt that still running rich? does boost have that much effect on ratios?

[The Mafia]

losing good mid range power and gaining a very pissweak 10rwkw means 2\10's of f**kall to me.

You aren't at 6500 - 7000 rpm all the time are you?

Mid range is where you are the most I say... Tune the power back there...

[blk180]

off boost maybe they can get up to 14.7 but mine tuned for about 11.8 at full song and im still gettn knock readings in the 40s dam money pits

[rob82]

Hmmmm if nissan couldn't do knock feedback timing above 4000rpm what makes you think that a PFC can distingish between engine noise and a detonation event? Your tuner should no what real knock is by listening to the engine with or without a chassis ear not to mention NOx levels going through the roof. I know it might sound like an amazing thing but knock levels will be different for different cars/engines all this comparing knock levels is BS.