Hot start issue

zerofighter · 11-26-2013, 10:38 PM

I seem to be having an issue with my M coupe, I've searched and no one really has a definitive answer. The car has issues starting when the car is warm/hot whether it is due to driving for a little bit or even if it is a hot day. I turn the key and hear a click, all accessories/nav/radio work and there is no diming of lights. It would usually take a few times trying to turn over the car by pulling the key out and putting it back in. I know a few people have had this problem and I have PM'd them and no response.

Symptom
-After being driven for a little bit or it is hot outside it will not turn over and you just a somewhat loud "click" from the engine bay. Car will turn over if it cooled down for a while or the next day. No diming of lights and all accessories/nav/radio works fine. The car is in storage so I can't really do anymore testing until next spring.

Diagnostics/tests
-Battery - Less than 2 years old and even after I charged it fully this issue would still occur. Dealer tested alternator and said the output was good and the closed circuit draw was within spec. However, they said the battery was weak, so I charged it a few times and the issue still happens only when hot.
-EWS/keys - Tried with both keys and issue occurs with both, keyless entry functions work on both at range.
-Clutch stop - No modification, OEM one still in place.
-Clutch switch (?) - The faint click is still present when putting the clutch in while the car is off and the key is in.
-Starter - I've heard people with the same issue replace starters and the same issue occurs. If there was a bad spot would it not happen randomly? My issue only happens when hot.
-Ignition switch - Same deal with the starter, people replace and the problem prevails.

I would think it is related to something in the engine bay since on the colder days it doesn't get really warm in the cabin as if it was a hot summer day when the issue comes up. The one thing that seems to remain constant with the issue is a hot engine and engine bay, so that's why I would maybe rule out the ignition switch and clutch switch, I could be wrong though.

Any help would be greatly appreciated as I haven't had much luck resolving this issue.

Thanks
-Pearson

yousefnjr · 11-27-2013, 07:38 AM

I had a similar issue about a year ago. Intermittent starting issue progressively got worse, and it ended up being the ignition switch. Here is that thread.

Hopefully yours is an easy fix!

Pheonix · 11-27-2013, 10:20 AM

There might be some issues with one of the relays! This is a very comon problem with late model Honda; the Main Relay (which also control the fuel pump) would have intermittent problem with the solder joint and fail when it gets hot. I don't know if our cars have similar electrical configuration. However, try and see if you could get a schematic and see if you locate relays that related to the fuel system and check them out. I would pull them out of the box and cool them down to see if that solve the problem (or you could buy spare one, if not too expensive and swap them out). Good luck and please let us know what you find

Gallardo Rosso · 11-27-2013, 11:51 AM

Easy test... Run a small light from the switched 12v lug on the starter to the chassis ground. Just let it rest at the window base or tape it to the windshield. This way you can see it from drivers seat. When you crank it should light up.

If it lights and the car won't start.... Starter is bad.

If no light in cranking. Move the wiring to the relay side (12v trigger) of the starter. If no light it's likely ignition or one if the "interlocks" like the clutch switch.

Your basically building a test light/volt meter but it's constantly attached and you don't need 2 people.

Just make sure there's no potential of a short. 12v at the starter has a lot of amps directly from battery.

zerofighter · 11-27-2013, 07:25 PM

Quote:

Originally Posted by Gallardo Rosso

Easy test... Run a small light from the switched 12v lug on the starter to the chassis ground. Just let it rest at the window base or tape it to the windshield. This way you can see it from drivers seat. When you crank it should light up.

If it lights and the car won't start.... Starter is bad.

If no light in cranking. Move the wiring to the relay side (12v trigger) of the starter. If no light it's likely ignition or one if the "interlocks" like the clutch switch.

Your basically building a test light/volt meter but it's constantly attached and you don't need 2 people.

Just make sure there's no potential of a short. 12v at the starter has a lot of amps directly from battery.

Thanks for the info. Since the car is sitting for the winter I'll wait until it is nice out to try to replicate the problem and check a few other things.

The issue only happens when the car is up to temp, would this test work on a cold engine? The car starts up fine when cool but not so much when it is up to temp.

Quote:

Originally Posted by yousefnjr

I had a similar issue about a year ago. Intermittent starting issue progressively got worse, and it ended up being the ignition switch. Here is that thread.

Hopefully yours is an easy fix!

Not sure if we have the same problem, seems like your issue happened randomly whereas my issue happens only when hot. Thanks though, I will keep it in mind if all else fails.

Gallardo Rosso · 11-27-2013, 09:52 PM

You need to confirm that you are delivering 12v to the starter...hot or cold. If starter has 12v it has to crank over or the starter is bad. But you also need to make sure it's 12v.... If voltage drops a bad battery is likely. The click you hear is the relay or "Bendix" trying to engage. The teeth on the starter reaching to engage the ring on the flywheel.

