Detonation Sensor Fault on ECU

[mambastu]

Hi Guys,
I have a '91 UK 200SX with a T3 and FMIC and ND FCD chip. I recently checked my ECU for fault codes because the car was feeling a bit flat and I'm getting code 34 which is a det' sensor fault. I don't seem to be getting any voltage out of pin 23 on the ECU which is supposed to produce 3 - 4 volts with ignition on (according to the workshop manual). I presume that there is an internal fault with the ECU as even if the sensor was faulty there would be voltage being produced at the ECU end of the wire to the sensor. Can anybody check their ECU to see if they get the voltage ? I don't want to buy another ECU because the manual is wrong.


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Cheers

Stu

[Brucemc]

I dont think you should get a reading from the sensor with the ignition just on. The det sensor is a piezo electric device which "generates" a signal when it is vibrated at the frequency that it is looking for. You can diagnose the problem by unplugging the sensor at the rear of the engine bay and bridging the terminals with a 1M resistor. (the resistor is required as ecu expects there to be this resistance)
If this cures the problem, you have either a faulty sensor or wiring from the sensor to the connector, if the problem still exists (after reseting ecu) with the resistor in place, then the wiring to the ecu is at fault (or the ecu itself).

Bruce

[mambastu]

This won't work on my S13 because it only has a single wire with one teminal, not two, leading to the sensor. I have tried plugging one end of the resistor in the wire from the ECU and earthing out the other end with no obvious effect. According to the Nissan Workshop manual the 3 to 4 volts should be present at idle (not detonating) so presumably when detonation occurs the voltage must alter. If anyone could test their ECU it would be a great help. Will need to be a CA18DET though.

[Brucemc]

Oh i see, (mine is a sr20 with 2 wires).
According to the ca manual you should see continuity between the sensor and ground at the harness? is this so? Do you also see this continuity at the ecu pin 23? (EF&EC8)

[mambastu]

yup, I show continuity but get squidly diddly from the ECU. Think its knackered anyone got a spare they want to sell me ? http://300zx.co.uk/200sx/ubb/wink.gif


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Cheers

Stu

[Brucemc]

Putting a newish ca18det in a mates silvia tommorow, i'll take along the multimeter and check for you.

[mambastu]

Hi Bruce,
Any joy with the volt meter ?


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Cheers

Stu

[SteveSadler]

how do you actually reset the ECU?

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Bayside Blue S13.
Janspeed&D-Cat Pipe/Pace FMIC/BMC F1 Filter/Standard T25 @ 15psi
15.4 @ 98mph - North Wield Air Strip
Flywheel Figure 213bhp/209Ib ft @ 5375RPM
Power at the Wheels 166bhp
(as of 15/6/01 @ Power & Engineering)
SE Phase 2 Chip now fitted & S14 T28 awaiting fitting. :)

[mambastu]

Hit it with a hammer http://300zx.co.uk/200sx/ubb/wink.gif

When you've finished checking the code go to mode 4 I think it is and that clears it.

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Cheers

Stu

[Jez]

Or just disconnect the battery for a couple of mins

[mambastu]

So....my car seems to be suffering from the following :

BIG flat spot 2,000 to 3,000 rpm
Bloody rich at idle and on boost
Weak as Mr Bean on light load
Pinking in Fourth and Fifth gear
Fault code 34 on ECU

It has a T3 at 17psi with Janspeed, FCD Chip, FMIC, K&N, Group A fuel pump (buzzzzz).

Has anyone had similar and did they find it to be the det sensor or the ECU ?


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Cheers

Stu

pssst..anyone got a spare ECU ?

[Jez]

Your problems don't sound as if they're only down to a dodgy detonation senor.

Sounds more like a knackered fuel pressure regulator and/or incorrect ignition timing (maybe becuase you're using the std ignition map or maybe because the sensor isn't aligned correctly)

[kerfumph]

Think jez is right. Just to double check, your chip just removes the fuel cut? if so i think thats some of your problem (but not the det.sensor though).

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Graham
90' s13
Trust me, I know everything.

[mambastu]

I think the knackered det sensor error is causing the ECU to run in emergency 'RAF' mode (rich as fu^k)whilst retarding the timing.

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Cheers

Stu

pssst..anyone got a spare ECU ?

[Jez]

Might be but wouldn't have thought so. BTW where in the manual does it mention the 3-4 volts bit - can't find it?

You could try disconnecting the det sensor. If the ECU "sees" no voltage from the det sensor it will assume theres no detonation going on. The det sensor produces a voltage when the engine pinking (uses a quartz crystal - works a bit like one of those clicky/sparky cigarette lighters) - Although having said that I guess it's very unlikey that the det sensor is producing a voltage randomly. Could be moisture in a connector or something....

Thats probably not much help really is it....

[This message has been edited by Jez (edited 07-08-2001).]

[mambastu]

I haven't got the manual in front of me but its in the section that gives pin outputs for the ECU. Like you I was under the impression that the det sensor produced voltage when it detected pinging. In the Workshop manual the ECU produces an output on pin 23 (which I don't have) and fault code 34 which to me suggests an ECU fault rather than a det sensor problem. As you're probably aware the det sensor is a total bastard to get to and I've been quoted over £100 for a replacement :<

I've tried earthing the det sensor wire with and without a resistor with no difference in the fault code thats being reported however without having another ECU to try I'm a bit stuck.

[Avinitlarge]

I have got a spare ECU http://300zx.co.uk/200sx/ubb/biggrin.gif

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1989 S13
Private plate
K&N Filter
Bleed valve
Loadza Alpine ICE
Bumped on the front

[This message has been edited by Avinitlarge (edited 07-08-2001).]

[mambastu]

So you keep tellin' me !

Trouble is it would cost me more in petrol to get up to Rotherham than it would to import a gold plated example from Japan ;>

[mambastu]

Cured it !!

Tried swapping the ECU with another healthy ECU and produced the same fault code 34.

On further testing a technician friend found that some of the pin outs showed slightly lower voltage than normal and there was no output from:

Pin 23 - Detonation Sensor
Pin 28 - Engine Temperature Sensor
Pin 38 - Throttle Sensor
Pin 41 - Crank Angle Sensor
Pin 42 - Crank Angle Sensor

and some of the power in pins, amazing the car ran at all http://300zx.co.uk/200sx/ubb/frown.gif

After checking all the plugs that we could find for corrosion we cleaned the two earth ring connectors on the o/s inner wing and it cured the fault !

No more fault code 34 and all the pin outs show the correct voltage.

Performance is back to full strength and to celebrate I used about 2 gallons of fuel in the 12 miles back from his place http://300zx.co.uk/200sx/ubb/tongue.gif


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Cheers

Stu

[colin]

Well done matey http://300zx.co.uk/200sx/ubb/smile.gif

wanna cruise?

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91 S13 De catted. Completely held together with jubilee clips. Anti-shake rear view mirror adaptor for optimum smelly tree wafting.
Uprated carpet filth with matching dents all round.
Streamlined sig

[mambastu]

Why does the BB not refresh properly ?

Just read your post Colin,I'm guessin' its a bit too late.




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Cheers

Stu

[Kzip]

It might be your Internet Explorer caching the page - try holding down CTRL and pressing the refresh button to make sure that you have the most recent version.


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Kzip.
'90 s13 [~200bhp]
"Don't believe the hype" - Public Enemy

[mambastu]

Not that KZIP I've set it to refresh every time I access a page. Tried it anyway, doesn't work http://300zx.co.uk/200sx/ubb/frown.gif