Car 'coughing'/hesitation when driving.

JustAnotherSaver

Don't really know how to phrase it so i'll just describe it.


Wife had mentioned that there was a sort of juddering/lack of power when she was driving & i may need to clean the throttle body out (had similar with a previous car and that sorted it .... for a while). I knew this wouldn't be the issue as i cleaned it in the summer time and it doesn't get that caked in 12 months never mind 5-6 months.



So we took it on a 2 hour round trip drive, i drove & didn't experience a thing. There was one moment where i wondered if it had done it but i wasn't sure so left it.


I questioned if it was when she was at low revs (was thinking high gear, low revs) but she said not the case.



So then i took it to work which is a 25-30 minute drive. It did it twice there in the morning (quite a cold morning in case that means anything to anyone) but not on the way back.


First time it did it I was in 5th gear, dropped to 4th to get some pull, i was probably at 50-60mph when it did it and it was only for a half second or so but it felt like i was being pulled back. Like the car was coughing/hiccuping kind of thing. After this half second or so it was fine and the drive was smooth.


A couple minutes later i'm now coasting at about 65-70 in 5th gear and it does it again. Not quite as harsh as earlier but it still does it.


Didn't do it for the rest of the drive or the drive home. It had warmed up by that point but obviously not shorts & T-shirt weather (again, in case the temperature makes a difference to any of this, though doubt it).


Any ideas on what to start looking at in some sort of check this first, then try that kind of order of likeliness?

Any further info required just ask.

daveyjp

Basic info such as car type, age, fuel would be very useful as starter for ten!

JustAnotherSaver

daveyjp wrote: »

Basic info such as car type, age, fuel would be very useful as starter for ten!

Sorry i didn't think it would be a vehicle specific thing & would just be something that could happen to any vehicle.



Astra H on an 07 plate but the Z16XEP engine and not the Z16XER.
Petrol.


Again, anything else you need then just ask.

Inner_Zone

daveyjp wrote: »

Basic info such as car type, age, fuel would be very useful as starter for ten!

Probably the one with the ongoing fuel leak:


https://forums.moneysavingexpert.com/discussion/6084775/keep-smelling-petrol

Ant555

My (28 year old) mx5 did something similar - occasional hesitation or missing when accelerating under certain loads and it was the spark plug leads - very cheap and easy job to swap them and it fixed immediately.

Hope this helps.

Scrapit

Petrol engines have a basic function. Fuel, air, spark. A lack of all or any will cause problems.Check those first.

JustAnotherSaver

Inner_Zone wrote: »

Probably the one with the ongoing fuel leak:


https://forums.moneysavingexpert.com/discussion/6084775/keep-smelling-petrol

No. It's the one in the post before yours. This is where going thread digging can bring up bad info.

Ant555 wrote: »

My (28 year old) mx5 did something similar - occasional hesitation or missing when accelerating under certain loads and it was the spark plug leads - very cheap and easy job to swap them and it fixed immediately.

Hope this helps.

On one of these is that the coilpack then or is that something else entirely? I don't think there are any leads as such to the spark plugs. I remember photos of old engines and like a sea of wiring but that isn't the case here.

Scrapit wrote: »

Petrol engines have a basic function. Fuel, air, spark. A lack of all or any will cause problems.Check those first.

Well it has juice with no leak. For some reason Vauxhall/GM thought it a good idea to have a lifetime fuel filter on these cars so i can't really change that without great cost which would also require the whole fuel tank being changed too IIRC.


I don't think the air intake or even filter are in bad nick. I change the filters in line with the recommendation.



Which would then bring it to the spark - and to be honest i can't remember if i've ever had these changed on this car or not. I'd have to dig out paperwork but i think we bought it towards the end of 2017 and if i had to place a bet then i'd say no i haven't actually changed the spark plugs on this car.



Car has done 95-97k miles.


Would you reckon that would be a good place to start (changing the spark plugs)?

tberry6686

At that mileage it is more likely to be a coil pack breaking down than spark plugs.

It is possible that the coil packs are mounted straigt onto the spark plugs rather than connected by leads.

JustAnotherSaver

tberry6686 wrote: »

At that mileage it is more likely to be a coil pack breaking down than spark plugs.

It is possible that the coil packs are mounted straigt onto the spark plugs rather than connected by leads.

Thanks for the advice


Looking at EuroCarParts (always risky. Wouldn't be the first time i've had an incorrect part sent out that's apparently for my reg) the cheapest would be about £85 https://www.eurocarparts.com/p/haas-ignition-coil-413720321 Goes up to near £150 for other brands.



Great if it works, costly if it doesn't & was never the trouble.


I've plugged in op-com and as far as DTCs go - there is none.



Maybe if you actually go off some readings for specific things you could start identifying issues but that's beyond my capability with op-com.


What the Z16XEP looks like. If it's anything like my Z18XE engine then the spark plugs will be underneath that ecotec plate.

Inner_Zone

JustAnotherSaver wrote: »

No. It's the one in the post before yours. This is where going thread digging can bring up bad info

So can not giving the info in the first place.


Not Mystic Meg so had no idea a second car was involved.


As above it's probably the coil pack but on some engines the HPFP can give the same or similar symptoms.

JustAnotherSaver

Inner_Zone wrote: »

So can not giving the info in the first place.

Ok i'll give you that. As i explained though, i thought this would be just a general mechanical issue and not car specific. I know a small bit about cars but don't pretend to know a lot.

Not Mystic Meg so had no idea a second car was involved.

You don't need to be mystic meg though. The answer was right there. If our posts were at the same time or a minute or so apart then i could give you that also but they were 10 minutes apart. I make long posts but that one with the answer to the question was short. You scrolled beyond the OP to see daveyjp's answer which was a small post so you must've seen my follow up too.

As above it's probably the coil pack but on some engines the HPFP can give the same or similar symptoms.

Is there an easy test to determine whether it's the coil pack or fuel pump or is it a case of replace one and see if the problem continues?