B6 crank no start

[Philoby]

My 04 ultrasport 135k miles 6spd.. Did 2nd air inj delete, new plugs, oem coolant sensors and new evap purge valve. Everyday when i leave work at 7 pm ( car sits for 10hrs ) i go start car, i can hear pump prime. Crank and no start? It wants to but feels like it has no fuel at the rail.. Crank for 2min or so finally starts and runs rough( miss ) smells real rich.. When i get it running on all 4 cyl, car runs great i can shut it off and will fire up no problem. Wont start only when it has been sitting for a while, it doesnt matter if i have 1/4 tank or full tank either. I replaced fuel filter i was told on the B6 the fuel regulator is built into the filter. Did not change anything still crank no start. Please help

[jonan]

when i had these symptoms it was my crank position sensor, although once my car started it didn't run rough or smell rich...i would just crank for 10-15 seconds in the mornings before it would want to start and wouldn't have problems starting up again until the next morning...

[rocket1420]

If you are literally cranking for two minutes you are going to burn out your starter.

Codes? Anything we can say without codes would just be guessing. My guess is the crank sensor as well.

[Alenas]

My a4 with 1.9 tdi engine does almost exactly the same thing:
If it has less than ~1/4 tank of fuel and sits for a while, it takes around a minute of cranking to get it started and then it runs, starts and drives good. Let it sit for more than few hours and it takes a minute or so of cranking again ( in series of shorter cranks of course).
No codes thrown at all.

[Philoby]

My tach moves off of zero but runs real rough and smells rich, would it still be crank sensor

[Philoby]

No codes

[chad99]

A crank sensor failing will not always cause a code, if I were you I would try that first, and soon, it is possible for the sensor to fail so bad it reaches a point where the car will not start at all.

Also if it is indeed the crank sensor, if the car won't start within the first 3-4sec of cranking, remove the key then try starting it again, it's a better method than holding the starter on for 1-2min straight...as someone else stated, you might kill the starter motor if you continue doing that.

[Philoby]

Ok cool man thanks alot ill try that first! What would ur 2nd choice be if that is not the issue? Could it be fuel pump related or no

[chad99]

2nd?...Maybe cam position sensor? But last time I had that go bad the code was stored in ECU, light wasn't on but code was stored.

I would think the fuel pump would be ok, usually you would hear noises and or problems under hard acceleration but they have also been know to just straight up fail with no symptoms.

I have had both crank and cam sensors fail, they both have similar symptoms but I do remember when my crank was failing it would hard start, then sometimes when it would start it would smell rich.

[Philoby]

Ok man ill give that a shot

[jonan]

A crank sensor failing will not always cause a code, if I were you I would try that first, and soon, it is possible for the sensor to fail so bad it reaches a point where the car will not start at all.

Also if it is indeed the crank sensor, if the car won't start within the first 3-4sec of cranking, remove the key then try starting it again, it's a better method than holding the starter on for 1-2min straight...as someone else stated, you might kill the starter motor if you continue doing that.

true, now that i think of it, i didn't have any codes when my sensor was failing...so i thought it was fuel related and changed the fuel filter...still had problems starting in the morning...

everything was kosher again when i changed out the crank sensor...

[Philoby]

Cool man i got one ordered ill let you all know if that solves the issue, im hoping it is it just started to do it few weeks ago

[Philoby]

I replaced crank pos sensor, still has same issue, im not sure what else to do

[chad99]

Humm ok...I know you mentioned you can hear the pump prime, does the problem change at all if you prime it x2 in a row before attempting to start the car? On my old b6, the check valve failed and would not start easily unless I let the pump fully prime, but this never gave me a rich fuel smell.

Another check is remove all injectors and put a cup under each injector, prime pump then wait and see if any injector is leaking also you could remove spark plugs before any starting attempts and check if you can see or smell gas in the cylinders. Pulling the plugs and sniffing is easier as a first check before yanking the injectors out so I would try that first.

Also no loss of coolant or typical headgasket symptoms right?

[uzone02]

Bad MAF also can't be start

My car was down months ago
Will crank but no start,
Did lots of research on Internet, asking garage,
Basically check
(Make sure battery and fuel is enough )

1. Fuel pump ( usually most likely ) ( crank for 10-15sec, go to exhaust to smell it, any gas smelling, if yes, it's ok )

2. Will it crank ? Rpm goes up ? ( if yes, ECU should be fine )

2.1 ignition Coil
( Connect the coil to the plug,
Connect the outer shell of the coil to the ground (( make sure there is grounded )) )

3. Bad crankshaft pos sensor ?

4. Bad camshaft pos sensor ?

5. MAF sensor
( #3-5 have to replace and try)



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[uzone02]

My experience last time was
The ignition coil was NOT firing



There a "up voltage"( I dunno the name ) unit was rusted

All the electricity cant pass thu to the coil


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[Bmase]

Shot in the dark here but are you tuned or have you played with lemmiwinks or unisettings on your car? I used to have this problem in my mk4 1.8t and after i reset my ecu back to basic settings it never happened again. It used to give me once chance to get it started with flooring it if i didn't get it i was trying for 15 min sometimes to get started.

[Let it snow]

Can you check your coolant temperature sensor readings with Vagcom or equivalent? See if that is reading close to ambient on a cold start.

[Philoby]

Thanks everyone for the help, still havin same issues. I Replaced crank pos sensor no change. The car does have a tune i belive its apr, i had vagcom hooked up, coolant temp was normal, im not sure what the maf sensor should be on cranking but it is going thru some coolant but not leaking im assuming its burning it, im gonna try compression test and fuel press test see what they are but its driving me insane its so odd, it jus started doing this month ago after i did 2nd air delete but only does it when it sits for a day at a time so its hard to diagnosis. Any body wana buy it i need new rs4 lol

[Let it snow]

Since it happened right after the SAI delete did you plug all the hoses and ports associated with the system? Also try cleaning the throttle body and do an adaptation. Couldn't hurt.

[BARRY]

so you've checked spark? you stated you do smell fuel.

[Philoby]

I pluged all ports for SAI yes, i havent pulled plugs yet im going to do that and pull the rail w/ the injectors to see if there bleeding off and not holding prime

[BARRY]

i'd check spark first...i've not once heard of anybody here having fueling issues in that regard. unless the pump has died or filter clogged i'd start with spark.

one thing to mention is that when my crank angle sensor died...if i recall correctly, spark stopped but fuel didn't. crank angle sensors are like 18 dollars or something. i'd just change it. its real easy to change as well. 1 bolt reaching from under your car with a long extension.

[Philoby]

I did replace crank pos sensore, did nothing, also new coolsnt temp sensor. Same issue. Ill check spark see ehat happens

[uzone02]

If the VAG said, Bank 2 & 4 Coil are not CLOSED circuit,

Does it affect start up?

[Jvt]

Cam pos sensor. Gotta be. Under the timing cover

[Let it snow]

If the VAG said, Bank 2 & 4 Coil are not CLOSED circuit,

Does it affect start up?

Yes. Check your coil wires.

[BARRY]

^ yes. my first B6 was giving me troubles as i was chasing down misfire and run issues. it so happened that the #4 coil wiring had split which caused the power lead to arc to the valve cover causing a no spark for #4.

a few retailers here sell a ignition coil repair/replacement kit. if that is in fact the culprit take a look.

[uzone02]

Thx guys


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