Hyundai Sonata Check Engine/high Idle

[davidleeis14]

Bought a 2001 Hyundai Sonata Auto (2002 face lift model year) and after a couple of days my CHECK ENGINE light came on. I took the car to the dealer and they told me that there was a problem code. The code was PO507 High Idle. I noticed that when in neutral that the car did idle a little high (1250 rpm). Anyways I took the car back to the garage (not a Hyundai dealer) which I bought it from and I think that they changed the Idle Air Control valve (they got the unit from an Elantra which was also for sale on the forecourt) and they cleared error thus switching of the light. The car then idled at around 1050 rpm (dropped to 800rpm in D or R). Drove the car for a few weeks (4000 miles) and on Tuesday the light came back on Took the car back to the dealer from which we bought it from. The took the car in the garage but they could not get the code reader to work, but they noticed the high idle rpm (1050rpm). Anyway I think that they have put my old Idle Control Valve (the donor Elantra was still there and its bonnet was up) on again as the car now idles how it used to, 1250rpm. The garage advised me to take the car to a Hyundai dealer which i did and the same fault code came up again (no surprise). The garage told me that I could fix it by putting Shell V-Power/BP Ultimate fuel in my car and taking it for a hard drive on the motorway and when doing so I should expect to see black smoke from the exhaust. Did what the dealer said and have driven the car in a lower gear on the motorway for about 80 miles but still no black smoke and my rpm at idle and sometimes when in gear are still high. My question is, what should I do now as the dealer said that the car would fail the emisions test at MOT time. A few notes, when operating the Air Con at idle in Neutral the rpm is sometimes normal and every so often the revs drop as if the car is about to stall, although the car does recover. Also I think when the engine is cold the idle rpm are normal. Other interesting thing is that when the car is put into N from a Drive or R gear the rpm's rise to around 2000rpm and then after a short deley, drop to around 1250rpm. Any advice would be greatly appreciated!

Thanks

Davidleeis14

[87-XLT]

From my 02 Sonata shop manual:

P0507 Idle control system rpm higher than expected:

Possible cause:

Improperly adjusted accelerator cable.

Air leak in intake system between head & throttle plate.

Faulty PCV valve (vacuum leak)

Poor connections in throttle position sensor circuit or faulty TPS.

High resistance between IAC valve & ECM

Faulty IAC valve.

This is straight from the Hyundai factory shop manual -same as your dealer has- & they should have checked these items.

Good luck, hope it helps.

[davidleeis14]

Thanks very much! Don't know what most of that means but I will take the car to a repair shop and will show this to a mechanic and see if they can work out the fault. Thanks! Out of interest how much do you guess this will cost to fix?

[davidleeis14]

Turned out to be a leaking air pipe. For a £2 part the did make alot of fuss. Thanks for your help!

[byronguidry3732]

Dear david,

A leaking air pipe? Is that what us Yanks call a vacuum hose? Yes, a vacuum leak ocurring after the Mass Air Flow Sensor causes havoc.

I had one on a 2001 Sonata when the hose just in front of the throttle body (connected to the cam shaft cover) popped off. I could not keep the engine running without constant throttle pumping. Got out of traffic, pulled to the side of the road, opened the hood, and it was very easy to spot. connected it back, cleared the Check Engine Light code, and everything worked fine.

Byron

[87-XLT]

Originally posted by davidleeis14@Jul 18 2007, 02:07 PM
[b]Turned out to be a leaking air pipe. For a £2 part the did make alot of fuss. Thanks for your help!

[snapback]98075[/snapback]

Good deal, glad to hear it was a nice simple -as in cheap- fix.