a normal car should start up everytime w/ just one crank of the key, cold or hot.

 

You need to further diagnose your fuel pressures. If there is some sort of delay in starting to "prime"...then you are losing fuel pressure when the engine is off. That is not normal. Could be leaking injectors or the check valve in the fuel filter (if it has an internal check valve) could have failed.

 

the fuel pump has the check valve in it. common cause of a long crank issue.

 

You could check the fuel pressure on the fuel rail / schraeder valve ...
Should be around 51 psi .

 

and at shutoff, the pressure should hold, then start to drop off gradually, i cant remember rate of drop that should be seen, hopefully another fester can chime in on this.

 

it's not fuel pressure issue if it's not sputtering while cranking.

 

No experience in fuel pressure testing at the fuel rail. Can anyone recommend a reliable tester at a reasonable price?

No sputtering while cranking. I’d like to try/learn testing cause the shop will charge $100.

 

Define "3 cranks" Do you have to crank the car, turn it off crank again, on turn off crank again? A video would be extremely helpful.

 

I’ll try to record it when car gets days off.
3 cranks as in a quick (tch tch)-(tch tch)-(tch tch)- Zoom!

 

harbor freight has a fuel pressure gauge thats cheap enough, around $20. the test valve on the fuel rail is a schrader type valve, same as a tire pressure test valve. ford also uses the same valve. one can rent a gauge at most major parts houses, just leave a deposit, use the gauge, return it and get your money back.

 

It costs $29.99 today (Maddox fuel injector tester at hf)
The shop I visited in pandemic time said my fuel pump might be weak and gave me the scare that it’s common with this model. Five years later, it’s still running with original fuel pump.

What I don’t like is the car doesn’t want to seem to rest, otherwise, all sort of issues pop up. Winter is coming and I expect it to rough idle at cold start and SRS (airbag) light up until end of winter. 🥶

 

Someone’s article:

If anything:
I have a little long cranking when car is rested for more than 1 day.
Also, it’s been 17mpg city driving.

1- How many minutes should I let the car run when monitoring pressure?
2- How many minutes do I keep the tool attached when monitoring “hold pressure”?

 

Someone’s article:
View attachment 1151181
If anything:
I have a little long cranking when car is rested for more than 1 day.
Also, it’s been 17mpg city driving.

1- How many minutes should I let the car run when monitoring pressure?
2- How many minutes do I keep the tool attached when monitoring “hold pressure”?

Maybe 20 seconds ? lol .
However long it takes to get to near / around 51 psi ...

 

pressure should jump up immediately when running.
as to the hold pressure, id chart the pressure over time (up to an hour) and see how it holds. unfortunately, as stated, i dont remember pressure/time right off, have a chart somewhere, just dont know where. am looking for it.

 

The spec from ISTA is, the fuel pressure should drop no more than 0.5 bar after the engine has been switched off for 20-30 mins.
So your pressure should read no less than 2.8 bar, assuming that you have the correct fuel pressure of 3.5 bar +/- 0.2 bar.

 

From Bentleys…..
It shouldn’t drop more than 7 PSI in 20 minutes after you shut the engine off.

 

First thing in the morning cold start:

No priming (quick start), with 1 or more days rest = 3 cranks then car starts

No priming, no rest, driven daily with 12 hour rest = 2 cranks then car starts

Priming for 10 seconds = 1 crank then car starts

*priming = putting the key in ON position for 10 seconds before switching key all the way to start position.

M52TU 2000 528i

A while ago I had one similar experience with my 2002 530i (290K miles). At one time after I replaced the intake cam sensor with an OEM part, I needed to crank 2 to 3 time longer to start the car. May be that's what you said 3 cranks, I thought it was 3 turns of the crankshaft at that time. I removed the OEM sensor and did my bench test with a setup, the output pulses were nice and clean when observed on the oscilloscope.

I then carefully compared the OEM's with the original BMW sensor. I found the OEM sensor comes with a much thicker o-ring, With it installed the sensor element, a Hall IC in the sensor assembly actually located about 0.020" farther away from camshaft sensing wheel. It required the camshaft to turn a bit faster to create the same magnetic field strength (as using BMW sensor) to trigger the Hall IC. Thus it took the starter longer to rev the engine up to that higher speed. After replacing the O-ring, today my car still starts within 1 to 1.5 second after turning the key.

 

A while ago I had one similar experience with my 2002 530i (290K miles). At one time after I replaced the intake cam sensor with an OEM part, I needed to crank 2 to 3 time longer to start the car. May be that's what you said 3 cranks, I thought it was 3 turns of the crankshaft at that time. I removed the OEM sensor and did my bench test with a setup, the output pulses were nice and clean when observed on the oscilloscope.

I then carefully compared the OEM's with the original BMW sensor. I found the OEM sensor comes with a much thicker o-ring, With it installed the sensor element, a Hall IC in the sensor assembly actually located about 0.020" farther away from camshaft sensing wheel. It required the camshaft to turn a bit faster to create the same magnetic field strength (as using BMW sensor) to trigger the Hall IC. Thus it took the starter longer to rev the engine up to that higher speed. After replacing the O-ring, today my car still starts within 1 to 1.5 second after turning the key.

