BG5 Twin Turbo no power

[Rosssub]

I think the ECV is the last of your problems, it can\'t cause backfiring under Primary Boost. (over fuelling/weak ignition/timing)

With the fact that it\'s worse when cold, would suggest an O2 Sensor or Coolant temp Sensor fault.

Coolant Sensor not giving \'warm temp\' voltage so AFR is only set by the AFM. O2 only joins in once up to running temp.

With an Idle Up Relay (maybe AC) having a seizure and Idle fluctuating with it, there are some electronic faults going on somewhere. Possibly all related.

Have you tried pulling the faulting relay and going for a drive?

Edit: Sorry, can\'t help with the BG earth points...

[Fast Eddie]

Yea, trying to eliminate mechanical faults before I move onto electrical.

Whats curious is if you do the parellel turbo bandaid/lazy mod the car runs fairly normally if not a bit gutless obviously.. And if you tweak the ecv so that the valve is open/partially open even at idle (basically like parallel) then again runs normal as in you can apply any amount of throttle at anyload and it will pull from idle to redline no hiccups. As soon as you adjust the ecv so primary boost builds up faster/lower rpms then the backfiring occurs.

O2 sensor readings normal on data monitor, temp sensor output also normal on data monitor and in the cars actual gauge.. I\'m fairly used to sensor faults and diagnosis as they are common occurance at work.

Anyways - still gotta try some stuff out and will update then. It\'s an unusual one but i\'ll get there in the end

Cheers again - all good about earths ill take manual home next week and start having some real fun with wiring diagrams

[Fast Eddie]

Oh and yes the idle/relay thing is def not a great sign.. Was leaving that til last - do you think it will run with idle up relay removed? Guess i cant see why not. Will try it

[Rosssub]

Definitely keen to know which relay it is?

Idle up comes on with Air Con, also both Fans at once.

Normally only one Fan engages, with normal Cooling/Operating temps.

Both fans if \'high coolant temps\' detected by the ECU/Coolant Sensor.

Are both fans kicking in when the Relay clicks over and Idle changes?

[Fast Eddie]

Nup no fans come on, I should add air con compressor, condensor etc all removed by someone before me. Dunno why, hardly a race motor.

But yea, I think there are three relays above accelerator. One i think is ignition, one fuel pump.. And the 3rd idle up if not part of ign? I will b playing with it tmoro hopefully make a break through. Spent today on an audi leaking water into cabin and heater blower motor brushes.

[soopersubaru]

Partially blocked fuel filter...OR fuel pump failing. (Not allowing required flow for WOT). :

[Fast Eddie]

Mmm.. Maybe, sort of already eliminated that. Fuel pump runs at 42psi approx and went for run with guage and it never went below 39psi.. Flow rate part of the gauge not working thanks to someone losing the little metal ball and just chucking a wee ball bearing in.

Swapped in another FF a while ago and no change.

Symptoms happen at basically 5-10% (read can also not happen at that throttle. Its intermittant and the symptoms can come at various times, as has been said before seems to improve with heat, but this is not always true lol) throttle so its not a WOT starvation issue, far more complex issue of either wiring or the twin turbo system

[soopersubaru]

 Fast Eddie said:

Mmm.. Maybe, sort of already eliminated that. Fuel pump runs at 42psi approx and went for run with guage and it never went below 39psi.. Flow rate part of the gauge not working thanks to someone losing the little metal ball and just chucking a wee ball bearing in.

Swapped in another FF a while ago and no change.

Symptoms happen at basically 5-10% (read can also not happen at that throttle. Its intermittant and the symptoms can come at various times, as has been said before seems to improve with heat, but this is not always true lol) throttle so its not a WOT starvation issue, far more complex issue of either wiring or the twin turbo system

Ah Ha... Now I see!!...Your fuel pressure should increase as boost comes on not decrease.

So its either a broken vac line to the fuel reg or a faulty fuel reg.

[Fast Eddie]

 soopersubaru said:

Ah Ha... Now I see!!...Your fuel pressure should increase as boost comes on not decrease.

