[Mk2] [Turbo] knock sensor packed up, twice!!!!!

[hnygt4]

ok about a month ago my car randomly showed code 52, and ran like crap, aswel as making its own antilag!!!(pulling timing and adding fuel, meaning full boost around 2k rpm and hitting fuel cut no matter what i did with the boost controller)
so I changed the knock sensor and all was well again(except the blitz bov packed up, but i dont think its related)
yesterday i hit fuel cut again (while overtaking, scary lol) and then it threw code 52 again and get the same antilag symptom, making it almost undrivable.
when the car was running ok it wasnt obviously pulling timing or anything(detecting knock) seemed good and wasnt down on power.
any ideas why I'v broke another sensor?? could it have been faulty??
I'v checked the wiring and its all ok. someone said code 52 can also mean my ecu has died, but the symptoms are the same as before so i dont think its that,
any help or ideas are greatly appreciated
cheers

[Goto10]

Hitting fuel cut at 2k rpm?
Is error code 52 definitely the only stored code? As you mentioned, 52 just puts everything into safe mode, retarded timing, richness & boost limitation (on stock vsv) but it wouldn't affect the fuel cut point which is related to the amount of boost generated (e.g. you should still be able to floor it up through the revs, albeit feeling as flat as an NA :p).
What method of boost control are you using?
Do you have a boost gauge? It's possible you're suffering boost spiking which is causing both detonation/fuel cut and destroying the sensor in the process.

[hnygt4]

sorry, what i meant was that because of the retarded timing and extra fuel the turbo can spool super early and high, which is pretty normal for a code 52 problem(some people have this some dont) last time this happened changing the sensor and wiring sorted it. my problem is getting through 2 knock sensors in a month!!!!!

[Goto10]

sorry, what i meant was that because of the retarded timing and extra fuel the turbo can spool super early and high, which is pretty normal for a code 52 problem(some people have this some dont) last time this happened changing the sensor and wiring sorted it. my problem is getting through 2 knock sensors in a month!!!!!

Ok, back to the boost control question, are you using mbc or ebc? What boost pressure are you running?
Boost spikes kill knock sensors, especially likely with an MBC - otherwise maybe a gain/teach issue or a faulty solenoid with an EBC.

[hnygt4]

I only have a mbc, which has been reliable and never caused spikes. i have standard fuel cut at around a bar. this spiking only happened once on this knock sensor and when it did happen it boosted very early and the cel came on. a weird thing is, is that when this happened last time the bov stopped working!!!!!! it only throws the cel if i go over 270000rpm, if i keep it below this no funny issues at all, as soon as i go over and the cel comes on i get 10psi by 2000rpm!!! but i can feel the timing being pulled big time, under load its like trying to drive with the intercooler pipes removed, gets slower the more it spools lol.
last time i thought it was the mbc causing trouble so i removed it completely and changed the vac lines, didnt change a thing!!!

[Goto10]

I only have a mbc, which has been reliable and never caused spikes. i have standard fuel cut at around a bar. this spiking only happened once on this knock sensor and when it did happen it boosted very early and the cel came on. a weird thing is, is that when this happened last time the bov stopped working!!!!!! it only throws the cel if i go over 270000rpm, if i keep it below this no funny issues at all, as soon as i go over and the cel comes on i get 10psi by 2000rpm!!! but i can feel the timing being pulled big time, under load its like trying to drive with the intercooler pipes removed, gets slower the more it spools lol.
last time i thought it was the mbc causing trouble so i removed it completely and changed the vac lines, didnt change a thing!!!

270000 rpm!
2750rpm is the point at which the check is made, I think it may be 'IF +ve boost AND rpm=>2750 then check knock sensor' - I'm also pretty sure it doesn't make the check until the engine is warm also, but not 100% on that - so a fried knock sensor won't trip the cel until those conditions are met (as you are finding)
I still strongly suspect mbc spiking, especially as you are hitting fuel cut, might be worth taking it off and cleaning - e.g. it may have started to fail a month ago and is now getting worse.
The BOV makes no sense though, although that would then point to a possible plumbing issue - any of the silicone hoses perished/perishing/kinked?

