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Old 04-12-2011, 05:23 PM   #1
blowin 4
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Default warm engine start problem.

Ok guys my 94 318 will start every morning fine . turn it on for 30 seconds shut it off restart's fine 4 0r 5 times . as soon as it warms up it wont restart unless i wait 5 minutes or hold the pedal open and crank it for 30 seconds i believe it's a bad crank sensor or coil pack . maybe even a bad dme relay any feed back will help crank shaft sensor on it's way hope that solves the problem. every thing else is new except for the coils . thanks
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Old 04-13-2011, 07:55 AM   #2
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I would think it is a relay. Crank sensor would most likely not screw up on a constant basis, also I don't think they stop working then start working. They usually die and never work again.

Might be a hard one to track down with a relay sticking or maybe it is in the tune. Maybe too much enrichment when the car is warm.

I had the same issue with my car when the DME temp sendor was not plugged in fully. It was telling the DME the car was ice cold so it always started fine when it was cold but after it warmed up it was 30 seconds of cranking with wide-open throttle to clear out the flooded motor from enrichment fuel. It never threw a code for some reason but Barrie found the temp sendor issue when looking at the values in INPA.

John S
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Old 04-15-2011, 12:56 AM   #3
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I would think it is a relay. Crank sensor would most likely not screw up on a constant basis, also I don't think they stop working then start working. They usually die and never work again.

Might be a hard one to track down with a relay sticking or maybe it is in the tune. Maybe too much enrichment when the car is warm.

I had the same issue with my car when the DME temp sendor was not plugged in fully. It was telling the DME the car was ice cold so it always started fine when it was cold but after it warmed up it was 30 seconds of cranking with wide-open throttle to clear out the flooded motor from enrichment fuel. It never threw a code for some reason but Barrie found the temp sendor issue when looking at the values in INPA.

John S
. I think your right about the relay now I'm getting code 1211 bad ecu so I pulled the plug after worm up found the spark was very weak let it cool down had strong spark car fired right up ordering relay .
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Old 04-15-2011, 04:45 PM   #4
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. I think your right about the relay now I'm getting code 1211 bad ecu so I pulled the plug after worm up found the spark was very weak let it cool down had strong spark car fired right up ordering relay .
Sounds kinds odd and I hope that is the issue. You might be on a chase to find this issue, relays normally work or they don't. You should not get weak spark, either no spark or good spark.

Best of luck finding it, John S
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Old 04-15-2011, 05:04 PM   #5
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Sounds kinds odd and I hope that is the issue. You might be on a chase to find this issue, relays normally work or they don't. You should not get weak spark, either no spark or good spark.

Best of luck finding it, John S
lol i been chasing it for a month trying relay if that dont work should have my crank sensn today. if both dont work has to be my coils i bought them used from ebay who knows what they been thru!!!!
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Old 04-15-2011, 06:31 PM   #6
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lol i been chasing it for a month trying relay if that dont work should have my crank sensn today. if both dont work has to be my coils i bought them used from ebay who knows what they been thru!!!!
I would like to say your unloader realy is not unloading and causing too much load and not enough power to your coils to start the motor when it is cranking. Just my thought since the unloader cuts all power except fuel, DME, spark and starter while cranking. If all other items are on like radio lights and all; there is too much draw to get the coils saturated for a good blue spark.

Opinon only

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Old 04-16-2011, 07:03 PM   #7
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I would like to say your unloader realy is not unloading and causing too much load and not enough power to your coils to start the motor when it is cranking. Just my thought since the unloader cuts all power except fuel, DME, spark and starter while cranking. If all other items are on like radio lights and all; there is too much draw to get the coils saturated for a good blue spark.

Opinon only

John S
hummm which relay is the underload that sounds like the problem right there.
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Old 04-19-2011, 05:10 AM   #8
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hummm which relay is the underload that sounds like the problem right there.
This hot engine start is killing me new crank sensor new cam sensor ,cold start sensor ,dme /fuel relay coil/plugs swap ecu swap clean all body grounds & battery ternimals few things left engine temp sensor, 02 sensor . could it be bad ignition cylinder going to trace wire harns and conectors .car runs super good idles great pulls like crazy as soon has i shut her down after a hard run will not start till cools down help please ....
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Old 04-19-2011, 03:24 PM   #9
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Engine temp sendor. If this is bad and tells the DME the engine is cols all the time is will be a bear to start when warm. I had this issue when my sensor was unplugged and it took like 30 seconds of cranking or more to start my car when it was warm. Bad temp sensor or unplugged will cause starting issues like you are having.

