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Corsa lite jerking when accelerating
- Thread starter Casz
- Start date
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- corsa lite gasket jerking
As is classic in this forum and for mechanics in SA, everyone throws ideas out that make perfect sense because they are all possible problems that *could* lead to those symptoms.
However I don't see any indication that any testing was done.
Engines take fuel and air, compress it then ignite it. The last part of this equation is timing.
Typically a mechanical check of the engine will show if it is getting the air it needs and compresses said air.
If the compression is gone, a compression test will reveal it. If the cam and engine are misaligned it can be verified mechanically.
If those two aren't a problem then the air part of the equation is sound and there is no point skimming the head and what not.
Second ignition, really the simplest way to test this reliable, in my opinion, is to measure O2 from the exhaust. If the ignition failed there will be O2 rich exhaust. For this a wide band O2 sensor is needed but they really aren't cheap.
I mean there are other ways to test it, like if it happens all the time, you can disconnect each HT lead, put a spark plug in and see if it fires, but this isn't a reliable test for many reasons.
So most people opt to just go ahead and replace the coil pack and HT leads on a Corsa because they are notoriously bad.
That said, if you call yourself a mechanic, there is no way you just replace things because that is what an amateur does and not a professional.
Next up testing fueling. The only reliable way to test this is to verify the injectors still squirt the right amount of fuel and verify the fuel pressure under high engine load.
The last part is timing. The amount of fuel injected and ignition are controlled by an onboard micro controller called the "ECU". It uses sensors to determine how much fuel it needs to add and when to fire the spark.
Testing it is not trivial and beyond the scope of a general mechanic.
On a Corsa, changing out the ECU and the engine harness is a 2 hour job. I would test it that way (including the sensors).
Obviously buying all of those is beyond the means for anyone that owns a Corsa. So you would hope the mechanic has what is needed to do this and then figure out which are the actual unusable components.
In order of likely:
1) Coil pack + HT leads + spark plugs
2) Mechanical issue such as misaligned crank wheel (60-2 wheel) or loss of compression.
3) ECU related sensor (especially if you or someone else have been "working" on your engine in any way). I don't care how good you are, the Corsa harness is a piece of crap and if you mess with it, or the sensors, they become unreliable.
4) Fuel injectors or fuel pump.
People tell me Corsa fuel pump failures are common. I have never, ever seen one. Except when someone "suped up" their car or tried to replace the fuel pump.
Obviously I assume you've replaced your fuel filter, air filter and spark plugs before even coming on this forum.
Lastly, if you recently ran out of fuel or you commonly run out of fuel, move injector and/or fuel related problems up to 2nd place.
However I don't see any indication that any testing was done.
Engines take fuel and air, compress it then ignite it. The last part of this equation is timing.
Typically a mechanical check of the engine will show if it is getting the air it needs and compresses said air.
If the compression is gone, a compression test will reveal it. If the cam and engine are misaligned it can be verified mechanically.
If those two aren't a problem then the air part of the equation is sound and there is no point skimming the head and what not.
Second ignition, really the simplest way to test this reliable, in my opinion, is to measure O2 from the exhaust. If the ignition failed there will be O2 rich exhaust. For this a wide band O2 sensor is needed but they really aren't cheap.
I mean there are other ways to test it, like if it happens all the time, you can disconnect each HT lead, put a spark plug in and see if it fires, but this isn't a reliable test for many reasons.
So most people opt to just go ahead and replace the coil pack and HT leads on a Corsa because they are notoriously bad.
That said, if you call yourself a mechanic, there is no way you just replace things because that is what an amateur does and not a professional.
Next up testing fueling. The only reliable way to test this is to verify the injectors still squirt the right amount of fuel and verify the fuel pressure under high engine load.
The last part is timing. The amount of fuel injected and ignition are controlled by an onboard micro controller called the "ECU". It uses sensors to determine how much fuel it needs to add and when to fire the spark.
Testing it is not trivial and beyond the scope of a general mechanic.
On a Corsa, changing out the ECU and the engine harness is a 2 hour job. I would test it that way (including the sensors).
Obviously buying all of those is beyond the means for anyone that owns a Corsa. So you would hope the mechanic has what is needed to do this and then figure out which are the actual unusable components.
In order of likely:
1) Coil pack + HT leads + spark plugs
2) Mechanical issue such as misaligned crank wheel (60-2 wheel) or loss of compression.
3) ECU related sensor (especially if you or someone else have been "working" on your engine in any way). I don't care how good you are, the Corsa harness is a piece of crap and if you mess with it, or the sensors, they become unreliable.
4) Fuel injectors or fuel pump.
People tell me Corsa fuel pump failures are common. I have never, ever seen one. Except when someone "suped up" their car or tried to replace the fuel pump.
Obviously I assume you've replaced your fuel filter, air filter and spark plugs before even coming on this forum.
Lastly, if you recently ran out of fuel or you commonly run out of fuel, move injector and/or fuel related problems up to 2nd place.
rietrot
Honorary Master
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+1 above. If your backyard macanic just start changing out parts for no reason he is a crook.
Feul pump is also a common problem for corsas, check the feul pressure and then it should be about R1000 for a new pump and 30 mins of work to install it
Feul pump is also a common problem for corsas, check the feul pressure and then it should be about R1000 for a new pump and 30 mins of work to install it