kzak104

iTrader: (1)

mine is around 12.5. is that safe? i did a datalog and sent it to vicne but have been waiting for around 3 weeks and just want to make sure.

also i currently have stock plugs that have never been touched, what should the gap be running 22psi? im at 32000kms, should i change my plugs?

BlackARCA06

iTrader: (5)

Thats fine, I see 11's sometimes but its mostly in the 12's. If your not misfiring I dont see a point in changing the plugs but the gap should be .32 if you do. I bought a set from the dealer and they come gapped...I still check them though.

EXsoccer1921

iTrader: (14)

X2 on the plugs. no sense in changing them if you aren't getting blowout or a misfire. plugs are a fine line between having enough gap to get a full burn but not too big of a gap where it blows out.

as far as afr's i can't say, a part of me is telling me aside from the stoich 14.7, afr's were different with the the lnf's cause of the DI but i don't remember what they were

kzak104

iTrader: (1)

alright thanks guys for the help! just wanted to be sure i wasnt going to blow up my engine with the a/f rations, everyone tells me its lean but they dont have Di cars...

BlackARCA06

iTrader: (5)

Yea single digits is when you have to worry. My first tune from vince was in the high 10's.

07MetallicSC

iTrader: (16)

I change plugs every oil change. I figure whynot they're cheap. Wot I'm around 11.3-11.1

DirtyBalt09

iTrader: (2)

Im at 12.2

I've heard most power is made around 12.5-12.8 with richer being safer.

OBZ

Mine is about 11.5 with the tune on, and about 12.2 with it off.

2000Firehawk

It's been well documented on this form, that .82 - .88 PE lambda is best for the LNF...

.82 Lambda = approx: 12.0 AFR , the 'safe' , richest , error on caution, for premium petrol
.88 Lambda = approx: 12.9 AFR , best for E47.5



I've been at .88 for a few years, runs like a raped-ape...

prevsrt4owner

Yep, 12.8-12.9 AFR = sex for the LNFs. I'd say anywhere between 12.5-12.9 would be the best.
Remember, the LNFs are DI, haha. On the SRT-4, sweet spot was 11.5-11.8. Meth/e85 was around 12.3-12.5 for the best power.

dakotaspeir

iTrader: (9)

11.8-12.1

silverbullet08

That tune needs a lot of work. AFR has a horrible curve. Up top 12.5 is not bad at all. Your safe/conservative with that AFR as long as your not getting knock. If you ran the dyno from a lower RPM you would probably see more power. 4800 rpms is too late to start.

kzak104

iTrader: (1)

doesnt the car have a lean spike when you first start the dyno run? and ya the place that did the dyno as never seen a cobalt im pretty sure, they said my car is running extremely lean and i shouldnt even be driving it.

it would be nice if vince would get back to me so he could get it sorted out if it does in fact need sorting.

mexi_loco

iTrader: (7)

i'm at 12.4, but then again I'm on e

rnjmur

Ideal AFR on an LNF is 12.5 - 12.9

I run 12.9 in the low end then ramp up to 12.6 at the high end. Many of the LNF tuners typically run 12.9 - 12.8 through the entire RPM range.

With that in mind, your tune is actually a little on the rich side except for when you initially go WOT. Vince typically runs his tunes on the richer side for safety so I would say that your AFR is exactly where Vince would expect it.

The tune is probably spiking at WOT which is causing the lean spike. That in itself can be fairly easily tuned out with a little work.

T-Man

iTrader: (3)

You should calcuate AF based on e10 stoich or 14.13 as most people run it as opposed to the typical 14.7

I command a lambda of .90 in the low/midrange tapering down to .89 and .87 past 6K

OP,

I honestly wouldnt worry as the tailpipe sniffer is usually a few tenths leaner than actual lambda readings. I noticed this on my previous sedan while on the dyno. I was commanding .88, HPT showed .875 to .88 and was seeing 13.2 AF on the tail sniffer reading... lol

What were the SAE numbers?

kzak104

iTrader: (1)

Sae numbers?

09CobaltSS1

I'm pretty much right in this range as well, however I'm on e47. I tip in around .90-.92 and command .88 from there on. (.88 lambda is 12.9 a/f OP)

SAE is a correction factor. Your numbers are uncorrected.

T-man is also correct about the tailpipe sniffer registering a tad on the lean side from your actual commanded lambda is. If you're seeing 12.5 out of the tailpipe then you're very likely sitting at a commanded .82-.83 lambda (12.1-12.2 a/f). Either way, you are by no means lean at all. A 12.2 a/f is actually a tad on the rich side for my liking.

Most shops aren't used to seeing DI setups so they automatically think the engine is running lean when they see anything leaner than 12.8 or so. Trust me, I've gotten into heated discussions with shop guys who arent familiar with DI setups telling me about how my engine is going to blow if i dont richen things up quite a bit and yadda yadda yadda. Direct Injection = a totally different animal than Port Injection.

CannonBalt

I see 10.5

kzak104

iTrader: (1)

i guess it cant be to lean if its running at 12.5 yet still depositing black soot all over my tailpipe. thats usually an effect of running lean is it now?

but ya the dyno i went to, the guys specialize in mustangs :P so they dont know what there talking about i guess, i figured this but just wanted to make sure.

Dart_SI

iTrader: (1)

im at 12.8 at redline

T-Man

iTrader: (3)

I'm jealous. I use to have an E station that was 5 minutes from my house. They stopped selling E in September of last year

I guranatee that he's sitting around .82-.83 with a Trifecta tune and I agree, a bit too rich IMO.

I was told I'm going to burn holes in my pistons (possibility with but highly unlikely with fuel being sprayed right into/on the crown of the piston).

A pretty smart dude once mentioned that you hardly see LNFs blowing from running too lean but that many that were running excessive boost and excessively rich (for DI) were going kaput.

I mean FFS, people for the longest time were going WOT with a **** poor PE table and a jacked DAL table and being WOT while still commanding stoich lambda

Soot is a typical GDI trait but can be exacerbated by running too rich and using poor quality fuel.

Area knows whats up

BEG4MRC

12.3 12.5 at wide open throttle