hi all,

i'm running a remapped ECU. let's say i'm running way too rich....
a/f ratio of 7 to 8.... on my stock twins...

boost pattern 0.9 0.8 0.9 BAR.

if i were to push the boost to higher level, can the engine burn out the extra fuels ? or another question, can stock engine or stock twins support higher boost level than 0.9 BAR with current air fuel of 7 or 8 ?

 

I understand your logic here but you're forgetting something:

If you increase your boost, your ECU will see it and add even more fuel.

If I were you I'd try and get your car running properly before turning up the boost. If you can tune it for .9 BAR and you have the fuel system/supporting mods/ecu to accomodate more boost, you can work on that next. Keep in mind as you lean out your fuel curves you will be making more power without changing the boost.

 

great.. thanks for the advise...

 

Are you sure you are running an AFR of 7 or 8? That is very rich. If so, you must be having alot of soot on your tailpipe and alot of backfiring. You should verify the AFR reading before you raise the boost.

 

your plugs would foul at one wot run and then your car would miss like **** all over the map.

7-8 afr is just ugly.

but as said before turning up boost wont lean you out at all, if anything fatten it up.

and your at the limits of the stock twins with your .9 bar right now.

 

I don't buy it.

I've never seen an AFR meter read below 9:1 ratios. Most of the professional meters used at dyno shops do not read below 10:1.

Please indicate how you are reading 7-8:1.

 

yeah... i got the 7-8 reading from the tuners.... unfortunately, my ECU is not PFC... can't tune it.. it's some sort like a remapped ECU from Japan.

when i dyno my babe.... the graph shows.... idle around 12..... and rev... it moves up and down.. maxed at 12.... and after 5 K RPM onwards...

it's a flat line of 9.8.... i've never seen before flat line on air fuel... that guy says it had reached the limitation of the sensor... approximate to be at 7 to 8.... too rich...

another tuner on other shop.. he has 2 AFR sensors... one of them reads from 9 onwards... the other one that reads below 9... i'm yet to bring it there to get "exact" number instead of estimation from the sensor limitation.

the interesting part i that my car does not have any wierd boost pattern or any boost creeps or spikes.... it's solid 0.9 0.8 0.9.... never seen it shot higher than 0.9.... at hot days... it lowered to max at 0.8 due to the air intake is hotter.

 

seems like it's either i ditch my ECU for PFC, or source for another ECU... or dump in a AFC to lower the fuel....

having extremely bad millage.... one tank only runs me 210 KM on short city roads with heavy traffic...
pure freeways make it better at 356 KM to one tank...

 

I'm thinking an upgraded ignition will definitely help you. Once stock boost levels are exceeded, the stock ignition is not adeqate!

 

if you get the car tuned just for the boost your at you should increase your power substantially. You are loosing alot of power if your car is running at 9.8. My bimmer is supercharged and i am loosing something like 70 horses because it flatlined at 5500 RPM. Get it tuned it should make a huuuuge difference

 

got it..... need to invest on AFC......

lean it up to around 11 or 12....

when i hit around 6500 RPM... peaked power is 248 Bhp.... while reach 7500 RPM.... power is left 160 bhp.... not good....

ok ok got it..... lean it up.... i'll be a happy man...

 

latest update.....

i replaced my air filter with a brand new one.... chucked away my old and dark and dirty Apexi Dual Funnel intake.

guess what....

i'm boosting at rock solid 1 BAR... a little bit scared....incredibly FAST....
the stuttering at high RPM disappeared (on 1 try... WOT 3rd gear)... i believe with more air ramp into the engine, the excesss fuel burned up....

probably my root cause of low a/f reading is the blocked air intake...

i believe with more air rampped in... my air fuel is slightly higher now... but not too sure about the exact reading if it's still flat line at 9.8.... will update if tomorrow going for a dyno session.

if it's still flat line 9,8... really need to adjust using AFC.....

no boost cut for my ECU.... shall i continue to run at 1 BAR or put in boost controller and also AFC tune down plus control the boost ?

 

1 BAR on stock twins.... quite scared....

 

another update....
boost pattern as below
0.9 0.9 1.0

stuttering pushed upward to 7K RPM...
most likely still running very rich......

 

Install new spark plugs and wires.

 

it's the way too rich that cause my stuttering... it was stuttering at 6 K rpm onwards.. with 1 BAR (by changing air filter, previously 0.9 BAr), the stuttering point moved to 7 K... ... most likely still run extra rich... will get it dyno maybe tomorrow. just to check the readings..... getting the REAL A/F ratio which is below 9.8....

 

You also might be running your injectors to the limit, I remember on my stock injectores i was running about 1 bar and i was at 100%, eventually blew my motor becuase of it, cause it was lean, If your at 1. bar and still running rich, then i believe they should be at 100% also. I ran like that for a long time but eventually the motor didn't take it anymore.

 

Yep, the stock injectors cannot supply enough fuel to run rich at those boost levels....in other words you have some other mechanical problem that is preventing clean ignition. You do not want to be running 12:1 AFRs at 1 bar on pump gas either.

 

What those "Chipped" ECU's seem to do is just open the injectors to 100% at WOT at high RPM's, they aren't really a tuned map. I had an RE Amemia Chipped ECU that did the exact same thing. When running 12lbs it would studder in the upper(boost) range. Then I turned up the boost to almost 15lbs and it got better(but did not completely go away). What helped was installing an HKS Twinpower ignition amp. When I took it to the dyno it would studder again since dynos don't give you an "actual street" load, and my AFR's were below the 10 mark(which was the minimal reading on the graph). I have since installed a Power FC.

 

exact situation.....

i'll get it dyno today..... will see the result...
if PFC is unavoidable... need to start saving money for it.

the previous owner for the ECU is running FMIC, DP, MP, boost controller (1 BAR), free flow exhaust. did not see any issue.
the only difference my setup is stock IC, and i don't have a DP, my boost running 1 BAR...

will run on dyno for the reading today. stay tuned...
actually i was planning to put in AFC and tune down the injector duties...

at high boost (1 BAR), what is the recomended A/F ratio ?

 

latest update....
Dynoed....
peak horse power... 245Bhp on the wheels....

realised that i have a charge relief hose disconnected from my air intake, causing my boost to increase to 1 BAR (taking in fresh air).

during dyno, i'm running 0.9 0.8 0.9 BAR pattern...

lowest A/f ratio logged from my car...... 7.9
highest horse power appering at 6200RPM ( 6200 to 7500 not utilized due to stutering).
idle A/f ratio logged approx 10.3

now i'm thinking...... E manage or AFC to lean up the curve.
how lean should i run ?

 

how are your plugs not carbonized?

 

At 1 bar and only making 245, something is seriously wrong with your car, Its probably either running way to rich and killing about 60 hp, or the car is extremly unefficent. But over all, if you buy a Power FC, you wont regret it. I believe that the power fc was the best mod on my car. Cleared up all studdering my car had and made it run like a dream.

 

u want good advice? take your care to a qualified rotary mechanic. things i am reading in this thread make me nervous!

 

the real rotary mechanic, it doesn't exist in my country....
it's either they are good at engine transplant, fixing mechanical stuff....
or
the other places where they mod cars like skylines.
to be specific, don't have anyone that is really expert on it.....

i'm starting to get worried as well....i don't have a scanner, but the dyno graphs shows the air fuel is declining to richer as the 2nd turbo comes in...it ends at air fuel 7.9 the richest...