My M5 (95T) won't start when the ambient temp. is at freezing (0 'C) or lower. It started being a bit grumpy, but only at low temps. When it first starts it runs smooth like always. But lately we've been having lots of snow and temperatures below freezing for more than a week, so no way of getting it started. I'll tell you what it isn't: Battery is good and sparkplugs are good (just changed them). Any ideas? I will have a friend run a diag. tool (PC) on it in a few days, to see if any codes are surfacing.... But, as mentioned, it is freezing cold here and the car is buried under 1,5 foot of snow right now! :-(
Any serious input is welcome! :-)
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'95 M5 Touring Fjordgrau (Almost bone stock!).
'86 Chevrolet Camaro Z28 IROC-Z (MODIFIED!).
You really need to be able to see what the input sensors are reading. If the air intake temperature sensor is not working there is a possibility that not enough fuel is being delivered for the low temperatures. When the AIT sensor is not working the ECU will assume a very high temperature and fuel accordingly.
It could be other sensors also.
Diagnostic with live data read of ALL sensors will possibly give you a much better idea.
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Avus Blue 6 speed 3.8L E34 ///M5 Sedan
Evolve ECU Remap / Chip | Evolve Carbon Intake | Powerflex Black | Whiteline | Eibach Springs
Check those fault codes first. I suspect the same as Cyrus about the problem. DME should notice the cold temperature outside and use choke but it seems that your engine doesn't do that.
Well.... Did a diagnosis with Carsoft and nada! (It just showed ABS error [probably due to dead battery earlier] and one of the motors [central locking], which is a bit slow when the weather is cold). Absolutely no codes on engine or related systems...
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'95 M5 Touring Fjordgrau (Almost bone stock!).
'86 Chevrolet Camaro Z28 IROC-Z (MODIFIED!).
Well.... Did a diagnosis with Carsoft and nada! (It just showed ABS error [probably due to dead battery earlier] and one of the motors [central locking], which is a bit slow when the weather is cold). Absolutely no codes on engine or related systems...
Water temp sensor faulty (not the one for the gauge, there`s two tempsensors. the other one is on the exhaust side of the engine on a coolantpipe). also I would check the crank sensor, if its dirty It may collect ice and condensation in cold weather and loose signal. also clean the contacts for all sensors.
does the car even try to start when this happens or is it just turning over???
Is there an aftermarket alarm on the car? on my dads 325ix , the DEFA alarm would not disengage when it was cold altough the doors opened. and the car would not start. A long shot, I know , but wort a thought.
Sakke
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"You can´t afford cheap things if you´re poor"
Agree that it's unlikely that you wil get a MAF failure fault code on EOBD1 vehicle.
You would have to unplug it or break a air temp sensor wire on these cars to get fault code.
Regardless of air intake temp, if coolant temp is cold or, not being read, the default is a rich mixture to cold start.
On older cars with worn MAF's, this will result in a AFR @ 13-13.5 :1
Is it possible that air intake has iced the MAF hot wires.
Only one is heated !
Dr. Sakke, the car is just turning over as of now. When the problems started to appear, it was hard to start and needed to be turned over a little while (like 30 sec. or so), before starting. And when it first started it would run just fine. But when the ambient temperature dropped below 0' C, it became impossible to start. Yesterday and today we've had pos. temperatures, so I will try again today and see what happens. I just have to boost the battery first, to be sure that it is not causing any problems!
The alarm is the OEM BMW, so that is not a problem. I have had the same problem as you, but with an Enforcer alarm, many years ago.
A guy here in Norway thought maybe the cold start injector is faulty...
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'95 M5 Touring Fjordgrau (Almost bone stock!).
'86 Chevrolet Camaro Z28 IROC-Z (MODIFIED!).
Dr. Sakke, the car is just turning over as of now. When the problems started to appear, it was hard to start and needed to be turned over a little while (like 30 sec. or so), before starting. And when it first started it would run just fine. But when the ambient temperature dropped below 0' C, it became impossible to start. Yesterday and today we've had pos. temperatures, so I will try again today and see what happens. I just have to boost the battery first, to be sure that it is not causing any problems!
The alarm is the OEM BMW, so that is not a problem. I have had the same problem as you, but with an Enforcer alarm, many years ago.
A guy here in Norway thought maybe the cold start injector is faulty...
Or low fuel pressure? Are you driving the car or just starting it once in a while? Bad fuel pump(relay?) could be one suggestion.
Sakke
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"You can´t afford cheap things if you´re poor"
Hmmm..... The car was my daily driver, until it died, about 1,5 week ago...
Todays update (tried updating earlier, but the server was down):
Boosted the battery and tried starting it, nothing. I also tried with "startgas" (Ether on a spray can) into all 6 intakes and NOTHING. Not even a sputter! I could smell the ether from the exhaust pipes, so it was sucked through the engine. This tells me that there is no spark at all, because the ether ignites VERY easily. After discussing this with some friends, I have concluded that it is probably one of the following things:
-ECU (not very probably) or cable harness.
-Crank sensor.
-Camshaft sensor.
Tomorrow I will check for voltage to the coils (I am quite sure there's nothing), sensors and so on. I will also check for corrosion in related connectors. I will also spray the conectors with CRC 5-56 to remove any moisture.
Does anyone here know where I can find the Ohm/Volt values for the sensors, harness, coils, etc.?
Where is the crank sensor located? Is it possible to reach it from above?
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'95 M5 Touring Fjordgrau (Almost bone stock!).
'86 Chevrolet Camaro Z28 IROC-Z (MODIFIED!).
Some of the values can be found in Bentley:
Engine coolant temp sensor -10C : 7-11kOhm, 20C : 2.1 -2.9kOhm, 80C : 0.27-0.4kOhm
Air inlet temp: same as coolant temp sensor. You should also be able to measure 5V at the connectors (between ground and power).
M5 won't start when freezing temp! :-(
Linear Mode
