# Passat V6 problems starting, help diagnosing?



## chetpan (Jan 9, 2005)

Hey everybody. 

I have a 2001 VW Passat GLS V6. Generally runs pretty well, but I have some issues starting the car. If the car has been sitting longer than a couple hours (i.e. a day or more), it has a little trouble starting. I have to turn the ignition several times (usually 3 or 4) while pumping the gas pedal to get it going. On the first couple tries, the engine doesn't "catch" (for lack of a better term) - you can hear the car trying to crank but the engine just doesn't turn over.

Then even after it "catches", I have to rev the engine several times or else it will shut off again. As I'm doing this, I hear several "pops" or "knock" sounds, and with each of those sounds the engine feels more engaged... and finally once all the sounds are gone, the engine is fully engaged and the car drives fine after that.

It's also possible that the problem is worse when the car is parked on a hill (sloping upward, i.e. the front is higher than the back) but I can't really be sure.

I don't believe the problem is battery-related, as the radio, AC, windows etc all work with no problems even as the engine is having this issue. I also replaced the spark plugs (just as a precaution... and hey, it helped my gas mileage!)

I briefly discussed the issue with a mechanic friend of mine and he said he thought the problem might be related to the throttle body. So I tried to clean that as best I could with some throttle body cleaner. I couldn't actually get the TB out, so I had to reach in and clean what I could, which ended up only being the bottom of the TB plate area... but it didn't make any noticeable difference.

My questions for y'all - 
- Any ideas on what could be going on? Does it seem like it might be the TB, and if so, how could I further diagnose?

- If it turns out I need to replace a part like the throttle body, is there a good source of used VW parts online? I'm not in great shape financially right now, so I'm trying to avoid more than a couple hundred dollars on repairing this if at all possible.

Anyway, really appreciate any advice you'd have.
Thanks!
Chet


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## afawal (Oct 18, 2005)

Hey Chet,

Sounds like you have the advanced version of what my passat had. Mine was a 2000 GLS V6 4-motion with similar symptoms. If it sits (typically 8+ hours), I put the key, crank, no problem. While the car was still warm/hot, sometimes it had trouble "catching" as you were saying, especially when sitting between 1-4 hours. 

Honestly, I could never figure out what it was. I always suspected a bad ignition coil, but never had the opportunity to verify this. I have sold the car since, but still drive a VW 

Others have told me that it could be the coolant sensor, a bad coolant sensor might make the car think it's cold when hot, and flood the engine while trying to turn on, but i suspect it would still turn on then, hence leading me to my previous suspicion. 

I too cleaned my throttle body, it made a difference in throttle response after I cleaned it, but the problem persisted. New plugs (OEM and non-OEM) and wires didn't remedy the issue either. My fuel economy was not suffering, and I had no engine codes...

I did notice one thing though. In winter, on cold days (sub zero temps), if I turn the car on for a few seconds and shut it off again, the following time I tried to turn it on, it gave me a VERY hard time.... I would have to crank it a lot before it kicked in, and then, as you said, give it gas or it would shut off.

As I said before, my best guess would be ignition coil, OR the fuel injectors themselves. Sometimes, a bad fuel injector can cause startup issues but when the car is on, it's fine; I have experienced this before with my dad's car. So, my advice is to use an OBDII reader with live data to see if the ECU is feeding both banks equally. I don't know if you can get your hands on a second ignition coil, and swap the one you have and see if the problem goes away.

Hope I was able to help, good luck!


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## chetpan (Jan 9, 2005)

This is really helpful, thanks! So one additional problem is that my coolant is really old and pretty gunky. I hadn't considered an issue with the coolant sensor/misreading the temperature.

I need to do a coolant flush anyway, so I'll give that a shot. Then maybe I should try to get my hands on an alternate coolant sensor? 

Great tips, thanks for the response.


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## chetpan (Jan 9, 2005)

*Fixed.*

Fixed it! afawal, Thanks much for the help. 

The culprit was a bad coolant temperature sender (sensor). It was caked with dirty coolant, and the coolant was also actually leaking up to the electrical contacts, so I'm sure it was shorted out anyway. 

No more CEL, no more hard cold start! $14 part. 










Also did a coolant flush, hopefully won't have this problem again.


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## deveouzmindz (Aug 15, 2011)

*I have the same problem, except I didn't find out what the problem is*

My 02 b5.5 v6 2.8l 4 motion, its not ” catching” but I got a timing belt with water pump and temp changed with tensioners...can I still have a coolant sensor problem? I also changed my plugs and wires, I'm thinking of changing the coil, to see if that wool do anything, I talked to a mechanic/dub enthusiast he said it might be a cam sensor...hopefully not that sounds expensive...please help!!


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## deveouzmindz (Aug 15, 2011)

*solution........... I hope.*

It was my cam sensor, hooked up to a vag-com, cranked the engine, didn't see any revolutions/minute, so switched it, car starts, no problem. In the list, fuel pump, fuel filter, getting a rain guard anyone have one will to part with it with a seal is be more than happy to give you 40 w/ shipping....trying to fix on a budget


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