Two years of intermittent hard starts, please help!

[DropTopKingM3]

I just tried starting the car for the first time in 24 hours and it just happened.

[S54B32]

I reached out to a friend of a friend who’s a 25 year BMW dealership tech and showed him my video. This is what he said. I also attached a real oem diagram. I’m guessing it’s 15, 16, and 17. Cheap enough to try it out as the vacuum lines aren’t too expensive. I’m going to order the lines and replace them along with the DMTL pump which arrived today.

I started up my car tonight for the first time in about 2 weeks and it fired up on the first crank. This is puzzling lol.

With 25 years of experience he should know how a fuel regulator work. The vacuum line is to balance the pressure difference that comes from the n/a engine (vacuum in intake manifold) so if the engine is off, the line is at ambient pressure (like when it’s plugged off). So if you drive without the attached line, you will end up with a massive rich mixture.
And in my opinion only that the engine runs not rough, doesn’t rule out a faulty injector. Some injectors that are clogged, can leak when they get very cold and flood the combustion chamber. But when they get to operating temperature they work as usual. A professional injector cleaning and checking should be always on top of the list.

But if part number 4, the regulator it self is faulty it can indeed leak fuel back in the tank.

[DropTopKingM3]

ATB88 I hope you don't mind if I start blogging in your thread. If you'd like I can start a new thread.


Tomorrow I'm going to be installing my new scza (which has nothing to do with the cold start). My car will be on the lift so I will start replacing all of the things that could be causing the cold start issue.


I've already replaced:
Fuel Pump
Fuel Filter
Fuel Pressure Regulator
Alternator
New Battery
Replacement key

Tomorrow I'll be replacing:
BMW Hose - Genuine BMW 11727837591 | FCP Euro
BMW Metal Tube Corrugated (Ø 45mm) - Genuine BMW 12517508831 | FCP Euro
BMW Blue Silicone Vacuum Hose (1 Meter) - CRP 11731259996 | FCP Euro
New Genuine BMW Vacuum Hose 64111368684 / 64-11-1-368-684 OEM | eBay (purchased on eBay, sold out everywhere else)


2000-2002 BMW Evaporative Emissions System Leak Detection Assembly 16-13-6-756-440 | The BMW Mini Part Store
2001-2021 BMW Leak Detect Pump Grommet 16-13-1-183-912 | The BMW Mini Part Store


I have also purchased a set of freshly cleaned and tested injectors to cut down the downtime. They come with new orings as well. I couldn't find new Bosch injectors and I'm not sure if they would do me any good since they're now produced in China.


I've recently done a restoration on my car and pretty much-replaced everything. I didn't have a problem forking over some extra $$$ to kill this symptom and cause.

Once the work is complete I will be doing a daily test. I will cold start my car every single day for 10 days. If it doesn't start on the first try on either of these days then it's back to the drawing board.

[DropTopKingM3]

The surgery today was a big success. I will be sending out my old injectors to get tested and cleaned just for shits and giggles. I would love to know what condition they were in.

I cant tell if its from the SCZA exhaust install, the injectors, or anything else that was done. But the car is idling so smooth and it just feels perfect. Im really hoping this fixes the problem.


I will begin starting the car tomorrow and every day/ every other day to test and see how it starts on the first crank each time. I will keep a daily blog and report back in about a week or so.



PS. I love the SCZA! Highly recommended for those who dont want an over the top exhaust sound. I just retired my billy boat exhaust after 15 years so its a big change for me. No more noise in the cabin which im very happy about.

[bigjae46]

Did the OP ever fix this?

If not, did you clean or replace the ICV? Although many try, you really can't clean the ICV. There's all sorts of crap in the bottom of the valve where the solenoid sits. It might look clean but the solenoid is likely gummed up

I would try replacing it. Check the air tract into the air rail. Blow out the air rail and replace the o-rings on the tubes. Also check the ICV wiring.

One possibility is you have an air leak which is allowing some air into the engine through the idle air tract which goes behind the ITB butterflies. Then the ICV is gummed up and takes a minute to open or there is a poor connection/burned wire.

- replace ICV
- check resistance on ICV wires
- blow out idle air tubing and air rail
- replace air rail o-rings

Similar design on an M54 except the S54 has an external air rail and the M54 has runners built into the intake manifold and a separate idle air opening in the cylinder head. Starting issues - look at idle air. Smoke testing will not catch a leak in idle air unless you have the ICV open and the ITBs closed.

Just an idea...

[DropTopKingM3]

Day 1

Earlier today I started the car. Maybe I'm paranoid but it did start on the first crank but I felt that it sorta hesitated for a split second.
I turned the car off and started it again and it fired right up..
I turned the car off and on the 3rd try it didn't start but it did start on the 4th which was strange.

[jet_dogg]

I feel for you guys man, hope this gets resolved.

[Irhase46m3]

Hi There - I had a similar issue when coldstarting the car, in my case it was the brake booster 1 way valve, i replaced it starts right away without any issues no matter how quickly i turn the key to start it. I replaced 7, 6 and 8 (used worm clamps)



Hope this helps!

