Hard start after lapping session
07-15-2013, 03:14 PM
#1
Rennlist Member
Thread Starter
Hard start after lapping session
I took my '02 cab for its first lapping session yesterday. This is after a full engine rebuild this past winter due to cam chain failure. The car performed flawlessly. 135 mph at the end of the straight at Road America. Thanks to LAPS Inc for a great day. Beautiful weather, a historic track, great people.
Anyway, after coming off the track and letting the car sit for 15 minutes or so, I went to start it and it seemed like the battery was low. Mind you, temp and pressure were all normal during and after the lapping session. Not problems at all. It turned over slowly and finally caught. Ran perfectly, no smoke, temps were good, oil pressure was good. I drove it home later that night (2 hours). No problem. It started up later that night with no issues. Turned over like it should. The volt meter showed it was charging on the way home (~13.5 volts).
Could it be the starter was hot after the laps and lost its umph until it cooled off? Any thoughts?
Anyway, after coming off the track and letting the car sit for 15 minutes or so, I went to start it and it seemed like the battery was low. Mind you, temp and pressure were all normal during and after the lapping session. Not problems at all. It turned over slowly and finally caught. Ran perfectly, no smoke, temps were good, oil pressure was good. I drove it home later that night (2 hours). No problem. It started up later that night with no issues. Turned over like it should. The volt meter showed it was charging on the way home (~13.5 volts).
Could it be the starter was hot after the laps and lost its umph until it cooled off? Any thoughts?
07-15-2013, 07:12 PM
#3
Race Director
Could be starter heat soak. In my personal experience, tracking is hard on batteries, although someone is sure to argue with me. Autocrossing my 986 Boxster on two different occasions resulted in a very similar experience - it started great the first time my run group went out, and the battery seemed weak when I went to start it when my run group was called for the second session.
On another date, the battery didn't have enough amperage to start the car at all when I went out for my second session, but I had parked on an incline and pop-started it (which I'm sure will result in even more arguing.
)
On another date, the battery didn't have enough amperage to start the car at all when I went out for my second session, but I had parked on an incline and pop-started it (which I'm sure will result in even more arguing.
)
07-15-2013, 09:39 PM
#4
Rennlist Member
Iv been chasing this problem for over a year now. I think I am almost there. I have one more test to determine the issue. Watch my post "lets discuss Crank Position sensors for a moment"
07-16-2013, 03:22 PM
#6
Instructor
I've noticed this exact same thing during a number of track days. Especially on hot days. Between the startup hesitation and the occasional cloud of smoke on startup, I tend to get some curious looks from other people in the paddock. Then, after an hour or so on the highway on the way home, everything is fine again.
I think that these cars (most cars really) can respond to heat in a number of ways. After all, the M96 wasn't really designed for track use. I remember reading that Porsche determined that their "road" cars were never subjected to more than 1.4G by customers, and they designed the engine around that and similar parameters. I suppose that some other components (starter motor? electrical system?) were designed and built with a similar mindset.
I think that these cars (most cars really) can respond to heat in a number of ways. After all, the M96 wasn't really designed for track use. I remember reading that Porsche determined that their "road" cars were never subjected to more than 1.4G by customers, and they designed the engine around that and similar parameters. I suppose that some other components (starter motor? electrical system?) were designed and built with a similar mindset.
07-16-2013, 04:30 PM
#7
Three Wheelin'
I've noticed this exact same thing during a number of track days. Especially on hot days. Between the startup hesitation and the occasional cloud of smoke on startup, I tend to get some curious looks from other people in the paddock. Then, after an hour or so on the highway on the way home, everything is fine again.
I think that these cars (most cars really) can respond to heat in a number of ways. After all, the M96 wasn't really designed for track use. I remember reading that Porsche determined that their "road" cars were never subjected to more than 1.4G by customers, and they designed the engine around that and similar parameters. I suppose that some other components (starter motor? electrical system?) were designed and built with a similar mindset.
I think that these cars (most cars really) can respond to heat in a number of ways. After all, the M96 wasn't really designed for track use. I remember reading that Porsche determined that their "road" cars were never subjected to more than 1.4G by customers, and they designed the engine around that and similar parameters. I suppose that some other components (starter motor? electrical system?) were designed and built with a similar mindset.
, still manage to post some much better times than the M3/Mustang/Corvette pushers on the track, but I've frankly never had the smoking / hard start issues - but then again....I do have a brand new motor in the thing
