Advice on fuelling after injector size changed

[woz]

Can someone who is expert in these matters confirm my understanding of what I may have done?

I have fitted white injectors instead the standard orange (1996 T5), and no other subsequent changes.

My udnerstanding is that : -
the ECU will sort out the fueling when running closed loop, but when i go open loop and it is running off the map, it will probably set the duty cycle for an orange injector and hence be running rich, in proportion to the ratio of injector rating??

If I am correct (?) I will be OK fuelling wise at idle(?) and fast idle (?) but any other boosty type times will be a bit rich??

This assumptions are base on my understanding of how the system works, and diggingthrouogh books an manuals. It seems to be borne out by the fact that steady runs I get the same or better fuel consumption (35mpg on a 200 mile round trip) but driving round town I am now about 15% worse than normal. Acceleration is also not quite so frantic, but I have lost the misfire under full boost.

I guess someone who has deep understanding of tuning these systems can answer this once and for all and save many of us problems in the future.

If this is right, is there a simple step a tuner can take to tweak the ECU so it knows what injectors are now fitted and sort itself out? I run a RICA 280 in fact FWIW.

Cheers chaps - thanks in advance.

[M-R-P]

Turn the boost up a bit to compensate

[woz]

Turn the boost up a bit to compensate

Did that first!! :>) then the injectors to compensate.

[M-R-P]

I can't see whites making that much difference unless your old ones were knackered and making the car run lean?

I got much better mpg when I fitted clean blues.

[Volvostorm]

You have gone from 315cc to 350cc, good idea as you have upped the boost

Unplug the ecu for an hour or so, it will make it relearn

[mitchyboy01]

Hi Woz,

You are right in your theories and as for the advice so far given, they should be asking you for advice! Not you asking them

Closed loop is basically the ECU fuelling real time using data from the lambda sensor and adjusting the fuelling to match the correct AFR. Closed loop is used for idle running and part throttle with low load. The ECU may 'learn' in closed loop but it certainly doesn't learn in open loop.

Once the ECU senses enough load it will revert to open loop. In open loop the ECU runs from a preset map and is not adjusting AFR using real time data. It is using preset parameters and these parameters are based on you running the hardware it was originally mapped with. i.e 315cc injectors, stock MAF, turbo etc.

For example - If you are running 20% bigger injectors with a 315cc map, in open loop the car will be overfuelling by 20% until you reach the point where the old injectors would have hit 100% duty cycle. Only then will the bigger injectors be of any benefit. (Probably the reason it's cured your full boost misfire).

In short, for the car to run optimally you need to get it mapped. The mapper will change the injector scaling to suit which I am told isn't too complexed to carry out, although I am no expert whatsoever.

You may 'get away' with not mapping it for a while as it will be rich rather than lean, but what's the point in changing hardware if it means the car isn't running at it's optimum. Also, running too rich for prolonged use can result in bore wash over time.

Hope this helps,

Cheers, Mitch.

[mitchyboy01]

You have gone from 315cc to 350cc, good idea as you have upped the boost

Unplug the ecu for an hour or so, it will make it relearn

The ECU may 'learn' in closed loop but it certainly doesn't learn in open loop.

[M-R-P]

Closed loop runs off 1 sensor, not 2 mate

[claymore]

rica 304 is more than capable of running orange injectors at full load, so they must have been knackered, as for the whites, the ecu will be more than capable of compensating. Although the rica 280 is optimized for ordinary unleaded, have you run the car with super unleaded?

[woz]

You have gone from 315cc to 350cc, good idea as you have upped the boost

Unplug the ecu for an hour or so, it will make it relearn

Thanks Paul - already done that. In fact I swapped it for another ECU for a day or so. Then put my RICA one back in as it was better.

[woz]

Mitchyboy - Thank you - you have confirmed in semi-tech terms what I thought I knew, and had implied from my observations. I hope eeryone reads your post which lays some myths to rest.

