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[Ali Ch]

hi
i have omega 1996 2.0l, i had the management light on for a long while due to the oxygen sensor wires are damaged (tried to fix it but its ripped of off the sensor leaving a hole :S) and i could not get my hands on a new one.
few weeks ago it started to knock under load (even a slight load when accelerating smoothly) some times it keep on knocking even when doing steady speed of 40-50 km/h, it lasted for a few hours and it got back to normal. the next day it started knocking again, and this knocking thing kept one day on and another off, some time i can feel the engine performance change when i am at the traffic light.
i did the paper clip test and found the following:

0130 oxygen sensor
0135 oxygen sensor heater
1110 Switch over valve solenoid
0340 cam sensor

so i got new cam sensor last week, replaced it, engine performance is slightly better but the knocking/pinging did not stop.
now the codes only read the first three, the cam error is gone. i don't know about the 1110, i keep getting it each time i had a problem but it goes away when i fix all the other things.

the thing is, it some times work perfectly and all of a sudden it starts knocking, first i thought it is the knock sensor sending the wrong signal, so i disconnected it to get the timing fixed (assuming it was going back and forth) but that did not effect neither performance nor the knocking (it just registered a failed knock sensor with the codes).
i kept the knock sensor disconnected for a few days, and the behavior did not change either, some times ok some times not.

what else can i do??? my mechanic has no clue, he got me to change the fuel pump, cleaned and tested the injectors, and replaced the spark plugs. he "assumed" the problem to be in the fuel system because it tend to quit on me when it is hot as if i am running out of fuel (like 95 C, it used to run fine in this temp last summer, as the whether here is extremely hot, 55 C :S) or after a few hours drive (3-4), i give it a 2 to 3 min rest and it starts.
oh and another thing, when i first start the engine in the morning it misfires for a couple of seconds.

any ideas of what to be the problem??any tests i can do?? i ll appreciate any help, thanx in advance.

[same #same#]

it maybe a bad connections either at the ecu or in the main wiring loom, check all sensor plugs and look for white copper if there need to clean it off.

[Andy H]

I don't understand why you haven't fitted a new lambda sensor :-/

[Ali Ch]

thanks for the reply
i ll check the connections first thing in the morning....
it is hard to find new parts for any car where i live...we replace failed things with second hand parts from chop-shops, which most of the time are failed too, i tried half a dozen cam sensors and they all didn't work...i had to wait two weeks for the cam sensor to arrive to the only dealer that imports them....and i am still waiting for him to get the lambda sensors ....i have been waiting for it fore 3 months now (and he said its not genuine but from a Turkish maker) :-/....may be i ll make a trip to him tomorrow...i d like to see how the mgmt light behave when its knocking as its now always on because of it....
today it never worked properly...it kept on knocking 

[PhilRich]

Ali, update your details with a location/Country, so we can help you better? 

[Andy H]

I don't understand why you haven't fitted a new lambda sensor :-/

Ahh. I understand now I can see your location.

I suppose import restrictions would make it difficult to source a replacement

[Ali Ch]

hi again
couple of things i might left unmentioned (my bad)...
1-the car is loosing water, a 2 to 3 hours drive will get the bottle empty and it needs about 2l to fill it up....no traces of mayo any where ... so i was looking for the leek for a few weeks and keeping a spare water container in the car (did not find a thing till this morning when i was checking the wiring as samesame suggested ). the metal base of the power steering pump was wet, under the thermostat cover....i checked pipes for leek but it seems ok....i don't suppose the water can come from the head gasket???!!!!
2-the engine some time "run-on" when i switch it off...don't no if the name is correct, it does an extra cycle with a hard knock sound after the i switch it off

last year i had the head gasket blown with the same amount of water loss and no signs of mayo too....it was blown from the rear side of the engine allowing water to get into the piston chamber, and causing a lots of air bobbles in the water bottle (no bobbles this time), i read some where that head gasket can cause similar symptoms of what i am having (the knocking and run-on) :-/

regarding the results of the wire connections...no white copper....but i noticed if i unplug the knock sensor for a few minutes, when i connect it back the car runs fine for few minutes then it starts knocking again, i tried it three times, i can do about 200m before it starts knocking again :-? (the connection is clean, and i also used wd-40 on it) the last time i connected it it ran ok until i got home, don't know if it will come back but it did the hard knock (run-on) when i switched it off....so i am confused now, if those are symptoms to one thing or i am having a bad luck of a lots of failed things at once?  :-/
i ll do more detective work on the wires, may be its a cut ...

[Abiton]

The thermostat housing has an o-ring seal onto the head, this may be leaking.  Not likely if this was replaced during the last headgasket change, quite possible if it wasn't.

The running-on and pinking may be caused by the engine having run for some time (?) with no lambda/oxygen sensor info for the ECU to get the fuelling correct, thus causing carbon build-up in the cylinders.

