My astra has been causing me some grief for some time now and has slowly been getting worse. It started out that about once a month the engine management light would come on at start up and the car would run in limp mode until i turned it off and started it up again, however this has been becoming more and more frequent. I have had several garages look at it, all of which have given me the car back having failed to rectify the problems, I don't have the cash to go to vauxhall so I was hoping someone may have experienced a similar problem and/or may be able to help shed some light on what may be wrong as it is killing me to repeatedly keep spending time and money only to find the problem has not been cured. Below is a list (or more like an essay) of what's up and what's been done..... any help would be greatly appreciated!!
Astra G 2.0 16v SRI 2000 (W)
Intermittent engine management light running in limp mode
Low oil pressure, light illuminated @ start up and low idle. (below 1500RPM)
Noisy tappets on start up..
Varying levels of performance (it feels like you need to keep pressure up in the engine for it to run well)
Leaking coolant from somewhere towards the rear of the engine block.
Work carried out by me
Oil and filter changes with both thicker and thinner oil.
Engine flushed numerous times.
New hydraulic tappets fitted.
Replaced timing belt.
Replaced fan belt.
Removed oil sump and cleared pick up pipe strainer.
New spark plugs and leads.
New exhaust manifold, original was cracked, some level of noise cured but not the actual tappet noise.
Oil pressure release valve spring attempted however spring provided by Vauxhall was an inch longer; original spring looked to be in good condition.
Flush followed by oil and filter change from Vauxhall.
Work carried out by A&K Auto Electronics
Diagnostics read by A&K indicating a fault from the cam shaft sensor.
Replaced cam shaft sensor with several aftermarket sensors (4 in total) none of which registered with the ECU.
A Vauxhall sensor was fitted and worked however the engine management light came on straight away.
Vauxhall sensor removed and original refitted.
Wiring to and from sensor tested and replaced although does not look awfully professional as it has been patched in halfway down the original wire and not taken the full length of the wire.
ECU had a software upgrade no idea what exactly.
Ideas as to what may be wrong
The engine management light has been coming on with increased frequency, I have managed to work out that if it comes on you have to drive approx 200 yards in second gear up to about 25/30mph then let the engine slow the car at which point you can switch off, wait a second then start it up with a good rev and the light will go off. You cant just rev it you have to drive it and when driving it you can tell when you have oil pressure as the car feels smoother.
Since I changed my oil for Vauxhall 10 /40 the oil pressure seems to drop if when stopped at traffic lights etc the oil pressure light comes on but a rev of the engine turns it off, which is strange because I previously had thinner 5/30 fully synthetic in. I would have thought thinner oil would drain quicker than thicker.
Also when driving even if the engine management light is not on now and again you can feel that there is something wrong with the oil pressure especially when changing gear; you often get a dip in power until pressure increases which is also apparent when accelerating from low revs.
Oil pump failure.
Oil pump primer faulty.
Pressure release valve.