looking for some advice on a strange fault , 93 300 zx auto tt, driving to work this morning , i noticed when accelerating that my boost pressure was down. pulled up at the tolls turned engine off , paid the reaper , started up set off, again, immidiately noticed full pressure was being achieved. Then this evening headed home and strangely the same again as in couldnot developfull boost pressure ,so again i pulled over , turned the engine off then straight back on , set off a lo and behold had full boost , what on earth is happening and why, any ideas, how can i stop this

looking for some advice on a strange fault , 93 300 zx auto tt, driving to work this morning , i noticed when accelerating that my boost pressure was down. pulled up at the tolls turned engine off , paid the reaper , started up set off, again, immidiately noticed full pressure was being achieved. Then this evening headed home and strangely the same again as in couldnot developfull boost pressure ,so again i pulled over , turned the engine off then straight back on , set off a lo and behold had full boost , what on earth is happening and why, any ideas, how can i stop this

 

sounds like safety boost mode... it cuts in when a fault is detected from the sensors.

 

I've never encountered this, but I'm pretty sure you wanna get it on a conzult sharpish...

 

Turning the engine off and on again might be a temporary fix, but you could end up damaging the engine. Its a quick fix but possibly not a clever one...

did the car perform differently? Or are you just going by what the gauge was telling you, and if so, is it the original boost gauge?

yep dett problem...fault clears every fresh start but code stays

Yes Tudor the car did perform differently, when not boosting fully i had 2 thirds off full gauge, when boosting fully it was nigh on at the top of the gauge. yes it is the original gauge .....car starts , runs ( whether boosting fully or not ) well and smoothly, idles absolutely fine etc etc

the reason I said that is because the stock boost gauge is known to be inaccurate and could be giving a false reading, but you just cleared that up... Have you tried doing a diagnostic check? http://www.zmods.org/index.php?page=ecu_diag

thanks i will try that, strange thing is though when i restart the engine it performs really well for miles as i travel home, yet i know when i go to it tomorrow the boost pressure will be down from the get go on the first run of the day until its restarted

could be many things matey, but doing the diagnostic check might give you a good idea, and post your findings on here and we'll go from there...

all, Jeff at Zedworld ran a diagnostic for me, it turns out the car is stuck in safety boost due to a failed Dett sensor, its okay to drive just not developing is full power etc, this combined with a failed thermostat is also making the engine run cold and be stuck in in cold mode i.e it is drinking fuel . ive now booked it in for a new cam belt and the other issues will be attended to at the same time.

 

Neil

hi neil, good to meet you on the weekend! glad to hear you know what the issue is, hope you get it all working correctly soon!