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The mkiv Supra Owners Club

Overfueling on start up


dude

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Ever since i fitted the 550's and resistor pack the car has been a pig to start except when hot and left for a short time , when it starts from cold it stinks of fuel , it has plugs 2 heat ranges colder than stock but was the same with BCPR 7ES,

Mods

Mines ECU

walboro pump

FSE

550's

hks induction

FMIC

SAF-C

Apexi ITC

Blitz SBC-ID

De-cat

super dragger

12v pump mod

True twin conversion

 

have tried diff. map sensor and idle air control valve , is the ecu overfueling on start up , the fueling is pretty good when running according to Mr Thor and his dyno , Help it embarrasing being smokey on start up , what tells the ECU how much fuel to stick in on start up ??????

 

Dude (old smokey):flame Dev

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usually water temp adjusts the fueling and there is usually a cranking modifier. i think with yr setup the water temp map will b adjusting a modified signal (from the safc), so that will b ok. the cranking is usually a duty amount (open so long) so this will b too rich cos increased pressure and big injectors.

 

i would have thought there would b some kind of setting in the afc for this? but ive never used one so i have no idea.

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Originally posted by dude

Eyefi does the ecu take its temp reading for cold start from the sender for the guage or a dedicated one ?????

 

Dude:flame Dev

 

im not sure if the water temp is referenced until startup has happened. iirc its (gauge and ecu ref) all from the same temp probe, b44 is the ecu pin.

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if the fpr is setup correctly (stock pressure at idle), running in 9 or 12v shouldnt make a difference at startup cos the pressure is governed by the fpr.

 

how does the safc work? does it alter the pressure voltage to make the ecu think its in a different place on the fuel map? or does it alter the injector signal?

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AFC works by modifying the MAP or MAF signal (JDM or UK)

Only ever anygood during open loop control. i.e. under boost.

 

Closed loop control would be under the control of the O2 sensor mainly. The ECU will try it's best and self modify to correct for the excess fuel (when going up in pressure or injector size) but there is a limit.

 

Added to colder plugs makes self cleaning more difficult for them and hence they foul up easier. That again doesn't help starting.

 

During cranking the temperature must be know. No point starting the engine and then finding out "oops I need more fuel as it's dam cold out there"

 

Rather like trying to start an old car in winter with no choke!

It aint gonna work.If it starts then it never needed the choke anyway.

 

So it could be a whole host of small problems related to the cold starting issue.

 

Fitting a simple fuel controller or boost controller won't effect your starting or idle but fitting a larger pump an FSE valve plus colder grade plugs all will. With differing degrees of effect.

 

I always say the easiest way to find this kind of fault is start disconnnecting or turning off gadgets until you find the culprit.

 

Regards

Pete

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Originally posted by GavinL

I would suggest reversing the 12v fuel pump mod if you haven't already.

 

You have a high pressure pump and an FSE I don't see why you need the 12v mod with that combo

 

I thought the Walbros only worked properly at 12V, so you wouldn't want to run it at 9v by reversing the mod?

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Originally posted by SimonB

I thought the Walbros only worked properly at 12V, so you wouldn't want to run it at 9v by reversing the mod?

 

I'm sure mine runs at 9v/12v. Doesn't have any problems to my knowledge.

 

I do know that I had a problem with an FSE valve a couple of years ago that was made worse by running constant 12v

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  • 1 month later...

Hey dude,

 

Did you get to the bottom of your rich start up problem?

Temp sender, o2 sensor ??

 

When you fitted the 550's did they need much "trimming" with the safc for idle/low speed? The reason I ask is you have the MInes ecu don't you, which I was told was mapped for 550's anyway.

 

Any ideas?

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Dude

 

I did the 550 mod etc, same problems you had. I've fitted an AVCR to reduce the fuelling. At start up the overall fuel adjustment I had to make to get it to start properly and idle with the correct mixture was -13%. The lambda sensor could not cope with making such a large adjustment on its own.

 

It might be the temp sensor for the ECU, but I doubt it.

 

Mark Brown

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I thought the Walbros only worked properly at 12V, so you wouldn't want to run it at 9v by reversing the mod?

that's what I was advised by TDi when I bought mine ! !

 

They say the Walbro is NOT happy running in 9v mode...

 

....wether that is THEIR experience, or, just what THEY'VE been

 

told I don't know. ? ? ? ? ? ? :conf:

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I thought there were TWO water temp' senders ??

(at least, there are TWO senders just on/around the water-pump

- top-left corner of front of head area)

 

Pretty sure ONE is guage and 'tother is ECU one ??

 

SO, yes, the guage can read right but ECU get wrong temp' signal

 

????????????????

 

(NOT that THAT's what it is...........)

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