May want a volt meter hand too.

11-26-2013, 10:38 PM	#1
zerofighter projecttechnik.com 108 Rep 215 Posts Drives: F80 ZCP Join Date: Aug 2006 Location: Calgary, AB Canada iTrader: (2)	Hot start issue I seem to be having an issue with my M coupe, I've searched and no one really has a definitive answer. The car has issues starting when the car is warm/hot whether it is due to driving for a little bit or even if it is a hot day. I turn the key and hear a click, all accessories/nav/radio work and there is no diming of lights. It would usually take a few times trying to turn over the car by pulling the key out and putting it back in. I know a few people have had this problem and I have PM'd them and no response. Symptom -After being driven for a little bit or it is hot outside it will not turn over and you just a somewhat loud "click" from the engine bay. Car will turn over if it cooled down for a while or the next day. No diming of lights and all accessories/nav/radio works fine. The car is in storage so I can't really do anymore testing until next spring. Diagnostics/tests -Battery - Less than 2 years old and even after I charged it fully this issue would still occur. Dealer tested alternator and said the output was good and the closed circuit draw was within spec. However, they said the battery was weak, so I charged it a few times and the issue still happens only when hot. -EWS/keys - Tried with both keys and issue occurs with both, keyless entry functions work on both at range. -Clutch stop - No modification, OEM one still in place. -Clutch switch (?) - The faint click is still present when putting the clutch in while the car is off and the key is in. -Starter - I've heard people with the same issue replace starters and the same issue occurs. If there was a bad spot would it not happen randomly? My issue only happens when hot. -Ignition switch - Same deal with the starter, people replace and the problem prevails. I would think it is related to something in the engine bay since on the colder days it doesn't get really warm in the cabin as if it was a hot summer day when the issue comes up. The one thing that seems to remain constant with the issue is a hot engine and engine bay, so that's why I would maybe rule out the ignition switch and clutch switch, I could be wrong though. Any help would be greatly appreciated as I haven't had much luck resolving this issue. Thanks -Pearson __________________ projecttechnik.com My F80 European Delivery - M HQ, test mules, Nurburgring, etc
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11-27-2013, 07:38 AM	#2
yousefnjr salty cowboys fan 6155 Rep 3,402 Posts Drives: ‘06 Z4MR, ‘20 X7, ‘22 M4x Join Date: Dec 2012 Location: Bay Area, CA iTrader: (2)	I had a similar issue about a year ago. Intermittent starting issue progressively got worse, and it ended up being the ignition switch. Here is that thread. Hopefully yours is an easy fix!
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11-27-2013, 10:20 AM	#3
Pheonix Captain 371 Rep 999 Posts Drives: 2007 Z4 M Coupe 2012 e93 M3 Join Date: Sep 2008 Location: Bay Area, CA iTrader: (8) Garage List 2007 BMW/Z4MC [0.00]	There might be some issues with one of the relays! This is a very comon problem with late model Honda; the Main Relay (which also control the fuel pump) would have intermittent problem with the solder joint and fail when it gets hot. I don't know if our cars have similar electrical configuration. However, try and see if you could get a schematic and see if you locate relays that related to the fuel system and check them out. I would pull them out of the box and cool them down to see if that solve the problem (or you could buy spare one, if not too expensive and swap them out). Good luck and please let us know what you find
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11-27-2013, 11:51 AM	#4
Gallardo Rosso Enlisted Member 0 Rep 46 Posts Drives: 2007 Z4M Coupe Join Date: Apr 2013 Location: Philadelphia iTrader: (0)	Easy test... Run a small light from the switched 12v lug on the starter to the chassis ground. Just let it rest at the window base or tape it to the windshield. This way you can see it from drivers seat. When you crank it should light up. If it lights and the car won't start.... Starter is bad. If no light in cranking. Move the wiring to the relay side (12v trigger) of the starter. If no light it's likely ignition or one if the "interlocks" like the clutch switch. Your basically building a test light/volt meter but it's constantly attached and you don't need 2 people. Just make sure there's no potential of a short. 12v at the starter has a lot of amps directly from battery. Attached Images
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11-27-2013, 09:52 PM	#6
Gallardo Rosso Enlisted Member 0 Rep 46 Posts Drives: 2007 Z4M Coupe Join Date: Apr 2013 Location: Philadelphia iTrader: (0)	You need to confirm that you are delivering 12v to the starter...hot or cold. If starter has 12v it has to crank over or the starter is bad. But you also need to make sure it's 12v.... If voltage drops a bad battery is likely. The click you hear is the relay or "Bendix" trying to engage. The teeth on the starter reaching to engage the ring on the flywheel. May want a volt meter hand too.
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