yabbadoo4

iTrader: (8)

needing some opinions on what im seeing in some logs ive taken. for the last few months ive had a strong stench of fuel and i suspect a leak but cant seem to find anything obvious under the bonnet just the very strong stench of fuel. i also suspect a vacuum leak which might explain the (what i think) is overfuelling im seeing in logs. there also seems to be a lot of timing being pulled in the learning views at certain rev and load ranges. the car was mapped by andy forrest so would the timing ranges be part of the mapping where andy sees knock and has pulled the timing back in those areas? i have 3 LV snags and they all have the timing pulled in the same rev and load ranges :







the ecu seems to be chucking in a load of fuel and then removing it again to reach target afr as well, would that be right ? this is a 3rd gear pull to red line i logged recently and the afr sees to be ok from my limited knowledge. any insights to what the logs are showing would be really appreciated as im paranoid as hell just now and am driving like miss daisy. will be contacting andy for a tweek session asap but any ideas would be welcome.

bludgod

iTrader: (3)

MAF learning values would suggest a leak somewhere, get it smoke tested and fix the leak then reset the ECU.

I wouldn't be pushing it hard with that amount of timing correction either, -7 is a lot of timing to be pulled - could be because of lean AFR or could be something else that needs looked at.

yabbadoo4

iTrader: (8)

is 11.3 lean? i thought 11.5 was roughly the area to shoot for on wot.

bludgod

iTrader: (3)

is this reading from the stock sensor? You can't use that on boost in the stock location it could be 11.8 or it could be 9.1 the sensor just isn't able to get you an accurate reading when it's under boost and jammed in the headers pre-turbo. Also with the A/F corrections showing such high values you can't be certain what fuel your actually getting on boost and that's where the danger is.

You can move the stock o2 sensor from the headers to behind the turbo and it will be a little more accurate but I still prefer the readings from the LM2/MTX to see what the car is at.

yabbadoo4

iTrader: (8)

still having problems with this, got a local subaru mechanic hoping to have a look this week or next. just wanted to add some info as ive been logging a fair bit to try and get as much info as possible. was driving the missus to work the other day and by the time i got home car was up to temp coolant was sitting around 95 deg. as i was grabbing some stuff keys etc it was just idiling then i heard the fans kick in as they should and i felt the rpms rise. so i checked out the gauges and the fuel corrections shot right up to around 24 -25 % ! they have been sitting around +10-12 % when warm because of the suspected vac / fuel leak but does a jump that big (almost double) help confirm a leak either fuel or vac? im guessing the fans kicking in are blowing the hot air over the engine and its being sucked in at the point of the leak thus causing the fuel corrections to rise? would that be right? just trying to get as much info for the mechanic as i can. any help very appreciated. thanks

yabbadoo4

iTrader: (8)

this happened again today!! it was warm up here around 20 deg. p171 system lean code again. car had been sitting in the sun for a few hours and was hot obviously. temparature obviously plays a part in this for sure. STFT shot up to 25% same as before. i reset the code and drove home slowly and it seemed ok as the IAT was lower once the car had cooler air flowing over it ( around 22 deg) and i sprayed the intercooler with water a few times for good measure.

yabbadoo4

iTrader: (8)

any help with this guys? watched a few videos and got some ideas but its a bit beyond me. why would the fans kicking in at 96 deg cause the fuel trim to almost double then drop back again when fans cut off? is it as i suspect thet hot air is being blown either over the maf or being sucked in at the vacuum leak source?

tjmatt

iTrader: (1)

I would have thought that the density of the hot air wouldn't be able to have such a high impact on the required MAF correction.

It's more likely that the fans have created a higher load on the engine and the ecu compensates by opening the idle control valve more and possibly changing ignition timing. Its probably just moved which cells are being used in the map slightly and caused a bigger correction.

I can't see from the graph, does the AFR change at all or is it stuck? Have you checked your O2 sensor to see if it is oscillating between 0.9v and 0.0v every second at idle? Or are the later cars wideband O2s?

If its not the O2 sensor playing up, then having to add fuel at idle but remove it under load means a leak would likely be after the turbo, and for quite a big correction at idle, possibly after the throttle body - i.e there is a large vacuum at idle so small leak can have quite a large effect.

I'd have thought you'd hear most leaks on boost. Not a leaky VTA dump valve? Boost gauge/pipe leaking vacuum?

I think the MAF correction is the opposite for a broken fuel pressure regulator - but you can always change the vacuum hose to that too.

yabbadoo4

iTrader: (8)

there is a strong stench of fuel at the drivers side around the inlet manifold injectors area. would a leaking fuel injector seal cause these symptoms? there would be the double whammy of possibly not enough fuel delivery coupled with extra unmetered air in system?

bludgod

iTrader: (3)

have you leak checked the system yet? most garages will be able to perform this for you at a small price, this will show you clearly if there is any air getting in/out of the system. If it stinks of fuel is it definitely fuel or could it be exhaust? Don't take that as me having a poke at your sniffing powers but if your sure its fuel then whatever injector(s) or rail it's leaking from will be messing with your AF corrections as the ECU isn't making per cylinder adjustments it's just an overall blanket adjustment.

You could also see this behaviour if the injector latency was drastically off (not the smell obviously - but the corrections). The idea is the same at low IPW values the leaking amount of air (or reduced fuel quantity from the leak) has a greater impact on the correction than at higher maf voltages (say when the ECU increases the idle due to high electrical load). You could always test with a portable fan and blow air over the maf when the fans aren't running - but I think you'd be wasting your time.

If you can smell fuel/exhaust coming from somewhere get to the bottom of that first then look for the next issue if there is one.



tjmatt - yes and no btw, newage cars have a sort of wideband sensor so you'll be looking for a 0-5v signal coming through, the idea is the same though if the sensor is failed you can get a static voltage reading from it which will throw things out of whack.

yabbadoo4

iTrader: (8)

thanks bludgod was hoping youd jump in with more advice. the fuel stench is extremely strong no doubt what it is and is only at drivers side around fuel rail area. the log above shows it adds near 15% at idle which is why i guess i smell fuel so strongly at idle/startup. then when driving it starts removing it progressively at higher loads/rev ranges where im guessing the vac leak or extra air is less noticable as the throttle plate is open and letting in air anyway? will have to find a garage who will do a leak test. thanks for your help and ideas/thoughts its very helpful.