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wideband lambda sensor?


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getting a wideband would help you assess the situation. If you current narrowband sensor turns out to be faultysome of the widebands come with a 0-1v narrowband emulation then you can use that instead of the standard lambda. you would need to get the bung welded in so it can be fitted further down the exhaust.

How is your driving? do you use boost a lot? are you running higher boost? RRFPR?

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I'm using a SARD RRFPR running around 5 bar which i think is too high? and i am on boost quite a lot tbh, this week i have taken it easy and reckon i will get 240 miles out of it this time. I run around 0.95 boost on a ct9


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Leanish mixtures do the best power. It depends on chamber design. For the 4efte around 11.8 gives the best power. Newer VW TSI engines go for leaner than 13 afr.

Stock ecu, ct9 at 0.9bar will go up to 10 AFR. So there is no need to increase fuel pressure at all.

RR frps are for special cases or for bling. Sad but true.

(I run my sard rrfrp at 2.2bar idle with vacuum on and still hitting 10.5 at wot after 5k rpm.)

Edited by mech5107
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the ecu doesnt control fueling as well as a rrfpr? The ecu controls the injections period/length to add or remove fuel. a rrfpr is a mechanical band aid for a problem that doesnt exist.

For an N/A -T conversion i would suggest a rrfpr as a cheap fix if it was just a crap car you wanted to boost as it adds extra fuel in areas the ecu doesnt know how to operate (on boost) But for a turbo car that already adjust fueling according to boost pressure you do not need one within the ecu's limits.

If you find you do need one, bigger turbo or wanting to fuel past boost cut then a piggyback/P&P is recommended. A rrfpr just doesnt work like people seem to think it does...

It ends up adding fuel where the ecu has already added fuel and so acts as a multiplier (length x pressure) but then higher up where the ecu doesnt know how to fuel the air its recieving the rrfpr continues on the same direction depending on its rate. 1:1 - 1:7 and everything above, below and in between.

So you either end up running very rich on lower boost and then when you get upwards of 10-14psi you run nice afrs or you run nice afr's down low and lean up top..

Its not exactly that simple but i think most people dont understand what they are fitting and just follow the crowd..

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Leanish mixtures do the best power. It depends on chamber design. For the 4efte around 11.8 gives the best power. Newer VW TSI engines go for leaner than 13 afr.

Stock ecu, ct9 at 0.9bar will go up to 10 AFR. So there is no need to increase fuel pressure at all.

RR frps are for special cases or for bling. Sad but true.

(I run my sard rrfrp at 2.2bar idle with vacuum on and still hitting 10.5 at wot after 5k rpm.)

Thats because they are rising rate. if you put your standard fpr back on it would run better and probably make more power. The ecu is perfectly capable of fueling a ct9 up to fuel cut.

As i will advise everyone, always get your fueling checked when you make such a change.

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Thats because they are rising rate. if you put your standard fpr back on it would run better and probably make more power. The ecu is perfectly capable of fueling a ct9 up to fuel cut.

As i will advise everyone, always get your fueling checked when you make such a change.

Both stock and sard give exactly the same result.

I think that also the stock one is rising rate.

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A rising rate fpr regulates the fuel pressure based on the pressure it sees from the manifold.


There's no difference whether you run the stock fpr at stock fuel pressure or run an aftermarket at 2.3 bar, both are going to be at the same pressure.



If you set the fpr with the vac line off this is its base pressure under atmospheric conditions ie 1 bar. If you set it with the vac line on this base pressure may be altered because the manifold pressure may be in vacuum when you set it giving a lean conditions at WOT. Although some people have tried both and say its made no difference so just make of it what you will really.


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