81k mile car, have had it since 45k miles. For the first year it had always fired up beautifully with no hesitation or stumble. Two cranks then on, to a rock steady idle, every time.
After going in and re-timing the engine as well as doing a valve adjustment back in October, ever since getting the car back together, there has been some degree of hesitation in starting the car. Basically, it has a 60/40 chance of struggling for a second or two on start up. Sounds brutal for a second or two, but eventually does start. Sometimes it fires up perfectly first try with no hesitation. I can't seem to find a pattern in when it has trouble and when it doesn't.
Every one in a while (quite rare), the car will completely fail to start on first try (it'll just keep cranking but not catch). When that happens, if I stop for a few seconds and try again, it'll start right up on the second try.
Once the car actually starts, no issues, car runs great! At least, as well as a car with stock cams runs on a stock CSL tune. But in the 7 months between when this issue started and when I switched out the OE airbox for the CSL, the car seemed to be a perfectly running stock example other than this problem.
Here are relevant seeming parts that have been replaced in the last year/few thousand miles (all OE BMW or in a few cases OEM):
-plugs and coils (NGK OE and Eldor OEM)
-MAF (Bosch OEM) ---> recently replaced by Bosch MAP for CSL airbox conversion
-fuel pump (OE)
-fuel pressure regulator (OE)
-fuel pressure regulator vacuum line to manifold (OE)
-fuel filter (OE)
-fuel injectors and o-rings (Bosch OEM)
-fuel pump relay (OE)
-pre-cat O2 sensors (Bosch OEM)
-intake and exhaust camshaft position sensors (OE BMW and OEM VNE)
-crankshaft position sensor (OEM VNE)
-idle control valve cleaned
-most CCV related vacuum lines (OE)
-secondary air shutoff valve (replaced with new CSL with airbox conversion)
-both engine bay TPS (OE)
-Alternator (Valeo OEM)
-Starter (Valeo OEM)
-Battery
Compression and leakdown test gave fantastic results.
Any advice on what to look into here? The start of this problem coincided precisely with taking the valve cover off/back on, so I checked all of the electrical connectors involved with that job -- O2 sensors, ignition coils and that little ground wire on the exhaust side of the VC. All look good and feel properly secured. Maybe they need a closer look? Anything specific to look out for? Car passes VANOS test with flying colors, and I'm certain that the valves are in spec, as I re-adjusted while the valve cover was off for the timing job after which all of this started.
Thoughts and suggestions appreciated! Can post vids of hard starts if that would be helpful!
After going in and re-timing the engine as well as doing a valve adjustment back in October, ever since getting the car back together, there has been some degree of hesitation in starting the car. Basically, it has a 60/40 chance of struggling for a second or two on start up. Sounds brutal for a second or two, but eventually does start. Sometimes it fires up perfectly first try with no hesitation. I can't seem to find a pattern in when it has trouble and when it doesn't.
Every one in a while (quite rare), the car will completely fail to start on first try (it'll just keep cranking but not catch). When that happens, if I stop for a few seconds and try again, it'll start right up on the second try.
Once the car actually starts, no issues, car runs great! At least, as well as a car with stock cams runs on a stock CSL tune. But in the 7 months between when this issue started and when I switched out the OE airbox for the CSL, the car seemed to be a perfectly running stock example other than this problem.
Here are relevant seeming parts that have been replaced in the last year/few thousand miles (all OE BMW or in a few cases OEM):
-plugs and coils (NGK OE and Eldor OEM)
-MAF (Bosch OEM) ---> recently replaced by Bosch MAP for CSL airbox conversion
-fuel pump (OE)
-fuel pressure regulator (OE)
-fuel pressure regulator vacuum line to manifold (OE)
-fuel filter (OE)
-fuel injectors and o-rings (Bosch OEM)
-fuel pump relay (OE)
-pre-cat O2 sensors (Bosch OEM)
-intake and exhaust camshaft position sensors (OE BMW and OEM VNE)
-crankshaft position sensor (OEM VNE)
-idle control valve cleaned
-most CCV related vacuum lines (OE)
-secondary air shutoff valve (replaced with new CSL with airbox conversion)
-both engine bay TPS (OE)
-Alternator (Valeo OEM)
-Starter (Valeo OEM)
-Battery
Compression and leakdown test gave fantastic results.
Any advice on what to look into here? The start of this problem coincided precisely with taking the valve cover off/back on, so I checked all of the electrical connectors involved with that job -- O2 sensors, ignition coils and that little ground wire on the exhaust side of the VC. All look good and feel properly secured. Maybe they need a closer look? Anything specific to look out for? Car passes VANOS test with flying colors, and I'm certain that the valves are in spec, as I re-adjusted while the valve cover was off for the timing job after which all of this started.
Thoughts and suggestions appreciated! Can post vids of hard starts if that would be helpful!
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