[Mk2 Turbo] Error code 52 Knock Sensor after engine rebuild

[drlunch]

Car = Rev4 GTS turbo.

My piston rings recently went requiring a bottom end rebuild, i had a new piston in no. 4 and all pistons had new rings fitted. The symptoms of this problem were low compression on cylinder 4, oil smoking out the dump valve and the engine warning light reporting knock sensor.

I got the car back and i'm currently 400 miles into running it in. 2 minutes into a short journey yesterday, the engine warning light comes on. I check the error and it's error 52 knock sensor.

I've read on here that the knock sensor detects engine noise. Is it likely that something has gone seriously wrong again? or does it simply need a new sensor? or could it be something completely different?

Please help!

[Turbo\'ed2Pete]

Hi mate,

Apparantly the Toyota knock sensors are quite delicate, I've just replaced mine as the ecu went into safe mode with error code 52. The only way to fix it was with a new sensor.

Sounds to me like you broke your knock sensor when the engine originally failed and you've rebuilt it and the sensor still needs replacing?

GTS Chris does GM ones machined to fit for £70 I believe and its a ten minute job to replace them. The one I got from MR T. for my Rev2 was £108

HTH
Pete.

[ulysess1966]

I had a similar problem with my MK1 SC and wasn't about to pay the £100+ for a new one as the actual piezo sensor costs about £1!

In the end I got a pair off a Supra turbo shipped from the States for £40 all in so I have a spare. The knock frequency of the 6 cylinder engine is different by a couple of hundred Hertz, but that is less than the bandwidth of the sensor so it works okay.

You can buy tunable sensors for about £30 that should work but you'd need to work out the knock frequency and tune the sensor.

[drlunch]

Thanks for the info guys. I'm still a little worried. I took the car out earlier for a 4 mile drive and the engine warning light didn't come on. Surely if the knock sensor had actually "blown" then the engine warning light would be on constantly?

[Turbo\'ed2Pete]

When mine had gone the EM light would come on after a few seconds of starting up and stay on constantly - did you pull the fuses out after your build to clear the original error code?

Having said that you probably disconnected the battery when you stripped the engine, worth a check though?

Pete.

[drlunch]

The battery was disconnected when the engine was rebuilt. The situation now is that i've since done another 30 miles since i reported the error code. During those 30 miles, the EM light has NOT come on once to report the knock sensor or anything else.

Perhaps that was just a "glitch" before?

[matt_mr2t]

If your knock sensor had blown you'd know about it. Car goes into safe mode and you basically just about have a limp in terms of performance.

I think it's located under cylinder no.4 so get under and check it's tight and the connection is tight.

As fort he GM ones, I have one on mine but I'm convinced it pulls timining when it shouldn't AND doesnt when it should.