Hi guys
I have signed up now after spending the last couple of weeks searching not only this forum but also every 1.8t forum i can to help my friend fix his recently acquired 54plate fr 1.8t AUQ
So i never test drove it but i took him to collect the car and therefore followed him back. It standard no mods at all yet it sounded noisy under boost. Very raspy as though it had a decat, what i used to call the aeroplane noise on my old mazda mps
Over the last couple of weeks we have been looking into it and come across several things now;
So first of all i drove it and the noise in the drivers seat sounds like its coming from in front of the exhaust or at least from the passenger side. Very loud SCORRRRRR kind of sound under load boost. not noticable when revving whilst stationary.
from the passenger seat it sounds like its in front of you behind the dash, it almost sounds like intake noise, when the windows are up but with them down its a loud boost escaping noise more harsh and aggressive and loud than a smooth intake or turbo spool whoosh. and bare in mind its not modified at all.
anyway along with all this i drove the car and it seems restricted to me, it revs slowly and has no urgency even in say second gear. So we ordered a boost gauge and a new n75 valve.
When they arrived replaced the valve, didn't notice a difference. So went about fitting the gauge. Installed all the interior wiring and gauge etc, then whilst in the engine bay realised that the upper breather hose was basically home plumbers fittings and literally where it comes from the crank case wasn't even attached. traced down to the lower breather where it attaches to the oil filter housing elbow and the little square valve thing and it was snapped completely.
So replaced the upper breather hose, lower breather pipe, oil filter housing elbow and new o ring.
all bolted up tightly and installed the boost gauge. took it for a drive, still has exactly the same noise from the exhaust / engine bay under boost? boost seems to get to around 6-8psi
also took for a bit of a longer straighter test and realised the car wouldn't hit the redline in any gear, gets to around 5 and struggles like mad, put in third - 5000 rpm and it feels like its stuttering, foot to the floor, eml flashes so backed off and drove calmly back. Plugged in code checker and showed cylinder 4 misfire. Replaced the coil pack for cylinder 4 still drives the same initially first and second gear pull seemed stronger but then opening up on a straight road the revs still struggle past 5krpm and theres the stuttery feel.
plugged in code checker and no codes found, although never pushed on it when stuttering to flag a code like the previous time.
Thinking to give the car a full service including plugs and maybe get another 3 coil packs next
but all of this still to me doesn't explain the loud exhaust boost noise it makes under load.
And i have checked all engine back connections, tried unplugging the maf. PCV pipes have been checked over and over when i replaced them.
I read about the little rubber valve that the lower breather and oil filter housing elbow connect to and give it a bit of a wipe down but not sure if that would create the issues? also haven't replaced the PCV puck or the standard DV - car has done 100,000miles
full service history loads of stamps in the book, tonnes of receipts, cam belt done twice, car is solid and in really good condition inside and out just seems to be this issue thats causing annoyance since he got it home now.
any advice appreciated. sorry for being long winded wanted to cover everything as best i can
Cheers!
I have signed up now after spending the last couple of weeks searching not only this forum but also every 1.8t forum i can to help my friend fix his recently acquired 54plate fr 1.8t AUQ
So i never test drove it but i took him to collect the car and therefore followed him back. It standard no mods at all yet it sounded noisy under boost. Very raspy as though it had a decat, what i used to call the aeroplane noise on my old mazda mps
Over the last couple of weeks we have been looking into it and come across several things now;
So first of all i drove it and the noise in the drivers seat sounds like its coming from in front of the exhaust or at least from the passenger side. Very loud SCORRRRRR kind of sound under load boost. not noticable when revving whilst stationary.
from the passenger seat it sounds like its in front of you behind the dash, it almost sounds like intake noise, when the windows are up but with them down its a loud boost escaping noise more harsh and aggressive and loud than a smooth intake or turbo spool whoosh. and bare in mind its not modified at all.
anyway along with all this i drove the car and it seems restricted to me, it revs slowly and has no urgency even in say second gear. So we ordered a boost gauge and a new n75 valve.
When they arrived replaced the valve, didn't notice a difference. So went about fitting the gauge. Installed all the interior wiring and gauge etc, then whilst in the engine bay realised that the upper breather hose was basically home plumbers fittings and literally where it comes from the crank case wasn't even attached. traced down to the lower breather where it attaches to the oil filter housing elbow and the little square valve thing and it was snapped completely.
So replaced the upper breather hose, lower breather pipe, oil filter housing elbow and new o ring.
all bolted up tightly and installed the boost gauge. took it for a drive, still has exactly the same noise from the exhaust / engine bay under boost? boost seems to get to around 6-8psi
also took for a bit of a longer straighter test and realised the car wouldn't hit the redline in any gear, gets to around 5 and struggles like mad, put in third - 5000 rpm and it feels like its stuttering, foot to the floor, eml flashes so backed off and drove calmly back. Plugged in code checker and showed cylinder 4 misfire. Replaced the coil pack for cylinder 4 still drives the same initially first and second gear pull seemed stronger but then opening up on a straight road the revs still struggle past 5krpm and theres the stuttery feel.
plugged in code checker and no codes found, although never pushed on it when stuttering to flag a code like the previous time.
Thinking to give the car a full service including plugs and maybe get another 3 coil packs next
but all of this still to me doesn't explain the loud exhaust boost noise it makes under load.
And i have checked all engine back connections, tried unplugging the maf. PCV pipes have been checked over and over when i replaced them.
I read about the little rubber valve that the lower breather and oil filter housing elbow connect to and give it a bit of a wipe down but not sure if that would create the issues? also haven't replaced the PCV puck or the standard DV - car has done 100,000miles
full service history loads of stamps in the book, tonnes of receipts, cam belt done twice, car is solid and in really good condition inside and out just seems to be this issue thats causing annoyance since he got it home now.
any advice appreciated. sorry for being long winded wanted to cover everything as best i can
Cheers!
