Hi all -

I need you help. You know how a weedeater all of a sudden revs out all freaky just before it runs out of gas? Well that's what my sweet Sonata did (99, 180k) after I changed the spark plugs because I left the Air Intake Collar loose (just past the Idle Air valve) when I started it up after the change.

It revvvvvvvved.....and then died.

Now it only turns over but never starts.

I get no codes on the reader.
I've disconnectedd the battery and reattached.
Retighted. Checked theInjector wiring harness.
Replaced any questionable hoses.

I just know I've done something silly to cause this....so is the high revving the clue?

Please help.

 

Throttle position sensor or crankshaft position sensor is my guess. Make sure EVERY connector is tight and no wires a pinched. If you had your intake totally off, check to make sure all the sensors are plugged in, and that they are plugged into the CORRECT connectors. If there are two that have similar connectors, let me know what you find and we can check the wire colors int he schematics. (Or if you want to do that yourself, here's a guide to how to access and read Hyundai's online service manual:
http://www.dfwhyundais.com/diy/DIY-WebTechGuide.html)

I agree, if it was running okay previously, it's probably something simple. I've been there, done that. Once I took it to the dealer and they fixed it "under warranty" (*wink wink*). The other time I found a connector hadn't been plugged back in.

High revs tell me it's throttle position sensor or possibly a speed sensor. No codes could be any number of sensors but my local Hyundai tech tells me the crankshaft position sensor is the one that goes bad. But if your intake was off and you unplugged any of the connectors on that, make sure they are all connected properly.

 

Sounds like a vacuum leak to me. Did you tighten the air intake collar? Which motor do you have? If it's the V-6 where you have to remove the upper intake manifold to change the back plugs make sure your gasket there didn't slip or tear. I've had this happen to me doing an intake manifold gasket job on a 3100 engine i found the leak with a little bit of starter fluid.