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Discussion Starter · #1 ·
Could not sleep (3am) so went for a drive!
Set boost to 1.3 bar for the first time ever. (usually 1.1 bar to play safe - felt brave tonight!)
My car car has HKS racing suction, magnex de-cat, but standard TM exhaust.
HKS EVC, APEXi S-AFC (bascially used to lean out below 3,000 rpm. Anything above was not set, ie: zero correction), A/F meter and Defi boost / oil pressure gauges.
Standard Fuel pump, injectors and regulator.....still trying to decide if I need to upgrade. I still got my standard con-rod bolts too!
Floored it every gear and experience no fuel cuts that many ppl talked about. My A/F meter showed 11 at WOT (still rich!) I thought my injectors should have maxed out!
Got home hit the 'peak' button on the defi and it showed 1.39! But no fuel cut detected.
I realise this was the first time I pushed the boost to 1.3, but do you gurus think it's safe to keep it at this level with the mods (or the lack of them!) that I've listed above?


Discussion Starter · #2 ·
no idea about the ware on the engine, but it sounds great. Is it the EVC that controls the boost? and if so ,is it fully adjustable or does it have fixed settings. I presume you need the other meters to see exactly whats happening under the bonnet.

Discussion Starter · #4 ·
One days run on 1.39bar does not mean it will never fuel cut at that point. It is a misconception that 1.3bar is the fuel cut threshold level, there is no set fuel cut boost level. 1.3 bar is only mentioned as that is the rough point when fuels cuts will probably occur. The level will vary as the ECU does not measure boost pressure directly but works it out from the airflow meter and temperature sensors. The colder the air is the denser it is and so the 'sensed' pressure will go up on cold days. Thats why you get more fuel cuts in winter if your boost is set to a borderline level.
I have also run 1.4 bar on the standard ECU over a several months and experienced only 3 fuel cuts in that period. I fitted a boost gauge and found out my new engine was running that level of boost so I dropped it down a bit quick! I now run 1.2 bar peak with 1.1 bar sustained personally I think that is acceptable level on a standard ECU without touching anything else, anything more and I would start getting concerned.

Discussion Starter · #5 ·
Well, my evo5 hits fuel cut at 1.08 8(

The Apexi AFC will only help bypass fuel cut if you use it to lean the mixture
at high revs; evo6tm said it was set to zero at high revs.

I do believe the TME may well have a higher fuel cut threshold as ive heard
of others running high boost on a TME with a stock ECU.

Stock injectors/pump/ecu will be on their limit at 1.4, so be carefull !

Discussion Starter · #6 ·
hi justin
your evo5 and the evo6 gsr are different form the TME in the respect they run lower boost as standard. that is because the tme has got a smaller turbo compressor (15g instead of 16g for the E5,6) so they should have different fuel cut limits.
i think but i am still new to this evo business ?


Discussion Starter · #7 ·
Regarding the A'Pexi SAFC and getting around fuel cuts.
The way I see it is this (please correct me if I am wrong as this is only an guesstimate of how it works):
If you raise the boost then you need to raise the fueling with it or the mixture will become lean. The way the AFC alters the fueling is to intercept the airflow signal from the airflow meter and then add a percentage value on or off depending on what you set the controller to.
For example:
The airflow meter may say 100% airflow but by the time it gets to the ECU the AFC can have changed that to 115% airflow. The ECU will then fuel for 115% airflow or in other words will have added roughly 15% more fuel.

The trouble comes because the ECU may see 115% airflow as overboost and a fuel cut will occur, not what you want!

The way round it is you need to provide more fueling as standard. In other words for example so 100% ECU sensed airflow provides 115% fueling. To do this you need to either uprate the injectors or increase the fuel pressure (or a combination) basically anything that can provide more fuel reliably.
Now when you up the boost, say to 115% airflow the AFC can turn the signal down so the ECU sees only 100% but the ECU will provide 115% fueling due to the uprated fueling provided by the injectors etc. This effectively moves the fuel cut up the boost range, in the example given it will move the fuel cut up by 15% or it won't fuel cut until 130% real airflow if the fuel cut was at 115% before.
Obviously the AFC can fine tune the fueling throughout the rest of the rev range so it won't run rich at lower revs.

I hope that it explains it sort of correctly ;)
Please feel free to pick holes in it as I'm no expert!

Discussion Starter · #8 ·
Can I ask a supplementary (probably daft border|EQU| 0 align|EQU| absmiddle >) question. If you uprate the fuel pump for one that delivers a higher flow rate, will the ECU control the air/fuel mix adequately so that you dont get overfuelling or running too rich - or is it essential to spend £100s on all the electronic gismos?


Discussion Starter · #9 ·
There is no need to fit a supplementary 'piggy back' unit with regard to fuel when uprating boost. Raising the boost means more air is drawn into the engine, this obviously measured by the air flow meter and ECU will adjust the fuel characteristics accordingly. The air flow meter will read the quantity of air up to approx. 1.7 bar boost, this is also around about the limit of the standard fuel pump.

Discussion Starter · #10 ·
Thanks for your comments guys!

What I really like to know is: Has anyone actually damaged their engine by not changing the con-rod bolts to ARP ones when runnning 1.3 bar? What is the highest boost for standard engine internals?


Discussion Starter · #11 ·
i have been running a lot more than that for nearly 2 years
with std bolts
make your own mind up,but in my eyes its scaremongering,or some people need the work ????

Discussion Starter · #12 ·
I would like to see you run 1.7 bar on a standard ECU without fuel cuts! The example was meant to show how to get around fuel cuts with the SAFC and fine tune the fueling in the process ;)
Long live the king though :)

btw Elvis Do you know what the Ralliart ECU was mapped to exactly? (i.e what exhaust, induction and boost level?)
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