Cold start problems and injector question

[Kridre]

Hello!

I have small problem with my M119 equipped MB. When car is not used for longer period of time it starts really weird. It fires almost immediately after turning the key and I can smell some unburned fuel and it idles poorly. I removed fuel rail to check for any leaky injector and everything is ok. So at this point I decided to clean injectors with carb cleaner and replace o-rings and sadly I broke one of pintle caps at the end of a nozzle. I ordered new pintle caps with kit 1287010704 and I found out that pintle caps are completely different... They have smaller hole and are taller than old ones. Sadly i didn't found any pintle caps that looked correctly only similar ones with wrong hole diameter. So I drilled bigger hole in my caps to make it fit and I think they work correctly. Spray pattern is identical to the old caps but I want to ask someone smarter than me if it is right to do so or should i just find correct caps for this injectors. Maybe someone knows what is going on with this start issue. I replaced every critical part of fuel and ignition system: caps, rotors, insulators whit o-rings, camshaft seals, fuel filter and engine harness. Only thing that is old are ignition cables but i don't think they are the issue. Engine starts to run smoothly after 2 min.

Old cap

New Cap

Repair Kit

 

[gsxr]

For the starting problem (too rich)... how old is the fuel pressure regulator? If the diaphragm is bad, it could be leaking fuel into the #8 cylinder. Do you have access to a digital scanner to view live data on a cold start?

@JC220 may be able to help with the pintle cap question.

 

[Kridre]

I think its original so around 25years that's the next part on the list after reinstalling injectors. I don't have any access to digital scanner.

 

[JC220]

Yes there can be issues with new pintel caps and most all of them will require drilling to closely match the original items.

If fuel is suspected to be leaking from the fuel pressure regular do the sniff test. Remove the little black vacuum line and sniff it for the smell of Petrol. If there is a ready small of raw fuel from that hose then for sure its dumping fuel into the intake manifold.

 

[gerryvz]

All of the replacement pintle caps indeed that I've seen, have much smaller holes. I know that @a777fan also found this last year when he replaced his pintle caps. I replaced mine a couple of months ago and I had to drill them larger, as seen in this post.

I think that four or five of my pintle caps cracked and broke when I removed them.

RESTO PROJECT: M119 / W124 / E500 Engine Top-End Refresh | Member Roadtrips and Project Journals

See my previous post — I added some photos at the end. It looks to me like the seal is nearly flush with the timing cover. No question it is original. I will do the latter like you did, but will also gauge with the seal tool.

www.500eboard.co

 

[gsxr]

Dumb question. Does anyone know the purpose of the pintle caps?

 

[gerryvz]

Dumb question. Does anyone know the purpose of the pintle caps?

They basically just keep things neat and tidy at the tip of the injector, and help keep the lower o-ring on and in place. They do not affect the injector's operation, and the injector will work perfectly fine WITHOUT the pintle cap installed.

 

[Kridre]

There is no fuel smell from fuel pressure regulator. I will check again tomorrow and as I expected I need to order new caps from injector planet. I think that this are correct ones. Click.

 

[Kridre]

A little update. Injector caps still didn't arrived, so I left that one pintle cap and putted everything together and replaced the fuel pressure regulator. There is no cold start problem anymore so that's a win but now when cruising at 4th gear and pressing gas pedal around 60% there is some hesitation up to 2,2k RPM. I don't know what it is I hope is that one pintle cap that is not correct for the application or that BOSCH fuel regulator is junk. This is more noticeable when the engine is cold. Or maybe after 50k km it's time for caps and rotors replacement.

 

[Kridre]

Hi!

This is what I found out today. Caps and rotors look brand new but there are 3 errors stored on pin #4 and I cannot erase them:

-24 Left adjustable camshaft timing solenoid (Y49/1), open/short circuit

-25 right adjustable timing solenoid, engine 119 (Y49/2), open/short circuit

-27 Injectors (Y62), open/short circuit

I checked cam magnets if they even work and there is 11.93V on the plug but when I plug a test light nothing lights up when engine idles or revs up. I replaced wiring harness upper and lower, so I don't think this is my problem. Then I unplugged engine harness and checked voltage on main plug with ignition ON and still nothing. Multi meter shows 11.93V but test light still doesn't light up. When I use ground from different place test light light's up.

Could this be bad LH module? I found out that broken LH module can cause relay clicking under the dash and rough idle. Sometimes I hear rapid clicking for 2 second after starting the car and nothing more, everything is quiet after that, or maybe someone can tell me how to check that voltage on cam adjuster plugs. Am I doing something wrong?

 

[gerryvz]

Looks and sounds to me like a bad or mid-connected upper wiring harness.

 

[Kridre]

Hello!

Thank you @gerryvz it was the right call. I cleaned contacts at the main connector and there are no issues. I also replaced that bad pintle cap with correct one and filter baskets. Still, when engine is cold it runs like garbage so that wasn't the issue. I will check the spark plugs after short drive and maybe that will give me some ideas, or I will search for someone with star diagnosis.