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eauto
eauto, The Car Guy
Category: VW
Satisfied Customers: 15071
Experience:  ase certified tech
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I just bought a 2003 VW Passat GLX V6. The car is hard to

Customer Question

Hi,
I just bought a 2003 VW Passat GLX V6. The car is hard to start and has a P0421 check engine light code. Last night, the car started fine with jumper cables to my other car. Today, it started okay, but slow (took several cranks). Then, later, I tried to start it and it wouldn't. Battery has 12.4 volts across it when not running. I am trying to check the alternator voltage while running, but couldn't get it started.
Things I have done:
- Replaced the air filter (it was filthy and the inlet was clogged. The guy I bought this car from has apparently done zero maintenance to it.)
-Checked spark plug gaps and wire brushed the IK20 spark plugs
-Checked inlet and outlet temperature of catalytic converter with a laser temperature gun. Inlet temperature more than 100° F hotter than outlet.
Any ideas? I can provide more details as needed.
Submitted: 10 months ago.
Category: VW
Expert:  eauto replied 10 months ago.

when it runs does it have good power?

Customer: replied 10 months ago.
It seems to have good power once it gets going. Hard to know for sure though because I have no reference point. I bought the car with the problem.
Expert:  eauto replied 10 months ago.

does t crank good?

Customer: replied 10 months ago.
It cranks fairly well, I think. Want me to send you a link to a Youtube video of me cranking it?It runs very smooth, and idles smooth about 800-900 rpm when it does start.It appears to be leaking oil onto the exhaust manifold. I can smell and see the smoke. Spark plug holes had a very minor amount of oil in them.
Expert:  eauto replied 10 months ago.

yes

Customer: replied 10 months ago.
Okay. Give me about 15-20 minutes.
Expert:  eauto replied 10 months ago.

k

Customer: replied 10 months ago.
Video will be here in a few more minutes of uploading to Youtubehttps://youtu.be/3wEKWs7ivaE
Customer: replied 10 months ago.
I checked the oil. It is low. It is on the lower orange marker, but not in between the orange markers on the dipstick. I think I am at least a quart low. I will fill it up before I try to crank again.
Customer: replied 10 months ago.
Video live.https://youtu.be/3wEKWs7ivaE
Expert:  eauto replied 10 months ago.

have the converters been checked for restrictions?

Customer: replied 10 months ago.
No, not other than me checking the temperatures with my laser temp gun. Last time a I checked at idle, inlet temp around 170 F, outlet around 75 F, if I remember correctly.
Expert:  eauto replied 10 months ago.

can you unthread the upstream oxygen sensors and see if it starts?

Customer: replied 10 months ago.
I did so. The car did not start. It turned over fairly quickly like before, but did not start. I cranked it for about 3 seconds. At the end, there was a pop like a small backfire or something.While I was removing the passenger side upstream 02 sensor, I noticed a tiny (1/8"?) plastic line that was broken due to brittleness. (See attached photo)
Expert:  eauto replied 10 months ago.

replace the broken vacuum line but tats not going to cause a no start does it have spark , compression and injector pulse?

Customer: replied 10 months ago.
Well, it started a few days ago, so apparently at the time it had all these things. I have a compression gauge I can use to check compression.How do I check spark and injector pulse?
Expert:  eauto replied 10 months ago.

We will have to pinpoint what the engine is missing.

Spark

Fuel

Compression

All three of these are tested when the engine is being cranked over. There are two way of checking for fuel. Fuel pressure and fuel trigger. Both are very important and must be present for the car to start. Fuel pressure is self explanatory. You just hook up the gage and see what the reading is. Fuel trigger is check with a noid light. The injector gets unplugged and the noid light gets plugged in to the injector clip. With the engine cranking over, this light must blink. This is the signal to the injectors from the computer. You can have all the fuel pressure in the world, but it wont matter if the injector is not pulsing gas into the cylinder like it should! Compression tester, spark tester, fuel pressure gage and noid light are all accessible at your local auto store. All three tests play a very important part in diagnosing a no start condition

Customer: replied 10 months ago.
Thanks! I will start with compression testing.
Expert:  eauto replied 10 months ago.

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Customer: replied 10 months ago.
Okay, so here is the latest...I came home this evening, put one new spark plug in the car (I had damaged one slightly while gapping them a week or so ago), put some starter fluid in the intake near the airbox, and tried to start the car. The car turned over, but would not start.Then, I pulled up my other car up next to it to jump it off. Hooked up the jumper cables. Turned the key. The car started right away (within half a second to a second of cranking) and ran fine.Turned the car off. Left jumper cables hooked up. Tried to start again. Did not start. So, I gave it a minute, and came back and tried again, and it started.While the car was running, I did test the voltage across the battery - 14.2 volts. (This was with no lights on, no radio.)So, I think part of my problem is my battery. But, I still have had trouble starting it while using jumper cables. Twice while using jumpers, the car cranked right up. Twice while using jumpers, the car cranked over and did not start.Another thing I did while the car was running (besides testing battery/alternator voltage) was unplug each coil from each spark plug. I wondered if all but one of the plugs was working well. However, the car hardly missed a beat when I unplugged all six.
Customer: replied 10 months ago.
I got a noid light today. But first, I am going to check compression.Do I need to disconnect the fuel relay before testing for compression? Anything else I need to do? Leave spark plug in coil and put the spark plug threads on the engine valve cover so that the spark has a place to ground to to prevent coil damage?
Customer: replied 10 months ago.
There is 14.0 volts across my battery with car running, headlights on, radio on, and interior lights on, so apparently, there is nothing wrong with my alternator.
Customer: replied 10 months ago.
On my instrument cluster...1. clock
2. odometer
3. tripmeter...are constantly on, even with keys out of the car, door closed, and car left alone for 15 + minutes.Is this normal for my car? Could this be causing a parasitic loss on the battery and making it hard to start?
Expert:  eauto replied 10 months ago.

o have you performed any tests?

Customer: replied 10 months ago.
I have not done a compression, noid-light, or spark test yet. But, I put a brand new battery in the car, and it starts up great now. There is a tiny bit of hesitation to start (half a second to a second or so), but it starts up reliably. So, I am not so worried about doing the tests right now.Now I just want to make sure I have solved the root of the problem with the battery.I still get a battery light when I turn the key to the on position. But, the battery light goes off after the car is started.
Expert:  eauto replied 10 months ago.

sounds like you fixed it

guess your battery test was inaccurate

Please remember to only rate my service when you are satisfied. IF you feel the need to rate "Poor Service" or "Bad Service", please stop and reply to me via the REPLY TO EXPERT button with the issue you have. I will be happy to continue further and do everything I can to provide you with the service you seek.

I am not paid unless I get a rating of 3 to 5 Stars/Smiley Faces. If I have helped you with your question, please give me an appropriate rating so that I get credit for helping you

Customer: replied 10 months ago.
Do you have any ideas on why my battery light comes on and stays on until the car starts? (See video) Is this telling me that I still have an unresolved electrical problem?https://youtu.be/PhqT8u1-KgU