problem starting during cold start

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badass_ck

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Dear Sifus,

My N42 2004 is having a problem starting every time I cold start it ie after I left the car for a few hours.

Just few weeks ago, I'd changed the (1) battery (2) camshaft sensors (3) ignition coil.

Why does the problem still persisting? Diagnosis says ok. Appreciate your input.
 
It sound like pressure regulator leak, for my M52 is on fit on rail, for M54 fit on fuel filter, for N42 i dont know where it fit. it should on fuel filter also i think, change it , problom gone. dianose off course ok, this do nothing with electrical.
 
Thanks. Sifu jarance indicated could be fuel pump or filter too. I need to check the tank level. Relly giving me headache.

Thanks again
 
copy from another thread.

There is a simple way to check the fuel pump.
1. Press the odometer reset button and turn the ignition to position.
2. You will see a "Test Display". Press the odometer button many time until it come to "19.0"
3. Pause for a few seconds and then when the display change to "1.0", press the odometer button until it display "6.0"
4. The display will then display "123220". The first 3 digits (123) show the fuel on the left tank and last 3 digits (220) show the fuel on the right tank.

Note : Do this test when the tank is half full. If it full, the display will show 240330.

5. Start the engine and drive around. Observe the display. The first 3 digit on the left show will gradually decrease to 000
and the right 3 digits should increase.

This test will prove the strength of the pump. If the pump is good, then the return fuel from the fuel regulator will return
back to the left fuel tank. it will pass thru the fuel jet pump and will suck the fuel from the left tank and transfer it to the
right tank where the fuel pump is located.

Recently, I have problem starting in the morning and also some error code on misfiring on #4 cylinder.

I did the above test and found that there always some fuel in the left tank at 1/4 tank. Sometime my car also stalled at 1/4 tank
but it is OK at full tank.

I bought a new fuel/sender from BA for RM350 and install it myself. So far in the car for a few weeks and the problem of hesitate
cold starting is no longer encounter. BTW, I also change my fuel filter as well.
 
Hi Jarance,

I've just checked mine using your shared method, want to confirm is it when the right tank is always having more fuel than the left, then it's confirm the fuel pump already weak and need to replace?
From the test just now, when running, the left tank always remaining 150+ value whereas right tank always remain at 250+ value. During idling, it was once the left drop till as low as 30+ and the right went up to 300+ value. However, the left tank has never reduce to 0 value as you mention.
If changing the part, is it just the fuel pump only or should change the jetter pump (part # 16146755880 ) too?
 
kw930 said:
Hi Jarance,

I've just checked mine using your shared method, want to confirm is it when the right tank is always having more fuel than the left, then it's confirm the fuel pump already weak and need to replace?
From the test just now, when running, the left tank always remaining 150+ value whereas right tank always remain at 250+ value. During idling, it was once the left drop till as low as 30+ and the right went up to 300+ value. However, the left tank has never reduce to 0 value as you mention.
If changing the part, is it just the fuel pump only or should change the jetter pump (part # 16146755880 ) too?
150 + 250 = 40.0 litres. that is about 2/3 tank full if your tank is 60 litres. So whatever that is pump from left tank to the right tank will overflow back to the left tank.

As mentioned earlier, do the test at 1/4 tank.

Just change the pump only if it weak. Once you have a good pump the fuel return will be stronger and it will suck the fuel better. The jet pump work on venturi principle, the higher the return pressure, the better the vacuum.

typical-cross-section-ejector700x344.gif
 
I seldom drive with so less fuel remaining at the tank since I've 1 experience that my car start and immediately engine die off though the gauge showed it was still 1/4 of fuel remaining. Well, maybe I should take some risk again to do this experiment.

So, from your explanation, seems like the jetter pump is a dependent role, it's function will depend on how good the fuel pump is, right?

BTW, is a weak fuel pump will affect the fuel content reading inconsistently too? I found that my fuel content reading not consistent and accurate. I can have burnt out 20-30% of fuel, but the fuel gauge and the digital display may still showing almost full tank. Normally when the car in a long idling or restart several time again, it may show back to 70-80% fuel remaining then.
 
Hello all,

my problem had been persisting for a few weeks then 2 weeks ago, it became worse. I had to start for at least 15 mins to start the car after the engine became cold.

So what happened was:

1) changed camshaft sensors;
2) changed ignition coils;
3) changed fuel filter;
4) changed fuel pump.

(after changing fuel pump, the minutes i took to start from cold became shorter to 1 2 minutes)

then:

5) changed crankshaft sensor;

and voila... everything is ok now!

phewwww
 
Herbert said:
So items 1 to 4 were replaced unnecessary.
Not really. It is part of the preventive maintenance. I have changed all the aboves over the years.
 
Dear sifus,

After all the works and replacements, the problem is still persisting.

I have to leave the car with the workshop next week for them to check.

Sigh.
 
It is rather unfortunate that the problem still persists.

