O2 and fuel trim values

[bulbsubaru]

Can anyone tell me what the standard ltft, stay & o2 sensor values should be? My car is over fueling really bad!

 

[bulbsubaru]

Stft not stay sorry! Bloody predictive text

 

[MicKPM]

"Fuel Trim" is EODB nonsense and we don't use it. Take some data logs showing ATS/CTS vs H02 and plots them as over laid graphs... then I can help - Numerical values fluctuate way too fast to be of any real use here.

 

[bulbsubaru]

All iv got is an autel scan tool that does live reading and fault codes! Need to find someone local that can tell me 100% what's wrong with it as its lumpy at idle and stinks of fuel

 

[MicKPM]

Assuming it is running okay and not misfiring - 100% guessing here but most likely either a CTS or H02 fault... normally one of these.

 

[bulbsubaru]

Cts is that the crankshaft timing sensor? What is h02? Sorry not up the abbreviations? She's not misfiring and goes very well when you plant your foot, the previous owner decated it so I don't know if that will affect it, iv just replaced an injector due to it misfiring and thought that would cure the rough idle and strong smell of fuel but it didn't.

 

[bloke]

coolant temp sensor

 

[bulbsubaru]

Surely coolant temperature sensor wouldn't cause a lumpy idle and stink of fuel ?

 

[da rok]

Temp sensor can cause lots of strange problems, ho2 is the heated oxygen sensor, or lambda sensor, this should range from around 0.2 to 0.7 volts, should go up and down once a second, max and min values are 0 and 1v

 

[MicKPM]

The CTS is the main sensor from which the ECU determins environmental condition... if it thinks the engine is colder than it actually is it'll ramp up the fuelling to enrich the mixture and bring the car up to temp... but that's just one issue.

DeCAT normally means fucked H02 though... a very quick scope test will confirm the function though as using numerical values to try and work out where an issue lay is nigh on impossible when a plotted sine wave plotted from your data log will show you instantly. Sometimes it is easier to just pay someone to tell you what is wrong OR you could take a 50/50 guess on the CTS/H02.

 

[bulbsubaru]

Anyone local to me that I could take it to?

 

[bulbsubaru]

Put an ats on and a map sensor but made no difference! Just wondering if the plug leads are the wrong way round? Coil pack is numbered a nd lead 1 is going to the cylinder closest to the cam belt 2,3 then 4 closest to the flywheel is this right as I thought they should be the other way around?

 

[da rok]

1st cylinder is flywheel side

 

[MicKPM]

Anyone local to me that I could take it to?

Dan@SJM

 

[bulbsubaru]

Right iv found out that the plug leads are the wrong way round so iv swapped them over now the car misfires intermittently?

 

[bulbsubaru]

The car was running a little better with the leads the wrong way around? don't understand it!

 

[bloke]

you know it's a twin coil pack?

 

[bulbsubaru]

Do you mean it sparks 1+4 +2+3 at the same time?

 

[bloke]

yup (had to scratch me head for a mo on that!!)

assuming you mean 1+4 and 2+3?

 

[bulbsubaru]

So it doesn't matter which way the leads are then?

 

[chris chalc]

Please don't take offense but from your threads you really should be going to a garage if you don't understand the abbreviations and advice ,you will end up with a screwed engine by guessing. Just pay an hour's labour.

 

[bulbsubaru]

No offended mate, I can do the mechanical side of things, just not very good with the electronic side of it! Spoke to Dan@sjm today, really nice bloke gonna book it in with him as soon as the missus has given birth! Will post the outcome on here.

 

[bulbsubaru]

Right guys, quick update! Fitted new nkg plugs and magnacor race leads yesterday, made a little bit of a difference but not a lot, this afternoon I binned the decat and centre pipe for a 2nd hand renault cat and resonated scorpion centre section, cat came with a new sensor which put in the downpipe and hey presto no more over fueling or lumpy idle! So I'm hoping that the problem is now solved :spanner::up::yum:

 

[da rok]

So it was the lambda sensor... or a leak on the exhaust

 

[bulbsubaru]

Think it was a bit of everything no leak in the exhaust but it did have a decat on it so I put an original cat on it which came with a new sensor so I put that one as the pre cat and used my original post cat sensor in the replacement cat seems to have sorted out the lumpy idle and over fueling issues