[hnygt4]

from what I'v read, and seen, the ecu checks for knock under any condition, as long as the revs are 2700, or 2750(not 27000 lol) the boost spiking only happens when the cel comes on, from what i'v seen on the U.S forums, its fairly normal for the retated timing to allow the turbo to boost faster than the wastegate can control it. I will be getting a ebc soon, if i ever get any spare money lol, I cant imagine 15psi(or whatever fuel cut is) being high enough to blow my KS, the car has a 1.4mm mls headgasket and a chargecooler, Im thinking more along the lines of a clogged injector or something, but if its been doing that for a month it should have pulled timing when detecting knock from running lean?? thinking about it, in the day or two running up to throwing the cel, i did think it was pulling timing a little bit, boosted a tiny bit earlier than normal and hit fuel cut twice in total. well it looks like another £150 on a knock sensor.

with the bov, i stripped it apart, cleaned it, oiled it and put it back in, it worked 4 times and stopped lol. if i blast it with the air compressor it opens a tiny bit, i think the spring has gone funny?!?!?!?!
cheers

[Goto10]

2nd hand is your friend! I picked up a knock sensor for £40 from here (someone breaking their car) - works like a charm. I think the cheapest new I found was £117 from a Toyota main dealer, although I do not recall if that was including vat.
I'd read horror stories about how fiddly it was to remove also, I swapped it in about 8 minutes, one of the easier jobs in life!
Injector going lean is very plausible too then, I'd be looking to get that sorted/checked before laying out for more sensors though.
Stock bov or a vent to atmosphere jobby?

[hnygt4]

the car is a gt4(please dont stop helping now you found this out lol), 1993 so it basically has a rev2 3sgte, with a blitz ss bov, as this car doesnt have one standard?!?! yea I dont really wanna keep relacing them so finding the problem is a good idea!!!! changing the sensor is literally a 5min job. a mate of mine has got an injector flow bench so I think i'll see how there doing. I changed the head gasket a few months ago with a mate, swapped a rev1 head on which i skimmed and rebuilt before hand, and got one of the shim clearances wrong and it ticks slightly, dunno if that could be causing enough noise through the block to upset the knock sensor, cant really see that happening but it is a possibility, i will be sorting this out soon, its hardly noticable and i kinda forgot about it. since the HG change i have has to raise the idle to keep it smooth, but i think its because it now got 256's, set to standard timing untill i get a ecu and tune it. also thinking, i might check my ignition timing again, if the ecu pulling timing can basically give me anti-lag it could well be retarded slightly, but then this would give less chance of det?!?!?! thinking about it I'v probobly just ruined the entire engine its driving me nuts recently, very tempted to part it and save a bit for a rev3 tubby lol

[steve b]

The BOV makes no sense though, although that would then point to a possible plumbing issue - any of the silicone hoses perished/perishing/kinked?

If you've no BOV then you get a boost spike for a fraction of a second (between throttle body & turbo) if you lift of the throttle suddenly before pressure goes back out via the compressor, could be related. Could confuse the AFM? MAP cars with reading from manifold side of throttle body not applicable.

[Goto10]

the car is a gt4(please dont stop helping now you found this out lol), 1993 so it basically has a rev2 3sgte, with a blitz ss bov, as this car doesnt have one standard?!?! yea I dont really wanna keep relacing them so finding the problem is a good idea!!!! changing the sensor is literally a 5min job. a mate of mine has got an injector flow bench so I think i'll see how there doing. I changed the head gasket a few months ago with a mate, swapped a rev1 head on which i skimmed and rebuilt before hand, and got one of the shim clearances wrong and it ticks slightly, dunno if that could be causing enough noise through the block to upset the knock sensor, cant really see that happening but it is a possibility, i will be sorting this out soon, its hardly noticable and i kinda forgot about it. since the HG change i have has to raise the idle to keep it smooth, but i think its because it now got 256's, set to standard timing untill i get a ecu and tune it. also thinking, i might check my ignition timing again, if the ecu pulling timing can basically give me anti-lag it could well be retarded slightly, but then this would give less chance of det?!?!?! thinking about it I'v probobly just ruined the entire engine its driving me nuts recently, very tempted to part it and save a bit for a rev3 tubby lol

