Wideband Discrepency

[Room42]

I put my car on the dyno at Rotomotion on Friday to get my tune checked. I was/am using an innovate wideband that is about 3 months old. Anyway there was a 5 point difference between my wideband and the one at the dyno. Mine read 12.0 to 1 at wot. The dyno read 12.5 at wot. I got my tune adjusted accordingly. Scored and extra 5 rwhp as well. Anyway just putting it out there. It would suck to melt something cos of trusting a $260 sensor/gauge.

[DVS JEZ]

i have found the same,

will also be different between before cat and after cat,

did you have yours logging on the dyno? if not maybe its hitting different load cells on the road compared to dyno.

[MBS206]

Where is your O2 sensor, and where was the Dyno one?

You will get a different reading between reading in the dump Pipe, VS after the Cat

[Room42]

Of course. I didn't even think of it being different after the cat. Mine is in the dump pipe. The dyno is in the tail pipe. So...where is the best spot to measure from ya's reckon?

[JonnoHR31]

best realistic spot is in the standard o2 position

[89CAL]

The instructions for my AEM wideband said the best spot was about 1m from the turbine exit

but this may be to prolong sensor life?

[Room42]

I have tuned most of it myself over the last few months. I was still at work while the car was being tuned. I didn't get to see any logging when I picked it up so I'm pretty sure they just had a look at it and changed the bits I asked them to. I got it to 247 rwhp with the stock turbo at 12 psi and they found the extra 5 rwhp by adding 1 degree to load 16.

[JonnoHR31]

The instructions for my AEM wideband said the best spot was about 1m from the turbine exit

but this may be to prolong sensor life?

yep, too much heat will kill a sensor pretty quickly

[Room42]

I might lean it off a bit then so it uses a bit less fuel. Not that it is a huge consideration when you do up a skyline but it has got me kinda worried how much it will use when another 200 rhwp is added to it

[89CAL]

leaning out the tune under high load/boost wont really improve fuel economy. You want to have the AFR's there Safe rather then economical

The economy comes from your lean cruise points, so at constant 60km/h, 80km/h, 100km/h etc. Having your own wideband + tuning software makes this easy and you can get it running pretty good

My best friend used to tune my car for me and he said my car actually responded better to having a bit more fuel chucked in when boosting

[lilcrash]

[quote name='89CAL' timestamp='1313234034' post='5964918'

My best friend used to tune my car for me and he said my car actually responded better to having a bit more fuel chucked in when boosting

Flame takes up more space in the exhaust, more fuel equals more flame equals more spool, that's how antilag works. If you boost up on your cold start map you will see this very well.

[89CAL]

Yeah im talking about power not spool time but

[Room42]

When I said lean it out I only meant from the 11.5 it reads now to 12. Safe is good tho. On the subject of spooling up early its gotta be lean to get the exhaust gas hot and expanded to create more volume of gas to turn the exhaust wheel. Having the timing right for spool up is equally as important. Enough but not too much or it will run rich. Cars will have more power leaner but run a lot hotter. Then you reach a point where you lose power cos there aint enough fuel there. However that point is far beyond safe under high load. Don't go there! Running lean (16.5-1)and high timing (30-39) at light load on my car is optimal as I use bugger all fuel and have the engine ready to spool early. As soon as it spools and gets up in the revs (over about 4k) you gotta cool it off with the extra fuel. Antilag is not like spooling up in the normal rev range. You use stacks more fuel and completely different timing to achieve it. Phew... back to movies and beer

[89CAL]

You don't necessarily gain more power by running it right on the edge (12:1 or so). It was discuss not long ago that the japs run 10:1 AFR's and more timing to get just as much or more power as tuning done over here with leaner mixtures and less timing.

I think 16.5:1 is a bit lean for the lean cruise AFR's personally. But that's more up to you

[D_Stirls]

Did you do another free air calibration and see if the gauge is still different than the dyno reading. But i agree with the others there will be different reading at the end of the exhaust compared to up near the turbo.

[KiwiRS4T]

If the tuner is used to using a sensor in the tail pipe he should be able to do a good job but both tuners i use will put another bung in the down pipe for their sensor if there is not a spare already, Just takes a few minutes and then its there for next time.

[Room42]

I have thought of running super rich and more timing but haven't tried it yet. Its a pity the weather is wet or I'd have a go today. I have found though that the amount of fuel used between 12 to 1 and 11 to 1 is very noticable. I can get around 650 ks a tank running at lean at light load and obviously heaps less on boost. I have found that anything past 16.5 to 1 the car surges, although most of the time in normal driving it is under that. 16.5 is just when my foot is still on the throttle at 60kph.

[STATUS]

You don't necessarily gain more power by running it right on the edge (12:1 or so). It was discuss not long ago that the japs run 10:1 AFR's and more timing to get just as much or more power as tuning done over here with leaner mixtures and less timing.

I think 16.5:1 is a bit lean for the lean cruise AFR's personally. But that's more up to you

12.5 is safe on a RB... when tuned right... even seen 13's on a 500hp endurance engine so 12's is nowhere near the edge.

To the OP 0.5 is often the approx difference from dump to tailpipe depending on cat and dyno pickup design at the tip.

[Room42]

So Trent, do you reckon that 12.5 is fine for mine? Most of the RB dyno sheets I have seen are at 12 to 1. I figure that seeing as it is only driven on the street and isn't at wot for very long it wont get too hot. I haven't got a pyrometer so I cant really tell tho. In saying that I still have a stock turbo so I dont want to spit the exhaust wheel out just yet.

[gotRICE?]

Did you consider unplugging your wideband from the dump pipe and putting the tuners one in there and seeing what you got?

(sorry if you did, i skimmed a bit of this)