Rs Four S Strange Boost Loss

[flapsIOW]

Been scanning through the topics, and I can't really find a definative answer.

I have a 1998 Series 2 Nissan Stagea RS Four S(neo engined).

It has developed a strange boost issue, after using the turbo for a short period, it will go from making full boost to making only half boost.

If I stop the car and switch the ignition off, start it again and drive down the road, I will get full boost again for a short time, then the issue will return.

The car is standard apart from an apexi air filter.

Always run on 99 ron petrol.

When the car recieved a full service the mechanic noticed, the recirculating dump valve had been disconnected and blanked off. He reconnected it and plumbed it back in, however I didn't experience the boost loss immediately after this had been done.

Is it safe to run the car without the recirculating dump valve? I experienced no issues before the car was serviced, apart from coilpack failure, the car mis-fired and shuddered from 3800rpm to 5000rpm.

I have checked all the hoses and can't find any leaks.

I have been told it could be a temp sensor, near the top radiator hose.

The recirculating valve could be leaking.

The turbo actuator, could be sticking open.

Does anyone else have any suggestions, or let me know if you have experienced this problem.

Cheers everyone

[jayzedition]

bro i have the exact same issue as of my last service......iuno y have u sorted it out yet?

[neoRSwagon]

f**k MAN !!! MINE DOES THIS TOO !!! it goes from 7 and a half for about 2 seconds, sometimes longer, then all of a sudden drops to about 4 to 5 ish.. you can watch it happen on the boost gauge.. weird? anyone know about it ? im thinking the ecu controlling it ? mines all stock exept for some pretty blue intercooler hoses and a pod.

[lilcrash]

I used to have that problem, buy a boost control and remove the factory one. Its the ecu f**king up. I've got a turbosmart boost t on mine and havent had a problem since

[neoRSwagon]

oh yeah i thought it would be that lil bastard of a thing xD :-P

[neoRSwagon]

would you be able to post a picture up of where you got the boost T ? obviously between the actuater and turbo, but how do you bypass that stupid solinoid without causing any dramas? lol

[Stagea1]

Hey I've got 96stagea n it looses power when I floor it. Is that similar issue? Seems to sound common. Boost control to fix it?

[neoRSwagon]

yeah i might have to do the same. after i fix some other lil dramas im having with my wagon at the minute xD

[Dingus]

Even better, ditch the factory boost control setup, and swap out the actuator for one off an rb20 turbo, 10psi

Did it over the weekend on mine, was easier than I expected (never done anything like that), and is much better. Being S2 you already have an R34 intercooler, which is more than up for that amount of boobst.

[neoRSwagon]

oh really? shit! so just straight off a silver top 20 ?

[Dingus]

Yeah, just the actuator from one.

[neoRSwagon]

and still connect the ecu controled solinoid to it and everything?

[Dingus]

Nah, I've ditched the ecu controlled stuff, blocked off the line going to the bov return, and just have a vacuum line straight from the intercooler pipe to the actuator.

[lilcrash]

I just unplugged the stock solenoid and put the boost t in it's place, just don't put it in backwards.

[Chris_Beli]

I used to cop this all the time, having a boost tee doesn't help as that's what I currently have, when I asked this question I got told something along the lines of when u increase your stock boost the ecu detects the high boost levels and enters retard mode returning it to factory boost ie like 7 psi, when u turn the car on and off the ecu resets back to normal and ur away, so ur solutions are change to more sophisticated boost control or just turn your boost tee down a bit, it used to only happen to me when I was really going hard and usually in hot weather and since turning my tee down a bit it hasn't happened again I vaguely remember it having something to do with setting of the engine knock sensor aswell? Hopefully someone can elaborate I don't remember the details as it was awhile ago and haven't had to worry about it since

[lilcrash]

Your theory is wrong for my car, I was constantly hitting boost cut and never had it drop below 10psi apart from when it ran out if puff at 4500 rpm when it crept down to 5psi

[Chris_Beli]

Your theory is wrong for my car, I was constantly hitting boost cut and never had it drop below 10psi apart from when it ran out if puff at 4500 rpm when it crept down to 5psi

What would cause your car to restrict itself to less boost? As in what u be doing that would cause the boost to retard? Like I said when it used to happen to me was usually when I was going pretty hard and nearly always when going up a hill, and like I said also I know there was more to the explanation then what I said I just really can't remember

[lilcrash]

I think it's just one of those random Nissan things. None of our cars act the same. Mine was always when ever I was driving slowly then went to over take it would only have 3psi as if it never had full boost from that start up sort if thing.