Last Friday, I left my car to the workshop and on Saturday, I got a call to inform that they 'detected' the problem. I confirmed a few times and they said one of the sensors caused the problem. I agreed to replace it as advised by the owner of the shop.

On Monday at about 3 pm I collected my car. I managed to start it without any problem. Once, I reached my house at about 4pm. It remained until this morning.

The "Essentric Sensor (used)" costs me RM 400 and "Essentric Sensor Cover" costs me RM 80. I didnt snap a pic because I was so excited that my car was fixed but sigh....

When I started my car at about 9.40 am, the problem recurred. RPM was about 800 dropped 7-600 and fluctuated for a bit then the engine went dead. I called the workshop immediately and put him on speaker to show that the car can't start. He was perplexed to and said he had never encounter such problem.


I wonder what else I can do. I have resent my car to the workshop and I am going to go over to the workshop to restart the car.

Dear Sifus,

Can anyone help me on this? :(

Thanks.
 
Just curious, is ur engine loosing compression? A delayed response/lag when u step on the accelerator?
 
Urmmm... more of either:

1) when I cranked it and it started but RPM fluctuated around 800 -600 then died; or

2) I cranked it but engine wont start.

Always these two.

BUT it is perfectly alright if the engine has been warmed up ie driven around. Once cranked, engine started,it is good to go.
 
Urmmm... more of either:

1) when I cranked it and it started but RPM fluctuated around 800 -600 then died; or

2) I cranked it but engine wont start.

Always these two.

BUT it is perfectly alright if the engine has been warmed up ie driven around. Once cranked, engine started,it is good to go.
 
Have you check the all air hoses from MAF to the throttle body for vacuum leak? Check also the aux hose that is connecting to the main hose.

Another thing you can try is to disconnect the MAF and try to start the engine.
 
badass bro, how is your water level? Do you have to topup every now and then?

I ask because one of N42 driver had this problem before, his problem is that water is seeping into one of the cylinders. This happens after the engine overheated on the highway. Clearly the overheat caused damage to the engine that let water to seep in.

The mechanic found water in one of the cylinder after resting the car. His failure symptom is very similar to yours, car hard to start after a rest.

This could not be your problem, just sharing.
 
badass bro,

I know it is frustrating as I gone thru this previously. Lots of money gone to the engine as I have replaced every sensors, hose, pipe, pumps, etc. and yet the problem persists. Finally I found out it is my engine block that give way and leaks coolant to the cyclinder and it cant be fixed therefore lead me to change my engine to N46.

Currently all the new parts of my previous engine is in my guest room and open for sale here http://www.bmwclubmalaysia.com/newforums/index.php?/topic/37440-n4246b20-engine-parts/
 
jarance said:
Have you check the all air hoses from MAF to the throttle body for vacuum leak? Check also the aux hose that is connecting to the main hose.

Another thing you can try is to disconnect the MAF and try to start the engine.
No, I have not but I will take note of this. Thanks very much. Sigh


aidilj said:
badass bro, how is your water level? Do you have to topup every now and then?

I ask because one of N42 driver had this problem before, his problem is that water is seeping into one of the cylinders. This happens after the engine overheated on the highway. Clearly the overheat caused damage to the engine that let water to seep in.

The mechanic found water in one of the cylinder after resting the car. His failure symptom is very similar to yours, car hard to start after a rest.

This could not be your problem, just sharing.
YES! the water level can be reduced to ridiculously low after 100 or 200km of drive? This is the time i experience so fast of dropping in the water level.

But there is no overheating. However, after I am able to cold start it, drive around 30km and stop the car. Then, I leave it for 10 mins and I start again, the heat meter goes up (not till red though) but drop to slightly less than half as it has always been.

What should I do to repair this? sorry, i am really a noob.


anaksarawak said:
badass bro,

I know it is frustrating as I gone thru this previously. Lots of money gone to the engine as I have replaced every sensors, hose, pipe, pumps, etc. and yet the problem persists. Finally I found out it is my engine block that give way and leaks coolant to the cyclinder and it cant be fixed therefore lead me to change my engine to N46.

Currently all the new parts of my previous engine is in my guest room and open for sale here http://www.bmwclubmalaysia.com/newforums/index.php?/topic/37440-n4246b20-engine-parts/
Meaning i have to change the engine? Can I overhaul it? Reason is because I don't want to get a used engine which I need to repair when I can just overhaul mine. The costs are almost the same i guess?

Dear Sifus,

I am now on 'trial' where the mechanic replaced a used "air mast" to my car. I won't say that my problem is gone but I can start the car in less than 5 mins with the usual symptoms I have mentioned above.

I am really at a lost now.

Thanks for the input. I really appreciate it.
 
had yet another change today. A brand new Air mass. I stopped the car for 2 hours. Then a heavy downpour when i entered the car. First 2 attempts, car died. 3rd attempt, it started.
 
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