Fault code P0300 on TS Astra 2.2 - vibrating at higher speeds!

Driver78

Member
Got my Astra SRI 2.2 two and a half years ago with 80k on the clock and no problems whatsoever up until a couple of months ago – only a few days after getting a service the engine won’t start. Battery on its way out it would seem so I get the roadside mechanic to give me a jumpstart. Car is revived however I get the dreaded emissions management light on the dash, never seen it before but the car is driving fine so initially I don’t panic.

(Notice also that i need to keep the electric window button depressed to close the driver's side window and the cruise control is not working)

Anyhow I knew the car had to go back into the shop to get the front shocks replaced (and mounds and brake discs and pads too it turns out) so I get them to check the fault code while they are at it.

P0300 is the fault – Random/Multiple cylinder misfire.. As far I know the car has never misfired though I am no expert it seems like something I would have noticed had it actually happened. My Mechanic agrees, reckons he can’t find anything wrong and that the engine is running beautifully, he even changed the spark plugs and cleaned out the throttle housing in the hope that would fix the issue. Unfortunately within 2 minutes of leaving the shop the EML comes back on.

I drive the car on and off for about 2 weeks and monitor the engine, but notice no problems, even with the EML randomly flashing on the dash, occasionally it would stop flashing but remained illuminated.
Then I get another flat battery. The roadside assistance mechanic says the same thing as the last guy, reckons every TS Astra gets ECU problems around 100,000kms and that I should have bought a Japanese car instead.

At this point I discover this website and all the other ones and have tried desperately to find a solution to this problem. While I notice that everyone else with this car is pretty much dealing with the similar issues I can’t seem to find anyone else with problems that match mine exactly.

As I live in Sydney and don’t get out of the city much I rarely get above 60kph. Finally I get on the freeway and get up to 80kph which is when I notice the engine struggling a bit, I’m getting vibrations from the front end as I can feel it in the throttle and steering. Basically, the engine is not stopping me from going faster but it is certainly reluctant and I get the feeling it wouldn’t be a good idea. This happens literally a day after getting a new battery, new tyres and the obligatory balance and alignment so the vibrations can’t be from the wheels.

I take the car back to the mechanic for a new alternator, genuine of course and decide we should try a new coilpack too, also genuine. Still no joy getting rid of that light though and the same fault code P0300, every bloody time.

Then we remove the ECU and all its bits and send it away for testing and reprogramming. I ask him whether it could be the EGR valve or cat, he reckons they should be fine so I now find myself without a car for 2 weeks while the ECU takes a trip to Melbourne.
According to Holden the ECU is fine but I pretty much expected them to say that, just wish it didn’t cost me another $800 to find that out.

I’m still getting the wobbles and lack of power above 80kph and then, under hard acceleration, I notice sudden and complete loss of power for a split second, followed by a rather unpleasant bunny-hop as it kicks back in again a moment later. Now I am genuinely concerned. This happens again the following day but at a lower speed under normal acceleration, and after it kicks back in the throttle seems to be more sensitive, like I suddenly gained an extra 20 horses. At this point I buy an OBD2 adaptor and I start running Torque on my Nexus 7 whenever I drive so I can clear that code and monitor my engines behaviour in realtime. Still no new clues though.
I purchase a blanking plate and cheater (thanks guys!) and did this particular job myself a couple of days ago. The engine is now running a lot better. More power and sounds better too, and acceleration has been smoother than ever. The EML is still coming back with the same fault code of course but it is staying off for longer periods now. I almost thought it was gone for good today when I drove for nearly half an hour without it coming on, but alas, there it is again for no particular reason it just keeps turning back on whenever it feels like it. Such a shame as the engine really is feeling so much better, though I did get it up to 100kph and experienced the same shuddering coming from the engine as well as that awful flatspot followed by bunny-hop.
I am not sure what to make of these symptoms. Injectors? Pre-cat? Timing chain? I’ve had a timing chain go before – not pretty and I really don’t want that to happen to this car, I love driving it and I have spent a small fortune on it in the past 2 months so I absolutely want to get to the bottom of this, but at this point I am out of ideas and hoping for some advice before I take it back to the shop.
And sorry about the length of the post, thought it best to give you all the details up front.
 

Driver78

Member
Nope. Always 98 octane when I fill the tank, and the previous owner was a close friend who only used 98 too. the owner before him had the car for the first 45000kms probably didn't though when you consider that the manual suggests 91 as a suitable option. My mechanic asked me the same thing after he checked the fuel tank in desperation looking for an answer. He did find some dirt in there so he cleaned it out and suggested that if I brought it back with the engine light still on that it might be time to have at look at the injectors. He has only worked on a couple astras before though .

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MikeS

Former Staff
Senior Member
drop the cat to see if it is blocked

if it is not electrical then think mechanical

p0300 does not mean anything
 

evocarlos

Stupid Bollocks
Staff
your windows will need resetting after the battery is removed to make them auto up and down
how to:-
sit in car with the door closed
turn ignition on wind both windows down and hold for 4-5 sec once there at the bottom
then wind them all the way back up
they should now work again with the one touch
have to do this with mine every time i mess lol
 

Driver78

Member
The fact I keep getting this particular fault code has always been the issue, as there hasn't been any misfire to speak of so therein lies the difficulty - how to track down the cause when the fault explanation bares no relevance?
Just last night I did a get new fault amidst the all the usual P0300 s -
P1404=Egr closed/heated catalyst voltage too high.?! So I'm thinking that cheater I fitted is faulty and I really dont want to put that egr valve back on. However I drove for well over an hour this morning without getting it again, just the usual misfire fault as per usual - with no new egr/cat faults displayed I'm asumming its fine and I'm hoping it continues to do its job.
Guess its time to have look inside that cat, though. When I think about the way my car is behaving it seems reasonable to assume that a blockage in that region would be the culprit. Certainly beats replacing injectors like my mechanic suggests.

