e39 hard starting (flooding) and black smoke, what to check?

[genphreak]

A friend is going to bring around their mint condition e39. I told them I know nothing about e39s but they are coming anyway, perhaps they want to stress me out (Any job that take >3 beers can do that, but I hear e39s sometimes need a garage-based mini Oktoberfest to fix seemingly simple things).

The car has been looked after but only ever done short trips but has had oil changes every 6 months religiously, not sure what else.

Apparently it is having trouble starting- more often than it used to.

Does anyone know what to check? They told me the battery is not very old and I did notice last time the oil cap was a medium to dark-tan colour underneath. It's a 04/97 built e39 euro 523i (M52B25TU) that has only done 82,000km. For a 16 year old car, that's a lot of short trips...

i.e. It isn't the older one; 7727
it is this one:
7726



Symptoms:
Flooding on occasion when starting; always happens when re-started after running for less than a two minutes. Has to be started the 'Italian way' (Wide Open Throttle) which results in a bellowing of black smoke all over the place once it fires up.

- does the CCV cause trouble on the later engines?
- perhaps a blocked dipstick return pipe is possible?

I was thinking it might be worth checking the
0. Coolant for oil, oil for coolant
1. Cam Position sensor
2. O2 sensor
3. engine temp sensor
these no doubt need to be done as preventative maintenance, but I figure to just check them first to find the root cause.

Thanks in advance for any other ideas/suggestions on other things it could be...

[Tiger]

Sounds like injector is leaking

[genphreak]

Indeed... thanks. Could well be the root cause.

Is this common in e39 M50B25TUs? I've Never seen it cause flooding in other M50s- but haven't seen that many. Certainly would explain the flooded engine after a short drive + shutdown.

Will attach a fuel pressure gauge and watch for pressure drop after shutdown- though I don't know how fast it will drop due to other things- I've got nothing to compare it against, so may remove the rail and watch for leaks with the pump going.

[shogun]

I do not know the E39. But recently we had a similar problem with an E32 750. Turned out that the fuel pressure regulator diaphragm was broken and fuel always or sometimes leaked into the engine even when engine was off = dripped till the pressure from the system was down.
I made a post of that with details for the other on the E32 forum, copied here:

Problem: E32 750iL facelift engine with 0261200352 1.7 Motronic: Had 1221 code,replaced a leaking vacuum hose and all was fine for a bit. Now have the 1222 code and the car runs like crap on idle like when I get to a stop light/ sign it sounds terrible, but as soon as I step on the gas it sounds fine and has plenty of power. Has brand new o2 sensors, spark plugs, dis cap and rotors.
Would the fuel pressure regulators cause this to happen if they are bad? The car also has a hard start and I removed the vacuum lines from the regulators and they leak fuel. Could the regulators be the whole cause of the codes and hard start?


Cause and remedy:
Got the parts = 2 new fuel pressure regulators, finished installing the new regulators and they fixed it, fixed hard start, crappy idle, and check engine light.

Description of operation: fuel pressure regulator
Depending on requirements, the fuel pressure regulator regulates a low or high fuel pressure. This requirement is set with the help of the pressure regulator. Depending on the engine's operating state, less or more fuel is needed:
- at idle speed, less fuel
- at full load, considerably more fuel.
The injection rate is precision-adjusted by means of the injection time; the injection time is controlled by the DME.
The partial vacuum in the intake manifold serves as engine load information for pressure regulation. The diaphragm of the pressure regulator is actuated with this partial vacuum.
A partial vacuum builds up in the intake manifold during idling operation or in overrun mode. Depending on the partial vacuum value, the fuel pressure decreases starting out from the nominal value. The nominal value is stamped in the fuel pressure regulator housing.
At full load, the partial vacuum in the intake manifold is approximately equal to zero. The fuel pressure regulator regulates the fuel pressure to the nominal value stamped in the housing.

----------------------------
Notes on fuel pressure check (reference pressure: intake manifold pressure)

Feature of this version with intake manifold pressure: The connection for the vacuum hose of the fuel pressure regulator is located in the intake manifold after the throttle.

Test precondition:
The correct fuel pressure regulator is fitted.
- Using the EPC, check whether the fuel pressure regulator suitable for the car is fitted:Connect test adapter, refer to 13 31 029.
Description of operation: fuel pressure regulator
Depending on requirements, the fuel pressure regulator regulates a low or high fuel pressure. This requirement is set with the help of the pressure regulator. Depending on the engine's operating state, less or more fuel is needed:
- at idle speed, less fuel
- at full load, considerably more fuel.
The injection rate is precision-adjusted by means of the injection time; the injection time is controlled by the DME. The partial vacuum in the intake manifold serves as engine load information for pressure regulation. The diaphragm of the pressure regulator is actuated with this partial vacuum. A partial vacuum builds up in the intake manifold during idling operation or in overrun mode. Depending on the partial vacuum value, the fuel pressure decreases starting out from the nominal value. The nominal value is stamped in the fuel pressure regulator housing. At full load, the partial vacuum in the intake manifold is approximately equal to zero. The fuel pressure regulator regulates the fuel pressure to the nominal value stamped in the housing.

