1995 Hyundai Sonata • 14,000 miles


I am encountering problems with the car mentioned.

Issues are as follows:

-rough idle on cold start
-missing when accelerating when cold
-extremely poor gas mileage (about 8km/litre) and its only a 2.0 16valve, in-line 4cyl.
-it also makes a hissing sound at cold start, which I think is a vacuum leak and I have checked over and over trying to identify the source of the leak but no luck

The vehicle I actually own is an Elantra, but with the above mentioned engine.
The vehicle originally had a 1.6 litre engine and I had to use the 1.6's ignition coil pack for the 2.0 because of different connectors.

Will using a 1.6l ignition coil on a 2.0 cause such problems?

Please help!
January 19, 2013.

It could be a problem. However, if you hear a vacuum leak, I would say that is a big part of the problem. Have you tried finding it with carb cleaner?

I have tried carb cleaner but did not find anything. I haven't done the search thoroughly merely because I ran out of carb cleaner but I plan on buying another can today and try it again.
Is there any specific location on the engine which you would suggest I try looking at where these problems usually occur?

Where the ignition coil is concerned, I will contact a local Korean parts store who I usually buy parts from and find out by them whether the coil packs are the same, because the 2.0 engine is exactly the same as the 1.6 the vehicle originally had.

If I have no luck, you will most likely hear from me again.

Thank you for your response.

Jan 19, 2013.
Let me know how it goes. Check for vacuum leaks along the intake manifold.