[Corsa B 1993-2000] Corsa B, jerky behaviour.

[emtor]

1997 Opel Corsa B, X12SZ engine.
Bought the car a couple of days ago for my better half and drove it home.
During acceleration I noticed a little jerk, then one more after a few miles. This went on for a while and the engine ran smoothly for more than 300 kilometers after that. (Yes, long distances in the north of Norway).
Went for a short trip the next day and the jerking became worse. It's just like the engine hesitates for a second or two and then makes up its mind to act as its supposed to.
I've checked the spark plugs. All plugs are fine having a light brown colour.
The spark plug leads look like they've seen better days.
Did the paper-clip test and no fault codes have been stored.

This morning I started the engine and opened the bonnet and listened to it running. It goes like this:
"mmmmmmmPOPmmmmmmmmmmmPOP-POPmmmmmmmPOP" and so on.

When pushing the accelerator gently from idle the engine revs up nicely, but when pushing it hard the engine runs very rough for a second or two and then it revs up in a normal fashion.
I tried disconnecting the MAP-sensor while the engine was running, and it stalled right away. Diconnecting the MAP-sensor showed up quite as expected when reading out the fault-codes (code 34). This should indicate that the MAP is OK. The fault codes has then been erased.
I've checked the throttle housing on top of the engine and it is clean. Read somewhere that dirt and oil here can mess things up.
There's two large hoses going into the air-box, one has a hose clamp, the other one hasn't. Also there are hose clamps missing on the smaller rubber hose going from the engine to the air-box. -How sensitive are these engines when it comes to air leaks? My Audi Quattro won't even start if it is presented with even the smallest air leak, but as for the Corsa engines I have no idea how sensitive they are. The engine starts and runs fine even when the air-box is removed.

[Taurus]

On the 1997 model it can be either the distributor ignition or the DIS module type. In either case make sure the HT leads are good. Poor leads will give the kind of problems you refer to due to weak sparks. On the distributor type of ignition also check the distributor cap and the rotor arm inside it. The cap, rotor and HT leads are worth replacing every 50k miles (no idea what that is in kilometers).

They don't like air leaks any more than any other engine.

[emtor]

Thanks for replying.
It's got a DIS.
The previous owner is a competent mechanic, but things like new spark plugs, leads and fuel filters etc. is not within his vocabulary.
I've ordered new spark plugs and leads and I'll dismount the DIS to ensure it is clean (inside HT-lead connections and grounding).
My better half is worried that this car is just waiting for to break in half at any moment, but I've told her that anything mechanical that left the assemblyline in good working order can be restored to its original state. So too with this car.
The Corsa is a nice car for town use and this one isn't petrol hungry at all.
I'll keep the forum posted as soon as the plugs and leads arrive.

50.000 miles equals 80.000 km.

[Alanco]

Your better half thinks youve bought her a crap car

good luck with that

[emtor]

Our better halves ALWAYS think we bought them crap cars, unless of course the interior is coloured pink.

[emtor]

Spark plugs and cables are on the way, so while waiting I removed the aluminum tubing that sorround the spark plugs.
Spark plug on cyl. 4 was dry and sooted, much more than the others. It turned out the cables for number one and four didn't seat properly.
A little squeeze with a pair of pliers and all the plug leads seats properly now. Much of the behaviour with stumbling when flooring the accelerator is gone now, which leads me to believe that new spark plugs and leads will make a big difference.
Also the mmmmmmmmPOPmmmmmmmmPOPmmmmm-sound is pretty much gone when it's idling.

[Vegas]

Tell her to buy her own cars :/

[emtor]

In either case make sure the HT leads are good. Poor leads will give the kind of problems you refer to due to weak sparks.

Spark plugs and HT-leads arrived today. Started the car and floored the accelerator . . . real hard,-several times. No hesitation or rough running. No pops when the engine idles. It runs smoothly as butter. Took it for a short trip and no jerking, responds nicely when accelerating. I've also put on hoseclamps where such were missing and I've blinded the EGR-valve. I do expect the car to run nicely for a good while now. Next thing is an oil and filter change plus a new air-filter and fuel-filter and a new fan-belt.

[Taurus]