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Discussion Starter #1 (Edited)
Hello all,

Yes I searched. Please keep reading. :)

I am getting constant code 52 CEL. Like every time I get the car over 3k rpms constant. I suspect the wire as the sensor is new. It's one of the ATS sensors. ATS Knock Sensor - ATS Racing

I have searched for hours but all the posts about this issue seem to be quite old and give inconsistent advice. Some suggest using coax, others suggest microphone wire. Some say splicing is ok, others say to replace the entire wire. I hope to get some concrete info on how to DIY this repair. If someone sells a pre-made solution for this I would love to buy it.

Coax is all solid core (that I could find) and doesn't seem to be the best fit for automotive applications. Seeing as my options are limited I have a 5' microphone wire on order. https://www.amazon.com/gp/product/B004TP4IZU/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

My plan at this point is to replace the entire stock wire. My understanding is that this is a single wire circuit going from the KNK plug on ecu connector to wire to knock sensor connector. (Does anyone know were I could get a new pin for the ECU connector?) I would also like to verify the shielding is solid from tip to tip. Does anyone know were this shielding grounds out? I will take my ohm meter to the stock wire and shielding tomorrow to verify the wire is the culprit.

When I wired in the ATS sensor I trimmed the stock wire back to expose the core enough to use a butt connector. I also installed some aftermarket wire shielding in an attempt to keep the signal cable as covered as possible. The add-on shielding is twisted together with the stock shielding. Everything was wrapped in electrical tape. This is the shielding I used: https://www.amazon.com/gp/product/B01BIBQESG/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1

After I wired in the ATS knock sensor the CEL went away for 1 drive. I got the car up to operating temp and was able to go above 3k without the CEL. The very next drive the CEL came back. I cleared the codes by unhooking the battery for an hour. The CEL came back again after the car got up to temp. :mad:

I know the inner wire goes to the knk pin on the ECU. What I was unable to find is the best practice for ground out the shielding of my new wire. I do know that I should only ground out the shielding at or near the ECU. Some people post about grounding it out to a pin on ECU but I want to verify what one I should tie into.

Any help with this would be greatly appreciated. My daily 99 4runner just ate its head gasket after 244k miles so my MR2 is now my daily. Getting these CEL and not taking the car past 3k rpms is getting really old.

Square

References:
 

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Have you checked the current wire for continuity? LP Engineering ( l0ch0w ) has made FCD (I have one it's really great) and also distributor pigtail replacement wires. It looks like he hasn't been active here in a long while but you might reach out to him for the wiring. Also, MR220V MR2 Wiring Harnesses does wiring swaps for MR2s. Definitely hit him up.
 

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Discussion Starter #4
Thanks Senna. I actually contacted @l0ch0w and he is making me a new knock sensor harness already. It had to dig around in his garage for the wire and pins but he said I should have it at my place in a week or so. I felt bad contacting him after he hasn't been active on here since 2013 but he totally came though for me.
 

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I have a FCD he'd made and it's really a nice little bit of kit. Direct plug and play and most importantly it works! I think you'll be very happy with what he delivers to you.
 
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