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Driver78

Member
Still no change to the current problem though I haven't done anything that would solve the issue, only done some mods to improve efficiency and performance (de-restrict air - box, installed K&N panel filter).
The car is still shaking and vibrating when I get above 80kph and it is still randomly bunny-hopping whenever it seems to feel like it. Its only a single hop too, at any speed and whether accelerating, decelerating or even idling it doesn't matter it just appears randomly. Really hate it when it happens when I'm accelerating, the sudden jerk back and then forwards is enough to give me whiplash and at lower speeds it's obviously not as severe. I've been all ready to look at the pre-cat but I have no garage, only on- street 45° angle parking and its far from flat too. Not to mention live on a busy intersection so opportunities get under the thing are almost non - existent, plus it seems to rain every farkin' weekend! Back to the shop is starting to seem like the only option but after spending an obscene amount on it in the past couple of months I'm not too keen on taking it back there. Not to mention its due for a new timing chain as its past 105k on the clock (which has decided to stop working ever since I pulled the cluster to replace a bulb).
On the upside, when it's not misbehaving the car is actually going very nicely since working the airbox, loving the new throttle response I must admit. To be continued..
 

Driver78

Member
Not yet unfortunately, the pre-cat is still unsighted and it wouldn't surprise me if that's the problem. Would I be right in thinking that as I accelerate over 80kph the rate of exhaust flow increases but with that busted pre - cat getting in the way the process is disrupted and the shaking and vibrating is the result? I'm starting to hope so because anything else will probably be a bigger pain in the arse.
 

Driver78

Member
Checked pre-cat, no problems in there but removed it anyway. Changed all filters and cleaned out everything from that I could get my hands-on and still that abrupt flatspot whenever appears it feels like it. Can't seem to find any constant factor to be present whenever it occurs. And she still wobbles like mad around 90-100kph, but will also behave itself at that speed sometimes, in high or low revs. Still scratching my head but forever plugging away at it.
Hoping to take it on a 12 hour drive north in a week or so but wont be going far if it keeps on shaking all the way up the highway
 

Driver78

Member
Haven't looked at the ecu myself but the last trip to the mechanic was 3 mths ago and the ecu was removed and sent to Holden in Melbourne for fault testing. Of course they found nothing wrong with it, re-programmed it and sent it back to my mechanic with an invoice for $800.. That was back when the eml light was topping the list of annoying things wrong with my car. The flatspot/bunny hop was evident back then but wasnt strong enough or frequent enough to raise too much concern, now though its becoming a regular feature and strong enough to give me whiplash if I happen to be on the throttle when it appears.
As for the shaking/vibrations, they never emerge until I'm above 80kph - though I rarely find myself driving at this sort of pace though as I'm yet to take the car on a long journey out of the city in the 2.5 yrs since I took ownership of her.
And I doubt 2.5 years of stop/start city traffic has done her any good, must be dying to see some open road.
Some slight damage around the grill and front bumper, courtesy of some anonymous dickhead had me wondering if the bumper was loose enough to cause the high speed shakes but I inspected it and secured it enough to know that its not to blame
 
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Stu66

Member
Holden also sell a factory blanking plate, that just needs to be followed up with a ECU re-program. This might solve your problem.
I recently did a full head/timing&balance chain kit etc etc replacement (without this forum wouldn't been impossible for this desk-jock I might add), which also included cleaning everything including throttle and injectors etc along the way; anything dirty, I spit polished it :). Anyway, she ran perfect for a few weeks after getting it all back together, but then I was getting a similar baulking of revs and random EMS light and suspected the EGR; a diagnostic confirmed with EGR code, and the mechanic (ex Holden dealership mechanic with 20+years) produced a Holden notice which indicated the EGR was not required to be replaced if faulty, as the engine meets all AUS emissions controls without it, and that a factory blanking plate can be fitted (which I did - AU$28), but the ECU must be re-programmed to run without the EGR (which I did - AU$240); no more problems with baulking revs, EMS light or error code.
 

evocarlos

Stupid Bollocks
Staff
Holden also sell a factory blanking plate, that just needs to be followed up with a ECU re-program. This might solve your problem.
I recently did a full head/timing&balance chain kit etc etc replacement (without this forum wouldn't been impossible for this desk-jock I might add), which also included cleaning everything including throttle and injectors etc along the way; anything dirty, I spit polished it :). Anyway, she ran perfect for a few weeks after getting it all back together, but then I was getting a similar baulking of revs and random EMS light and suspected the EGR; a diagnostic confirmed with EGR code, and the mechanic (ex Holden dealership mechanic with 20+years) produced a Holden notice which indicated the EGR was not required to be replaced if faulty, as the engine meets all AUS emissions controls without it, and that a factory blanking plate can be fitted (which I did - AU$28), but the ECU must be re-programmed to run without the EGR (which I did - AU$240); no more problems with baulking revs, EMS light or error code.
vauxhall did mine for free while it was under warranty blanking plate and deprogram the egr :) i requested it and told them it was sure to become faulty
 
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