Engine Sluggish at Start Up

[nb99]

Hi

I hope this is in the right section - apologies if not. I have a 3.0TDI Audi A6 estate late 2005. In general it works wonderfully but I've had a problem with starting it over the last few months. It's very sluggish to start. It turns over a few times and then usually starts, sometimes doesn't. I don't know cars but have done a little research and it seems the battery, fuel pump, spark plugs and starter engine are the main suspects. The problem is it has no other symptoms - no loss of power, no grinding noise on starting, no misfiring etc. I don't think it's the battery as the battery check shows 100% and if anything it starts worse after it's been running. The only insight I can give is, as per a suggestion I read, when it doesn't start, I simply turn it off, turn it to the "on" position without starting it, turn it off, repeat and then do start it and it always works. It's not temperature related and as I said, it's more likely to have trouble starting if I've just run the car rather than from cold.

Can anyone perhaps point me in the right direction before I head to a garage? I don't have a garage I know/trust and am a little worried they'll just start replacing things one by one until they find the right part.

Any thoughts/help/ideas much appreciated.

Thanks
NB

[Sibmets]

It's a diesel, it uses glow plugs instead of spark plugs. It doesn't use spark to ignite fuel, only pressure. In warm weather u don't need even glow plugs to start the car, if it gets colder, then u need them. If there's a correlation between ur car not starting and weather, It could mean that some of the glow plugs are bad. Do You wait for the glow plug symbol to go away before starting ur engine? While it's on, it is warming up glow plugs, the colder it is, the longer the warm up. At -15C it could take few seconds (~5). You described that after turning the key on few times it always starts - that suggests that glow plugs needed some warming up - that's normal, but depends on the outside temperature.

Sent from my E5823 using Tapatalk

[nb99]

Thanks for this. Unfortunately my problem started at the end of the summer and has continued into winter so isn't affected by weather/hot/cold. But I didn't know about glow plugs or why I have to wait for the light to go out before starting the car - so thanks for that!

[Lukenkarl]

Vcds will show if glow plugs are out. Also will show state of charge for your battery. If it’s older than 7 years it’s probably no good. Battery in mmi nearly always shows 100% unless it’s totaly goosed.

Have it scanned, saves a lot of guess work

[Rob69]

No expert in these engines but I have seen and heard of trouble with injectors and cams, could be something cheap / simple though like glow plugs or temp sender unit. VCDS diagnostic scan would be good first port of call and injector checks in measuring blocks. check cranking speed as well as poor starter motor (or battery) could be failing to crank it above minimum firing speed. (280 rpm rings a rusty bell, could be wrong though !!!)

[nb99]

Lukenkari - This is interesting. As I said I know little about cars so didn't know the batteries had such a short life. Mine's over 12 years old so quite probably due a change and being the cause of the problems. I did wonder if the MMI battery health was reliable. I think I'll start here and see how it goes from there. Thanks.

Rob - thanks for your suggestions. I'm going to start with the battery which is apparently long overdue a change anyway and if that doesn't sort it will try your ideas at the local garage. Thank you.

[nb99]

Hi - Just as a follow-up. Went to the local garage who tested the battery and alternator and found no problem. For some reason they couldn't test the glow plugs but suggested I go to the audi garage for that. Guess that's my next stop!

[nb99]

Hi again - final update in case anyone is interested/has a similar problem. Went to Audi who immediately informed me the battery was nearly dead so needed changing. They did that which partially fixed the problem but after running diagnostics decided the starting motor was on its last legs. So they changed that too. Wasn't cheap (€1300 in total) but car is perfect again now. First thing to go wrong on the car after nearly 13 years so can't complain really. Thanks to everyone though for help and advice.