kia 3.5 v6 no start

2003 KIA SORENTO
6 CYL
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BANUS
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the car is a 2003 sorento 3.5 v6 with only 34,000 miles,the car is only used once in a while,and is in spain ,the last time i used the car i topped up with fuel and went to do my journey.a mile or so into journey the car started miss firing badly and backfiring a few times no power ect,until finaly it died,it did restart but would only tickover and then died,it would not then restart. towed car home, only fault codes on code reader where p0303 no 3 missfire and p0102 mass air fow. I have fitted new plugs,new mafs and also crank position sensor,all timing marks where spot on,i have checked fuel pressure,compression ect.i have also checked fuel quality ect,as i had only just put fuel into car. now when i try to start engine it appears to be flooding, i say that because i have a fuel pump cutout switch fitted,and after trying to start with fuel pump on as normall it may fire a few times,but not run, if i then switch fuel pump off,it will after a few turns fire up momentary as though its burning the fuel left in the cylinders, there are no fault codes showing.
any help please
Apr 5, 2011 at 10:15 AM
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KHLOW2008
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Is the MAF new or used and is it of the correct specifications?

If the cylinder is flooding, it could be due to faulty injectors or PCM and that is where you should be looking at since everything seems to be working correctly.
Apr 5, 2011 at 1:02 PM
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BANUS
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new mafs, injectors seem fine, think its worth changing cam position sensor , thats the only other thing i can see may be upsetting injectors, though giving no code
Apr 5, 2011 at 1:12 PM
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KHLOW2008
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Cam sensors would normally cause a no spark situation.
Apr 5, 2011 at 1:18 PM
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BANUS
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piece taken from kia tech manual. (the ecm sequentially activates the six fuel injectors through six individual ground controlled circuits,during initial engine cranking,the injectors are actuated simultaneously until no 1 cylinder is detected via the cmp signal. each injector as four individual spray ports)
thats the only reason i asked about cmp sensor. i am an old school mechanic (plugs points disy carb no problem)but todays electronics i am lost,
Apr 5, 2011 at 2:25 PM
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KHLOW2008
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Based on these information, it is worth giving the CMP a try.
Apr 5, 2011 at 2:56 PM
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BANUS
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will try cmp,i will let you know what happens, unfortunately. i will have to wait for one to arrive,
Apr 5, 2011 at 4:18 PM
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PLATINUMHYUNDAITECH
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you never said if there is any spark,You need to verify this. You will still have spark with a bad cam sensor with this engine. The crank sensor innitiates spark with this system.Cam is for injectors.
Apr 6, 2011 at 11:32 PM
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BANUS
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sorry, yes good spark on all plugs(new)every cylinder
Apr 7, 2011 at 8:04 AM
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GORDON GROSSNICKLE
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Your situation seems to be exactly, word for word, what I've been dealing with on the same car. Please, did you find the problem???
Jul 19, 2021 at 10:27 AM
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JACOBANDNICKOLAS
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Hi,

If you are having the same issues, I first suggest checking fuel pressure to confirm it isn't too high. Here is a link that shows how it's done:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Pic 1 below shows the manufacturer's specs for fuel pressure.

If the pressure seems within spec, the next possibility (if it is flooding) is the engine coolant temp sensor. If the sensor is telling the computer it's extremely cold, the computer will make the fuel mixture extremely rich to allow the engine to run in those conditions.

Here is a link that explains common symptoms related to a faulty coolant temperature sensor:

https://www.2carpros.com/articles/symptoms-of-a-bad-coolant-temperature-sensor

Interestingly, if the sensor sends a signal, the computer doesn't know it's wrong, so it doesn't set a code.

The best way to check the sensor is by using a live data scan tool. Simply go to live data and confirm the temp signal is where it should be. For example, if the engine is cold, the sensor should indicate near ambient temperature. Check this as well.

I attached a couple of pics below showing the location of the ECT (or in this case WTS). Here is a link that shows how one is replaced:

https://www.2carpros.com/articles/coolant-temperature-sensor-cts-replacement

Let me know if this helps or if you have other questions.

Take care,

Joe

See pics below.
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Jul 22, 2021 at 9:22 PM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.