Ahhh, there's the problem then, the engine is at the wrong end of the car
All 3SGTEs have BOVs as standard, they just recirculate the air rather than dumping to atmosphere though.
I think getting the injectors checked would be a good starting point from now though, then maybe switch to the stock VSV setup and run stock boost for a bit, if the problem doesn't reoccur then switch back to boost control, try and limit the variables.

[hnygt4]

st185's had no bov standard, nowhere for it to go, or to recirc on the standard intake and adding one requires tapping off a vac line at the intake manifold, but yea i'm gonna get the injectors checked, and run the ct20b's standard boost, gonna try the led knock vsv meter mod thing too.
any other ideas???
cheers

[hnygt4]

ok now I'm confused.

havent used the car much because of this problem, everytime i went over 2500ish rpm cel comes on, timing pulled like hell, hardly drive-able.
tonight i had to use it and was just curious as to the exact revs it comes on at, 2500, nothing, 2700, nothing, 3000 nothing???? i pulled over and reset the ecu (as it had the code 52 stored) drove it around, nothing. a little bit of spirited driving, boosting up to 6000ish and still nothing wrong?!?!?! I havent touched it scince i parked it a coule days ago with the check light on!!! any ideas? i think i'v got a faulty sensor from toyota??!? some people are unlucky enough to buy lemons, mines bloody cursed!!!!

[Dale_V]

I have a good working knock sensor here if you need another, £35 plus post, cheers

[hnygt4]

cool, sent you a pm

[Goto10]

ok now I'm confused.

havent used the car much because of this problem, everytime i went over 2500ish rpm cel comes on, timing pulled like hell, hardly drive-able.
tonight i had to use it and was just curious as to the exact revs it comes on at, 2500, nothing, 2700, nothing, 3000 nothing???? i pulled over and reset the ecu (as it had the code 52 stored) drove it around, nothing. a little bit of spirited driving, boosting up to 6000ish and still nothing wrong?!?!?! I havent touched it scince i parked it a coule days ago with the check light on!!! any ideas? i think i'v got a faulty sensor from toyota??!? some people are unlucky enough to buy lemons, mines bloody cursed!!!!

My knackered knock sensor also 'went good' for a short time too, although it soon reverted to its error code. £35 is a bargain (unless he charges you £90 postage )

[hnygt4]

weird. code 52 for the last couple days, now no code tonight?!?!?! least of my worries at the moment, someone reversed out if their drive without looking thismorning and swiped the side of the car smashing the wing and bumper!!!! MY CAR IS TRUELY CURSED!!!!!

[raptor95GTS]

weird. code 52 for the last couple days, now no code tonight?!?!?! least of my worries at the moment, someone reversed out if their drive without looking thismorning and swiped the side of the car smashing the wing and bumper!!!! MY CAR IS TRUELY CURSED!!!!!

I feel your pain, did they leave a note, mine didn't

[hnygt4]

I feel your pain, did they leave a note, mine didn't [/quote]

that sucks mate cars like these are obviously someones pride and joy, all that money and heartache because someone couldnt be ar$ed to drive properly

well i was in the car at the time, being nice and letting them out of their drive, he didnt see me and scraped fron the bumper along the wing to by the wheel, and drove off!!!! I got them to pull over and they denied it!!! they were in a toyota mpv thing and didnt see me or feel their car crushing my wing?!?!?!?!
luckily they realised they had done it and its getting sorted. . . . .