Two years of intermittent hard starts, please help!

[sapote]

Leaking check valve will pull more air than is metered and cause a rough start condition.

You can check fuel trims if vac leak is suspected.

But in his case, the leaking check valve fixed itself once engine warmed up (he had hard brake pedal only when cold start up). So once the DME closed the loop with O2 feedback, but then the leak fixed itself, then everything looked normal. An interesting situation and he just luck out fixing the brake and also cured the hard start issue.

[sapote]

Here's a video of my cold startup problem. Ive had this issue for years now. So far I've replaced the fuel pump. I'm currently having the fuel filter, fuel pressure regulator, crank, and camshaft sensors replaced.

This starting is so wrong with the long crank. Your starter will have short life for sure. Engine acted like there was no spark or no injection during the first crank. Can you try push start it (rolling down the hill and jump the clutch in 3rd gear)? I'd like to know how this test run with the ignition not switching twice (on-off-on).

[DropTopKingM3]

This starting is so wrong with the long crank. Your starter will have short life for sure. Engine acted like there was no spark or no injection during the first crank. Can you try push start it (rolling down the hill and jump the clutch in 3rd gear)? I'd like to know how this test run with the ignition not switching twice (on-off-on).

sapote I can do that. My garage is uphill too. Should I do this after the car sat overnight?

When push-starting should I let the car roll in 3rd gear and pop the clutch or try and start the car as I'm popping the clutch? Also which position should the key be in? The first position or the second right before actually starting the car?

Thanks

[Tomba]

I own a 320i (facelift) with M54B22 engine. My car would always start in an instance. Suddenly I got intake camshaft sensor error codes and VANOS didn't work. Very low power/torque. Replaced it for a aftermarket one (Hella) and it does start, but not always as good as before. If it doesn't start on first attempt it does on the second (already fuel in). I'm quite sure its the aftermarket sensor.
I would suggest to buy OEM crank and both intake and exhaust positioning sensors. In S54 the exhaust tooth wheel has the missing tooth to detect correct position of the engine.
Don't use aftermarket sensor as we see lots of problems with them. Why did you buy them Tomba? Because I thought to take the gamble again! LOL
Sometimes the pattern was inverted (high was low, and visa versa).

[sapote]

sapote I can do that. My garage is uphill too. Should I do this after the car sat overnight?

When push-starting should I let the car roll in 3rd gear and pop the clutch or try and start the car as I'm popping the clutch? Also which position should the key be in? The first position or the second right before actually starting the car?

Thanks

1) do this at the same condition as you had bad starting before, so I guess cold engine on morning.
2. Engage 3rd gear engine off and hold the car by engine braking. Turn key to ignition on (not starting), push clutch pedal down to let car roll and gain speed (be careful as you have no power brake but heavy brake pedal still work), release clutch pedal to turn engine (like cranking with starter) and it should fire up. IF not let it roll in gear for 3 sec at good speed, if not turn off key, then repeat again and it should fire up as with 2nd start as you normally have done.

I could roll down forward or backward and pop the clutch in forward gear or in Reverse gear to start.

[DropTopKingM3]

1) do this at the same condition as you had bad starting before, so I guess cold engine on morning.
2. Engage 3rd gear engine off and hold the car by engine braking. Turn key to ignition on (not starting), push clutch pedal down to let car roll and gain speed (be careful as you have no power brake but heavy brake pedal still work), release clutch pedal to turn engine (like cranking with starter) and it should fire up. IF not let it roll in gear for 3 sec at good speed, if not turn off key, then repeat again and it should fire up as with 2nd start as you normally have done.

I could roll down forward or backward and pop the clutch in forward gear or in Reverse gear to start.

Thank you. I’m going to try let the car sit overnight and push / roll start tomorrow

[DropTopKingM3]

I mentioned this last week but I’ll update here. I purchased a set of “clean” injectors from another member. I installed them in my car and the problem was still happening. I sent my old injectors out for a cleaning to RC injectors in CA. I’m going to pop these back into my car.


These are 72k injectors.

[sapote]

These are 72k injectors.

I wonder the injectors that dripping during ON or OFF. If dripping during off (injector closed) then they created a rich mixture or flood condition for the next start up.

My guess they were dripping due to the bad spray pattern and not dripping when closed.

[jet_dogg]

I mentioned this last week but I’ll update here. I purchased a set of “clean” injectors from another member. I installed them in my car and the problem was still happening. I sent my old injectors out for a cleaning to RC injectors in CA. I’m going to pop these back into my car.


These are 72k injectors.

Man I miss Russ, he was the fuckin man. Numbers lookin good player, need to drop mine off soon.

[DropTopKingM3]

One week update.

I’ve cold started the car every day for the past week. It only happened one time and that was the morning right after I replaced the DMTL pump and the filter next to it. Still not sure about the injectors I put in my car but I will be reinstalling my original injectors now that they are cleaned. I will also be replacing all the orings on the air rail.

I don’t want to jinx it but I think I’m getting closer to solving this. 🙏💪

Id still like to replace the fuel pump relay since the pump itself is brand new.

day 1 - didn’t start on first crank. Fired right up on the second.

days 2-7 started on the first crank.

note: day 3 I turned off the car about 2 mins after and I tried restarting and it didn’t start on first crank.

[Redline]

I’ve been dealing with this going on 2 years as well, even started my own thread which is mostly talking to myself at this point as you seem to be getting more help.

Ive replaced everything electrical besides the DME and engine harness. Whole fuel system, sensors, vanos, etc.

hard starting at random and it takes longer than normal to warm up or runs cooler below 60° outside ( oil temp between first dot and 210 and never above, coolant gauge dead center or just a mm left) with a very random engine temp implausible code that will show up but no CEL. Thermostat is new but I’m thinking the rich condition is causing it to run cold. Smell a bit of gas in the oil. Something is causing it to run rich I’m thinking or related to this somehow.

one moment the car rips next it feels like the vanos is locked and has no bottom end power at random.

I gave up. Just following to hopefully see what else to look for.

only thing original at this point is the block, head/gasket, pistons/rods, Main bearings cams/rockers. Everything else is new….I have essentially a bumper to bumper warranty sponsored by FCP euro at this point 😂

[DropTopKingM3]

lol @ bumper to bumper 😂😂 let’s compare order history over a beer one of these days.

I hear what you’re saying about crickets. There was once a time where you could start a new thread before bed and there would be 15 responses by the time you woke up in the morning. The game really changed and for the worse. Forums are dead, FB groups are dead, and instagram is one huge clout-fest.

I wish you luck tackling and solving your issue. I know first hand that it can become expensive and frustrating.

[bigjae46]

I would be checking vacuum lines and the intake system. An air leak can cause a car to run rich.

Stock tune?

[DropTopKingM3]

Day 8 - started on first crank 💪
So far I’m on a 7/8 streak. Only one no start issue the morning after.

I can’t wait to get MY injectors back in there along with all new air rail orings.

Im hoping the combination of the temporary “clean” injectors and the dtml pump did the trick! 🤞

[S54B32]

Day 8 - started on first crank 💪
So far I’m on a 7/8 streak. Only one no start issue the morning after.

I can’t wait to get MY injectors back in there along with all new air rail orings.

Im hoping the combination of the temporary “clean” injectors and the dtml pump did the trick! 🤞

Congrats! Keep this updated if it comes back or went complete away.

I think more the Charcoal canister (if you mean this with „filter“) was the solution in your case, according to E39 m5‘s (source m5 board) where this is often the solution for starting problems.