edizio

So I've been getting into ECU tuning and have got a fairly basic understanding of timing and fueling however I've got a few questions regarding fueling: -

1. When working on the fuel map, assuming I'm not on boost but at high rpm, i.e. changing down from third to second ready to plant the foot (5000rpm), am I still looking at providing enrichment or should this be at stoich (14.7) until the boost comes on? I'm currently playing around with low 13s at this point just because I've always thought that under load, an engine should probably be just south of stoichiometric.

2. The phrase, 'coming onto boost', I've got my AFRs lowering as soon as I go onto positive boost, so at 0.1bar I'm starting to get into the high 13s, 0.2 low 13s, in a kind of fluid graph, i.e. no sudden jumps. This to me seems like common sense, but my question then is, some cars are boosting more than others, so is there a point where the boost level, i.e. 0.1bar should always be at high 11s, low 12s. Let's assume someone has a huge turbo, 0.4 bar for them could be pushing just as much air in as someone with a much smaller turbo at 1.4bar and thus the guy with the smaller turbo at 1.4 would be at 11.5 whilst the guy with the larger turbo would still be at high 12s.

3. Just out of curiosity, what do you guys run your AFRs at? I'm happy at 11.5 on full boost because I'm always overly cautious but I've seen some people running 13.1-13.5 on drag strips but I guess that's quite a small margin for error with exhaust gas temperatures getting extremely hot.

piehole1983

iTrader: (7)

I was advised to run at 11.1 AFR on full boost and yes, I think your right about gradually enriching as boost increases rather than having a big jump.

edizio

That is interesting; quite rich! What boost are you running? I assume quite high if you're going that low. I guess that does mean that when cold winters come along, your AFR is still in a safe zone.

Still kind of interested about what AFR to sit at when at high rpm but no boost. At low 13s I'm not hearing any signs of detonation but some confirmation would put my mind at rest.

piehole1983

iTrader: (7)

I'm actually running about 1.2bar at the moment. I was advised that 11.1 would be a good target AFR to set the map to. In reality the actual AFR's logged by my wideband are slightly higher, maybe 11.3 or so. I haven't really given as much attention to partial load AFRs to be honest, I know I should and will do. I simply enriched them slightly in the areas that lean out. Have you got a wideband sensor installed too?

edizio

Yes, I use an MTX-L innovate wideband; I was aiming for high 11s on full boost so I have 11.8. I do think I come onto boost a bit high to be honest, probably should be low 12s as I reach 0.5 but in actual fact, I'm more like 12.7-12.8.

I've got my greddy protecB boost controller running at 1.0bar right now; boost comes on at 0.8bar with gain set to 3%

It feels fairly good and sure, I think I could squeeze more power out of it by going leaner and advancing the timing but I think my weakness is paranoia. I set the timing by advancing until det but instead of pulling back just 1 degree, I've actually pulled more like 2-4 from each cell.