Dieseling EFI engine

Tiny
TSG333
  • MEMBER
  • 2002 HYUNDAI SANTA FE
  • 2.4L
  • 4 CYL
  • 4WD
  • MANUAL
  • 375,000 MILES
My vehicle does not switch off straight away and I have to stall the engine to turn it off. After I turn the key to off the engine does a slow lope until it is stall by me. I have no check engine light and an obd11 scanner finds no fault. The engine idles fast, 1250 rpm, uses a lot of fuel and shifts (manual) stiffly with revs staying very high between shifts.

At times I hear a loud bang and when I turn off the car I hear a crackling sound. I thought at first it was a hot muffler cooling after fuel catching but have since discovered massive vacuum in my fuel tank so much so it split the tank at the top! I have replaced the fuel cap but it has not changed. When I release the cap a great whooshing sound starts as air enters the tank.

At first I was told the dieseling was sensor related so all sensors have been replaced, IAC, TPS, MAF, new injectors, spark plugs, PCV valve, fuel regulator. Could this be an EVAP issue? Purge valve? Blocked carbon canister? Perhaps two separate issues? All mechanics I talk to say its impossible for an EFI engine to run on. But it does! After each 'fix' the car seems to run great for two to four days then goes back to its issues. Unleaded fuel seems to make it worse than e10.

Car has actually done 155,000 miles.

Please help. I am at my wits end!
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Tuesday, July 11th, 2017 AT 6:25 AM

20 Replies

Tiny
KEN
  • ADMIN
Hello,

One thing comes to mind on this one. It sounds like you have a large vacuum leak. Here is a guide to help you confirm:

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

I do not think it is a EVAP issue.

Please run this test and get back to us we are interested to see what it is.

Cheers, Ken
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Tuesday, July 11th, 2017 AT 4:01 PM
Tiny
TSG333
  • MEMBER
The first thing we checked when this happened was vacuum. We have inspected all hoses and gaskets and sprayed carburetor cleaner around. We did not find any leaks. I will however do it again today just to be sure.
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Tuesday, July 11th, 2017 AT 6:20 PM
Tiny
TSG333
  • MEMBER
May or not be related but there is a high pitched ring sound when driving, like it has a turbo.
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Tuesday, July 11th, 2017 AT 6:25 PM
Tiny
KEN
  • ADMIN
Hmm, like the exhaust is plugged please try this test as well.

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Please let us know what happens.

Cheers, Ken

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Tuesday, July 11th, 2017 AT 7:34 PM
Tiny
TSG333
  • MEMBER
I did the vacuum leak tests again and did not find anything. I did however discover that the high pitched noise is coming from the power steering pump. It has a leak too!
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Wednesday, July 12th, 2017 AT 3:21 AM
Tiny
KEN
  • ADMIN
That is one problem but I do not think it will effect the engine dieseling. I am wondering if the IAC motor is going bad.

Here is a guide to help you confirm:

https://www.2carpros.com/articles/how-to-replace-an-idle-speed-control-motor-iac

Please let us know what happens.

Cheers, Ken
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Wednesday, July 12th, 2017 AT 11:43 AM
Tiny
TSG333
  • MEMBER
I replaced the aic early on. I have rwad though that even new iac's can fail so I have. New one and will replace it again just in case. Thanks for help.
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Thursday, July 13th, 2017 AT 5:50 AM
Tiny
KEN
  • ADMIN
Please let us know what happens.

Cheers, Ken
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Thursday, July 13th, 2017 AT 12:05 PM
Tiny
TSG333
  • MEMBER
Hi Ken. I replaced the iac valve. No change. Still runs on.
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Friday, July 14th, 2017 AT 8:02 PM
Tiny
TSG333
  • MEMBER
My car isnt running on as much as it did. But still 1 in 8 times it does. Better than the every time it was doing. Would a faulty IAC cause the vacuum/pressure in the fuel tank?
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Thursday, July 20th, 2017 AT 4:58 PM
Tiny
KEN
  • ADMIN
No it only adjusts the idle air inlet. Lets scan the car for codes again

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please let us know what happens.

Cheers, Ken
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Friday, July 21st, 2017 AT 10:19 AM
Tiny
TSG333
  • MEMBER
There is no check engine light on but a scan threw code: po335 camshaft position sensor.
This has appeared and disappeared once before. Could this explain the problem?
Thanks for persevering!
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Sunday, July 23rd, 2017 AT 6:46 PM
Tiny
KEN
  • ADMIN
Yes, that can cause the problem for sure. Here is a guide to show you what you are in for and some diagrams below to help you get the problem fixed.

https://www.2carpros.com/articles/camshaft-angle-sensor-replacement

Please let us know what happens.

Cheers, Ken
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Monday, July 24th, 2017 AT 3:35 PM
Tiny
TSG333
  • MEMBER
Crumbs! P0335 is crankshaft not camshaft sensor. I wrote wrong one! I gather this can cause the problem too!
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Monday, July 24th, 2017 AT 5:14 PM
Tiny
KEN
  • ADMIN
No problem,

Here is a guide and the location of the sensor. The guide will give you an idea of what you are in for when doing the job.

https://www.2carpros.com/articles/crankshaft-angle-sensor-replacement

Please let us know what you find.

Cheers, Ken
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Tuesday, July 25th, 2017 AT 11:29 AM
Tiny
TSG333
  • MEMBER
Would the crankshaft sensor cause these issues I am having or is it just another problem?
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Tuesday, July 25th, 2017 AT 5:04 PM
Tiny
KEN
  • ADMIN
Yes, it sure will.
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Tuesday, July 25th, 2017 AT 8:15 PM
Tiny
TSG333
  • MEMBER
I finally found the problem! (Two months ago). The purge valve that connects after the carbon canister was stuck open. So the engine was drawing air and vapor constantly back from the tank through the carbon canister. This had the effect of creating a massive vacuum leak causing the tank to implode and the mixture to run rich. After disconnecting the hose to the intake manifold and clamping it closed the car ran like a dream. Tested valve and it was stuck open. Replaced purge valve. All good.
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Thursday, February 1st, 2018 AT 2:48 PM
Tiny
KEN
  • ADMIN
That is a great find I will feature this post in our experts forum.

Use 2CarPros anytime, we are here to help. Please tell a friend.

Cheers, Ken
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Friday, February 2nd, 2018 AT 10:41 AM
Tiny
HMAC300
  • EXPERT
I have run into a purge valve problem like that many times especially on obd1 cars.
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Friday, February 2nd, 2018 AT 11:58 AM

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