How lean can I go
 

My ---- is donald trump rich in boost and I made go to ~13 or so under moderate throttle out of boost, but most of my cruising around town is MAD lean in the 16's sometimes popping up to 17 but average around 16.0... is this ---- going to wear down my motor faster? All light throttling around town.
This is on a 2.5l bmw m50tu, 10.5CR with near stock ign timing and 93ish octane.

Re: How lean can I go
 

I already asked this question in January.

https://www.homemadeturbo.com/forum/...494#msg1080494

got some great answers and my car is running in those areas on the highways and byways. IF the shortcut doesnt work the title was called "Where are you guys cruising at?" Try to find it! ;D

Re: How lean can I go
 

It's gonna help your gas mileage. I wouldn't worry about it hurting your engine if you're just cruising under light throttle.

Re: How lean can I go
 

advance your timing if you are running that lean at cruse. It will give you more power and also imporve you mpg. when you run lean like that your burn time on your fule is alot slower. Thats how people burn valves.

Re: How lean can I go
 

You drive your car out of boost? Faggot.

Re: How lean can I go
 

what about misfires? Ive got it puttering to work and back at 16.0 no problem but when I lift off the throttle it missfires for a couple seconds. I dont have access to decel/acel enrichments so I think thats something that I will either have to live with or hope the DME takes care of in openloop mode when setting target lambda to ~16. How damaging is a misfire to the car?

-edit-
http://www.wipo.int/pctdb/en/wo.jsp?...4&DISPLAY=DESC

So my china manifold wont like the missfires. I see... Damn I dont want to run any richer since it only missfires on throttle lift but it looks like my only logical choice.

Re: How lean can I go
 

What the hell are you using to tune it?

Re: How lean can I go
 

tunerpro
;)

free software ftw

Re: How lean can I go
 

Lean burn still requires just as much fuel to cruise. I'd just shoot for 15-15.5 AFR and not ---- around. It requires a bit of dicking around with ignition system and plug type to make lean burn fly.

Re: How lean can I go
 

BTW, can you link me to sweet BMW tuning stuffs?

Re: How lean can I go
 

Really? I don't think so.

-10% fuel, + 6-8 degrees of timing @ 10" of vac or more.

Guess tune by Blundar, wait until I ever take the time to refine it :)

Re: How lean can I go
 

You misunderstand, follow my logic:

- It takes X amount of horsepower to maintain a highway cruise.
- Power is expressed in airmass consumed, so for a fixed power X there is a fixed airmass Y consumed.
- If you are lean burning you are not consuming all the air. Therefore, more air has to enter the engine for Y amount of airmass to be consumed.
- The same amount of fuel is consumed either way.

The problem with stoich-targeted closed loop systems is that you swing into the too-rich range. This is why you *theoretically* want lean burn. However, without a complementary ignition system, plug selection, and in some cases head design, there tends to be a big loss in bsfc as the mix gets leaner due to inefficiencies caused by lack of gasoline density/droplets being too far apart.

I've been up late wanking to SAE papers, it shows.

Re: How lean can I go
 

Same amount of air enters, less fuel is used, but with a more complete burn, less of the BTU of the fuel is wasted going out the tailpipe or heating the water.

Stratofied for more complete burn.....less wasted out the taill pipe......but also NOx emissions go up.....which in my LIMITED knowlegde is the MAIN reason the cars of today aren't getting that good of mileage.

NACA/SAE = good paper to wipe your ass with :)

Re: How lean can I go
 

You can hate on SAE papers, but when they use a real life production engine and do mpg tests with different types of plugs and ignitions, the SAE paper may come back to hate on you.

Re: How lean can I go
 

I get noticeably worse gas mileage with ~15 then 16-17 even with light pops on off throttle. By like 2mpg.
Adding timing beyond stock only seems to help a little... I dunno. Really wish I had some more tuning skills and paraphenalia. For bmw tuning, bimmeforums.co.uk and the FI forum on bimmerforums.com
Between the two of those places I got 100% of my info.

Re: How lean can I go
 

Thanks, Yuriy.

I'm stillinterested in your translation skills, just been slack.

Re: How lean can I go
 

yea let me know when. There is a russian site I found that has a depository of like every factory bin for every odb1 car. Got all my honda/bmw bins and now I have been searching in vain to find it again. lets just say that ISPs and and KGB make websites go bye bye like 3x a week in the motherland. it sucks. I cant even get phat ---- from russian-town.com half the time. :P

Re: How lean can I go
 

Here we are.

http://chiptuner.ru/

If you think it's a goldmine I can run a web spider on it. I'm looking for info on offbeat tuning, especially reflashing OBD2 stuff.

Re: How lean can I go
 

Haha, I just checked your BF and BFuk links. It's funny to see peluca all over the face of every DIY hacking forum on creation.

Re: How lean can I go
 

damn man, they got some cool ---- on there... nothing I currently need, (I have to read VERY slowly through it, the use a lot of language that I was not familiar with when I left Russia in like 96) but they have a lot of random garbage on there, they focus a lot on poor people cars avail in eruope but the dudes on there seem to know their ----.

I recommend you sign up to their forum, grab a solid whole site translator and go to town. Planning on tuning some daewoo's? :1

Re: How lean can I go
 

Daewoos? No, although IIRC they run Mazda-designed engines sort of like Triumph made a variant of the 99 engine for their TR7, or the 4G63 NA in the Hyundai Elantras.

I wouldn't mind ------- with a Rio or Accent, though. I know of two wrecked 2.0 Tiburons I could get swaps from for an Accent from hell, and although it's not Honda quality those things aren't as bad as people have made them out to be. See also: using some misc crap wrecked car's EFI setup as a junkyard standalone to get WTF reactions, etc.