So its either a broken vac line to the fuel reg or a faulty fuel reg.

edit: Nope doesn\'t decrease if engine speed and load are increasing, they dip down to 38 or 39 for a sec when there is no throttle input

Cheers for the input anyway.. I wish it was something as simple as that buddy..

[soopersubaru]

 Fast Eddie']

[quote name='soopersubaru said:

Ah Ha... Now I see!!...Your fuel pressure should increase as boost comes on not decrease.

So its either a broken vac line to the fuel reg or a faulty fuel reg.

/quote]

edit: Nope doesn\'t decrease if engine speed and load are increasing, they dip down to 38 or 39 for a sec when there is no throttle input

Cheers for the input anyway.. I wish it was something as simple as that buddy..

Does the fuel pressure increase with boost coming on at all? It should do.. I understand the decrease under throttle off.

Must say that these TT units can be a pain in the rectum to sort out at times though.

There are some here who know them exceptionally well. Im surprised that one of them has not chimed in with a "how too" as yet.

[czar loc]

O2 sensor? My bg5 did similar things till I replaced it,

[Rosssub]

I\'d still be starting with finding out which relay is clicking on and off randomly, effecting Idle.

[Fast Eddie]

 Rosssub said:

I\'d still be starting with finding out which relay is clicking on and off randomly, effecting Idle.

Bingo

[Fast Eddie]

Have it set up in the cheats/lazy parrellel turbo setup.. Runs well like this.

Perculiar.. the relay seems to click less now..

Will figure out what these relays do, I can see them - but bloody awkward to get to, will remove fuse block and as much as I can so I can get up there.

[Fast Eddie]

When I say runs well, I mean it doesn\'t backfire and piss and fart with barely any throttle.

It drives pretty smooth at any throttle and rpm like an N/A car.. a low powered N/A car haha

[Fast Eddie]

 czar loc said:

O2 sensor? My bg5 did similar things till I replaced it,

Think its already been mentioned earlier, but have monitored o2 readings etc during test drives with data monitor. Readings/outputs are normal and no fault codes. Doesn\'t run like any failing o2 sensor I have experienced.

[Fast Eddie]

Sorry, how do you add photos to posts?

Tried to swap all the coils today but turns out my GT has some other version of coils fitted so the donor coils were no use, it has the coil with a lead/wire attached to it which goes to a plug further up by the injectors - rather than just having the plug directly onto the coil like most common I see.

If anyone has 1 that they could lend me for a day or two that would be awesome!

Checked fitment of all the intake and boost/charge pipes and intercooler. everything seems ok, still no leaks found, all plugs seem to be plugged in and cannot see any loose or disconnected earths anywhere. I have found 1 plug that goes no where amongst the transmission plugs (auto) I took a photo, curious as to if it should be plugged in somewhere (couldn\'t see anywhere obvious)

Going to bypass the relay that clicks tomorrow with just a straight wire connecting the power feed to on. I unplugged it and went for a run and didn\'t get rid of misfire/lack of performance. Not sure what it does.. There are 2 cylindrical relays and another one off to the side. Havent figured out what they do or which on is which yet. Assuming one ignition one fuel pump and not sure about the third. (why it ran when unlugged 2 of them seems to indicate they don\'t do much?)

[Fast Eddie]

also unplugged AFM and drove it.. didn\'t drive any better haha.. it still ran and was hard to tell if its worse since it runs like crap anyway. It didn\'t seem to be able to idle by itself with the AFM unplugged though.. if that means anything

[les666]

Just rereading things and if the car is running ok-ish with evc partially open or in parallel have you checked for a blockage in the primary down pipe? Maybe the cat in the primary down pipe has collapsed? Dunno? Just chucking out ideas...

Sent from my iPad using Tapatalk

[Fast Eddie]

Nope haven\'t checked primary downpipe for a collapsed cat yet, may do that tomorrow - gotta admit I was planning on taking it to a muffler shop and asking them to remove the CAT(s) and just put in straight bit of pipe.

