Forged pistons and knock code 52?? - SOLVED!!

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Forged pistons and knock code 52?? - SOLVED!!

Postby Shaggz00 » Tue Dec 15, 2009 3:40 am

I researched this, but couldn't really find the answer to this (specifically whether or not the knock code can have anything to do with forged pistons).


What do you guys think.. So I got this persistent knock code, and I can't get it to go away! I replaced the wiring with new shielded cable, grounded the shielding, replaced the sensor numerous times, but it still drops a code 52 on me. Could running these JE pistons be tripping the code?

You know how they make the engine kind of sound like a diesel engine or something... well I'm wondering if the knock sensor is picking up on that. It's not like I'm flogging on the engine at 6K when the CEL comes on, it's putting along, slowing to a stop, or taking off easy that it trips. It does it all the time and it drives me crazy!

The only time that it doesn't come on, is if I reset it (key off and on) and cruise at higher RPMs. From that point I can stomp it and I don't get any CEL at all. It's when I slow down to a stop that it decides to come on.

Ideas?
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Last edited by Shaggz00 on Thu Dec 17, 2009 12:25 am, edited 1 time in total.
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Postby LegacyofDan » Tue Dec 15, 2009 4:01 am

i assume your A/F ratios are within a fair tolerance?
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Postby ___Scott___ » Tue Dec 15, 2009 4:38 am

Base spark timing set correctly?

Buy some higher octane fuel and see if it makes any difference. If it does, you can't blame the piston noise for the knock code.
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Postby Shaggz00 » Tue Dec 15, 2009 10:36 am

I don't know what my AFRs are because I took out the wideband. I thought it was interfering with the knock signal, because the code showed up after the wideband install a few months ago.

I have the ATS 264 cams, and the Ex. is retarted 6 degrees per a recommendation from ATS. The In. is set to Zero because any advance caused knock. I'll set the Ex. back to zero, and recheck my base timing this afternoon and see what happens. I'm not opposed to the idea that it is actually some pinging that the sensor is picking up, I was under the impression that knock is kind of a higher RPM/in the boost type of thing :shrug: .

As far as fuel octane, I always run a 93 or 94 from Sunoco. I have tried different fuel from Shell, and Mobil/Chevron with the same result. Also, my fuel economy is dismal, could this be from fuel dumping caused by the 52? I'm talkin 12-14MPG... Driving 70 miles a day for work isn't helping :doh:
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Postby Shaggz00 » Wed Dec 16, 2009 1:51 am

I checked both cams and base timing today, and they are all spot on. Cams are Zero'd out, and timing reads 10 degrees with jump connector in. I re-wired the sensor again, and made sure the pin to the ECU was good.

Also, I had previously grounded the new shielding to the frame/body, but this time I grounded it to the original knock sensor shielding where it doubles back into the harness. Still no luck... This is knock sensor #2 (used as well), so tomorrow I'll try a third and fourth and fifth sensor if I have to just to rule that out.

Going crazy with this stupid thing!!
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Postby LegacyofDan » Wed Dec 16, 2009 2:17 am

you can have pre-ignition in all rpm's, and from my understanding(and logically thinking about it, it makes sense too) the bad pre-ignition is in high rev's, where as the lower ones are bad, but not nearly as bad as the high rpm ones.

but with that put aside, and thinking more outside of the box, alil bit.

see if you get a code 52 when the knock sensor is not in the block...like just hanging by the wire loom, well zip tie temporarily somewhere so that its not stressing the wire connection and not "knocking" around...haha pun.

again logically thinking...if you still get a code 52...then something is messed up with your sensor, ECU, or wiring...

and if you dont, then you actually have pre-ignition...

just an idea, it makes sense in my head that it should work, assuming that the sensor is not listening for actual ignition and if it doesn't hear it, have it default some a 52 or something...but i cant imagine the sensor working that way...

oh well, its just an idea :)
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Postby Shaggz00 » Wed Dec 16, 2009 11:09 am

I was reading on someone else's thread that the ECU is looking for some kind of signal from the sensor while the car is running, so I dunno if just unplugging it would give the desired result :shrug: either way, I'll try these ideas tonight and see what happens. I'll let u guys know
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Postby LegacyofDan » Wed Dec 16, 2009 12:22 pm

i dont mean to unplug the sensor from the ECU, i mean for the sensor to not be in the block, therefore unable to listen to knock....
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Postby Shaggz00 » Wed Dec 16, 2009 3:26 pm

yeah, I got you. I was reading somewhere on here that the sensor needs to be screwed into the block, because the ECU looks for some sort of coninuous frequency from the knock sensor to know it's there. If it doesn't hear that frequency, or it hears the knock frequency, then it trips the code.

Eric was telling me last night that Toyota had problems with Previa knock sensors, and Toyota had to come up with some sort of complicated knock sensor delete with diodes and all that electronic crap. So I don't think it's that easy.


*edit* n/m, I guess I read the post wrong, I just looked it up. They were talking about snipping the wire, not unscrewing it from the block. So maybe I can just unscrew it... but still it's not very safe. I'd rather figure out the problem :P
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Postby LegacyofDan » Wed Dec 16, 2009 3:33 pm

lol yeah its not safe but its temporary dude, its for diagnosing whats going on, if you still get a knock code the some is fubar'ed in your ECU or wiring.

and if you dont get a 52, then you probably do have knock.

make sense? :shrug:
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Postby Shaggz00 » Thu Dec 17, 2009 12:24 am

OMG I got it, lol. It's so simple, although I don't quite feel stupid...

When I said the Knock sensor wire was new, it's more like I replaced it 6 months ago, lol. So anyways, I was getting ready to install the new sensor, and I decided to double check my 6 mo. old soldering job where I had spliced the new wire to the old clip. WELL...

I say I don't feel stupid because when I saw the problem, I immediately identified it without having to guess. I unwrapped the electrical tape, and realized that the shielding wire was completely covering the inner wire. The inner wire was grounded out all the time! When I initially soldered it, I had pulled back the shielding, stripped and soldered the inner wire, then slipped the shielded portion back over so I didn't have to tape so much. Well anyways, you guys get it... SOLVED!

She's BACK!! WOOOO! :D
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'88 ST-165(Black) - Sitting... Waiting... Quietly... in the garage under 2 inches of dust...
'88 ST-165(grey) - gone to rusty Celica heaven
'91 MKIII Supra - 98% completion!
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Postby gearhead313 » Thu Dec 17, 2009 1:11 pm

i just love knock sensor stories... i could listen to them every night before i tuck into bed :)
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Re: Forged pistons and knock code 52?? - SOLVED!!

Postby pinoyGT4 » Tue Dec 22, 2009 11:38 am

good news!

jeez..

why is there so many knock sensor problem stories? :offtopic:
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