After finishing a tuneup the vehicle backfires then stalls when coming to a stop

Tiny
HARRIS63010
  • MEMBER
  • 2005 HYUNDAI SANTA FE
  • 3.5L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 175,000 MILES
Recently tried to do a tuneup on the vehicle. Removed plenum to access rear spark plugs. Replaced spark plugs, spark plug wires and ignition coils. After putting it all back together it seems like a backfire or coughing coming from engine compartment. Drove the vehicle a couple blocks and it stalls out when coming to a stop. Any ideas as to what I did wrong?
Saturday, February 15th, 2020 AT 6:57 PM

6 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
Hi,

Either there is a vacuum leak, a bad spark plug, or a bad or not fully connected coil pack.

Do you have a live data scanner? If so, scan the computer and see if there is a misfire specific to one of the cylinders or if there is a lean mixture code. By doing this, it will point us in the right direction. If it is a misfire, lets hope it is up front.

Most parts stores will scan it for you. Also, I wouldn't suggest driving it until we have it scanned. If it is a misfire, raw unburned fuel can damage the catalytic converter.

Let me know what you find or if you have other questions.

Take care,
Joe
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Saturday, February 15th, 2020 AT 7:05 PM
Tiny
HARRIS63010
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When I took off the intake manifold and seperated it from the throttle body there was a black plastic piece that was broken lodged inside the manifold. I removed it. Could this be a cause for a problem?
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Saturday, February 15th, 2020 AT 9:49 PM
Tiny
HARRIS63010
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I do not have a scanner.
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Saturday, February 15th, 2020 AT 9:50 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
Hi,

Yes, but where did it come from. I am going to provide the directions for removal of the intake. The attached pics will correlate. See if you can pinpoint where it was located. If you still have the broken part, can you take a pic of it and upload it for me?

__________________________

2005 Hyundai Truck Santa Fe V6-3.5L
Procedures
Vehicle Engine, Cooling and Exhaust Engine Intake Manifold Service and Repair Procedures
PROCEDURES
INTAKE MANIFOLD

pic 1

COMPONENTS

REMOVAL

pic 2

1. Remove the air intake hose connected to the throttle body
2. Remove the engine coolant hose and throttle body.

Pic 3

3. Remove the P.C.V hose and brake booster vacuum hoses
4. Disconnect the vacuum hose connections.

Pic 4

5. Remove the surge tank stay.
6. Remove the surge tank.

Pic 5

7. Remove the surge tank and gasket.

Pic 6

8. Disconnect the fuel injector harness connector.

Pic 7

9. Remove the delivery pipe with the fuel injector and the pressure regulator.

NOTE: When the delivery pipe is remounted, be careful not to drop an injector.

10. Disconnect the wiring harness of the coolant sensor assembly.

INSPECTION

SURGE TANK AND INTAKE MANIFOLD
1. Check the surge tank and intake manifold for damage, cracking or restriction of the vacuum outlet port, water or gas passages.
2. Check for distortion on the surface using a straight edge and feeler gauge.
Standard value: 0.15 mm (0.006 inch) or less
Service limit: 0.2 mm (0.0078 inch)

INSTALLATION

pic 8

pic 9

Install the intake manifold and delivery pipe reversing the order of the removal procedure.

____________________________

Let me know if you can tell which pic or location it was found.

Joe
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Sunday, February 16th, 2020 AT 4:44 PM
Tiny
HARRIS63010
  • MEMBER
  • 7 POSTS
In the first picture the upper intake. It was inside the upper intake on the right side where the throttle body disconnects from it. Does that help?
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Sunday, February 16th, 2020 AT 6:54 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,755 POSTS
By any chance, did you save the part? In that location, there really isn't much. I would think it would have come through the air intake / air box if it was there.

Joe
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Monday, February 17th, 2020 AT 12:57 PM

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