Description of operation: fuel pump
The control function of the fuel pressure regulator must be ensured in all operating states. The fuel pump must therefore always be able to generate a higher fuel pressure than the pressure regulated by the pressure regulator.

Description of operation: fuel return line
When the engine is at a standstill and the ignition key is in position 0, the fuel return line after the pressure regulator is at zero pressure.

Description of operation: pressure retaining function
The pressure regulator closes when the engine is at a standstill and the ignition key is in position 0. The fuel pressure in the delivery line is retained over an extended period. A non-return valve closes in the fuel pump. These measures help to retain the fuel pressure in the fuel system. Extended starting times are thus avoided.

Complaint: drive characteristic faults, lack of power
- Run engine at idle speed and measure fuel pressure.
- In order to simulate "full load" state: ne Disconnect vacuum hose from fuel pressure regulator and measure fuel pressure.
The measured value must increase by 0.4 to 0.7 bar depending on the engine. Note down measured value.
- If the measured value does not increase: Replace vacuum hose and measure fuel pressure again
- If the measured value still does not increase: Replace pressure regulator
- Measure fuel pressure again and note down measured value.
- Compare the measured value with the nominal value stamped in the pressure regulator housing.
If the specified measured value is still not achieved, you must carry out the following checks depending on the measured value.
If the measured value is less than the nominal value - 0.2 bar:
- The cross-sections in the fuel feed line are contracted or the fuel filter is clogged,
or
- the fuel pump voltage supply is not O.K., e.g. due to high contact resistance (corrosion) in the plug connection between wiring harness and fuel pump
If the measured value is greater than the nominal value + 0.2 bar:
- Switch off engine and then observe measured value.
- If the measured value drops to the nominal value, the cross-sections in the fuel return line are contracted or clogged.
- Check the fuel lines for kinks.
If no kinks are visible:
- Replace return lines.
If the measured value remains too high, the pressure regulator is most probably faulty.

Caution! With less likelihood, the return line may be completely blocked. When the pressure regulator is removed, fuel could escape under pressure! As a precaution, have a cleaning cloth ready and collect and dispose of any escaping fuel.Replace the return line but not the pressure regulator.

Complaint: starting problems
- Run engine briefly at idle speed and switch off.
- Note measuring value when engine is stationary.
- Read off measured value again after approx. 20 to 30 minutes with engine stopped.
The special tool 13 3 010 (hose clip) is needed for the following check. If the measured value has dropped by more than 0.5 bar:
- Start engine and wait briefly for a stable pressure increase.
- Switch off the engine and immediately pinch off the delivery line just before the pressure gauge with the special tool 13 3 010.
- Note down measured value.
- Read off measured value again after approx. 20 to 30 minutes with engine stopped.
If the measured value has now dropped by less than 0.5 bar, the following faults may be present:
- Fault in delivery lines
- Fault in in-tank delivery hose
- Faulty pressure-holding non-return valve in fuel pump
Check components. Replace faulty components.
If the measured value has again dropped by more than 0.5 bar:
- Replace pressure regulator
Note:
- All the fuel hoses and hose clips which were detached within the framework of the checks must be replaced.
- Fault messages may be stored in the fault memory of the DME control unit if the vehicle is operated in the intervening period. The fault messages "Incorrect lambda control" or "Lambda control at stop" must be cleared after the check is completed:

Interrogate fault memory of DME control unit. Check stored fault messages. Rectify faults. Now clear the fault memory.

13 64 582 Checking injector valves for leaks and cleaning

Special tools required:
· 13 6 200
· 13 6 205
· 13 6 206
· 13 6 207

Injector valves removed. Mark sequence of injector valves relative to cylinders on each injector valve. Caution! Observe country-specific safety regulations when handling fuels and cleaning agents.

Check injector valves for leaks: Clip fuel injectors into special tool 13 6 205.Connect special tool 13 6 206 to the injector valves.
To catch remaining fuel, wrap fuel injectors in clean cleaning cloth.
Connect special tool 13 6 206 to a 12 V car battery.This removes the remaining fuel from the injector valves.Connect special tool 13 6 205 to compressed air connection of max. 5 bar.Residual fuel is now blown out of the injector valves.

Caution! Carry out leak test only after remaining fuel has been blown out of injector valves.

