Knock Sensor / Iridium plugs

[RedP85]

After trouble shooting my intermittent code 52 (Knock Sensor),
-> replace Knock sensor (2)
-> replace ECU
-> replace coax wire from ECU to KS (edit: <----- did not use a good coax :nono: )

I still get the code pretty much every day (but not every one !)

Going in my papers, I just find out that in the same month as my
problems started, I installed NGK Iridium BPR5EIX-11 plugs....

Anyone with an 85/86 running Iridiums without code 52 problem ?

-I kept my Platinium, will re-install them this week to confirm

:whatever: this is really getting on my nerve !

[batmobile]

`1

[SupraFiend]

I have ngk iridium plugs in my 85 as well and no problems. However I don't have the model # handy, maybe they sold you the wrong gap or heat range.

[Supra5MGTE]

i'm sticking with basic NGK V groove plugs. nothing fancy for me. I had a chronic starting problem b/c of my Bosch platinum plugs. but didn't know it at first.. took me like 6 months to figure it out. it was like clock work. put the bosch in.. problem 3x week. put the ngk in... never have problem. I'd say swap back to a basic plug and see what happens.

[RedP85]

.... maybe they sold you the wrong gap or heat range.BPR5EP-11 (P=Platinum) is OE
BPR5EIX-11 (IX=Iridium) is what I have.
Re-installed the Bosch tonigh -I know, but I never had a problem with.

The only thing I notice is the plug had a little white color (lean),
but I doubt it causes the code 52 !
Here is a
http://i4.photobucket.com/albums/y108/Redp85/IX_tips.jpg

[StanS]

am running the bpr5eix-11 in my 84 6mge heavy breathing for at least 5Kmi with no issues.

[RedP85]

No offense, but the 84 ECU does not "listen" to the knock sensor, as there was no wires in the 84 harness & no input to the ECU.

PS: It's not that it did not run well, it is just this annoying CE light that is coming ON after 10 minutes or so... run with it for few more minutes, turn the key off and start again, no CE light...!!!???
Will see in the next days if the platinium fix this...

[MWebber]

IIRC, the -11 is a .032 gap. I forget what the gap on a 5M should be, but that's right for a stock 7M, although I regap mine a touch smaller.

If it is running lean, the KS might be picking up a pinging from that?? have you tried higher grade gas?

Mike

[Dave A.]

If it is running lean, the KS might be picking up a pinging from that?? have you tried higher grade gas? Mike


Ditto.....try running some higher octane gas.

[SilverMk2]

Supposedly code 52 is only caused by electrical problems supposedly. Welcome to my hell, I'm probably going to have to scrap the car because of it.

[SupraFiend]

I've never had a check engine light come on from pinging, but I do ping on 87 octane. Your plugs should look a tiny bit browner in color then that. Maybe you have a vacum leak somewhere thats causing you to run a little lean. Are all the fittings on your intake pipe in good condition? The stock ones are notrious for cracking if they're original.

[Dave A.]

Supposedly code 52 is only caused by electrical problems supposedly. Welcome to my hell, I'm probably going to have to scrap the car because of it.


This is true! It'll be interesting to see if swapping the Iridium plugs for the OE platinums cures the problem. Maybe the stock MKII ignition system doesn't like the Iridium plugs and some electrical noise/interference is making it's way into the knock sensor circuitry.

[Solo1Supra]

I had code 52 on my 85. I cured it by replacing the shielded wire going from the sensor to the ECU, bypassing the engine harness entirely. I used an old RCA cable from my car stereo.
Worked like a charm. I'm currently using platinum plugs, not iridiums though.

[RedP85]

The platinum (were there before) did not cure the problem. :sadsmilie
CE light came back today.

I am always using Shell Gold (premium $$)
so I guess it is not the fuel grade.

I had intake leak (on the runners) when I bought the car -sloopy idle
Fixed it since, but there was no CE light then. :scratch head

The strange thing about it is that the CE light come ON only
after 5 miles or so. When it comes ON, I never feel a change in torque, nor misses.
While driving, I then shut off the engine and start it right back to clear the CE.
The fault does not come back for a little while (few miles).