[Fast Eddie]

Removed TMIC, rev'd engine up. good air flow from primary turbo, no flow from secondary - assuming all OK/ECV not leaking.

inspected all plastic hard piping under TMIC and manifold, no leaks splits or breaks. double checked all connections and hoses etc etc no leaks breaks or anything missing.

tested AFM on another vehicle and that vehicle ran fine with my AFM, so discounting that.

Airflow from exhaust seems fine, discounting the CAT for now. Also engine feels choked at lower RPMS not higher RPM. if you stay off the boost it still runs **** below 2,000/3,000rpm once you get above that you can get it to redline if you do not let any boost build up. If it gets any boost it just misfires straight away and tries to stall. If you lock it in parallel it won't misfire but it won't boost either or make any decent power.. and it sounds like **** haha.

Spark plug gaps ok and condition ok. again double tripe and quadruple checked all wiring, earths, plugs, vacuum lines, boost piping etc etc etc - No faults found.

I need an ignition coil that instead of having the plug click onto the coil itself, I have coils that have a short wire and then the plug is actually further up by the injectors - anyone have a spare one I could borrow or buy that is known good?

Again if you stay off the boost you can redline it with no misfire. Any boost and it misfires, if you feather the throttle jusssst right you could maybe get 1-2psi boost and make it run ok. But what a faff around.

Can't think of anything else - bypassed the relays that click under the dash - no change. Still haven't found anyone that can tell me what the relays do. manual is about 3,000pages long so will read wiring diagrams and try figure it out when I have time but as always lots of things to do, so little time. I spend an hour or two on the legacy when I can. Really want to sort this thing out!

Any one else have any ideas? Cam timing appears to be OK, ignition timing seems OK although I can't actually check the timing mark on crank pulley. But it idles rock steady, and if you hold it at say 3,000 or 5,000rpm it sits there rock steady. One of the nicest idling legacy's I've had

Checked a **** load of stuff now, the only things I haven't actually tried is a set of good ignition coils or at least 1 good coil to swap around. And the next thing is like checking the whole loom out for some sort of break somewhere beneath the insulation - don't really want to go there though. IACV and TPS check out ok at the sensors and at the ECU harness. o2 sensor doing its thing...

mmmmm, can't be this hard to diagnose and fix!

[Marky]

Does it have a BOV, if it's the factory one make sure it's not stuck open

That paragraph there reads like a big air leak when there's positive pressure

Have you done a pressure test on the inlet side?

What do the plugs look like?

[Rosssub]

 Marky said:

Does it have a BOV, if it's the factory one make sure it's not stuck open

That paragraph there reads like a big air leak when there's positive pressure

Have you done a pressure test on the inlet side?

What do the plugs look like?

+1, Test your BOV diaphragm, (split diaphragm-no boost pressure to hold It shut). So it's blowing open with any boost, messing with on boost-AFR big time.

[Fast Eddie]

 Rosssub said:

+1, Test your BOV diaphragm, (split diaphragm-no boost pressure to hold It shut). So it's blowing open with any boost, messing with on boost-AFR big time.

yea think the threads getting too long. Was checked/mentioned a few pages/long ago and has been rechecked a few times inbetween.

I actually pinched my BOVs to use on another car at work which did have a leaking bov and they worked fine in that one, same with my AFM and coils have been used in other cars at work as donors and work fine.

Never mind.. Will have to just keep digging.. its got to be something electrical just the way the instrument lights flicker when you make it backfire a lot, the backfiring itself is bizarre, its more of a backfire in the exhaust than a misfire in the cylinder, the tachometer goes dead/drops to zero if you keep pushing it then comes back to life if you release throttle completely for a seconds etc.. something very weird is going on. Although I have run through the whole loom at a basic visual inspection level and all plugs connected, earths clean and tight, no breaks or obvious damage etc.. have tried a known good ecu in it. Have the manual here and have taken voltage and resistance readings of TPS and ISCV, o2 sensor reading normal...

beyond me.. again it runs a lot better if you lock it in parrellel but obviously makes no boost or very little..

[Marky]

Sorry, I don't read much I just kinda knee jerk reply

You're right, there's something electrical going on, or it's haunted

Probably haunted

My suggestion is park it somewhere with the key in the ign and let nature take its course