I dyno'ed the car a year back when it was stock (attached sheet).

i don't know why it was running lean, and i'm not sure what a stock 350z should be running the AFR at? and what possibly could cause this?

i've searched the forum for similar issue, but can't find any.

dyno'ed on DynoJet




vid of the dyno: http://www.youtube.com/watch?v=go4j2nz8k-I

 

BumP... 100 views.. no reply.

 

looking at the dyno it looks fine except it should be richer when you got WOT. Normal throttle usually keeps it about 14.7 best as possible.

General rule of thumb is to keep it below 12.0 at WOT all the way to redline. I keep mine about 11.3 above 6psi.

I'm not sure what the a/f is supposed to be on a stock car. If it's the stock ecu controlling it i guess you aren't responsible.

 

so, basically you're saying that 14.7 is suppose to be normal (stock form). and at WOT, it should be richer than 14.

altho i thought 11 is rich, does that mean 12 is suppose to be the best in all situations (including FI setups)?

on a side note, i'm getting an HFC and an exhaust installed soon, and i'm sure i'll be running pretty lean. shouldn't the ECU be able to refine the parameters for a proper mixture?

 

What i remember was 12.8 or 12.5 at WOT (correct me if i'm wrong) and FI is diff.

 

12:8-13:0 is ideal for NA.......My first un-tuned pull looked similar to that. Having a 12:8 A/F allows for some added timing as well.

 

alright, what could cause that?

 

Honestly, it could be any number of things. You plan to have the car tuned soon anyway.....correct?

 

stock ecu

and when you add your hfc's and other stuff the ecu should automatically adjust for the needed fuel. That's why there are 4 o2 sensors on the car. This works to an extent. A retune would provide the most power out of the situation.

 

yea, planning to get an osiris. and i might probably end up dyno tuning the car..

that actually makes more sense to why my car acts differently..

i mean, since this car was imported from the US, the ECU is set to burn the fuel @ a certain rate (set in the ECU for the US product). and since we have a different octane level here, it won't be able to burn the fuel at the same rate. that could be the reason making it lean.

am i making any sense?

 

i don't think octane would be the reason, but a difference in fuel could definitely be the reason.

did your elevation change drastically? that could also change.

You might want to take the battery cable off of the battery which allows the ecu to reset. It will take off the memory of your fuel trims and "relearn" your driving.

Judging by what everyone else is saying your a/f isn't bad at all for NA. I'm not familiar with the a/f ratio of this car when it's not boosted.

 

actually we're at sea level in terms of elevation. i mean, we're a small island surrounded with sea from every direction, and not a single mountain. humidity is always high and summer heat is like 6 months a year.

in terms of octane level, we're running 95-96RON (which is 90-91AKI) at the stations.

i'll defo. reset the ecu once i get both mods installed.

 

also, i just remembered. If you have an exhaust system that isn't "straight through" design doesn't taking a tailpipe reading show on the lean side of a/f? I could have swore someone mentioned that it did.

I don't think the octane is the problem with the a/f. If it has a higher ethanol content it might not be supplying enough fuel per unit volume or the a/f reading on the o2 sensor could be off due to the odd mixture of fuel.

 

any chance it could be the injectors not pumping properly/clogged? since the normal AFR @ 14.7, the injectors are spraying the minimum gas required, but at WOT the injectors should be spraying at a higher rate, and if the injectors are clogged, the AFR will be lean since the air will be more than fuel.

is that possible?

 

In my head, That is possible.

 

but that doesn't fit the reason why his a/f lowers in higher revs. That proves that the injectors are capable of pushing more fuel.

i would just have it retuned

 

that's why i thought the injectors could possibly be.

 

Oh i thought he was just asking about general A/F. (Not about his dyno)

 

I think your dyno looks fine, not perfect but nothing to hurt any. What mods do you running?

 

Isn't the ECU supposed to monitor/adjust that??