Car trouble - jerking/misfiring

[R13...]

So my trusty (and rusty) '09 corsa utility jerks and sometimes needs a gas boost when starting in the morning. So far I've,
- checked fuel filter (fine)
- air filter (replaced)
- took it into a workshop where they claimed some of the connections on the fuel tank weren't fitted properly and leaked. Tank removed, issue allegedly sorted out and tested.
- above workshop say nothing wrong with other fuel systems (their word)

But the car continued to make jerking motion when I apply gas, and especially in traffic where it appears to threaten to stall. When changing the air filter, we revved it up and a popping sound can heard every now and then coming from the air filter.

I'm at my wits end here. Anyone have any idea what could be the issue here? And oh, the workshop don't think it's the fuel pump but some backyard mechanic who was present during the air/fuel filter change thinks it may be the issue.

 

[PhireSide]

It could be the mass airflow sensor misreading and giving incorrect fueling values back to the ECU. The part shouldn't be too expensive to replace, but they can also be cleaned (VERY carefully) with the correct type of cleaner. They are quite delicate so replacement is usually the better option.

It should look similar to this:

They normally have a mesh that voltage is applied to to keep it at a certain temperature. By measuring how much amperage must be sent through the mesh to keep a stable temperature, it can calculate how much airflow is running through the intake manifold and adjust the fuel flow accordingly.

Sometimes carbon and other contaminants build up on this part and cause incorrect readings, which can lead to overfueling or underfueling in some cases.

 

[Nemus]

Sorry, might be duh but, did they change the sparks?

 

[longboy]

Check spark plugs - sounds like misfire.

 

[R13...]

It could be the mass airflow sensor misreading and giving incorrect fueling values back to the ECU. The part shouldn't be too expensive to replace, but they can also be cleaned (VERY carefully) with the correct type of cleaner. They are quite delicate so replacement is usually the better option.

Interesting, will look into that next.
Would that cause an issue where you need to apply gas if the car is parked in the cold overnight?

 

[R13...]

Sorry, might be duh but, did they change the sparks?

Check spark plugs - sounds like misfire.

No, they didn't but those were changed a year ago. Didn't think they need changing that often? But I did tell the workshop to check those as well, but can't really trust them.

 

[longboy]

If you can rule out sparks then try changing the fuel pump as a last resort. Jerking and misfiring is usuallly a fuelling issue or an air issue. You've ruled out the air filter so it's probably the pump, if not the mass airflow sensor.

 

[R13...]

Suppose I can eliminate from cheapest to most expensive. Still don't get why it struggles to start in the morning though, that sounds weather related and surely can't be fuel related.

 

[ArmatageShanks]

Also have a look at the coil pack and make sure you have no leaking spark.

 

[PhireSide]

Interesting, will look into that next.
Would that cause an issue where you need to apply gas if the car is parked in the cold overnight?

I am not too familiar with GM vehicles, but usually there will be a few sensors that will determine how much fuel to apply when starting:

TPS, or throttle positioning sensor which checks how far you have the throttle applied, if at all. This usually determines what fuel map to apply, ie. a lean map for coasting or a rich map when accelerating

Idle air control valve, which is a separate circuit that runs when your car is idling to make sure that it doesn't stumble when the revs drop to the idle range

Fuel Injection system as a whole which will sense the current inlet air temp and engine temp and adjust fuelling accordingly so that enough fuel can ignite and vaporise to enable the engine to run

Crank Sensor, which determines when to send fuel into the cylinder and when to fire the spark plug to ignite the air fuel mixture

I'd ask the mecchie to check spark plugs, HT leads and coil packs as suggested above as well before heading down the route and replacing other parts.

A code scanner may also help in finding any abnormalities with the control system. Again, I am not sure if GM vehicles use a certain protocol but most Eastern cars use the standard OBD protocol. Others, like VAG, have a different protocol that requires a specific type of scanner to be able to decode the data into a readable format.

 

[longboy]

Suppose I can eliminate from cheapest to most expensive. Still don't get why it struggles to start in the morning though, that sounds weather related and surely can't be fuel related.

Starting issues in the morning can be a bad battery. I once had a litre less of oil in my car through neglect and that also caused starting issues.

 

[R13...]

Starting issues in the morning can be a bad battery. I once had a litre less of oil in my car through neglect and that also caused starting issues.

Definitely not battery - I've had that before (actually running on a relatively new battery).

 

[TheChamp]

Suppose I can eliminate from cheapest to most expensive.

Do that, those are very reliable engines, and the problems are often very predictable if there isn't too much fiddling. check the idle control valve and clean, probably filled with soot if you have never cleaned it, the MAF if there is one, Coil pack and leads, also check the vacuum hoses for cracks.

 

[namzsteve]

If you can rule out sparks then try changing the fuel pump as a last resort. Jerking and misfiring is usuallly a fuelling issue or an air issue. You've ruled out the air filter so it's probably the pump, if not the mass airflow sensor.

Look at the throttle body too maybe.

 

[gregmcc]

Jerking and misfiring won't solve your car troubles. You need to see a sex therapist

 

[SauRoNZA]

On a Corsa previously due to their silly spring loaded nonsense on the spark plug leads I had a case where it wouldn’t make and stay in contact.

Car would be fine one day, then you go over a speed bump or something and it starts it’s ****, then on another it’s fine again.

This sounds suspiciously similar.

 

[Big Rat]

My mom's Kadett 160Is did the same. Turned out the throttle position sensor and idlecontrol valve.
Car has same symptyns as you. I sprayed carb cleaner into the tiny hole for Idle, then gently whacked the TPS and ICV. CLeared right up. That is why i mention both of those. the litle whack could have cleared the valve or sensor.

 

[Stokstert]

Here is the thread "The Corsa problem solver" which might help you find an answer to your problem.

 

[TheMightyQuin]

No, they didn't but those were changed a year ago. Didn't think they need changing that often? But I did tell the workshop to check those as well, but can't really trust them.

Check the plug leads. Wear and tear is not always obvious on them.

Start with the cheapest and easiest stuff first.

 

[RonSwanson]

The symptoms sound exactly to my own experience with a 1.3 Corsa a few years ago, when a friend inadvertently filled her fuel tank with diesel instead of unleaded. She filled up, and managed to drive the vehicle to my place, arrived all coughing and spluttering. The problem was especially noticeable when accelerating hard. The service station admitted that a tanker had filled the wrong tank the night before. Flushing the tank and the fuel lines, and replacing the filter ironed out the problem. She was her old smooth self again, despite the extra "upper cylinder lubricant".