No CEL had a crank shaft once cleared never came back. No I have not. I changed the fuel pump and issue still persists.
I used spray gas and same thing as starter fluid happened.
I simply can’t understand how is has to do with temp/humidty at this point, don’t know if it’s temp or humidty because if as a temp reading, the coolant temp needle is sligthly under operational temp the car starts then dies. If it’s completely in cold it won’t start.
Yes it is, I udnerstand I should keep everything under one post but at first this post was simply to know if I could spary some fuel and turned out into another thread hah a.
I have not changed the sensor yet again, I was missing a t40 bit… got it today but won’t have the chance to change it. It’s just, to me at this point is 100% seems fuel related as shown in my other post in this thread.
If the sensor is bad, I believe the fuel pump will not be energized
In that sense, it IS fuel related
I really think your next step should be to replace the fuel pump
But how can temp affect that?
Like I said, I changed the fuel pump myself already. First thing I did as it was a common issue on my car.
Temperature affects resistance. Most sensors are ntc . . . negative temperature correlation, or something to that effect
Low temperatures = very high resistance
high temperature = very low resistance
If the resistance is too high, it will essentially be open circuit
Sometimes a sensor will have sky high resistance, and the car will sporadically fail to start, and/or may stall. In this case, the resistance is clearly way out of spec
Also, sensors which are physically cracked, will tend to have the crack open up or close, depending on the temperature
Many crankshaft position sensors fail when the engine has been warmed up, and you’re cruising. No warning whatsoever
That’s what happened to my mom’s car. There wasn’t even a code! It would shut off while cruising, in the most inconvenient location. The sensor was physically fine, but resistance was over 2 megaohms, and the spec was around 1 kiloohm. I replaced it over a year ago, and the problems went away, from one day to the next, never to return
That’s backwards.
Low temperature = Low resistance.
High Temperature = High resistance.
That’s why fuses blow when they heat up, and how super conductors work by chilling the conductors.
Tester
I would also like to note, it’s not just ambiant temp, seems to also be engine/temp or whatever temp in the bay is to.
The problem is, you don’t provide enough information about the vehicle other than it’s a BMW 330.
What year?
I mean, if I don’t have all the information about the vehicle, there’s no way I can look up if there’s any TSB’s that might be related to the problem.
Tester
Yeah, I don’t know. I checked the values of the temp sensor and they all seemed ok, coolant temp being around outside temp as shown on my OBD2 tool.
How’s that coolant temperature sensor replacement going?
I thought OP had a code for a crankshaft position sensor
[quote=“db4690, post:31, topic:96036, full:true”]
I thought OP had a code for a crankshaft position sensor
[/quote]He did, but it went away, but the cold starting issue remained. I suggested the CTS in his other thread.
My gut feeling is that the crankshaft position sensor problem has not gone away, and the sensor is failing
in spite of no current code
I checked the coolant temp sensor on my OBD2 tool and it read around the outside temp so I believe it’s fine.
I don’t see how a bad crank sensor can block a car to start but is able to start if I spray fuel or starter fluid for some time and someoen cranks it, and that, to my knowledge, the only symptome I had is RPM moving 100 to 200 rpm when idle on the first time I start it with fluid.
When the car starts by itself after a hot day for example, it has zero issues. That’s also another thing that makes it hard to find.
I’m calling a F that (I hope I can say this) and prob bringing it to a indy BMW shop.
I’ll say this . . .
I’ve experienced any number of vehicles stalling out for lack of fuel, either due to running out of fuel, bad fuel pump, etc.
And they didn’t generate an associated crankshaft position sensor code
Sorry you don’t like my advice
But none of us, except you, are actually there, working on your car. It’s much easier to diagnose and repair a physical car, versus one that is only virtual
For you, the car is real
For me, it’s a virtual BMW, in cyberspace
A shop diagnosis is probably your best bet at this point. YOu can fix it yourself after they tell you what’s wrong if you like.
But back to the basics, if I had a car that would crank ok but wouldn’t start when cold but would start with some extra gas or starter fluid sprayed into the intake manifold, first thing I’d suspect is the cold start function is running too lean for some reason. The engine computer is supposed to inject much more gasoline on cold starts than hot starts. So either that isn’t happening, or there’s un-metered air getting into the engine. Either will cause a too-lean condition. For the former, start by researching how the cold start system works on your car. For the latter, ann intake manifold vacuum measurement and a proper vacuum system diagnosis is where I’d start. Best of luck.
Welp boys (and girls if any), my darn problem was the fuel pump relay… the first thing I wanted to check, which turned out I did not because my buddy who is an electrcican (lol…) told me a relay works or doesn’t, like a fuse, it can’t work semi.
I’m pretty pissed off but at the same time I’m happy that it isn’t a big issue. Mechanic first changed the crank sensor then found the relay.
Glad to hear you got it fixed on your own!
It’s the mechanic who checked it and found out. He first changed the crank sensors since he had the code then checked fuel delivery and pinpointed to the relay.
If you’re getting crank sensor codes you pretty much have to do something about it. The crank sensor is so critical to engine performance and cat life. So replacing the crank sensor is a good investment on your part. Might want to ask your shop to check for new codes periodically, b/c sometimes it isn’t the sensor itself that’s the problem. Note that diagnostic codes can be stored w/out the check engine light turning on.
So it turned out to be a lean mixture problem caused by the fuel pump running too slow? That’s consistent with the symptoms all right. It’s unusual that a fuel pump relay partially fails like that. So your buddy is correct for the most part what he said. Don’t be too hard on him for that advice. Just didn’t apply in this case is all. The common way fuel pump relay contacts fail is they start to corrode b/c of heat and sparking, which increases their resistance, and the extra resistance makes them heat up even more, and they fail completely straight away. But sometimes they can partially corrode (maybe just in one spot) and the resistance increases enough to slow down the pump motor, but not create enough heat to finish the job on burning out the contacts. Measuring the voltage at the pump connector or a fuel pressure test would have discovered that most likely.
Anyway, glad you are back on the road with a reliable starting machine.
If you’ll allow me some observations about BMWs. My advisor as a college student had a BMW, and really loved it. It wasn’t particularly reliable. But he didn’t care, he still loved it. It was a very common thing for me to arrive at his office for a meeting, and find him talking w/his wife on the phone about a car problem. He’d yell at her “Just take it to Bavarian!!!” … But the wife wanted to take it to Sears or something, b/c she thought it would be less expensive to have Sears fix it. So he’d yell out again “Don’t take it to Sears, Take it to Bavarian”!!! …lol … This would go on and on Sears! No Bavarian!! …lol
That how I got to thinking the B in BMW stood for “Bavarian” Bavarian Motor Works I thought. But I recently discovered the B stands for something else, or at least it did when BMW first started.