andydavies

I fitted a MBC a few weeks back currently running 16psi of boost, car is 97 uk turbo. Just fitted AFR tonight. At idle or constant speed is it normal for for the reading to fluctuate better stoichiometric and lean even goes off scale at the lean end. Under WOT reading is constant and well into the rich zone. Is the reading at WOT the only one I need to be concerned with? Also I now want to increase the boost slightly, presumably this will lower the reading at WOT. Question is at which point do you go beyond safe, anything out of rich or can you go into the stoichiometric region without any worries. I saw on another thread that the TD04 is unlikely to reach the lean zone before the fuel cut is reached, can anyone confirm this is correct.
Cheers
Andy

andydavies

BTTT

Brun

WOT is all you need to worry about.
Knocklink wants to be your next buy before you touch the boost

dowser

When it goues between rich and lean, your ecu is operating in closed loop fuelling mode. This means ecu swings fuelling back and forth over stochiometric (14.7:1) using your lambda sensor as input.

Richard

The_Judge

If your fuelling is OK, it shouldn't lower the WOT reading. If it does, you either have a problem with your MAF sensor, or your fuel pump/regulator/injectors can't provide the necessary amount of fuel to cater for the increased boost. Or the standard ECU fuelling map can't cater for the increased boost level.

Anything other than rich at WOT is unsafe (assuming your lambda sensor is healthy).

It's not the turbo that dictates whether or not you're running lean, as mentioned above. The TD04 will quite happily boost to whatever you ask of it. However, anything over 17/18psi with the standard TMIC, is gonna heat the air up way too much. And if you're not using octane booster with a good fuel like Optimax, you're looking at det-city. I'm not sure at what point the fuel cut is for your MY anyway.

As Brun says, you really need a Knocklink to know for sure if the boost level you're using is safe or not.

andydavies

Thanks for replies
Judge,
Quote:
It's not the turbo that dictates whether or not you're running lean, as mentioned above. The TD04 will quite happily boost to whatever you ask of it. However, anything over 17/18psi with the standard TMIC, is gonna heat the air up way too much. And if you're not using octane booster with a good fuel like Optimax, you're looking at det-city. I'm not sure at what point the fuel cut is for your MY anyway.

I realise that the turbo does not dictate the whether running lean or not, the point I was trying to make was if say the fuel cut is 18.5psi so set the boost at 18psi. Due the the smaller volumetric capacity the TD04 is unlikely to provide sufficient flow to create a lean condition. Maybe it would at say 20psi, but this being beyond the fuel cut.

At 16psi I'm well into the rich zone, I will try turning the MBC 1/4 turn and see what I get. I make look thick here but, TMIC??
Cheers
Andy.

The_Judge

Even at 20psi, assuming fuel-cut had been lifted/removed, it still shouldn't create a lean condition, assuming everything else is operating correctly. However, that doesn't mean to say it won't produce other problems...

I've been playing with boost, different fuels, and different octane boosters on my UK MY00 for months now. At ~17psi, my fuel pump and 440 injectors seem happy enough (as indicated by rich AFR gauge and quiet Knocklink). This is run on just Optimax. At ~18psi, my AFR gauge is still indicating the same rich level that it was at 17psi. However, I get occasional flickers on the Knocklink at specific revs/gears, for instance 3500rpm in 4th WOT. A bottle of Millers helps to quieten that down a bit (haven't got round to trying the NF Race yet... next fill-up ). This is basically where the TD04 is working too hard to produce the level of boost I'm asking of it. And this is with a full de-cat and Samco intercooler hoses (both of which allow the turbo to produce boost with less effort). The turbo heats the charge up too much, and the TMIC (top mount intercooler ) can't cool the charge down enough, hence the Knocklink activity. The octane booster helps a bit, but the cause of the problem isn't the octane level of the fuel, it's the temperature of the intake charge. So my next move, logically, is a different turbo...

If you're currently at 16psi, my advice would be to find out where the fuel cut is, and then stay at least 1.5psi away from it. Or get yourself a fuel cut defender. If you haven't got a Knocklink, get one, before you do anything else. You may find that 16psi is as far as you can safely push it, without changing other things. What mods have you done to your engine so far...?

vulnax999

iTrader: (7)

I think Andy means can the TD04 provide enough air ( cfm or whatever ) to run out of fuelling ( in normal engine conditions, no failures ) i.e. upping the boost may not have enough fuel to cope and hence lean.

AFAIK the MAF will take account of the increased air flow demand ( as boost increased ) and the ECU will fuel according to the map accordingly.
The Dawes he has fitted may bypass the boost control solenoid but the ECU will still read the actual air flow / volume passing the MAF and fuel accordingly.

The TD04 gets a bit too stressed at 17 PSI and above, working well out side the efficiency areas of the compressor map, and (over)heating the air charge. Which as you said can lean to det.

380 cc/min std injectors are ok for upto 300 bhp I believe, so ok a bit more boost.

Knock link is a very good idea though as the performance envelope is pushed on std. items!


What sort of BHP/torque you getting out of your TD04? Mine got 256/256 recently at Well Lane.

andydavies

[QUOTE=The_Judge]. What mods have you done to your engine so far...?

Not a lot really, its allways run on Optimax:
Dawes currently set at 16psi
Boost gauge
AFR
Full H&S decat
STI panel filter

Had it on the rolling road last Sunday at Prosport, got 243.5bhp and 241 lb/ft.
Saw your other thread about the H&S, your right about the sound, definatly big grin factor!
I must admit I was not planning on getting a knock link, as you suggest I will establish where the fuel cut is and take it from there.
Cheers
Andy

The_Judge

Might be worth getting the Samco intercooler hoses. They gave me another 1psi at the same setting on the MBC, allowing me to turn it back a twist, which is nice as the TD04 needs all the help it can get! Also, what spark plugs are you using?

andydavies

I get it serviced at the Subaru main dealer (Holdcroft) so I would assume they are standard plugs, what did you have in mind?
Andy.

Delboy2

Standard are NGKPFR6's but when increasing the boost they normally require changing to NGKPFR7's

Cheers

andydavies

Will keep that in mind next time I change them.
Andy.

vulnax999

iTrader: (7)

Are these necessary with just over 1 bar boost / 244 bhp? Won't they just be more prone to fouling?

Agressive and/or higher boost ( ok, all doen to cylinder temps ) would need colder plugs...

vulnax999

iTrader: (7)

Isn't that another 18 months mate?

Delboy2

I found some activity on my Knocklink @ 1.2bar with EGT's around 800degC which was only suppressed with Water Injection which lowered EGT's - When colder plugs (PFR7's) were fitted the activity on KL dissappeared suggesting plug tips were getting too hot causing pre-ignition

Cheers

vulnax999

iTrader: (7)

Delboy2

That makes sense, good solution I guess. But meant Andy's problem, not sure plugs would help, not a bad idea at next service though!

I can't measure EGT, hope the inner and outer ceramic coated steel headers handle it adequately! Knock link only lights 1, maybe 2 greens when at high revs booting it .... hope the top few lights are solderedi n ok ( see Harveys warning tread! ) as I wouldn't know otherwise!

TD05 time soon ..! see if I get more lights then.