HELP: Stock S15 running EXTREMELY lean

[eron]

HELP: Stock S15 running EXTREMELY *Rich

Ran my STOCK JDM AUTO S15 SR20DET on a dyno today.

Fuel ratio was 10:1. At this stage, I believe there should be heaps of black smoke coming out. But there wasn't.

AFM was good. O2 sensor was good. Spark plugs was good. Timing was good. There wasn't any leaks spotted. Water temp and oil temp good. No boost leak.

Dyno equipment all good.

Injectors maxing out at 100% duty cycle.

Ran about 115rwkw. (auto).
--
So, what's the problem?
Can a blocked cat converter cause this?

 

[Nicely]

Fuel pump? Fuel filter?

 

[eron]

Fuel filter was changed some weeks ago..
Fuel pump..maybe... But how so?

 

[ichi-go]

Definately wouldnt be o2 sensor as the ecu doesnt take readings when its wot

I'll be checking out the fuel pump if i was you. Most probably it's rooted. Just get a used gtr fuel pump for that extra oomph.


EDIT:
Hmm I thought running rich would cause alot black smokes? Not lean?

 

[Kango]

10:1 is rich. No wonder running high duty cycle. 14.7:1 is best for emissions and 12:1 is best for power, so as revs rise and throttle opens the map should get richer to 12:1 at WOT. This allows for the fuel to cool down the pistons a bit too.

 

[evade]

^^ Agree 10:1 is hell rich..are you getting any fuel economy at all??

Where'd you get it dyno'd? what were they're opinions on it?

 

[Nicely]

Yep, sorry. Skip the ratio bit. You've got some serious overfuelling going on.

 

[eron]

I'm still getting about 350kms.

Bringing it in on Tuesday again. He reckons there's a boost leak somewhere...

In my noob opinion, shouldn't the spark plugs be in bad shape if it's REALLY overfueling?

 

[Adam15]

a blocked cat would mean it would be down big time in power,, and if the spark plugs were in bad shape the spark would not ignite all the fuel,,but if they say there good then would'nt worry about that could be a boost leak alright..

 

[eron]

OOopsss..Just realised that I mean "running RICH", not "lean".

Well, there wasn't any noticeable boost leak... Whatever the case, I'll update again on Tues night.

 

[Nicely]

Have you checked for cracks in the intercooler inlet/outlet pipes? You've got to take the arch liner off to get a proper look.

 

[Adam15]

you mite also check is the ect (engine coolant temperature) sensor operating rite,,if not the car would run rich if its reading wrong,,

 

[eron]

The workshop removed the exhaust and ran it. No diff.

And yes, he thinks it's a boost leak too. And suspects that it's the intercooler. I'm getting it changed in a few weeks, so..he didn't really check it.

Could a injector clean have to do with it? Like is there anything that can cause it to run rich in between the process of replacing injectors?

 

[Nicely]

What do you mean replacing injectors? Were they cleaned or replaced? If they were dirty and then cleaned, at worst it would have gone from running lean to running normally. If they were replaced, it should run normally. If they were replaced with 440s instead the standard 370s which are in Spec R Autos, it'd be over fuelling like fook...

 

[eron]

They were cleaned. Just thinking if in the process, something could have broke or not put back properly? Like crank seals or some gasket.

 

[Nicely]

The only things which could go wrong when taking the injectors out and returning them is nipping an O ring on an injector or failing to re-connect a hose to the plenum (which could cause a boost leak). If it was an O ring, fuel would piss everywhere.

 

[auxoura]

I am also having somewhat the same problem.

I did a lambda on my car and found that on low throttle my car was running at about 13 - 14 afr....but on WOT at about 5-6k the lambda reads 10 - 11 afr.

The car also feels very sluggish....

help anyone?

oh yea...my 1st and 4th plug looks rich but the 2nd and 3rd looks fine...

 

[ichi-go]

Not sure if this helps but my dyno runs on WOT,

The AFR is stable from 13-14 then after full boost, AFR starts to drop and then stable at 11.3

 

[nitekid]

So a properly tune s15 which isnt too rich and neither too lean should be looking at what kind of Mileage? 400km? 450km?

I am only getting like 300km to max 350km only, at times even lesser.
Guess i am running real rich in that case. Have not tune yet.

What bout you guys? what are your mileage?

 

[dns15]

is it totally stock
u might wanna list ur mods and some details of ur car would be a good start