Unloader relay on my car is located in with the DME. It is the only relay in the DME compartment. When you crank your car all accessories should turn off until your done cranking...
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Old 04-19-2011, 05:19 PM   #10
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Engine temp sendor. If this is bad and tells the DME the engine is cols all the time is will be a bear to start when warm. I had this issue when my sensor was unplugged and it took like 30 seconds of cranking or more to start my car when it was warm. Bad temp sensor or unplugged will cause starting issues like you are having.

Unloader relay on my car is located in with the DME. It is the only relay in the DME compartment. When you crank your car all accessories should turn off until your done cranking...
Can't find any info about up loader I have a new cold start sensor I think it 02 sensor they say 02 don't start working till car warms up that the cold stat monitor engine then 02 takes over when hot I think it sending a rich signal to the injector pulse I'll find out got one coming .
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Old 04-19-2011, 06:37 PM   #11
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Can't find any info about up loader I have a new cold start sensor I think it 02 sensor they say 02 don't start working till car warms up that the cold stat monitor engine then 02 takes over when hot I think it sending a rich signal to the injector pulse I'll find out got one coming .
It is not the O2. Please trust me on this. Yo have a temp sensor on the head that tells the DME the head temp. That would be the issue on a warm start up issue. Have you changed it? Also A ELM-323 will detect this issue or INPA which is how I found out I had the issue
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Old 04-19-2011, 06:46 PM   #12
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Does all you accessories stay on whenyou crank the car? radio, interior lights, head lights? If so your unloader is not working correctly and you might not have enough juice to fire your coil correctly...Weak spark like you said you had on a hot start

Head temp sensor first though since I think that is the issue. Ok

JohnS
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Old 04-19-2011, 09:51 PM   #13
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Does all you accessories stay on whenyou crank the car? radio, interior lights, head lights? If so your unloader is not working correctly and you might not have enough juice to fire your coil correctly...Weak spark like you said you had on a hot start

Head temp sensor first though since I think that is the issue. Ok

JohnS
When test the coil I have 12.53 volts when I crank drops to 9.5 then steady 10.6. Not good!
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Old 04-20-2011, 03:26 PM   #14
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When test the coil I have 12.53 volts when I crank drops to 9.5 then steady 10.6. Not good!
Mine drops in the low 10 volts when cranking but no start issues.

Are you running after market coils?

Make sure you check your head temp sendor cause it sounds to me like your car is getting too much enrichment on hot start which would be the head temp sendor. ***The coil low voltage issue would cause issues with cold starts too.***

Another thing maybe a bad starter... check the voltage on a cold start and if it is much higher then your starter is bad and drawing too many amps when it is hot. I've had a bad starter when it was hot it would draw big amps due to a warped armature this was not a BMW but can happen to any starter. If the starter has low voltage on a cold start and starts the car fine then you need to go to my head temp sensor therory.

Last edited by xxxJohnBoyxxx; 04-20-2011 at 03:35 PM.
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Old 04-20-2011, 05:07 PM   #15
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Originally Posted by xxxJohnBoyxxx View Post
Mine drops in the low 10 volts when cranking but no start issues.

Are you running after market coils?

Make sure you check your head temp sendor cause it sounds to me like your car is getting too much enrichment on hot start which would be the head temp sendor. ***The coil low voltage issue would cause issues with cold starts too.***

Another thing maybe a bad starter... check the voltage on a cold start and if it is much higher then your starter is bad and drawing too many amps when it is hot. I've had a bad starter when it was hot it would draw big amps due to a warped armature this was not a BMW but can happen to any starter. If the starter has low voltage on a cold start and starts the car fine then you need to go to my head temp sensor therory.
my start is about 3 weeks old its oem .2 last things im going to try there are to sensor on the head one is cold start injector already changed then there is the hot temp sending unit i dont think that matter but im going to change it . 2nd new coils cause one set is eom but used 2nd set is aftermarket but older could have went bad ..i noticed all coils read .6 ohms cold but when i test them hot the jump from .7-8 -9 ohms never a steady # back in forth from .7-.8 . 9 could 2 sets of coils be bad ... if that dont work tracing wiring into dash and ignition cylinder.
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