I've spent a ton of time searching the forums and doing research on this but I'm still not exactly sure which way to go first. Any help would be appreciated.
When I bought my 2005.5 B7 S4 about 9 months ago it would start up just fine when cold. But if you drove it somewhere and then parked it for a short time, it would have trouble re-starting while hot. I never had to actually wait for it to cool down because it would always still start after a couple attempts at cranking it for about 5 seconds each time. I know I should have addressed the problem then, but I just didn't. It did the same thing for many months but would always start eventually.
About 3 months ago the problem got a little worse. It would just randomly have trouble firing up. The difference between hot starts and cold starts became much less noticeable. Sometimes it would fire right up and sometimes I'd have to crank it two or three times. The pattern became almost indistinguishable and the problem seemed completely random.
Now, in the last few weeks, the problem has gotten to the point where I have to address it ASAP. I'm worried one day it won't start at all and I will be stranded somewhere. It now needs multiple cranking attempts whether hot or cold. Every time pretty much. And now it takes sometimes 4 or 5 attempts before it fires. However, the car starts every time eventually. So far. It has also started to kind of burble and sputter a bit when it is about to fire up. I can sometimes give it some gas right then and it will catch and fire up. Other times it won't but it will fire up on the next cranking attempt.
I have no check engine light on at all. My traction control light occasionally randomly comes on while driving, usually at slow speeds in traffic. I am pretty sure I hear my fuel pump priming when I turn the car on. Today I tried to turn the key on, give it 5 seconds to prime, and then cranking it but it didn't seem to help. The car runs absolutely amazing once it is started. No problems at all and I am actually amazed how good this old car runs! Lots of power and no misfires or even idling inconsistencies. This is purely a starting issue as of right now. I have not checked codes yet but I will do that tomorrow (I had been thinking I wouldn't get any because I wasn't getting a check engine light, but I think I was wrong). My car has a JHM tune, piggy pipes, Magnaflow catback exhaust but all of that was done about 2 months after I bought the car and the problem had already been present and didn't get any worse after the install. Car has 118,000 miles, never had chains done, and has very minimal rattle at start up.
From my research so far, I'm thinking either Crankshaft Position Sensor, Fuel Filter, or Fuel Pump. Maybe a combination of those. Not sure if I should start with the CPS (how hard to replace?) or the Fuel Filter first, but need to figure this out ASAP. Any suggestions or similar experience? I appreciate any advice very much.
UPDATE 4/24/2018- I ran up to Advance Auto and borrowed their scanner to see what codes this thing may be throwing. A BUNCH of codes showed up, but I have never scanned this thing so who knows how long some have been there and what is causing them. Anyway, here they are:
(P0037): O2 Sensor Heater Contr. Circ.(Bank1(1)Sensor 2) Low
(P0057): O2 Sensor Heater Contr. Circ.(Bank2 Sensor 2) Low
(P0261): Cylinder 1- Injector Circuit Low
(P0264): Cylinder 2- Injector Circuit Low
(P0267): Cylinder 3- Injector Circuit Low
(P0270): Cylinder 4- Injector Circuit Low
(P0273): Cylinder 5- Injector Circuit Low
(P0276): Cylinder 6- Injector Circuit Low
(P0279): Cylinder 7- Injector Circuit Low
(P0282): Cylinder 8- Injector Circuit Low
(P0458): Evaporation Emissions Sensor- Purge Control Valve Circuit Low
(P0141): O2 Sensor Heater Circuit Bank- 1 Sensor 2
(P0161): O2 Sensor Heater Circuit Bank- 2 Sensor 2
(P2401): Leak Detection Pump
(P2257): Secondary Air Injection
(P0102): Mass or Volume Air Flow
(P0414)
UPDATE 5/11/2018
So the day after my last post my car completely shut off/stalled on the freeway on the way home. It would not restart. I tried MANY times. Stranded and not willing to tow the car back to my house hoping I could figure out the problem, I decided to take it to the pros. Had my car towed to my local indy shop. They called the next day and said it needed a new fuel pump. So I had them install a new OEM fuel pump and fuel filter for good measure.
I picked it up a few days later and she ran great. But right away I noticed I was still having the same old hot start issues. After stopping briefly at a store or gas station, the car takes a couple cranks to fire up. It is much better than it was and almost always fires up on the second crank. It is almost like my problem has receded back to when I first bought the car, but it's still there. Really weird. I have to think I have always had this undiagnosed problem and then coincidentally my fuel pump also went. Now that that is fixed I am back to my original hot start problem. Problems related? Any ideas? Car runs and drives awesome but I'd like to get this little issue fixed if possible... the car would be perfect then. Thanks, guys.
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) 2005.5 Audi S4
2011 Dieselgate Q7 TDI..... patiently waiting for my warranty to expire!!
Originally Posted by Jdsb6s4
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