Car coughs at more than 2/3 throttle

almoststew1990 · 30 Dec 2018 at 18:52

Last night when driving home from the airport (after it had been sat for a week) I noticed my car would cough and judder when putting my foot down. To such an extent it wouldn't actually accelerate if you put your foot down. However it runs smoothly like normal if you don't put your foot down past this threshold. It made for an interesting drive home at 1am as I estimate I only had about 45hp available and some hills were a challenge! It would just about sit at 70mph on the flat. The speed of the engine (as in RPM) didn't make a difference, it's just how hard I pushed the throttle.

As the engine ran and started fine I assume something is limiting the amount of spark, petrol or air getting into the engine?

paradigm · 30 Dec 2018 at 19:18

My guess would be lack of fuel. So pump, injectors, rail pressure, etc.

Simon · 30 Dec 2018 at 19:25

What car ? Sounds like damp ignition leads

andy_mk3 · 30 Dec 2018 at 19:27

Which car and engine?

almoststew1990 · 30 Dec 2018 at 19:32

@Simon @andy_mk3
Golf Mk IV 1.4 Petrol

andy_mk3 · 30 Dec 2018 at 19:40

Those go have ignition leads so as suggested they could be damp.

Is the engine light on? Could in reality be any. Number of things.

Kaeo · 30 Dec 2018 at 19:47

Your own assumption is correct. Carry on with your investigations. I like to start with air intake, then move to plugs.

Simon · 30 Dec 2018 at 19:48

Did you drive it today? Hot engine may have dried things out but leads that are old will make it missfire.

Could also be a spark plug but my money would be damp especially as it’s been raining and you’ve had it parked up for a week

Meaker · 30 Dec 2018 at 22:22

Had the same and it was the spark plugs so basically either air, fuel or spark has an issue.

mccarf · 31 Dec 2018 at 00:02

When I had this a few years ago in my octavia it was spark plugs

mollymoo · 31 Dec 2018 at 08:26

I've had this happen twice. First time many years ago on a Cavalier SRI, it was the distributor cap, it just needed to dry out. Second time was a coil pack. If it has beem stood then personally I would look at the leads plugs etc.

Rroff · 31 Dec 2018 at 08:41

Notice anything different with the exhaust i.e. noticeable white or black exhaust when starting up or accelerating? so many things it could be but injectors would be high on my uneducated list.

almoststew1990 · 31 Dec 2018 at 09:40

I did take it for a drive last night and it was much better, I could put my foot down and it would only cough once or twice. Hopefully it is just something needing to dry out!

No smoke when starting our driving it. There was a normal amount of water vapour when it was cold (when leaving the airport).

Orionaut · 31 Dec 2018 at 09:58

almoststew1990 said:
@Simon @andy_mk3
Golf Mk IV 1.4 Petrol

Does this one have leads/coil pack or pencil coils?

Pencil coils are a common issue on VAG motors and can cause these symptoms.

Sometimes one can get MIL on, but not always.

IAmATeaf · 31 Dec 2018 at 19:30

Mother In Law?

Mercenary Keyboard Warrior · 31 Dec 2018 at 19:55

Fuel filter?

Certainly exactly the behaviour one of my mates had who serviced himself and never did the fuel filter. Started to cut out on full throttle and high load, changed fuel filter and it was dandy.

Skilid · 2 Jan 2019 at 13:17

My money is on plugs/leads/coils. When were your plugs last changed?

Scythe · 2 Jan 2019 at 14:04

Sounds like a misfire or fuel starvation.

Coils (particularly stick coils) are common faults, I've replaced two sets now on older cars. Remove coils are check down the rubber boot for an green grime which is indicative of corrosion. Water ingress over time causes this and results in being unable to deliver a strong current to the spark plugs.

Check coils/leads and plugs first as it's easy to access and shows visible signs of deterioration. After that I would check the fuel filter, my partner's KA was neglected and the fuel filter blocked up.

Does the engine sound lumpy? With the engine running on idle and open the bonnet. Is the engine 'shaking' up and down slightly? This is indicative of a poor ignition or misfire on a single (or multiple) cylinders.