Wideband Issues
Turbo Mini Forums

Hi,
Andy .. I think first of all you need to get the boost pressure down. Have you got a IAT sensor in the inlet manifold hooked up to the ECU?
The ECU needs to have IAT retard set-up to knock the timing back/add extra fuel if temps get too high, it would also allow you to monitor charge temps
From looking at your chart the only place the mixture is rich enough is around 5K RPM. You want 12.8 ish for full power. The torque and HP curves aren't very smooth either?

Paul S ... I'd say no2 was the weakest, 1&3 the richest with 4 in-between?
Cheers,
Gavin :)

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What cam are you running? From the shape of the graph Id say its an SW5 or something very similar. That dip at 4500 is a little worrying

Edited by Paul S on 14th Sep, 2008.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Yep first thing im gonna do is get the boost pressure down to where it should be. Should i also relocate the inlet air temp switch in to the inlet manifold? at current its just sat in the engine bay as per the vmax set up!

Dave did say that there was trouble with interference or noise on the rolling road which may indicate why my map is so un-smooth

Yep im running an sw5 cam.

Its a Very intresting topic this, would it be best to run 2 wideband sensors or possibly 3? But even then theres no way to better the fuel distribution with a wet manifold set up is there?

Schrödinger's cat - so which one am I ???

Hi,
Yes, move the sensor, it should always be after the compressor in a boosted application. Does your ECU have any IAT compensation settings?
Cheers,
Gavin :)

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Slightly off topic in a way. But is it true that lead additives / octane boosters damage lambda sensors? If so how/why. Is there a way round it?

The lead will eventualy coat the sensing element. You can use them short term, but their life is dramaticaly reduced

Octain boosters are fine as are lead replacement addatives as they do not contain lead

There is no way round it other than to use unleaded with addatives

I can see that Avgass with the lead quantities it has killing lambda sensors and catalitic converters increadibly quickly

Lead itself (as in old leaded petrol) certainly does. Go to the site Paul S mentioned earlier and you'll find the link, otherwise it's on the Bosch site.

Whether the lead "replacement" additives are as bad on the sensors is unclear.....

What is widely reported is that one of the common "lead replacement" additives can damage turbocharger turbine wheels...... Across the sellers, there are four commonly used replacements for lead, ie, manganese, sodium, phosphorus and potassium and apparently the sodium ones are bad....

Just what I've read....

Schrödinger's cat - so which one am I ???

Yes the emerald does have compensation for changes in inlet air temp. Why would stuart gurr have not ever put them in the inlet? They all sit in the engine bay on the brake servo!

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

are you sure its not an ambient air temperature sensor?

The sensor that is being used is the original mpi sensor that used to be in the mpi inlet manifold. It used to have sit in a plastic bung which i take it was to prevent the issues associated with heat soak?

It may well be functioning as an ambient air temperature sensor then as the reading it displays is "Air Temperature" on the live adjustments page. Im unsure if this effects the map in anyway

Well if it's the IAT that the EMS / ECU uses to calculate how much fuel to inject, it needs to know the temperature of the air as it enters the engine, after compression/cooling - not how hot your engine bay is....

I'm not sure how Emerald works compared to the others but unless it has something really clever to work out the charge temperature from other readings (???) then what is the EMS / ECU using to calculate the charge density ???

An EMS / ECU needs to know pressure, volume (flow rate) and temperature to calculate mass (flow rate) so the temperature at inlet to the engine is essential to the calculation.

Volume is a function of RPM (calculated) but pressure and temperature at the actual inlet ports has to be measured.

Hope that makes sense...

Schrödinger's cat - so which one am I ???

Cheers for that Rod. I feel a quick call to Emerald and Vmax will be required in the morning to find out exactly whats needed. I fitted a map sensor on the advice of Emerald as it didnt have anything before. I dont see what the point of the air temp sensor in the engine bay is?? as its surely completely different to the temps after its been through the blower?

yeh very different!

Since there is no charge cooling and it is a crank driven compressor, I guess the actual intake temperature could be computed from the compressor efficiency and the ambient air temperature but that would not be something I'd like to use.

It may allow easier hot starting by avoiding heat soak but that's a really poor compromise to a correctly designed system, IMO.

Jean

http://www.jbperf.com/

As per Jean,..... It could be calculated by the ECU given the compressor speed (and hence output pressure and temperature) is directly related to crank RPM (I keep thinking about turbochargers rather than superchargers where there is no relationship to RPM) but....

it would rely on the supercharger maintaining its characteristics over its life, the belt never slipping, no further changes in temperature between compressor outlet and engine etc...

Is that what your EMS / ECU is designed to do and if so, how is the temperature vs RPM map entered and from what data ???
How would you change it if/when you change the pulley size ???

Just thinking out loud really....

Schrödinger's cat - so which one am I ???

In honesty i really dont know and hadnt really thought about it untill now. Will have to get the laptop out this week and have a look at the ECU settings. Sorry to veer of subject btw.

Right, just spoke to Dave at Emerald and he said that the air temp sensor should be in the inlet and in a plastic bush to delay the effects of heat soak.

I Might just make a full new inlet manifold as most of the charger outlet is just dead heading against the mounting plate!

Hi,
The relocation of the IAT should stop that pinking you heard on the way home from the rollers, as long as the ECU is set up right of course
Cheers,
Gavin :)

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I hope so Gavin. as you can no doubt tell im learning lots about the world of forced induction every day and no doubt still have a hell of a lot to learn. Its just difficult when you rely on people in the 'know' but they have done it wrong o taken the cheapest easiest route!

Well, in a way I'm glad that Emerald say you should have the IAT sensor to measure the actual temperature rather than it trying to work it out from engine bay temperature plus compressor in-efficiency but it might mean your session on the rollers was wasted....

Or does the Emerald EMS / ECU have a learning facility (ie, "auto-tune") from your own installed wideband so it can re-write the fuel tables for the new (correct) IATs it will be seeing ???

Schrödinger's cat - so which one am I ???

Just a note about measuring IAT. Measure it post intercooler but before the inlet manifold - or at least before the injectors as the fuel will evapourate off the sensor giving a false reading.

My MS uses IAT only to retard the ignition at a mapped rate.
Density variations due to air temp are taken care of with the closed loop fuel control.

the vmax setup is suck through