I replaced mine last January 2024 with OE version
BMW Camshaft Position Sensor
VNE-94513

FCPEuro.com insisted that the OE and genuine bmw are exactly alike. I checked the o-ring for OE and genuine BMW; both have the same size 17x3.

(backstory: car shut off by itself at a stop sign near home. I was able to restart car and drove back home. Scanned the car and got intake camshaft sensor error code. After that experience, I always bring my Peake scan tool in my glove box).

 

similar story: mine started to crank longer when I rebuilt my starter motor last year. it wasn't doing it all the time, it was completely random. engine was cranking way faster than before after the rebuild so I guessed maybe the crank sensor was unable to read properly?

I knew that a shim was normally needed (part #12141742693) between the sensor and the casing on these engines but mine didn't have it. so I ordered this part to try, installed it and voila... problem solved. not a single long cranking since then.

 

similar story: mine started to crank longer when I rebuilt my starter motor last year. it wasn't doing it all the time, it was completely random.

Yeah, positioning of the cam sensor is tricky sometimes and the result may depend on who made the sensor. Dealers alway say it works the same way and is a direct replacement of the original. My background is electronics, that I know those MLCC capacitors used inside the sensor have at least +/-15% tolerance in accuracy, if they used caps with R-rating. Then there's another +/-5% variation within the rated temperature changes, X5R type is good for -55°C to 85°C, X7R will be good for -55°C to 125°C. The variations creates output with slightly different pulse width.

When placed too close to cam sensing wheel with no o-ring, the magnetic field might be too strong, over powering the sensor, it results in noise at sensor output. It's like strong electromagnetic field is used to jam a flying drone. When a drone flys close to the strong field, the operator starts to feel noise interfering the communication, then intermittent, if he let it continue the same direction, he'll eventually lose the control of the drone.

 

Another possibility is If your battery works below normal condition, the starter might not rev the engine fast enough to produce timely sufficient pulses from camshaft outputs. You get slower response from ECM to fire up the engine. It's best to check the battery with a digital oscilloscope to capture the waveform of battery voltage during cranking. It'll show how far the voltage is sagged in that period of time. A simple multimeter won't show you the problem due to meter respond time is slow and not in realtime.

 

I assure you battery is not the problem.

if battery went down to the point that wouldn't crank fast enough, it usually wouldn't crank at all. just clicks.

 

A "decent" meter such as Fluke 87V updates its display in every 0.5 second in DC voltage measurement. What had happened within every 0.5 second to a fluctuated DC is unknown. At the end of a 0.5 second the meter displays, depends on the algorithm used in filtering/smoothing, mostly the average captured voltages. Cranking the engine for 3 second and monitor the battery with such a meter, you get 6 readings that our eyes will have difficulty to follow. While with a digital oscilloscope, the voltage changes in the entire 3 second can be captured for later viewing. It can be expanded to see what happened into mini second within that 3 second.

 

Battery voltage during cranking won't show much as the load is pretty much constant.
As long as the battery can crank the engine (11 volts is enough) over it will start.

The cam sensor signal while running looks like this.

 

Ha, great to see you also use Tek digital OSC, I use a slightly earlier model. The captured pulses look decent. Just a suggestion that on the horizontal axis there needs to be a starting reference for time zero, that's the time you turn the key on to start the engine. Then to the right of that reference time record the sensor output for the first couple of seconds. If you set the horizontal at 500ms per division and the trigger mode to Single, the oscilloscope will capture the first rising edge (ECM sets sensing input active) of sensor output and record at least 3 second of data for you. The first falling edge is when the camshaft rotates the timing piece under the sensor. If it's slightly late, it may miss the time ECM first pulls the data, or it may be the pulse width isn't what ECM is looking for. I do not know how fast ECM gets the data from cam sensor after ignition key on, but we'll know something by comparing outputs from using BMW sensor and from other manufacturers.

Other than camshaft sensor and battery, I don't know what else may delay engine startup and is temperature related ( when cold starting). Good luck your finding a solution.

 

Will the fuel pressure test help indicate if I have a leaky fuel injector?

I did multiple short trips today and all the warm/hot start were sweet to the ears.

 

Will the fuel pressure test help indicate if I have a leaky fuel injector?

yes.

and I'm telling again; fuel pressure is not your issue if your engine is not sputtering while long cranking occurs.

 

EMT-X5, if I have time in the next few days I’ll hook the scope up to the car.

bimmer, if your injectors are leaking you should see the fuel pressure drop off much quicker than the 7 PSI in 20 min after the engine is turned off.

 

Have you checked for pending codes (that won't set the CEL)? The Cam sensor may be on the way out.

 

yes.

and I'm telling again; fuel pressure is not your issue if your engine is not sputtering while long cranking occurs.

Have you checked for pending codes (that won't set the CEL)? The Cam sensor may be on the way out.

I have replaced the (intake) camshaft position sensor last Jan 2024 due to a fault code.

Would a faulty (exhaust) camshaft position sensor exhibit mild long crank in cold after 2 days or more rest?

I don’t have pending codes.

 

yes, faulty cps would cause a hard to, or no, start
& is often intermittent, tends to be more noticeable when the engine is cold.