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Discussion Starter #1 (Edited)
Hi, my 206 GTi 140 (pre-plex) with the standard EW10J4 engine has developed an issue that I can't seem to diagnose.

The engine intermittently loses all power when on partial throttle or closed throttle.

When cruising at a constant speed, the revs will start to die (as if I have lifted off the throttle) and then suddenly come back, lurching the car forward. This happens at all engine and road speeds, but never at WOT.

I initially suspected a faulty MAP sensor, but the issue persisted after replacing.
I have also tried disconnecting both the EGR and purge solenoid in case either were sticking but no improvement.
There are no vacuum leaks that I can find either.

Any ideas?

Note: I do not have a working diagnostic connector so can't read any codes.
 

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Discussion Starter #5
The car starts and runs with the camshaft sensor disconnected but the problem persists.

The issue is definitely getting worse. Now on start up it will idle for approx. 5 seconds, then drop and almost die, then go back up to 1000rpm for another ~5 seconds and then drop again.

Every so often it won't recover from the drop in rpm and will stall.

I don't suspect the crankshaft sensor as the tacho seems to reflect reality, that is, if going downhill when this happens the rpms do not drop, and when almost stalling I can see the needle hovering around the stall point rather than in freefall.

:confused::confused::confused:
 

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The fact that disconnecting the cam sensor makes little or no difference could mean that the issue is elsewhere, or that it is the cause, and the sensor is behaving so poorly that not having it connected makes little difference.

They are usually quite cheap.
 

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Discussion Starter #7
I am beginning to lose my mind!

I have now done the following:

Connected up an OMEX 600 ECU - which shows the same issues at light throttle. This rules out:
1) ECU
2) Coolant Temp Sensor (OMEX uses a different one)
3) Air Temp Sensor (OMEX uses a different one)
4) MAP Sensor (OMEX does not use one)
5) Camshaft Sensor (OMEX does not use one)
6) Wiring

Run a diagnostic on the TPS - it never misses a beat, clear repeatable signal at all throttle positions

Removed the injectors and checked for leaks (none) and fuel delivery (yes)

Coil Pack - Resistance looks OK and all 4 outputs give a spark

Spark plugs - All look identical and OK (they have done less than 5000 miles)

The reason I am not suspicious of the crankshaft sensor, is that this happens exclusively at light throttle, and irrespective of engine speed. I have never had an issue at WOT. Also, my OMEX data logger is not picking up any misses from that sensor.

I am thinking about the lambda sensor, but given this happens from the point of the engine being stone dead cold, I am not convinced.
 

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Did the wiring from ECU to coil pack change when you fitted the other ECU? If not, I would not be so sure the cause is not there.
 

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Splendid :thumb:

You aren't the first to have verified spark, but nevertheless have found the coil pack at fault.
 

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Damn - I'd look again at the crank sensor or the wiring from it.

EDIT: Actually, I still think the cam sensor is defective and that the problem is connected to the "lost spark", i.e. the plugs sparking at the top of the exhaust stroke - I'm thinking that Peugeot wouldn't have fitted a cam sensor unless there was some condition that warranted it.

My theory is that, occasionally, unburnt fuel is in the cylinder and is ignited by the lost spark at the "wrong" tiem.
 
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