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The mkiv Supra Owners Club

BPU advice needed


themodifiedkid

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Hey everyone, a wee bit of advice is needed.

 

Basically ive gone bpu, Double decat 3", hks hi power exhaust, restrictor ring, colder plugs, Afr wideband gauge, Boost controller,Thor FCD etc. Ive got a walbro fuel pump on order which should have turned up but hasn't so basically asking if it doesn't turn up by the weekend will it be safe to use the car with the stock pump in until the new one arrives as I was hoping to use the car at the weekend:D Hope this makes sense and is not a silly question:innocent:

 

Thankyou everyone in advance :cool:

Edited by themodifiedkid (see edit history)
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if my knowledge is correct (probably isnt) with the smaller fuel pump will mean your going to run lean and risk detonation. which as its name suggests is a very bad thing.

 

I would wait for someone who knows what they are talking about to comment though :p

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In terms of flow volume:

 

jspec (lowest)

walbro (middle)

UK (high)

Bosch (Very high)

 

It will run okay provided the stock pump is working correctly and the filter sock is not clogged. The stock jspec pump works absolutely fine to well above 1.2 bar, the reason it's advised to replace it is due to service reasons rather than it's capabilty to handle the flow at 1.2 bar. A potential 14 year old fuel pump and clogged sock filter isn't going to be optimal by any means.

 

Personally I'd not want to run the risk of it so just keep the boost below 1 bar until the new pump arrives

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Excellent cheers homer, thanks for the info.

Just one more thing, ill obviously be keeping my eyes on the afr gauge, but what readings should i be getting from it. I.e at idle and at exceleration, and basically what should the reading not drop below as a rule of thumb

 

Depends on spec - is it a stock TT with stock ECU and injectors? What boost is it running?

 

For idle it should always hover around 14.7, on full trottle and boost it shouldn't go above 11.5, but there is much else to factor in as well when talking about AFR readings. There isn't really a definitive answer.

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The stock pump is perfectly good enough for BPU as long as it's working 100%. If it's not you risk running lean and possibly doing damage to the engine .... However, you have an AFR gauge, so you can monitor that no problem. I'd go ahead and get the rest done, just watch those AFRs even more closely than usual.

 

:thumbs:

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Its jspec TT, BPU with 1 bar restriction. Stock ECU and injectors. will be running at 1- 1.1 bar and soon to be bumped to 1.2 via boost controller.

 

Im new to the tuning side of things and put an Afr gauge in,as im frightened that the fuel mixture will go lean and detonation. So just wanted a rough idea at what sort of figures I should be looking at

 

Only just fitted the AEM afr wideband gauge, and not had the chance to test it out yet, so a complete novice when it comes to afr readings

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When going BPU the tricky part in reading AFR's is not in the peak readings, it's at the changeover point when the 2nd turbo is just about fully spooled. That is where the stock map sends the car dangerously lean if the fuel system is not optimal. Hence the reply before that there is not a definitive answer your question. The AFR gauge (or more likely you) won't react fast enough to a lean condition during any potential lean spot.

 

I appreciate it's a bit of an inexact science, but from a safety point of view it is advisable to follow the bpu guide, *just in case*.

 

They near always run fine at WOT and high boost, even with very old and clogged pumps, the issue is at the changeover point.

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Without sounding like a complete noob, am I right in thinking that providing all parts are in top condition and working efficiently providing the maximum boost to go to is 1.2, everything should be ok/safe.

 

Obviously there is nothing that can be done with the possible lean point at changeover with the parts i already have. Sorry for all the questions Homer, its just I like to know when driving the supe that im not causing any unnecessary damage.

 

P.s what is WOT

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You really need to get that fuel pump and the fuel filter replaced if they are not near new. At 1 bar it *should* be okay, but really don't push it further - with BPU any weak point is exponentially stressed the higher the boost.

 

WOT = wide open throttle. I.e. very high load: 4th/5th/6th gear pull at maximum boost and foot to the floor.

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You really need to get that fuel pump and the fuel filter replaced if they are not near new. At 1 bar it *should* be okay, but really don't push it further - with BPU any weak point is exponentially stressed the higher the boost.

 

WOT = wide open throttle. I.e. very high load: 4th/5th/6th gear pull at maximum boost and foot to the floor.

 

Top man, cheers Homer for all the info, been a real help. Hopefully fuel pump will turn up soon anyway.

 

Again thanks :D;)

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