Vac leak on my M44 DASC @ injector base

[JP422]

Sup guys... Wondering if any of you had this problem...

I have a '97 Z3 1.9 w/ secondhand DASC... which runs perfect.
I purchased it with TT's upgraded injectors and machined adapters (used)...

Anyway, all was fine, but I started to notice a small vac leak.
Now it has gotten big enough to throw the A/F lean.

The upgraded injectors don't seem to sit very deep in the adaptors.
Can anyone who has TT's Stage2 or 3 check this too? Anyway, if I touch, wiggle, or rotate the injectors, I can hear the leak.

I also had the injectors serviced from RC Engineering, before I installed the DASC. I know they replaced the O-rings.. but I wonder if it could be a tiny bit too small? I don't know... I just don't know why it's leaking where the injector goes into the adapter.

any help?

Thanks!!

[bullmand]

When I had my injectors serviced by Marren Injection they didn't replace those o-rings because they told me they were a dealership only item. If that's true it may very well be the case that your o-rings are too small. Might be worth looking into.

[JP422]

Thanks for the reply... but it looks like it's not the base of the adapter that leaks... it's the new injector's tip.. that doesn't go very deep into the adapter. Feels a little loose if you touch it too. I'm going to see if RC Engineering has a fatter O-ring... but regardless, it's a bit odd that the injector doesn't sit very deep in the adapter... pretty shallow actually.

So I guess nobody ever had an issue with this?

[xxxJohnBoyxxx]

Bend you injector rail tabs to force your injectors deep into the adaptors. You can do this by installing the rail without the injectors and bending it. Problem solved...

I dropped mine 1/8-1/4 deeper into the adapter by doing this. It also ensures your injector squirt is not deflected by the adaptor and they get a clean shot into the head runner toward the valve.

Try it I think you will like it...

John S

[JP422]

Thanks John... I'll try that too...

For the O-rings, I stopped by RC engineering on Friday, and they gave me some extra Orings to try. As it turned out, the Injector to Adapter fitting was nice and tight... it was the adapter to manifold connection that was loose. Since I bought my DASC w/ upgraded injectors used, I didnt bother to pull the adapters out from the manifold. The Orings on the adapter looks squashed/deformed/ and even have flatspots on it like it was cut out. Strange.

Anyway, I think these are the leaky culprits. I hope RCE has these O-rings in stock. I need to get the roadster back on the road while the weather's nice!

[xxxJohnBoyxxx]

^^Good call...I need to check my adapter o-rings next time I'm in there and see what they look like. It is common for them to get that flat squashed look over time and need replacement. Thanks for the reminder since mine have been through many injector replacements without the adapter ever being pulled and inspected.

John S

[JP422]

No problem.. thanks for your help too.

Anyway, another update... I stopped by RC, and they didn't have the bigger BMW sized O-rings (for the adapter). I stopped by another fitting shop around the corner, and got 2 Orings that are near perfect, but that's all they had. They gave me some other ones that have a slightly bigger I.D. and it looks like they're squash down to fit fine... however, I want this to be a set it and forget it fix... so I'll keep looking. I'm gonna see if I can get BMW O-rings. Worst case, I have the backup rings to try.

[bullmand]

I should have the part numbers at home if you want them.
And here it is for posterity: 13 64 1 743 377.
Cost was $3.16 each.

[JP422]

Thanks bullmand... but it looks like anywhere online the prices are decent, but shipping is insane! I ended up buying them from the local BMW dealer for a little over $5 each... + tax. Sucks, but the cost would be the same shipped from online.

Anyway, it was a FAIL. I put the new oem O-rings on the adapters, and they were a perfect/snug fit. I installed the adapters and made sure they were in all the way (bottomed out in the manifold). The O-rings on the injectors felt nice and tight too. After reassembly, my Air/Fuel was still lean... wtf! so I checked the injectors again w/ the engine running. I can hear the leak, and if I handle the injectors, the sound changes. I did the final test of spraying carb cleaner on the injectors... and sure enough, it was leaking still.

I pulled the injoctors out again, and also pulled the adapters. This time, the new oem O-rings were damaged... in fact cut/ripped, etc. When I looked at the DASC manifold, I realized the thickness isnt consistent. Some areas of the injector hole are thicker than others. I think the adapter was going in too deep and the Oring wasnt sealed by the manifold anymore (in some areas). This would explain the big leak.

I also checked the adapter to the injector... to see how far it will go on. Suprisingly, the adapter will go on all the way untill it hits the injector body... not just past the Oring like I thought. This simply means the adapter should not be pushed in too far. This time I'll put the adapters on the injectors first... all the way, then they push the assembly into the manfold... and make sure they dont bottome out.


I have to throw down another $22 and get more O-rings... and maybe figure out a way to space adapters so they dont bottom out in the manifold.
Damn.. I need to get her running while the weather's nice!!

[xxxJohnBoyxxx]

Damn that sucks, did you lube them before install? That is a must or they will tear. I've torn mine from no lube. I have a O-ring kit from the auto parts store and just match up a o-ring and install, no OEM stuff on my injectors

[JP422]

That's a good idea... I should try auto parts store.

I used engine oil to lube. In the past I used vasoline, but someone from RC said engine oil is fine. You gotta use some form of lube...

Hope it works this time.

[JP422]

Problem fixed!

After careful inspection, the injector adapters must not go too deep (bottom out) or their O-rings go past the wall thicness of th manifold, and therefore leak.

I picked up some new Orings... and also some bigger onest use on the outside of the adapters, so it acts like a spacer and prevent the adapters from bottoming out on the manifold

Another important step, was to insert the adapters onto the fuel injector first!... and make sure they bottom out.

everything went back together perfect.. the overall height and spacing was perfect... no need to modify or bend any fuel rail mounts, ad best of all, no leaks!

Now my A/F is about .3 richer as well! The car starts perfect... idles perfect (I thought I stalled the engine a few times, only to see it's still running)... and accelerates so smooth~ Love it!

-Joe