To check for coolant going into cylinders, take out the spark plugs a few hours after the engine has run, and look down the holes with a small bright torch.  Hope not to see any coolant on any of the piston crowns.

[Ali Ch]

thanks for your reply
when i changed the spark plugs it had some carbon on it !!!!! but the mechanic (i doubt about his title) said its nothing to worry about....how can i know if it is the same inside the cylinders, and how can i fix that !!!!!

the water thing turned to be the thermostat housing....well there was no o-ring that fits it when i did the last head gasket, so we used a silicon gasket maker, and it is leaking now (was, as i just finished working on it). most of the water came out from between the rubber pipe and the lip, the lip is all corroded and salty, i cleaned it and cured it with some gasket maker but i thing i am gonna need a replacement if it leaks again

[Sixstring]

Ali......would there be many problems for you if parts could be sent out from the UK??

Many more places over here, and how about Ebay? do they send to your country??

Just trying to help you obtain a few more bits relatively cheaply and keep your car on the road where it belongs!!

Mike.

[same #same#]

dont forget engines, vectra's have same engines and a few others types, can change parts to fit on omega, carborn build up can also be low fuel pressure, but also in hot places it can be thin air so would need to be adjusted to suite,,

[Ali Ch]

would there be many problems for you if parts could be sent out from the UK??

the only problem is the coast....visa cards or similar services coast tonnes of money and comes with huge monthly fees, rendering it usable only by companies and government agencies...
i can make a bank transfer, but the min charge is 50$

and how about Ebay?

i think china branch ship to here....but i am stuck with the first problem

a friend tried a type of visa (prepaid cards, you buy, use it, and throw it away)...ordered some silly stuff (for testing) from ebay china, they told him it ll take a month to get here....i didn't ask again so i don't know if he had them or yet, it could be handy.

that leaves the coast of the shipping....i thing the options are limited (dhl, fedex,...). the coast is about 40$ per 1/2kg...that what i use when i order some expensive equipment over the net, not sure that would be useful for sensor that is a 50$ or so

now about the carbon build up...how can i make sure and what can i do?

[Abiton]

would there be many problems for you if parts could be sent out from the UK??

the only problem is the coast....visa cards or similar services coast tonnes of money and comes with huge monthly fees, rendering it usable only by companies and government agencies...
i can make a bank transfer, but the min charge is 50$

and how about Ebay?

i think china branch ship to here....but i am stuck with the first problem

a friend tried a type of visa (prepaid cards, you buy, use it, and throw it away)...ordered some silly stuff (for testing) from ebay china, they told him it ll take a month to get here....i didn't ask again so i don't know if he had them or yet, it could be handy.

that leaves the coast of the shipping....i thing the options are limited (dhl, fedex,...). the coast is about 40$ per 1/2kg...that what i use when i order some expensive equipment over the net, not sure that would be useful for sensor that is a 50$ or so

now about the carbon build up...how can i make sure and what can i do?

Check the condition of all the sparkplugs.  If they're all covered in thick carbon, you can probably assume that there's some all over the combustion chambers.

If you could run it with a working lambda sensor, that would probably burn off fairly quickly especially on a constant-speed part-throttle cruise. 

One trick which you may not be brave enough to try is to let the engine suck some water into the inlet manifold  (via a vacuum port) while holding the engine revs up (engine at full temp)  .  If any liquid water makes it to the combustion chamber it will 'flash evaporate' on contact with hot bits and knock bits of carbon off as it does so.  Not sure with the down-and-up-again design of the 4-pot omega manifold this has any chance of working. Has been known to work on other engines...

Is it possible to obtain a generic 4-wire oxygen sensor where you are, bearing in mind that it is a titania one, not the standard zirconia type, I think?

[Entwood]

An "old fashioned" way of removing carbon (de-coke) was to remove the spark plugs and put 5 cc of Upper Cylinder Lubricant (Redex) into each pot and leave to "soak" overnight. Then put some rags lightly over each plug hole and turn the engine over for 30 seconds - this throws out the oil and prevents "hydraulic locking".

Replace cleaned spark plugs and  go for a start. If it doesn't fire, take out and clean the plugs agin .. they might have oiled up. Once it fires, allow it to warm up then take for a run and "drive it like you stole it" for half an hour.

It will smoke - lots - for about 10 minutes as you burn off the carbon and UCL - so mind the wives washing !!

The idea is the UCL softens the carbon and you then burn it off/blow it out

In the days of carbs one would gently trickle UCL in whilst holding highish revs, this smoked really well   but cleaned the rubbish out nicely  - used to be called a "redex decoke" ..

[Omegafantasy]

How about SeaFoam? I see the Americans are all excited about it. Personally, I have no idea. Snake Oil?

A YouTube clip showing an example: http://www.youtube.com/watch?v=MzqohWTChwY