UK Sonata V6 / 2000 engine suddenly feel underpowerwed and juddering from standing start

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Peter

UK Model, Sonata V6 / Year 2000

My car has suddenly lost some power and when pulling away from a
standing start.

It exhibits a shuddering which is also noticeable just by revving the
engine. At over 1500rpm the shudder is barely noticeable but there is
nevertheless a significant loss of power in the vehicle.

As a wild guess it seems like some of the cylinders are not operating.

Can anyone advice on possible fault scenarios?
 
Peter said:
UK Model, Sonata V6 / Year 2000

My car has suddenly lost some power and when pulling away from a
standing start.
Click to expand...
Have Your Sonata TCS? If so, may be it had worked, control if the TCS lamp
is blinking next time.
 
UK Model, Sonata V6 / Year 2000

My car has suddenly lost some power and when pulling away from a
standing start.

It exhibits a shuddering which is also noticeable just by revving the
engine. At over 1500rpm the shudder is barely noticeable but there is
nevertheless a significant loss of power in the vehicle.

As a wild guess it seems like some of the cylinders are not operating.

Can anyone advice on possible fault scenarios?
Click to expand...

Any CELs?
 
Have Your Sonata TCS? If so, may be it had worked, control if the TCS lamp
is blinking next time.
Click to expand...

Yes I have TCS and I tried switching it off without any change. But
the fault exists even if I rev the engine and the car isn't moving.
 
Blown head gasket?

Yikes. that's quite serious, no? I have done about 2 hours driving
with the car in this condition and am now concerned that I may
seriously damage the engine.

Is there a simple way to check for a blown gasket? The plugs seem
really difficult to reach on this engine.
 
I don't think I'd jump to any conclusions. So far, it sounds like a
misfire caused by plugs, wires, or injectors, but you're unable to
describe it well enough for us to really understand how it feels. How the
car actually feels will be the number one source of direction for a tech
that has no other indications. You may want to consider taking it to the
shop for diagnosis.
 
I don't think I'd jump to any conclusions. So far, it sounds like a
misfire caused by plugs, wires, or injectors, but you're unable to
describe it well enough for us to really understand how it feels. How the
car actually feels will be the number one source of direction for a tech
that has no other indications. You may want to consider taking it to the
shop for diagnosis.
Click to expand...

Appreciated! My paranoia was overtaking me. It's a really nice car and
its engine was so running so sweetly, I just hope I haven't damaged
it.

The thing is that I am pretty technical but not in the field of modern
car engines so my diagnostics skills are sparse. I removed one of the
easily accessible spark leads while the engine was running and noticed
no audible difference in the engine. Then with the engine stopped I
looked at the oil and that seemed dark and clear and there were no
traces of gunky residue on the oil filler cap.

If you can direct me further with questions I am sure I could locate
the problem.
 
Peter,
I have the '99 model Sonata (UK) I had similar problems and it was a plug
lead which I suspected myself, and would normally have replaced myself in
the past on other cars I've had ,along with the plugs, these are the most
common causes of a misfire like you describe.

But one look at what was involved for a novice like me and I took it to the
local dealer !!
One word of advice, if it is a lead get them to replace them all.One of
mine went ,and within 2 months another went, getting at the back ones is
labour expensive, so you may as well get them all done in one go, cost me
about 70 quid to get the three back ones done including labour.

We had bother with the crank sensor too. This involved the car refusing to
start now and again and erratic tick over speed and juddering, it also used
to cut out, if you knocked the engine off and restarted it usually sorted
the fault but it soon returned. Hopefully this is not the problem as this
was expensive. It does sound more like the plugs or leads though.
 
Pull the three leads you can access off the plugs but do not remove them
from the holes. Place them back on the plugs but do not snap them on.
Start the car and gradually pull the wire off the plug. If the wire is
arcing in the hole, you should be able to see it jump through or off the
plastic as it gets far enough away from the plug to cause the spark to
jump elsewhere.

The two main causes of failure are carbon tracking on the outside of the
plastic and a small hole in the plastic allowing the spark to exit.

Of course if it's one of the rear cylinders, you are counting on a
significant job. I figure it's not since you've already found a lead
which has no effect when pulled. If the others all slow the engine and
one doesn't, then that's the cylinder you should investigate.

If you're around 100k kilometers, you should probably replace all the
plugs and wires.
 
UK Model, Sonata V6 / Year 2000

My car has suddenly lost some power and when pulling away from a
standing start.

It exhibits a shuddering which is also noticeable just by revving the
engine. At over 1500rpm the shudder is barely noticeable but there is
nevertheless a significant loss of power in the vehicle.

As a wild guess it seems like some of the cylinders are not operating.

Can anyone advice on possible fault scenarios?
Click to expand...

Could be nothing more serious than a defective plug wire.

Old_Timer
 
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