wotagr8bigchief

iTrader: (1)

Hello guys apologies for the long winded thread but as above I am getting some scary readings from my knock sensor on APFC and my is CEL flashing with revs. Car is MY93 WRX, it was mapped with crappy ebay headers fitted which started blowing at the up-pipe by the end of the session so boost was left at 1.1 to be safe until replacements could be sorted. Within half hour of mapping the power was noticeably down and the CEL was flashing with the revs not to mention the blow had started sounding quite nasty. I parked the car up and ordered a set of Harveys ported headers with matched up-pipe for my TD05 16G. I thought this would be the end of my problems but unfortunately not. I fitted the headers with brand new genuine gaskets, stud and nuts so there was no risk of them blowing again. On first starting the car it coughed out a cloud of white smoke witch cleared within a couple seconds, its never done this before but I'm not overly worried. Problem was the check engine light was still flickering, thinking this would go away I foolishly let it warm up then gave it loads of beans. The performance was sluggish to say the least and felt like there was a misfire, the boost was still down peaking at 14 psi which is a fair bit under the 1.1 bar/16 psi it was set at. I contacted my mapper who advised not to drive hard until he had tweaked the map for the new headers, as for the CEL and feeling of misfire he asked me to take a look at the knock readings to try and shed some light. Readings where 2 when idling but 70+ just reversing onto my drive, god knows what they would of been hitting when I was giving it stick earlier. Sooo I am hoping you guys can suggest what could possibly be wrong and perhaps guide me in the fault finding process. I live in Canterbury and there isn't anyone local that can take a look at it for me so I will have to sort it myself, I just don't know where to start!!
Worth noting that I fitted a new 12mm oil pump and GG cam belt a couple days before the mapping, my first time doing either job on a subaru but I took my time and triple checked everything. That said there has been a strange rattle coming from the right hand bank since then that isn't there when the belt cover is removed?? I will be stripping the covers off again and probably removing and checking idlers and belt tensioner but I am fairly sure this is an unrelated problem as CEL never came on until the car had been mapped and the blow got really bad. Cheers

yabbadoo4

iTrader: (8)

70+ !!! wow i wouldnt drive it at all and get the mapper out to look at it, its definetly knocking bad. from what ive read anything over 60 is a concern, and giving it some beans when it had these problems was not the best idea either. best of luck and i hope its nothing fatal.

wotagr8bigchief

iTrader: (1)

Yeah I know, typical me tho have to plant it! Didn't want to get mapper out until I had exhausted all other avenues as if its a mechanical problem having mapper out will be a waste of time and money. Cheers for that, fingers crossed its not to serious

Jolly Green Monster

iTrader: (4)

70+ blipping throttle to 3000rpm is best case loose knock sensor or misreading or internal engine damage making the noise.

Possible if it is misfiring and popping and banging to get that high a reading.

Simon

wotagr8bigchief

iTrader: (1)

Whereabouts are the knock sensors Simon? I take it the rattle from the right hand bank cambelt area is unlikely to effect knock sensor reading?

Jolly Green Monster

iTrader: (4)

Knock sensor is under inlet manifold just to passenger side rear.
12mm headed bolt holding it into block near water cross pipe.

Yes cambelt noise/rattle could be it

wotagr8bigchief

iTrader: (1)

Cheers Simon, I have a complete engine for spares so will change knock sensors and try and cure the rattling noise then go from there.

wotagr8bigchief

iTrader: (1)

Well I stripped off all covers today and noise remains, with covers removed it sounds slightly more central ie crank as opposed to head. Have removed and checked idlers and tensioner and tested for wear, from what I can tell they are all fine. Looks to be internal wear, the start of a big end knock most likely .
I was hopeful it would be a belt related noise as it is barely noticeable and certainly doesn't sound like the engine that came with the car that had a blatant knocking noise.
Has anyone else had a bearing fail that started with a mild rattle?

Never mind, I should of put a forged lump in it from the start. Found one with the following spec for a grand, what do you guys think?

New sti bottom end, Mahle forge pistons, sti9 crank and rods, ACL race bearings, uprated oil pump, new water pump, Uprated head gaskets, Uprated head bolts.

Has covered 8k from new and has reciepts for £4990

gildonvibe

we ran a test w/ a volt meter. And hey what do you know? The knock sensor wire was pulled out of the gray harness over by the passenger side.
This post relates to a high knock reading , its a wild shot ,we can try another sensor if reading the same worth testing : )