[DropTopKingM3]

Hi There - I had a similar issue when coldstarting the car, in my case it was the brake booster 1 way valve, i replaced it starts right away without any issues no matter how quickly i turn the key to start it. I replaced 7, 6 and 8 (used worm clamps)



Hope this helps!

Thanks for your response. I never would've thought a brake booster check valve would cure a cold start issue. Would you mind explaining?

[Irhase46m3]

Thanks for your response. I never would've thought a brake booster check valve would cure a cold start issue. Would you mind explaining?

I dont understand the mechanics behind this either, but i replaced all components in this thread + more and still had this issue. After that i noticed my brake pedal was increasing harder to press in cold mornings to the point that every time the car cooled off it would be hard. After replacing the 1 way valve it seems to have resolved the issue. Its important to understand that this is a one way valve with a diaphragm, i assume (i have no technical data here) that its not meant to work bidirectionally and hence it was leaking air a way it shouldn't. In my situation i could repeat the hesitation on coldstart by turning the key really fast (trying to start the car as fast as possible) and when in coldstart i would start it slow then turn the car off and on and it would struggle.

I guess an easy way to tell is if you have the hard brake pedal on cold mornings.

I hope this info helps

[ATB88]

Did the OP ever fix this?

If not, did you clean or replace the ICV? Although many try, you really can't clean the ICV. There's all sorts of crap in the bottom of the valve where the solenoid sits. It might look clean but the solenoid is likely gummed up

I would try replacing it. Check the air tract into the air rail. Blow out the air rail and replace the o-rings on the tubes. Also check the ICV wiring.

One possibility is you have an air leak which is allowing some air into the engine through the idle air tract which goes behind the ITB butterflies. Then the ICV is gummed up and takes a minute to open or there is a poor connection/burned wire.

- replace ICV
- check resistance on ICV wires
- blow out idle air tubing and air rail
- replace air rail o-rings

Similar design on an M54 except the S54 has an external air rail and the M54 has runners built into the intake manifold and a separate idle air opening in the cylinder head. Starting issues - look at idle air. Smoke testing will not catch a leak in idle air unless you have the ICV open and the ITBs closed.

Just an idea...

Yeah I still haven't fixed it. Given where I am with this, I think a new ICV is a reasonable idea -- I think I'll do it when I swap my airbox out for smog later this month.

Re: the other suggestion, I actually did try replacing the booster check valve lol. Didn't help my case, but hopefully it helps otheres!

[eacmen]

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.

[DropTopKingM3]

Yeah I still haven't fixed it. Given where I am with this, I think a new ICV is a reasonable idea -- I think I'll do it when I swap my airbox out for smog later this month.

Re: the other suggestion, I actually did try replacing the booster check valve lol. Didn't help my case, but hopefully it helps otheres!

Did you try this before he posted the suggestion? I actually googled this and I really didn’t see any info but it’s about $30 in parts so I ordered them. I also ordered a new MAF sensor.

I bought a set of “cleaned” injectors off another member. I installed those on Saturday but I think my problem has gotten worse. Two of the orings were chipped. The orings were blue so I’m sure they were replaced. I sent my original fuel injectors to RC via mail today. Once I receive my original injectors I will install those and see what happens.

In addition to the MAF, I also ordered a charcoal canister, fuel pump relay, fuel injector relay, the green relay, 12 orings for the air line next to the fuel rail, and an oring for the line that plugs into the fuel rail. I then placed a different order for a sucking jet pump and oring along with a fuel sender unit.

At this point I’m determined to fix this issue. It’s literally bothering the heck out of me! Yes it’s sucks that I keep throwing parts at it, but at least I’ll have all brand new stuff.

[jet_dogg]

Did you try this before he posted the suggestion? I actually googled this and I really didn’t see any info but it’s about $30 in parts so I ordered them. I also ordered a new MAF sensor.

I bought a set of “cleaned” injectors off another member. I installed those on Saturday but I think my problem has gotten worse. Two of the orings were chipped. The orings were blue so I’m sure they were replaced. I sent my original fuel injectors to RC via mail today. Once I receive my original injectors I will install those and see what happens.

In addition to the MAF, I also ordered a charcoal canister, fuel pump relay, fuel injector relay, the green relay, 12 orings for the air line next to the fuel rail, and an oring for the line that plugs into the fuel rail. I then placed a different order for a sucking jet pump and oring along with a fuel sender unit.

At this point I’m determined to fix this issue. It’s literally bothering the heck out of me! Yes it’s sucks that I keep throwing parts at it, but at least I’ll have all brand new stuff.

Sometimes you just gotta do what you gotta do. It's bound to get fixed at some point.

[sapote]

Yeah I still haven't fixed it. Given where I am with this, I think a new ICV is a reasonable idea -- I think I'll do it when I swap my airbox out for smog later this month.

Re: the other suggestion, I actually did try replacing the booster check valve lol. Didn't help my case, but hopefully it helps otheres!

How was the push or rolling down the hill jump start that I suggested before?