Emerald - rich running

[TomB]

Would like to get my recent 1.8k TB conversion fully sorted over the winter, but before I book an RR, there are a couple of things I need to sort out to get the best of out of the session and avoid having to go back again. My engine is a 1.4-1.8 conversion, using a standard Supersport K16 head, with the Fawn coloured injectors with the SLR/KV6 TBs. It has no lambda sensor. I’ve successfully run it over the summer on a DIY Emerald map.

 

I’ve got it to an acceptable state, cold start OK, and idle smooth, generally fine for driving, noisy and quick! However, it’s hosing through fuel, so much so I’m struggling to get 100miles out of a tank on the road, even on mixed motorway / gentle A roads (i.e. 4&5th gear, keeping up with normal traffic). The plugs are sooty and whilst accelerating hard onto the motorway last night, I was followed by a plume of black smoke! I don’t know what I should get with these TB, but it’s got to be more than 100miles from a tank.

 

It was mapped using a base map tweaked on the road with various load sites and interpolated across the nearby map sites. It’s OK, but needs a bit of refinement at low speeds, and as shown by the smoke last night, it’s also over fuelling when larging it.

 

Firstly injectors - currently it has the EU2 fawn injectors which may be too big according to DVA. Should I change these to the VVC blue 192cc injectors prior to mapping and alter the selected injector in the Emerald set up? Would the map therefore need changing straight away to get me to the RR?

 

In relation to injector suitability, does anything need looking on the software for duration of fuel injection from each injector?

 

I cant reduce the fuelling on the map with making it run poorly at a particular load site.

 

Secondly - Fuel pressure – its running the old 1.4 one which off the top of head is a 3 bar regulator. I don’t recall ever having messed around with it, so does this need changing, or can it be retained at 3bar if the ECU knows the setting and it’s mapped with it?

 

During the winter months, I intend removing the TB and matching the ports on the head, something I didn’t do when fitting them, and then I’ll map it. Would this affect any of the above?

 

Thanks for any advice

 

PS – At this stage, I haven’t looked into the ECU to see if I have any dub sensors (e.g. air temp sensor), I’ll do that one evening this week

 

[charlie_pank]

The ECU just controls the timing and duration of the opening of the injectors for fueling. Provided that the injectors you have are capable of feeding your engine with enough fuel at full chat for your given fuel pressure, and can give small enough squirts at tickover, then all the adjustment is within the ECU.

 

As you have an emerald, you could very quickly see if any of the sensors are giving duff readings by plugging it in to your laptop and running it in live update mode. But if you've had this problem since your conversion then it's probably a map intended for a different flow-rate of injector that is causing it.

 

I think DVA's website tells you which injectors are suitable for what power output. Also, if you can find out the flow-rate of the injectors, you can work out how much fuel is being delivered for each squirt (injector duration info is available by plugging in the ECU map). Then you can look at your estimated power output and the fact that the BSFC (brake specific fuel consumption) of a normally aspirated engine is between 0.3 and 0.5 lb/hp-hr to see if it's in the right ball-park (see here)... or you can wash your hands of it and take it to the RR (along with some spare injectors of different capacity) and let them do this bit for you!

 

Edited by - charlie_pank on 10 Sep 2012 15:42:38

[TomB]

Does the Emerald software allow for injector scaling, such that I could swop to a different flow injector (eg 192cc instead of the 220cc), without having to remap it? Im thinking this might be worth doing prior to a RR session, especially if the current injectors are running close to 90-100% and understand isnt desirable (I have yet to check this on the PC)

 

 

[charlie_pank]

Yes

[TomB]

Off on the scrounge/ eBay....

[John Hughes]

Tom

 

Surely if the injectors are currently running at 90-100% then you don't want to swop for lower capacity injectors

[Paul Deslandes]

there is a well established relationship between flow rate and pressure for any given injector so you might be able to reduce the pressure, so long as its not much, and achieve the same result. 220 to 192cc/min is not a huge step. You'd really need an inline fuel pressure gauge for 'before and after' and be able to measure wideband lambda.

Clouds of black smoke when giving it large possibly suggests too much acceleration fuelling which is a separate setting to the steady state fuelling map, although not totally unrelated. You need to sort that too as you'll be getting bore wash, taking the oil off the bores which will eventually lead to excessive piston and bore wear.

Pressure/flow relationship here.