Separate special tool 13 6 206 from the injector valves.
Install injector valves with special tool 13 6 205 in a container with hot water (60 ... 80° C). Adjust air pressure at connection ① on special tool 13 6 205 to max. 3 bar (motorsport models max. 5 bar).Note volume of air emerging.Permitted volume of air emerging: 2 air bubbles per injector valve within a 15 second period.Note injector valves with larger volumes of air emerging.Injector valves with larger amounts of air emerging must be cleaned. Remove fuel injectors from water and dry thoroughly with compressed air.

Clean injector valves:Install injector valves in special tool 13 6 205.Connect special tool 13 6 206 to injector valves and to a 12 V car battery.

Use ultrasonic cleaning unit 13 6 200 to clean injector valves.
Read operating instructions before operating ultrasonic cleaning unit.Attach injector valves to special tool 13 6 200 with special tool 13 6 205.Fill special tool 13 6 200 with cleaning concentrate 13 6 207 as specified by manufacturer.Perform cleaning procedure as specified by manufacturer.Repeat leak test on cleaned injector valves. Caution! Do not carry out leak test in cleaning concentrate but rather in a water bath. Only replace injector valves from which volume of air emerging exceeds the permitted limit of 2 bubbles within a 15 second period. Caution! Install cleaned injector valves immediately in engine and run engine.This flushes out any remaining cleaning concentrate thereby preventing injector valve corrosion.
Due to the risk of corrosion, cleaned injector valves can no longer be stored.
(from BMW Technical Information Service)

read this thread:

Subject: Losing my mind - hot start issue Author: cdnalpina

So I have been battling a hot start issue with my B12 5.0. I have done some searching and tried a few things to no avail. Here is what I have done...

I found a post about the vac lines being crossed to the FPRs could cause the problem - mine weren't.

I found a post saying that faulty fuel injectors leaking fuel into the cylinder could be a cause. I bought all new injectors, installed them and no improvement in the problem.
I found another post by Shogun about the fuel check valve install. I was able to locate a check valve, installed it and... same problem.
It's driving me nuts. From dead cold it starts like a champ. After being warmed up and driven it does not. Occasionally it will start ok (like this morning after I filled up with gas) but that is a rare occurance.

I am going to check all fuel clamps etc this weekend and listen for any sort of depressuring noise. One thought I had was, could one or both of the fuel pressure regulators be faulty ? I do not totally understand how they work but would it be possible for them to fail in some way so as to pressure fuel into the cylinder after the car is off ? One other odd note on the hot start issue. When I park my car in my parkade (25 degrees C), it is always hard to start, even when it has been sitting for 8 hours. Don't know if that helps with any suggesitons but I thought it was important to add that note.Rob

SOLVED AT LONG LAST - THANKS EVERYONE! Author: cdnalpina: 2010-09-01

So I pulled the fuel pressure regulators from my 850i and put them in the B12 and the car has started without issue and generally runs smoother. Fuel economy is also improved. Many thanks to everyone for your guidance and help! Rob

[genphreak]

Wow, thanks gents.

Erich, great info: I bet this turns out to be an atypical issue. Am glad it is not a hot-start issue- should keep it simple. Need to research the crankcase ventilation system a bit but I think its mainly a problem on the earlier M52s.

[Tiger]

Ahh.... I had an aftermarket injector stuck wide open... flooded my engine... and hydrolocked my engine... hence, my car is still not on the road. I learned something about fuel injector!

[genphreak]

Ouch. Not nice- e39? M50?

What are you going to do?

From what I hear, this is a common issue in some or all e39 i6 engines....

[Tiger]

540i... original engine is already out and replacement engine went in... then strike two... replacement engine is also bad... the valves are incredibly noisy... so... my plan now is to rebuild original heads from original enigne... and then swap it out and see what happens.

Engine are cheap... labor is not. I am really tempted to just get a 4.4L and put it in. Cost wise is about the same too.

[genphreak]

Def not the lifters? If an M60 doesn't run for a while it can take a long time for them to pump up, I had to drive one for a good 15 mins once before it quietened down.

The 4.4 is a nice option I'd like also. But added trouble w VANOS- not that it wouldn't be worth it of course, but more trouble for sure... woot!

[Tiger]

Mmm... stuck lifters? No, my original engine didn't have that kind of noise at all.

the 1997 and 1998 4.4L V8 are non-Vanos... it drops right in.

[genphreak]

No if an M60 hasn't run for a while the valves will be very noisy. (how bad is it?, it should sound bad, but not appalling)

You need to drive it a bit (push it hard once it's warm) and the noise will go away. Did you verify the oil pump bolts were ok first? You are probably well aware but the bolt holes need to be cleaned and some thread lock applied to stop them backing out.