I guess if it would be a faulty wiring, the fault would come right back ???

I will check timing, timing belt, ...

....unless the Ox sensor makes it run lean....little pings un-noticeable to the ears...

I will not scrap this car !
Something is making this happen.
Have to find it !

Thanks !

[SilverMk2]

Good luck. You might want to play around with where you ground the drain wire and make sure the KS is nice n tight. I'm hoping a new engine harness is going to fix mine. At least with the 5/6M you only have one to deal with. Around here any CE light means no pass on the smog, so my 7m swap is pretty much worthless right now. After all the money spent its going to suck going back to a 5M.

[RedP85]

You might want to play around with where you ground the drain wireon the other drain wire. Continuity checked at 0.4 Ohm to ground.

make sure the KS is nice n tightyou can bet it is !

[Dave A.]

Code 52 --------- open or short circuit in knock sensor circuit.

You might try checking the ground connection for the knock sensor which is located on the intake manifold. That particular connection has several ground wires (brown and also white w/black stripe) with ring terminals, all of which are the ground connections for the knock sensor, 02 sensor, ECU sensor ground (E2), and a couple of other grounds for the ECU. Also, check the engine to firewall ground wire. I'm suspicious of an intermittent ground wire connection at this point. Engine vibration may have caused one or more of the ground wires to break internally over time and make intermittent connection.

[lanky189]

Supposedly code 52 is only caused by electrical problems supposedly. Welcome to my hell, I'm probably going to have to scrap the car because of it.

hell..if you're gonna scrap the car over a code 52..just give it to me...

[SupraFiend]

You might want to try a different knock sensor too.

As for running premium gas, your wasting your money unless you really have your timing advanced. Running higher octane gas then what you need can hurt performance, milage and emmissions. I'd just stick with 89.

[StanS]

Listen to Solo1 and DaveA. Vibration causing intermittant wire failure especially near the wire termination point is a "common" failure mode.

[Solo1Supra]

Mine ended up being shorted to ground somewhere. That's why I replaced the wire/cable.
How I found the problem....
Unplug the knock sensor wire from the sensor. Unplug the correct connector with the knock sensor wire from the ECU.
Check the wire with an ohm meter.
Hold one probe on the terminal inside the connector to the sensor, and the other on a good ground. It should read open. Anything other than that, you found the problem.

[RedP85]

CE comes on at 2500-3000 RPM right away now.
I suspect the cable I used did not survive long.

This week-end, I'll extract the Knock wire from my spare engine harness
and install it on the car.

Will see !
Thanks for all the suggestions, but already did most of them
(I'm an Electrical Engineer, I guess I should be able to find a broken cable !)

[RedP85]

Last week-end I did replace the Knock Sensor wiring (again),
and cleaned all ground points of the engine block/head/runners/firewall.
Put back the Iridiums.

No CE yet. :woot:

So lesson learn: the cable of the knock sensor is fragile, as un-supported from
the distributor down to the sensor, and shakes with air turbulence.
I added a strain relief rubber boot (as seen on many electrical 120V cordset)
on the KS connector.

I guess I now have an extra KS, as the previous one was probably good.

Thanks for guidelines

[Dangerous Ken]

Last week-end I did replace the Knock Sensor wiring (again),
and cleaned all ground points of the engine block/head/runners/firewall.
Put back the Iridiums.

No CE yet. :woot:

So lesson learn: the cable of the knock sensor is fragile, as un-supported from
the distributor down to the sensor, and shakes with air turbulence.
I added a strain relief rubber boot (as seen on many electrical 120V cordset)
on the KS connector.

I guess I now have an extra KS, as the previous one was probably good.

Thanks for guidelines

Don't know if you read the turbo section, but there's a 7mgte trouble code thread going on there you could post to :)

Ken

[RedP85]

just did http://www.celicasupra.com/vbforums/showthread.php?p=183976#post183976

[85 rat rod]

i know its sevirely out of turn but the specified gap for a 5m is .044 lol

[Chrisfrom1986]

ew, i have mine set at .037. fucking stupid bosche catalogue!!!