 

Edited by - Paul Deslandes on 11 Sep 2012 11:56:23

[TomB]

Thanks, will have a look at acceleration fuelling too - that makes some sense that its over fuelling on the Acceleration Fuelling sub map. It was the first time Id noticed it, and was accelerating hard in 2nd or 3rd. I wonder which setting triggers the acceleration fuelling map to kick in - is it related to throttle position, or a rate of change in throttle position? If anyone could post up there settings for this map for me to compare my settings, that would be very helpful

 

John - AFAIK - you dont want injectors running close to full capacity I think nearer 75% is desirable.

 

Edited by - TomB on 11 Sep 2012 12:20:10

[Mr Locust]

Tom,

 

you have identified the main problem.

 

It has no lambda sensor.

 

Measuring how rich it is running by the level of visible smoke is not ideal

 

Even a basic narrow band sensor would give you more information to set up the part throttle/cruise areas of the map.

[TomB]

If mapped at an RR, do they usually put a Lambda up the exhaust if one isnt fitted? Ian, please can you send me your Acceleration Fuelling numbers for cross reference?

[John Hughes]

Tom

 

At present it is over-fueling by the symptoms - so if RR and mapped the injectors may well fall back into a more appropriate duty cycle when the fueling is optimised

[SLR No.77]

Tom, do you have a lambda boss in one of the primaries?

 

Stu.

[TomB]

No.

[SLR No.77]

Might be worth for the few quid it would cost having one fitted. The RR will use it to connect their lambda to do the mapping but in the meantime you could use something like an Innovate LC1 and gauge to take a readout yourself.

 

Stu.

[TomB]

Been into the map. Do these numbers sound right for the Accel fuelling map: Enrichment 25%, Clamp 20, Decay 20, RPM cut off 8000rpm.

 

For comparison, Ive found on an old DVA post here values of 20,30,15 & 4000rpm.

 

Does this mean my set up is continuing to enrich until 8000rpm? No wonder its smoking on hard acceleration if its applying this enrichment to beyond the full RPM range of my car!

 

Another observation is on my Injection Scaling settings - currently the injectors are set at 200cc/min at 2.7 bar, not the 220cc/min that I believe the fawn injectors are.

 

The max fuel flow is reported as suitable for ~169bhp. This is more than I expect my engine to produce, so should I rescale my injectors to produce ~160bhp?

 

If the engine has been mapped with these injector settings, can I change these details to 220cc/min or scale the injection to 160bhp without requiring modification to the main fuelling map?

 

 

 

[oilyhands]

Ignore the current injectror settings, they are notional. Your map will have been made with the 749 (218cc) injectors at 3 bar.

 

The injectors you have are absolutely fine, you just need to have the engine properly mapped. dont mess with another set of injectors or rescaling, you'll likely get yourself into a mess.

 

Have a boss put into your exhaust for a Lambda sensor. Whoever maps the engine can use a wideband for their purposes.

 

Oily

[charlie_pank]

Was going to write a reply, but the boss has spoken

[TomB]

Indeed, thats me told! However, in the short term until I get it mapped, would be worth scaling the injectors back for 160bhp to reduce fuel consumption and risk of bore wash / premature wear, or is there too much risk of running lean?

 

I can get a boss/ plug from Emerald for a few quid and for neatness Id prefer it welded into No4 primary inside the car. Ive read it shouldn't be too close to the head, so propose to weld it in towards the exit through the skin. Are they best welded horizontal, vertical or at an angle? For my level of tune, Id expect this would be OK, rather than having it put in the external 4-1 collector.

 

Should I be looking at permanantly fit a Lambda sensor, or do I just need to allow provision for it to be used during mapping?

 

If the former, to wire it into the ECU plug I expect that Ill have empty connections on the back of the plug (although as its an ex race car, anything is possible). Would I need to simply plug the leads from the Lambda into the correct pins on the back of the ECU or will I need to solder? I hope not as my skills in soldering are limited, to put it nicely .

 

 

 

Edited by - TomB on 12 Sep 2012 11:34:21

[SLR No.77]

Tom, get a boss welded in on the top of the straight bit of no.4 primary just before it exits the side skin. I have a blanking plug you can borrow if it helps - if you buy one get a mild steel one not stainless. As Oily says, a wideband lambda will be fitted by the RR then removed after mapping and the blanking plug will be refitted .... just get it mapped :)

 

Stu.