Been reading up on tuning fuel injection systems and ECU's a fair bit, but obviously different systems have their own idiosyncrasies. So advice someone with experience in the marque is what I needed. Everyone has been really helpful - but I think you really understood the question. thanks for taking time to reply. all my tuning engineering has really been done on carburettor cars.

The next step is indeed to be a remap but funds are tight so leaving it until after the 16T goes on, along with some intake mods. I bored out the manifold to take 3" throttle body when it was off anyway, so that will go on too. I am convinced the whole inlet tract needs attention to identify where the pressure drops are. Again, its low rev performance I want to focus on to get the airflow in, and exhaust speed up lower down the rev range.

So with the confidence that I now understand what I have done and need to do (fuelling wise) I can get the spanners out again. 50/50 whether I get the head brushed up a bit, but I am a great believer that careful head work will improve the low lift and hence low rev airflow, with the aim of getting the thing up on boost a bit lower down. It should counter any lag with the bigger turbo .

Thanks to all for the responses.

[woz]

Closed loop runs off 1 sensor, not 2 mate

Yup - only got one lambda sensor on the old girl.

And yes, my injectors were old - I'd them in for a couple of years after a good clean, which had made a big difference. But had suspicions, and with that misfire every time the boost went outside the white bit I decided to cough up for the cleaning but got some for whites first- all ready for a 16T. There is a plan!

[woz]

rica 304 is more than capable of running orange injectors at full load, so they must have been knackered, as for the whites, the ecu will be more than capable of compensating. Although the rica 280 is optimized for ordinary unleaded, have you run the car with super unleaded?

Thanks Claymore. Yes they were, and a previous clean had helped enormously. But they were part of a bigger plan. I think the RICA is actually optimised for super unleaded, although you "can" use 95, I almost always VPower or another 99 RON juice.(too much of it :>))

[Dangerous Dave]

If you fancy it you could always buy an M4.4 ecu and flash it with the file that they are developing on Volvospeed and change you own injector setting....

[960kg]

Rica 280 as claymore says is optimised for 95ron only whereas the Rica 310 is for super unleaded 98ron only........same as the HLM versions. I have the HLM 304

The Motronic 4.3 in your 850 motor does adapt as it says in the pic. for "Continuously to suit Running Conditions" which means it is not just idling or part load.

The EMS2000 fuel system as on the X40`s is far more complex!

[mitchyboy01]

If the new injectors fuel so much that the LTFT cannot cut enough fuel (adapt) in closed loop it will throw a lambda light but with Woz's injectors only being marginally bigger closed loop AFR should be fine.

The 4.3 ECU runs closed loop near till WOT when it goes open loop. In open loop the ECU does not know the ACTUAL AFR and relies on the open loop map and built in protection if it senses knock. There is no adaption in open loop.

Who meentioned EMS 2000?

[AndysR]

Hi Woz,

You are right in your theories and as for the advice so far given, they should be asking you for advice! Not you asking them

Closed loop is basically the ECU fuelling real time using data from the lambda sensor and adjusting the fuelling to match the correct AFR. Closed loop is used for idle running and part throttle with low load. The ECU may 'learn' in closed loop but it certainly doesn't learn in open loop.

Once the ECU senses enough load it will revert to open loop. In open loop the ECU runs from a preset map and is not adjusting AFR using real time data. It is using preset parameters and these parameters are based on you running the hardware it was originally mapped with. i.e 315cc injectors, stock MAF, turbo etc.

For example - If you are running 20% bigger injectors with a 315cc map, in open loop the car will be overfuelling by 20% until you reach the point where the old injectors would have hit 100% duty cycle. Only then will the bigger injectors be of any benefit. (Probably the reason it's cured your full boost misfire).

In short, for the car to run optimally you need to get it mapped. The mapper will change the injector scaling to suit which I am told isn't too complexed to carry out, although I am no expert whatsoever.

You may 'get away' with not mapping it for a while as it will be rich rather than lean, but what's the point in changing hardware if it means the car isn't running at it's optimum. Also, running too rich for prolonged use can result in bore wash over time.

Hope this helps,

Cheers, Mitch.

What he said ^^^