New to BPU

Picked my uk spec up today with fmic, full decat, fcd, etc. It goes like a saturn rocket but seems to smoke quite heavily at tickover, never did this before. Is it over-fueling? Never ever did it with the cats in, or is it pretty normal? My afr gauge isnt much use yet, says ive got to do 5-6 runs to get the egt over 700 for the sensor to work properly, or am i panicking about nothing? Is it worth getting an emanage and a mapping session?

Picked my uk spec up today with fmic, full decat, fcd, etc. It goes like a saturn rocket but seems to smoke quite heavily at tickover, never did this before. Is it over-fueling? Never ever did it with the cats in, or is it pretty normal? My afr gauge isnt much use yet, says ive got to do 5-6 runs to get the egt over 700 for the sensor to work properly, or am i panicking about nothing? Is it worth getting an emanage and a mapping session?

have you reset your ECU yet so that it can relearn for the new fuelling?

no! But im about to go and find out how! Thanks mate

Removing the cats will highlight turbo oil seal problems and probably valve stems too compared to leaving them in.

oh dear! uk spec 118k, could be the case...

oh dear! uk spec 118k, could be the case...

yep will be,also though off the subject go into the engine bay fuse box ,remove the 2 30a green fuses labelled on the plan as EFI.

leave them out for approx 5 mins then take the car out for a spin for 10-20 miles so that the ECU can adjust to BPU.The car may run a little lumpy until it has learnt the new improved fuelling.

Off to see if it makes a difference after ive eaten me tea, thanks Rich.

I must say I don't think you have to reset the ECU at all You've not really changed anything significant, just removed the cats and upped the boost. It'll be fuelling in open loop when you are on boost so no tweaky trim maps will be in action anyway, and when off boost you'll have slightly less back pressure, which means slightly better volumetric efficiency, which means a bit less fuel needed to tootle about and idle. Closed loop should adapt to that in about, oooh, 2 seconds.

The mythical ECU reset seems to be a bit of a cure-all snake oil sometimes. Yes, use it when you change fuel if you want. Any other reason makes me think "hmmmm...."

-Ian

I must say I don't think you have to reset the ECU at all You've not really changed anything significant, just removed the cats and upped the boost. It'll be fuelling in open loop when you are on boost so no tweaky trim maps will be in action anyway, and when off boost you'll have slightly less back pressure, which means slightly better volumetric efficiency, which means a bit less fuel needed to tootle about and idle. Closed loop should adapt to that in about, oooh, 2 seconds.

 

The mythical ECU reset seems to be a bit of a cure-all snake oil sometimes. Yes, use it when you change fuel if you want. Any other reason makes me think "hmmmm...."

 

-Ian

oh supra guru!

Removing the cats will highlight turbo oil seal problems and probably valve stems too compared to leaving them in.

Not related to your smoking question, but have you also fitted a boost controller to up the boost?

I must say I don't think you have to reset the ECU at all You've not really changed anything significant, just removed the cats and upped the boost. It'll be fuelling in open loop when you are on boost so no tweaky trim maps will be in action anyway, and when off boost you'll have slightly less back pressure, which means slightly better volumetric efficiency, which means a bit less fuel needed to tootle about and idle. Closed loop should adapt to that in about, oooh, 2 seconds.

 

The mythical ECU reset seems to be a bit of a cure-all snake oil sometimes. Yes, use it when you change fuel if you want. Any other reason makes me think "hmmmm...."

 

-Ian

I totally agree with what you are saying but get this:

my car used to boost at around 0.9 bar with both cats in

I did a double decat and walbro (already had the plugs, cat back etc)

took it out and it refused to boost past 0.9 bar at all after many tries. I was a bit disapointed that the performance was roughly the same.

then I reset the ecu. First few blips saw 0.9 then it peaked higher and higher and afer a 2 or 3 goes it was at 1.2bar

it seems to do this after a reset, I've done it again since and it def makes a difference.

how can this be if it is totally open loop? Is something else maybe being adjusted.

not fuel but timing based on readings from the sensors (knock sensors etc?)

