Two years of intermittent hard starts, please help!

[DropTopKingM3]

Everything but that, the canister, vapor line and fuel tank itself. Smoke test showed no leaks/issues with those parts and showed they were operating fine when testing so I left it alone.

Maybe I shoulda loaded up the parts cannon once last time 😂

I bought the last new charcoal canister. Other sites can get them but I’ll take 3-6 weeks unfortunately. You can try a Bosch pump from Fcp or even Rock auto with a coupon. Don’t forget the filter.

Day 9 started on first crank.

[DropTopKingM3]

Day 10 started on first crank. Today completes the one day interval testing. I’m going to leave it for 2-3 days at a time and see how it does 💪

[DropTopKingM3]

Hope everyone is having a good Christmas. I fired up my car a few hours ago and it started on the first crank. It’s been sitting for 4 full days in the garage. Best gift I got this year haha.

[s54plus`]

Did OP ever end up trying to replace the DMTL pump like DropTopKingM3? I've been having the same issue for about 3 months. I'd say that 90% of cold starts are fine, but warm starts require two cranks most times. So far I've replaced the fuel pump, ignition coils, and spark plugs... but no dice. It started right after I did my Vanos unit (Beisan) and a valve adjustment. Not sure if we have come to the conclusion that it's just coincidental that it happened right after that, or of if it's related to the issue. I've now seen a handful of people experiencing this issue after the same service.

About a week ago I got a CEL for a misfire on cyl 2 and immediately replaced my ignition coils as they were not done with the spark plugs about 8k miles or so ago. I thought that a bad coil may have also been the reason for my hard starts but it didn't solve it. Luckily the misfire is gone now... for now lol.

I have a fuel filter on order as I may as well replace that since I just did the pump, as well as a new Vanos solenoid coil pack from Beisan. They were really nice and sent me out a new one to test to see if it fixes my issue. If I'm being honest I doubt either of those will fix the issue... but I guess it's worth a try.

What would be the correct way to even diagnose this issue? I already had my mechanic check fuel pressure as well as checking the vanos values and everything is perfect. Open to any suggestions. It makes me sad every time I start my car lol.

[sapote]

Hope everyone is having a good Christmas. I fired up my car a few hours ago and it started on the first crank. It’s been sitting for 4 full days in the garage. Best gift I got this year haha.
.....
Maybe I’ll give this a try and report back.

It's hard to believe the new tank leak detector fixed it. Prove it by swap in the old detector.




"Originally posted by sapote View Post
I had read it and understood how the diagnosis works, but don’t see how it affects the starting.

If it were me I will install the “bad” air pump back to prove the problem comes back.
Maybe I’ll give this a try and report back."

[DropTopKingM3]

It's hard to believe the new tank leak detector fixed it. Prove it by swap in the old detector.




"Originally posted by sapote View Post
I had read it and understood how the diagnosis works, but don’t see how it affects the starting.

If it were me I will install the “bad” air pump back to prove the problem comes back.
Maybe I’ll give this a try and report back."

Hey bud… in that phase I replaced the following.

the air pump and grommet, the filter for the air pump, some vacuum lines that connect to and from the fuel pressure regulator, and a used set of clean injectors with chipped o rings.

For shits n giggles I sent out my old injectors to RC and 4 were leaking and 2 were fair. I plan on installing my clean old injectors since the orings on the current injectors have a chip or two.

I still have a few parts that I ordered. Since they’re paid for and I got them for cheap I will be installing them. I did a huge restoration on my low mileage car so new parts won’t hurt. Sucking jet pump, drivers side fuel sender, charcoal canister, and some vacuum stuff for the brake booster and mentioned in this thread.

Its been a solid 3 weeks since I started my car. I’m going to start it tomorrow and see how she fires up. I’ll report back.

[sapote]

the air pump and grommet, the filter for the air pump, some vacuum lines that connect to and from the fuel pressure regulator, and a used set of clean injectors with chipped o rings.

The fuel regulator vacuum lines or the injectors had fixed the problem, not the fuel leak detection parts; my guessing

[DropTopKingM3]

The fuel regulator vacuum lines or the injectors had fixed the problem, not the fuel leak detection parts; my guessing

I ordered everything at once. It was cheap enough to try the leak detection pump and I had everything installed together while I installed the scza exhaust. I’m glad it’s fixed now.

