Is there a difference between an S4 and RS4 N75 valve?

A stock N75 should be the same as far as i know Stumps ,but there are different ones. There is a race one to. HTH

Thought this was a thread about a Night bus then....

Is that the one which runs through Lewisham?

Speak to Rich (Viper) he was running a high performance one but I have a feeling it had to be mapped in

I mentioned to Aiden that I had a nearly new S2 one and he said not to use it on the RS, so maybe there are different ones

N75's are a consumable item, are on mine and my mates.

I've tried everything, inc the Industrial One that the S2 lads use. all frigging useless. One I bought from Unit 20,OEM lasted 6 months, Original from TPS 6 months, Online Ind one form s2_Bo 6 months.

Car has been sat for 3 months with only one runout and test ran her other day and running and surging like a pig. Put some Forte stuff in the fuel and the same so not gummed up injectors.

Scan revealed no faults but 99.5% sure it was the N75. Changed it for a new one yest and back on full power, running like a dream.

For reference, looks like we have a new manufacturer, different colour label etc and date of Man 25 June 12. so fingers crossed, they may not be chocolate anymore. Price is £49.26 with TPS discount, £45.32 +vat.

i'm not sure if there are any differences between s4 and rs4 n75 but there are different versions and certainly i've heard people speak about putting different model n75 for "aggressive boost". Personally I would check the part number and stick to the same one that your car was mapped to.

the differences are how the valve react to the same Pulse width modulation from the ecu. A bit like different capacity injectors.

Interestingly a guy on ASN compared the stock 1.8T valve to the common "race"/"upgrade" valve, which is the N75J i believe originally fitted to the RS2.

He found that the J valve gave a bigger spike as everyone said, but it actually made less boost further up the revs and peak airflow fell with it fitted.

Not sure if thats a function of the valve itself, or a result of the ECU boost PID trying to control the spike though.


TBH, If they're failing that often then theres something else going on. I just replaced the N75 on my own car, because it was getting a bit slow to respond and i was getting a bit of a delay of boost after a gearchange. The valve i removed was dated 1996, which means it was originally fitted to my old 195k AEB motor. If it can last 16 years and 205k miles, yours lasting 6 months suggests theres something untoward happening.

Perhaps its a wiring or hose fault and you jiggling/disturbing it all to install the new valve fixes whatevers up?

Have you tried refitted one of the "dud" valves? or tried a dud valve on another car?

Is it possible for some oil vapour to get into it from a faulty breather valve? Certainly it can affect one way valves.

I did test J88NYRs old N75 valve on a work bench and found that his just wasn't sealing properly. Without ripping it apart, it was hard to tell if it was a seal that had gone or the return spring.
But even that was an original valve and so was mine when I came to replace it. So like Aragorn says, it's really strange for one to fault after 6 months use.

Then again, I have noticed some parts have changed manufacturers from say Bosch to Valeo. So it could also be a bad batch or provider.

I did soak one in wd40 after cleaning and it worked fine.. Left again for a month or so and same old snags. New ones work briiant and quite a few of us have this problem.
Last one i could feel the car on the edge of failing snd if i turned engine off and on it would cure it for a while.