matt.rogers1257

Hi everyone!!

2001 Audi a6 2.7T. 153K miles.
Recently it has been cranking real long before turning over. Almost in excess of 5-7 seconds. I changed both coolant sensors, fuel pump, jet suction pump, fuel regulator valve. Charging system checks out. Coils check out. Injectors check out.

Any ideas? Its never not started, it always starts. I'm wondering if it's the cold...Colorado is just now starting to warm up and our garage isn't the warmest place.

Anyways, any thoughts? It's been doing this for about a month or so now. Let me know what you think.

Matt

SloopJohnB@mac.com

I have had previous instances on both 4.2V8s where a weak/old battery made the difference in starting. Yes, the old/weak battery would crank the engine for 10 seconds or more, but the car took a long time to start. A new battery fixed the problem. So load test your battery and if it's on the weak side next to the fail (some battery testers have color codes/zones as well as actual cranking voltage scales) consider replacing the battery.

IF you are so fortunate as to have one of those wheeled chargers with a 200amp starter circuit you could hook it up and turn it to start and then try cranking your engine. If it starts up quickly, wallah! Then you'll know you need a new battery…and get the biggest one that will fit (in terms of cranking power, sometimes standardized as cold cranking amperes or CCA). Just my $.02.

jseklund

Bad starter? Time for new spark plugs? Air leaks? It sounds like you've gone through a lot of more complicated issues and may be overlooking something more simple.

Have you scanned for codes?

mrogers1257

Yes we've scanned for codes. I had the entire charging system tested. Battery, alternator, starter. Everything. I did some research with people who were having some similar issues and I'm thinking it might be the crank shaft position sensor. If it's old, it may be communicating with the cars computer wrong in terms of how much fuel pressure to keep in the engine...kind of like the same issue with temp sensors. Spark plugs are good.

Air leaks could be something worth looking into. Think a leak in the turbo could cause it?

jseklund

I'm no expert but I would be looking for an air leak in the intake side of the engine - my reasoning may be off but I am thinking that if you have a sizeable air leak on the intake side, there won't be enough fuel in the mixture for a few seconds and it may take a couple sprays to get the car started. Thinking about this more, however, I think you would have misfires too if that were the case and it would run poorly once the car was warmed up because your ECU would be giving even less fuel. Not 100% sure, but that was my thinking and it may be wrong.

I like the CPS idea - I would look at that too, but I wouldn't just throw parts at this. It sounds like you've rebuilt quite a bit already....

matt.rogers1257

I'll look at that too. I'm going to take it to a shop that specializes in Audi and have them look at it. Gotta get it fixed before I go snowboarding. Don't want to run that chance in Colorado weather.

Thanks! Any more ideas would be helpful as well.

Matt

SloopJohnB@mac.com

Sometimes with the turbos you just have to smoke test the entire intake plumbing setup. Nature of the beast with time…hoses and tubing just dry out, rot, crack, leak. If you replace vacuum hoses wholesale use silicone hoses.

Just Me

if the starter was bad how would it crank for all thsoe seconds?

no.

Admittedly i'm stumped. Would have placed money on temp sensors....

or a lazy fuel pump or back-flow valve (one in the same)

Grant

Just Me

air leak could do it, but that would result in a mixture problem running, and likely codes....

G

mrogers1257

There are codes, they just aren't relevant to the problem. Old O2 sensors. Still have to get those replaced.

I think they overlooked the starter or alternator. I'm going to have another shop take a look at those to make sure...I know the whole gizmo where you hook everything up to the battery to test the entire system should do it, but you never know with Audi.

Keep them coming! I have a list now....