[DropTopKingM3]

Update. The car has been sitting for about a month on a battery tender in my garage. She just fired up without any hesitation. I can safely say the issue is resolved for me.

I hope the OP has his issue resolved.

Thanks to everyone who contributed.

[sapote]

I can safely say the issue is resolved for me.

Agreed, but I don’t know exactly what part fixed it. So this won’t help others with similar problem

[cobra]

Great to have this info on the forum!

In all my past issues with idle/start hesitation it has been a vacuum or idle circuit issue. The vehicle will not run right until it gets going and can adapt to the vacuum leak or lack of air.

[DropTopKingM3]

Agreed, but I don’t know exactly what part fixed it. So this won’t help others with similar problem

It was between:

6 used clean injectors and orings.
$40 worth of some vacuum lines from FCP
New DMTL pump $100
DMTL pump filter $60

If someone else experiences the same problem just try whatever me and the OP tried. More than likely it’s stuff they’ll end up having to replace as maintenance items anyway.

[ATB88]

Did OP ever end up trying to replace the DMTL pump like DropTopKingM3? I've been having the same issue for about 3 months. I'd say that 90% of cold starts are fine, but warm starts require two cranks most times. So far I've replaced the fuel pump, ignition coils, and spark plugs... but no dice. It started right after I did my Vanos unit (Beisan) and a valve adjustment. Not sure if we have come to the conclusion that it's just coincidental that it happened right after that, or of if it's related to the issue. I've now seen a handful of people experiencing this issue after the same service.

About a week ago I got a CEL for a misfire on cyl 2 and immediately replaced my ignition coils as they were not done with the spark plugs about 8k miles or so ago. I thought that a bad coil may have also been the reason for my hard starts but it didn't solve it. Luckily the misfire is gone now... for now lol.

I have a fuel filter on order as I may as well replace that since I just did the pump, as well as a new Vanos solenoid coil pack from Beisan. They were really nice and sent me out a new one to test to see if it fixes my issue. If I'm being honest I doubt either of those will fix the issue... but I guess it's worth a try.

What would be the correct way to even diagnose this issue? I already had my mechanic check fuel pressure as well as checking the vanos values and everything is perfect. Open to any suggestions. It makes me sad every time I start my car lol.

Sorry all, I've been focused on other stuff for a while (finished phd, started job) and haven't been able to touch or think about the car.

My issue remains. Glad to hear DropTopKingM3's got fixed -- though it sounds like his and mine were different issues in nature. Mine happens more often on warm starts than cold.

s54plus` : Okay, that your issue started right after doing vanos work and valve adjustment makes me raise my eyebrows. That's exactly when mine started too. Like yours, my vanos seems to be operating flawlessly. Yet, we both started experiencing what seems to be the same issue after doing vanos work. I had thought that it was simply a coincidence in my case, but this makes me think again. Huh. Are your hard starts more often on cold or warm starts?

I am curious to try replacing the DMTL pump for kicks. That's the only thing that DropTopKingM3 has done that I haven't. How hard is it to access/replace that? What has to come out to get access? Can I do it with the fuel tank still in place?

[DropTopKingM3]

ATB88 it was actually quite easy. I had the easy access since I installed my SCZA exhaust the same day as well. I replaced the DMTL filter too.

@s54plus’ in addition to the fuel filter I would also replace the fuel pressure regulator. Sending your injectors out for testing and cleaning will definitely help too. I also replaced the DMTL pump filter while I was in there.


Im dropping off my car tomorrow to have the subframe reinforced along with a new clutch and flywheel and ohlins r&t coilovers. I still have a bunch of parts that I ordered when I was troubleshooting the start issue that I’m going to installed since I already paid for them. The parts are: fuel pump relay, charcoal canister, sucking jet pump and drivers side fuel sender, and air rail orings. My car had undergone a full refresh within the past year so the more new parts the better.

Good luck guys.

[Redline]

DMTL pump didn’t work for me. It started throwing a cel for it right before I replaced it last month. Still having starting/power loss issues. Threw a random exhaust vanos fault that hasn’t returned. Probly directly related to the besian seals or a faulty solenoid on my car. Idk. I give up. I should have left the vanos alone. Was much faster before I did the seals. I just had a bad timing chain guide and figured why not do the seals while I had the vanos off…