Tough Cold Start

[Armazia]

Hello,

I'm currently facing an issue during cold start my E38. its a 2.8L so it has a M52 engine.
Whenever the engine runs cold it needs to crank like 3-4 seconds before igniting. This is not really a problem currently, but it seems like its becoming worse.
The car is also running on LPG but starts on Petrol. Things I've already done are;

Checked the idle control valve. hose was worn where it was clamped so the hose is replaced. I thought this was the issue but sadly enough its still there. Also cleaned the ICV.
Overall check of the hoses connected to the MAF, seem to be fine but could use more investigation.
Checked battery which is okay.
Drive the car only on petrol, as there could be some LPG leftover which might cause trouble but this also didn't make a change.
Did overall maintenance (filters, spark plugs, oil)
Added injector cleaner to the petrol and run it (this is what I am currently doing).

So next steps might be to

Check fuel pressure
Check injectors, revision or replace

Still I'm trying to find some common sense why the car is starting kinda hard. I also have an E36 and even with a nearly dead battery it needs like one short crank and it just runs.

So does anyone have some tips to for me to check? Or any idea what might be the case? Thanks

[Timm]

First call is fuel pressure, it should retain around 2.5 Bar almost indefinitely - and definitely overnight. The pressure should be maintained at the fuel rail and between the fuel pressure regulator and the fuel pump.

[Armazia]

First call is fuel pressure, it should retain around 2.5 Bar almost indefinitely - and definitely overnight. The pressure should be maintained at the fuel rail and between the fuel pressure regulator and the fuel pump.

I'll get some tools to check this out. Once I've check it I will come back. Thanks for your reply.

[Armazia]

This is somewhat an old topic, but still the issue hasn't been fixed.

I bought a fuel pressure test set but it did not read any fuel pressure.... Could screw it onto the fuel rail but simply didn't raise.
Now I can waste another 50,- euro's for another set and read it again but something else has come up.

The ignition coils seem to not look new... The bottom rubber part of the coil (where it snaps over the spark plug) is worn out and parts are falling off.
My question is if it would be wise to replace those... I measured the resistance in all coils and they seem to be around 0.6 ohms (which should be fine).

Can anyone give some advice about this matter? Otherwise I still might try finding another fuel pressure testing set.

[tomloans]

It is not that your engine is cold but that it has been sometime since it ran like over night. It is likely this...

https://www.newtis.info/tisv2/a/en/e...l-unit/CFhk1bm

[Armazia]

It is not that your engine is cold but that it has been sometime since it ran like over night. It is likely this...

https://www.newtis.info/tisv2/a/en/e...l-unit/CFhk1bm

This link doesn't work



However, there is some kind of progress of the investigation.

https://www.youtube.com/watch?v=KLAaPqX5Hwc

Got no codes whatsoever. this was the next step.According to my knowledge, fuel pressure should be 50psi, which is perfectly being maintained.

This was a cold start in my garage, as you hear the engine doesn't instantly start, yet the problem is worse when the car is outside in the colder temperature.
Next steps would probably be (in logical order)

- Replace Camshaft sensor
- Replace Crankshaft sensor
- Clean Injectors (not sure if this would help)
- Check all Coils

Can someone help me further into doing the right thing? Glad to hear from you!

[Timm]

Fuel pressure shouldn't be 50 psi when the engine is not running - it should drop to 2.5 Bar pretty quickly, and then stay there for weeks. If your fuel-rail pressure drops below a couple of Bar then you will have problem starting:

All explained here: http://www.meeknet.co.uk/e38/Fuel-rail-pressure.pdf

[Armazia]

Fuel pressure shouldn't be 50 psi when the engine is not running - it should drop to 2.5 Bar pretty quickly, and then stay there for weeks. If your fuel-rail pressure drops below a couple of Bar then you will have problem starting:

All explained here: http://www.meeknet.co.uk/e38/Fuel-rail-pressure.pdf

True. I read about that aswell after doing the fuel testing. fuel pressure dropped to 33 psi after engine has shut down, after like 20 seconds.

BTW: I immediately filmed after assembling the fuel pressure tester in the line, that's why the pressure is totally gone.

[Timm]

If the fuel pressure is retained then the next most likely problem is the MAF (as long as the car runs fine the rest of the time). Chinese MAF's are well known for this problem as are tired MAF's

[Armazia]

Is there a way to test the maf correctly? Cold start with maf unplugged was something I read. I can try that tomorrow.

Yet to note, I did have cleaned the MAF earlier.