Boost control is mechanical apart from the ECU saying "It's over 0.7bar, open the wastegate VSV". Once you decat your boost control is in the lap of the gods and a restrictor ring due to the weeny internal wastegate. You couldn't get the ECU to limit boost to 0.9bar if you tried (unless you stuffed it up the exhaust hahaha ). I remember on mine seeing anything from 1.1 to 1.5bar depending on gear, load, road incline, temperature, time of the month and if the day had an e in it

If you think about it, there is nothing the ECU can 'sense' to know it's not got cats in anymore anyway. The only thing it can sense that is related is boost pressure - which you clamp to 0.98bar anyway so it doesn't experience fuel cut...

It's not going to be timing either, you can't affect boost production that way, and it wouldn't change the timing map anyway as you hadn't changed anything to do with the knock properties of the fuel or the engine.

I'd say coincidence of some sort

-Ian

oh dear! uk spec 118k, could be the case...

yep...should have got a low milage jap spec

Boost control is mechanical apart from the ECU saying "It's over 0.7bar, open the wastegate VSV". Once you decat your boost control is in the lap of the gods and a restrictor ring due to the weeny internal wastegate. You couldn't get the ECU to limit boost to 0.9bar if you tried (unless you stuffed it up the exhaust hahaha ). I remember on mine seeing anything from 1.1 to 1.5bar depending on gear, load, road incline, temperature, time of the month and if the day had an e in it

 

If you think about it, there is nothing the ECU can 'sense' to know it's not got cats in anymore anyway. The only thing it can sense that is related is boost pressure - which you clamp to 0.98bar anyway so it doesn't experience fuel cut...

 

It's not going to be timing either, you can't affect boost production that way, and it wouldn't change the timing map anyway as you hadn't changed anything to do with the knock properties of the fuel or the engine.

 

I'd say coincidence of some sort

 

-Ian

that is very strangeI drove around for some time (weeks) without proper bpu boost until I reset it, I don't get it at all.

Could a safe timing map cause a slight misfire and thus reduced boost.

the car kinda felt hesitant and perhaps was not firing quite right before the reset, perhaps the plugs were on the edge of functioning correctly and a slight change made a big difference

hmmm I'm puzzled now and I don't think I'm the only one who has found a noticeable difference after going bpu and then ecu reset,we can't all be imagining it?

The ECU can get it's nickers in a twist sometimes without a reset. I've caught it getting stuck with the previous idle control settings, which was immediately fixed with a reset.

But that's the exception, not the rule.

Also a reset gives you gack a clean sheet of the timing maps, which may or may not be what you want. It's more likely to detonate under full boost for starters.

But I agree that most people use the ECU resets as a 'catch all' remedy for no good reason.

And no, it won't fix one's sex life.

that is very strangeI drove around for some time (weeks) without proper bpu boost until I reset it, I don't get it at all.

 

Could a safe timing map cause a slight misfire and thus reduced boost.

 

the car kinda felt hesitant and perhaps was not firing quite right before the reset, perhaps the plugs were on the edge of functioning correctly and a slight change made a big difference

 

hmmm I'm puzzled now and I don't think I'm the only one who has found a noticeable difference after going bpu and then ecu reset,we can't all be imagining it?

Well I don't get that at all either, but if it's behaviour that you experienced on a repeated basis and fixed it with the reset then I'm hardly going to say "liar liar pants on fire". There could have been anything up with it and it's still possible, although less likely, that it's coincidence.

-Ian

Picked my uk spec up today with fmic, full decat, fcd, etc. It goes like a saturn rocket but seems to smoke quite heavily at tickover, never did this before. Is it over-fueling? Never ever did it with the cats in, or is it pretty normal? My afr gauge isnt much use yet, says ive got to do 5-6 runs to get the egt over 700 for the sensor to work properly, or am i panicking about nothing? Is it worth getting an emanage and a mapping session?

My UK was 116k miles when i went decat. she smoked a little on start up prior to removing the cat's, and once the cat's had been romved, smoked on idle and when the throttle was blipped and in neutral. however...the smoke on idle and blipping the throttle has now stopped. dont know why..! i also did an ecu reset after the decat, plugs & FCD.

Yeah ive plugs IK24s, fmic, blitz sbc-id and power meter and am running the same numbers as branners in the technical discussion thread. Thanks for the advice boys, havnt being out in her today so ill have a go at it when it stops raining! But im not holding my breath!