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Guest Message by DevFuse

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EA82T knock sensor wiring help needed

EA82T knock sensor XT turbo EA82

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5 replies to this topic

#1 ShakotanBoogie


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Posted 20 December 2013 - 06:19 PM

Hey all, I'm working on getting my 1987 XT turbo back in proper working condition. The car has the flapper style MAF but a spider manifold was retrofitted by a previous owner, so there are all kinds of wiring oddities I am still trying to sort out as I get it closer to running properly. It was pointed out to me that the knock sensor is currently disconnected; I looked for a pigtail to plug into it but couldn't find one. I did, however, find two broken wires coming out of the harness that crosses over the block...I checked my spare EA82T manifold as well as my ER27 and it looked like the knock sensor plug was a single-wire setup. So, does anyone know what those two wires might be for, and if they are not the knock sensor plug I am looking for, where would I find it on the harness? I haven't been able to find anything. Pics below for clarification.



and the plug that appears correct on my spare manifold...

#2 TOsborn


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Posted 20 December 2013 - 07:36 PM

The plug appears correct, but the two wires (at least to me) look like the two wires that went to a mystery solenoid (the only solenoid I never found out what it did on my EA82T).  Though, I always left my knock sensor unplugged, time it right based off your fuel choice and driving style and shouldn't be an issue.

#3 naru


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Posted 20 December 2013 - 07:54 PM

There are 2 different knock sensors.1 and 2 pin,

Could be wrong,but.I thought EA81Ts and flapper EA82Ts used the single pin while hotwire EA82Ts used the 2 pin,

I believe they are interchangable by adapting the wiring.

#4 ruparts


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Posted 20 December 2013 - 07:59 PM

hi ,

 just to say the knock sensor system had 2 versions,  the 1 wire and a 2 wire,  that went to the actual sensor.  they changed the setup but not sure exactly when,  i know 85 & 86 both had the early set-up,  and 87 some had the early, some had the later version.   the later one is used on the ea series motors from that change date  on.

  i have a 87 turbo xt with the early version.   the problem is that the wiring from the later engine harness have some differences from the early version body harness they plug into, and don't just plug& play 100%.   to totally figure it out, you need a wiring manual from both 86 and 88, then you can find how they rewired  the knock system.

#5 jono


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Posted 21 December 2013 - 04:45 PM

early ones were flapper, 3 plug ecu with separate knock control module mounted between glovebox and outer body - you'll see two extra screws in door jamb when you open front passenger door, not on other models.


Flapper afm, and are white plastic knock sensor that are two wires supposed to be shielded come from the knock control module KCM. G for green is neg and R for red wire ? is positive.I suspect those wires loose when car is running or ignition on, may just be feeding pos power and earth to the sensor.


Green plastic KS are single wire from 4 plug ecu EA82, so makes me wonder if it is not just a spider been adapted to an early EA82 block - rather an entire spider engine dropped in ??? given the green sensor being there and not bothered to hook it up.

I'd look into fitting the two wire white sensor check those wires and where they are from, whats in them when ign on and cross fingers. Those sealed black plugs often stik on sensor so well, butchers pull the wires out of the back of the plug while trying to pull plug off to pull engine - in a hurry - what else can you do ??

Edited by jono, 21 December 2013 - 05:03 PM.

#6 MilesFox


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Posted 21 December 2013 - 05:11 PM

This one is flapper maf with mechanical disty/external knock control unit. I suggested the knock sensor grounds back to the KCU in the harness, as this is the earlier mpfi which is more like that of the ea81t.


another note is the long block itself was from an 87 rx, to replace the engine that was already in the xt with the spider manifold after it blew a HG. 


this car is the mnster wedge for those of you familiar with its pedigree

Edited by MilesFox, 21 December 2013 - 05:15 PM.

Also tagged with one or more of these keywords: EA82T, knock sensor, XT, turbo, EA82

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