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[david62]

would this cause the idle prob aswell as the holding back?..cheers for yr help

[3.2 manual]

might just be me being stupid..but doesnt a plug always fire under compression as there would be nothing to burn in a vacume?( except in the wasted spark principle) as used on some bikes when it fires on the exhaust stroke. is it a way of testing plugs?

[Kevin Wood]

might just be me being stupid..but doesnt a plug always fire under compression as there would be nothing to burn in a vacume?( except in the wasted spark principle) as used on some bikes when it fires on the exhaust stroke. is it a way of testing plugs?

Correct. The plug that does the work will be under pressure, meaning more volts are required.

Pre- 2.2/2.6/3.2 petrol Omegas are wasted spark.

Kevin

[CaptainZok]

might just be me being stupid..but doesnt a plug always fire under compression as there would be nothing to burn in a vacume?( except in the wasted spark principle) as used on some bikes when it fires on the exhaust stroke. is it a way of testing plugs?

Correct. The plug that does the work will be under pressure, meaning more volts are required.

Pre- 2.2/2.6/3.2 petrol Omegas are wasted spark.

Kevin

That's what I was trying to say earlier, hence grounding a plug isn't a good test for a spark and could be dangerous to boot.

[rustym95]

according to vauxhall it is the only way to test if there is a good spark there is no pressure needed as the engine should be set not to start ie remove spack plug leads, the DIS module can be test by arange of testers but this only proves that there is volts and position of spark, as there is a out put of upwords of 50.000volts to generats the spark on on any given lead ecu will not know if it is working or not only that it has power. you can test spark by A removing a spark plug and testing it on the side of the engine or B removing the leads and using another spark plug on the side of the engine, DIS module fault when in fault are, ruf running on idle excessive shaking when over 3000 revs, backfiring, resulting in damaging the CAT, othere fault wich also if the spark plug leads or spark plugs are damaged due to were and tear will result in same manner, DIS module should be replace with in a 4years of daily use. there are two types Bosh or SIEMENS, Bosh last longer that Siemens and have life time of upto 6years. this is quoted by mec at Vauxhall when I had mine done. dose not matter what size engine as DIS is used on all ECU engines.

[david62]

hopefully gona try coil pack this morn when vaux deliver...still no takers on looking at me car then if this dont work? ....david

[Andy H]

might just be me being stupid..but doesnt a plug always fire under compression as there would be nothing to burn in a vacume?( except in the wasted spark principle) as used on some bikes when it fires on the exhaust stroke. is it a way of testing plugs?

Correct. The plug that does the work will be under pressure, meaning more volts are required.

Pre- 2.2/2.6/3.2 petrol Omegas are wasted spark.

Kevin

That's what I was trying to say earlier, hence grounding a plug isn't a good test for a spark and could be dangerous to boot.

With non-wasted spark ignition one end of the high tension coil is grounded & the other is connected to the centre electrode on the spark plug. Assuming that the body of the spark plug is grounded then there is one small gap for the spark to jump. The voltage generated by the ignition coil will rise until it is high enough to generate a spark. If the spark plug body is not grounded then the voltage required to jump from the centre electrode to the body and then from the body to something grounded (probably the idiot holding it ) can be high enough to destroy the ignition coil (or a heart pacemaker).

With wasted spark ignition each coil serves two spark plugs. The high tension coil is not grounded, one end goes to the centre electrode of one spark plug and the other end to another spark plug. The cylinder that is not firing is at low(ish) pressure (it should be at the top of the exhaust stroke) the other should have compressed fuel/air mix waiting to be fired. The spark has to jump two gaps but as Kevin has pointed out a high voltage is required for the ignition spark and only a low voltage for the wasted spark.

Both types of ignition rely on there being a high tension circuit. If you lose that circuit (due to the plugs NOT being grounded or through damaged or disconnected leads) then the voltages generated get much higher than they should be which is dangerous and is likely to destroy the insulation in the DIS / coil pack.

[I_want_an_Omega]

well articulated

[david62]

ave tried coil pack and still the same so back to square one...any good mechanics on ere care to take a look asap plzzzzz ..[just to update ave tried gs sensor,airflow meter,egr valve and icv aswell..tech test and no faults coming up]now have no hair left to pull so be gratefull if some-one can ave a look..thanx david

[david62]

think i might of sussed it.took rear tailpipe off which looked the wrong one to me[only single pipe outlet instead of twin?]found blocked up which in turn has blocked cats.started car with them off briefly and ran fine.parts coming in morn about £350 all in inc gaskets n clamps.think its worth it has only paid £280 for car? keeping fingers and toes crossed for bout lunch time tomorrow..will let you know and post pics if works

[jonnycool]

2.5's have the single tailpipe as far as I know, only the 3 litre and 3.2 litre cars have the twin, but well done for spotting the blockage, hopefully it's sorted now

[david62]

hi just an update on me car.now revs to red line and not stalling but wait for this....just a slight misfire/holding back and idle fluctuates at sometimes 1400..1000...600 if you blip throttle it will steady itself..noticed on icv that there were burrs on bit that moves cud these be stopping it from doin its job properly? also the big valve infront of the cam covers[in pipe for egr circuit] when you take rubber pipe off is make an awful noise all the time but my mates is quiet...is there ne one close to me who like to take a look for me plz has im running of ideas etc..thanx david

[3.2 manual]

constipation for cars, i bet thats a relief now its gone, egr can cause a lot of idling problems, cause they are a crap idea, have heard they can be soaked in redex or blanked off, dont know if this can be done on the omega.