2003 Opel Corsa Too much knocking (pre-ignition)

RANABIRGHOSH

MEMBER
2003 OPEL CORSA
4 CYL
2WD
MANUAL
24,000 MILES

The Car used to behave very well and never gave any problem. I never missed a scheduled service and oil change. This is my second car and used sparingly.

First one of the cylinders was miss-firing accompanied by engine knock (pre-ignition) if I stepped on the gas. I checked and found one plug was shorting. I changed all 4 plugs plus full set of HT cable. Now there is no miss-firing but knocking is still there if accelerated suddenly. The car is never over loaded and 90% of the time there are only two passengers my wife and myself.

3 Replies

DAVE H

MECHANIC
13,384 POSTS

Does the enfine management light show on the dash display. When you say it is knocking "pre ignition". Waht do you mean by "pre ignition"?

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Tuesday, March 24th, 2009 AT 8:50 PM

RANABIRGHOSH

MEMBER
7 POSTS

Thanks for your reply. No the engine performance light does not light up when knocking. By pre-ignition I mean too early sparking (too much advance) so that full combustion takes place before the piston reaches TDC which makes the knocking sound (In UK it is called pinking). I am a mechanical Engineer 65 year old and accustomed to the older carburetor type vehicles, so I do not know how to adjust ignition timing in these computerized cars and how can the timing chage on its own?

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Tuesday, March 24th, 2009 AT 11:59 PM

DAVE H

MECHANIC
13,384 POSTS

Hello.

There is no way of advancing or retarding the spark timing on this vehicle .. it is all Computer controlled .. you could try removing and cleaning/replacing the CKP (crankshaft position sensor) .. sometimes if this is dirty or worn it sends faulty signals to the PCM(computer)

Coil Pack System
The EI system consists of a CKP sensor, coil pack(s), related wiring and PCM. The CKP sensor is used by PCM to indicate crankshaft position and speed by sensing a missing tooth on a pulse wheel mounted on crankshaft. The coil pack receives the signal from the PCM to fire at a calculated spark target. Each coil within the pack fires 2 spark plugs at the same time.
The plugs are paired so one plug is fired on the compression stroke, and the other plug fires the mating cylinder, which is on the exhaust stroke. On the next cycle, firing is reversed.
On single 4-tower coil pack applications (4-cylinder), the matched cylinder pairs are No. 1 and 4, and No. 2 and 3.
The PCM acts as an electronic switch to ground in the coil primary circuit. When the switch is closed, positive battery voltage applied to the coil primary circuit builds a magnetic field around the primary coil. When the switch opens, power is interrupted and the primary field collapses inducing high voltage in the secondary coil winding and the spark plug is fired.

hope this helps .. let me know