Hi, all

Having problem with 2008 Sonata with 2.0crdi (110 kw) manual. While accelerating you can feel the engine jerk (power sways or waves). Not dramatically but you can defenetly feel the jerking. It's more with the 1st, 2nd and 3rd gear but sometimes even when cruising in 4th, 5th or 6th. Computer does not show any errors. With new oil i changed air and fuel filter. That didnt have any effect. Then i changed EGR-valve (twice!) and it made it better but it still jerks. Then i changed MAF-sensor and it had no effect, it still jerks. EGR and MAF are good quality products, not the cheaper ones. Any ideas??

BR
Kaido

 

Did you take a look at the spark plugs?
Just make sure they have the correct gap and not fouled
Try throwing a bottle or two of fuel injector cleaner??
It could be fuel pump or regulator issue???

 

If I understand you correctly , the "jerk" feels like a momentary total loss of power. If this is correct something is interrupting the ignition system for that split second amount of time.
I believe if it was a single cylinder misfire you would notice a slight skip of power, but would recover quickly.
Can you help define the symptoms a little, thanks.


As a follow up, one thing that could cause a total loss of ign power signal could b a failing crank position sensor.
Most likely a failing coil would not be that drastic a response/

What do you think, avisitor, did I overlook something aside from what we both mentioned?.

 

@visitor Thank you for the reply! Sorry if i misunderstood you but what to you mean by "spark plugs"? As it's a diesel engine i believe it only uses the spark plugs on start-up, not while driving. Is there any way to check the high pressure fuel pump issues if computer doesent show any errors, even in a test drive with computer attached?

@hanky Thank you for the follow up! It's not a total 100% loss of power but more like reduce in power by 70-80%. I don't feel the engine completly cut off but it feels more like it doesent get enough fuel for that split second. It doesent happen on any every acceleration but it happens every time i drive. Can it be a symptom of aging high pressure pump? The start-up in the morning is perfect and it doesent smoke so i think the sprayer injectors are good.

 

I believe you have more than 1 fuel filter, Someone else had a similar problem, loss of power when accelerating, and found they had a 2nd fuel filter that was plugged

 

Where was it located? Was it the one in the tank?

 

I was thinking your problem related to this thread
https://www.hyundai-forums.com/threa.../#post-6010149