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Engine revs very high

Tiny
PETAR LJ
  • MEMBER
  • 2004 HYUNDAI SANTA FE
  • 180,000 MILES
Hi there, my motor revs very high 2,000 to 3,000 rpm at random. I have scanned the ECU no codes showing. When I wriggle the purge valve hose behind the inlet manifold the idle changes to high rpm's. Can’t hear and vacuum leaks. Not sure where to go from here.
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Wednesday, October 23rd, 2019 AT 3:40 PM

21 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,289 POSTS
Welcome to 2CarPros.

Unmetered air entering the engine will cause an idle issue. Since you hear the leak, you need to locate it and repair it.

Here is a link that explains how to locate a vacuum leak:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Let me know the engine size so I can provide some pictures which may help locate the leak.

Let me know.

Joe
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Wednesday, October 23rd, 2019 AT 8:36 PM
Tiny
PETAR LJ
  • MEMBER
  • 32 POSTS
Hi there Joe, the pulling of the purge hose seems to increase the air flow through the idle control valve and the revs go up heaps. If I unplug the idle control valve the revs go back down. It’s switching the control valve on or opening it up more.
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Wednesday, October 23rd, 2019 AT 8:41 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,289 POSTS
Welcome back:

Do you feel there is no actual leak?

Joe
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Wednesday, October 23rd, 2019 AT 8:58 PM
Tiny
PETAR LJ
  • MEMBER
  • 32 POSTS
Hi there again, I did check the purge valve and pipes no vacuum leaks. I had the ECU scanned again and in the history it came up with 4 logs. Will send you the photo of the history okay. Hope this can help. Thank you
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Wednesday, October 23rd, 2019 AT 11:11 PM
Tiny
PETAR LJ
  • MEMBER
  • 32 POSTS
I did fit a new idle control valve about 3 weeks ago. Okay, but now the idle dances around to 2,500 rpm's at random then the engine stops and will not start up again until the next morning. Thank you
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Wednesday, October 23rd, 2019 AT 11:13 PM
Tiny
PETAR LJ
  • MEMBER
  • 32 POSTS
Hi there Joe, my engine is a 2.7 V6 petrol.
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Thursday, October 24th, 2019 AT 3:57 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,289 POSTS
Welcome back:

You have a bunch of things happening. First, the IAC is an issue. Also, the coolant temperature sensor and the knock sensor can cause issues.

I attached the directions for testing the IAC below in the pictures.

DTC P1507 Idle Speed Control Actuator Signal Low of Coil #2

DESCRIPTION
The idle speed control actuator (ISCA) is installed on the throttle body and controls the intake airflow that is bypassed around the throttle plate. The function of ISCA is to maintain idle speed according to various engine loads and conditions, and also to provide additional air during starting. Moreover, it performs electronic dashpot during deceleration. The ISCA consists of opening coil, closing coil, and permanent magnet. Based on information from various sensors, the ECM controls both coils by grounding their control circuit. According to the control signals from the ECM, the valve rotor rotates to control the by pass air flow into engine.

Let me know if this helps.

Joe
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Thursday, October 24th, 2019 AT 5:55 PM
Tiny
PETAR LJ
  • MEMBER
  • 32 POSTS
I have fitted a new idle air speed control actuator about 3 weeks ago.
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Thursday, October 24th, 2019 AT 7:19 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,289 POSTS
Was there any carbon build up in the throttle body?
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Thursday, October 24th, 2019 AT 8:52 PM
Tiny
PETAR LJ
  • MEMBER
  • 32 POSTS
I also serviced the throttle body too when I did the air control sensor, also cleaned the mass air flow sensor too.
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Thursday, October 24th, 2019 AT 9:59 PM
Tiny
PETAR LJ
  • MEMBER
  • 32 POSTS
Now my car will not start. Has fuel pulse on injection, spark to plugs, battery good. Just cranking over but no start.
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Thursday, October 24th, 2019 AT 10:34 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,289 POSTS
Do me a favor. See if it starts for a couple seconds with starting fluid.

Honestly, if you fuel, spark, compression and the engine timing is correct, it should run.

Let me know,

Joe
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Friday, October 25th, 2019 AT 4:23 PM
Tiny
PETAR LJ
  • MEMBER
  • 32 POSTS
The car started fine today but still had very high revs 2,500-3,000 rpm's and the idle air speed actuator sounded like the air was gushing through it, when I unplugged it the idle went back down to normal plugged it back in and the revs were high again, for some reason the air speed actuator is opening too much and idling up the motet to high in rpm. Did the checks on the actuator and power input which was 11 volts.
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Friday, October 25th, 2019 AT 6:56 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,289 POSTS
Welcome back:

If you remove the actuator, is there any carbon inside that could be causing it to stick? Is the throttle plate clean and not sticking open slightly?
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Friday, October 25th, 2019 AT 9:41 PM
Tiny
PETAR LJ
  • MEMBER
  • 32 POSTS
Checked the actuator no carbon buildup throttle butterfly not sticking and clean.
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Friday, October 25th, 2019 AT 9:44 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,289 POSTS
Is the IAC adjustable? Normally I wouldn't suggest that, but maybe the pintle is out of adjustment.
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Friday, October 25th, 2019 AT 9:47 PM
Tiny
PETAR LJ
  • MEMBER
  • 32 POSTS
No adjustment on the IAC. I checked it with meter is with in specs you sent me. I have checked a the earth points and cleaned them up under bonnet and under dash. Checked the ECU plugs to make sure no bent or broke pins. Pulled fuse box apart checked all plugs under side of box all good no hot spots on connectors.
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Friday, October 25th, 2019 AT 10:09 PM
Tiny
PETAR LJ
  • MEMBER
  • 32 POSTS
I have just started my vehicle and at first the rpm was very high and started hunting up and down very high revs then finely went to normal idle. It’s got me beat again after all morning testing and cleaning and checking earth points all over the vehicle still have no clue what’s going on with no engine light coming on it any time while idling. Would there be a problem with the purge valve effecting the high idle?
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Friday, October 25th, 2019 AT 11:50 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,289 POSTS
Welcome back:

Any time there is an issue with vacuum related components, it can affect the idle. With the purge valve, sure, something could be causing an issue.

Can you return the IAC you have and say it's bad so we can try a different one? I'm starting to question if you got a bad one.

Joe
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Saturday, October 26th, 2019 AT 5:04 PM
Tiny
JAMESBRODE
  • MEMBER
  • 1 POST
Hi Petar,

Did you solve this problem, I am having the same issue.
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Thursday, August 25th, 2022 AT 3:41 PM

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