Car wont start in these cold temps

[Nycam]

Hi folks
2001.5 S4 Avant Tip

Car has always started flawlessly the past 18 months even in very cold temps.

Temp got down to 5f over the past few days and its cranking fine but wont catch. Never had this happen before. Drove home in heavy snow/ice and parked it and the next day she wouldn’t catch.

Tried hooking up a jumper pack to add voltage but made no difference.

Any pointer as to where I should start looking to fix it? I dont have access to vagcom etc unfortunately.


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[CELison]

Fuel and spark.

[belms4]

Sounds like it's cranking and battery/starter aren't the issue. I'd follow CELison's words and go checking for fuel and spark. Maybe fuel pump crapped out or something. Do you hear it prime when you turn the ignition to on? Spark plugs not too old? +5 degrees shouldn't be an issue, though I'll say my daily stage 3 b5 s4 started a little rougher than normal after being parked in our barn overnight when it got around -20F here a few days back.

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[SideMirror]

Verify fuel and spark then the Shot-in-the-dark approach may be to use a heat gun to warm the engine compartment to eliminate that issue.

What weight oil? may affect VVT from following a cold start ECU command.

Just a guessing

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[Nycam]

Thanks for the help guys. Confirmed spark and fuel but fuel flow was weak and spluttery.
Ordered a fuel pump and switched it out today and shes good to go!
Car has 207000 miles on it and its the original pump for sure so pretty happy about that!
Glad it didnt crap out on the drive home that night in the blizzard thats for sure!

After years of working on cars this is my first German and thank god it was a simple fix.

Thanks again for the help


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[LJS]

THANKS for providing an update...LOTS of folks ask for help and never follow-up on their resolution.....
Glad you got that worked out!
PS- Don't get too use to "simple fixes" The B5 can be a fickled bitch!

[Nycam]

Ok further niggles!

The following day after installing the pump the car is hard to start. Takes about 3-5 goes of trying to catch and then it finally catches and idles rough until it ‘clears it throat’. I cant put it into D and drive off otherwise it will stall. After a few revs its mostly fine

Car runs fine once this issue is overcome after a minute or so of driving. Feels like fuel pressure issue and the pressure is dropping out overnight and takes a few kicks to get it back up in order to allow it to fire up. Fuel pressure reg?


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[Nycam]

My research is telling me its possibly the CTS. Hopefully have it scanned this week and see if there are any codes.


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[CELison]

Does the pump you bought have an internal check valve?

[Nycam]

My research is telling me its possibly the CTS. Hopefully have it scanned this week and see if there are any codes.


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[Nycam]

Does the pump you bought have an internal check valve?

It was an oem replacement fwiw. The old pump was doing this before it completely died.


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[dannyn424]

Bosch check valve you can add one externally by fuel filter …you are welcome

[bmwpower603]

Have you visually inspected the fuel lines underneath ?

Can you smell gas?

[Nycam]

Ive not checked fuel pressure yet. And yes Ive checked fuel lines. No leaks underneath or anywhere that I can visually check. There is a small scuff near the hard pipes near the fuel filter but its been there for ages and does not look like it would affect supply. Fuel filter was changed about 6 month ago.

Car need about 8-12 attempts to start. It will then start and stall for another 3-5 attempts and then once it catches as soon as I touch the gas pedal it will stall. Needs about 2 minutes of idle to then be able to drive.

Further reading/research is pointing again to a bad cts not allowing a ‘cold start/choke’ to add more fuel to fire it up. Once the car is warm it starts perfectly even after 3-4 hours of sitting.

Ive ordered a cts to rule that out as I cant currently get access to a scanner or my local mechanic as he is on vacation.

Appreciate the help thus far.


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[Nycam]

Changed the CTS and it fired up first go perfectly. This may have been the culprit in the first place and not the fuel pump.

Anyone having similar issues I would change your CTS first.

Ive had trouble fitting the CTS and still cannot get it to seat properly in its place. Oring seems too thick.


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[Silverex]

You definitely got the old Oring out?

The bores they go into get pretty rusty so I took some emery cloth to mine, then cleaned it out, some lube on new o ring and it should go in pretty easily.

[Nycam]

Yea the old cts has silicone on it and didnt look like there was an o ring on it or in the seat. I cleaned up the seat and definitely no o ring left behind.

Will have a better look today.


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[Nycam]

Let there be light.

Thank you for making me double check. Now that Im not working with a torch there certainly was the old O ring which looked like it was from 700bc. Scrapped it out and of course it slips in perfectly. Thanks again.

Feel sorry for the people on the road last night when the thing spurted coolant out over the manifold. Big cloud of steam blinded everyone on the road for a second.

Thanks again folks. Always good to have help on hand.

Next job, front left cv is wobbling and clicking. What axels are people buying these days, there is so much debate about it. According to my mechanic its an aftermarket one in there already. Im trying to keep things on a budget at the moment so aftermarket is fine to get me through. Ideally would like an OEM one that I can rebuilt when I get a free weekend but time is of the essence. Hoping to get upto Montreal next week while on Vacation.


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[CELison]

Raxles is the way to go. They rebuild your oem axles. I've used them forever.

[Nycam]

Raxles is the way to go. They rebuild your oem axles. I've used them forever.

Thanks for the suggestion. Unfortunately the axle I need to replace is not OEM. I might try and find one off here and send it to them. Ive had a look at their site. Is it just a matter if email them to start the process?

Thanks again.


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