M104 Fuel injector question

[timmyr]

Hello to all,

I have a 1993 300E M104 with 110,000 miles on it.
I have had trouble with constant rough starts for sometime now, and have finally decided to pull my fuel injectors to have a shop clean them for me using their ultrasonic cleaner. But before doing so, i decided to visit my local benz dealer to inquire about replacement parts for the injectors, however the guy there was very uncooperative, and i barely managed to get him to order the fuel injector O-rings(50USD for 12 ) for me. i am aware of the fuel injector service kits online(caps, spacers, o-rings, screens), and have ordered in the past, but wasn't very thrilled with the quality.

what i would like to know is : does the dealer carry any genuine benz fuel injector parts other than the O-rings? or if someone could atleast let me know where i could find genuine fuel injector caps, spacers and screens for the particular fuel injectors found in my M104 engine, i would really appreciate it.

thanks,
tim

[deanyel]

Better and perhaps cheaper to send them out - they have all the refurbish parts, they clean them, test them and give you a test report. At 110k I would guess they're not likely the problem.

http://cruzinperformance.com/

http://witchhunter.com/

[tjts1]

Originally Posted by timmyr

what i would like to know is : does the dealer carry any genuine benz fuel injector parts other than the O-rings? or if someone could atleast let me know where i could find genuine fuel injector caps, spacers and screens for the particular fuel injectors found in my M104 engine, i would really appreciate it.

thanks,
tim

The injector caps and seals are generic for all Bosch injectors used by a dozen different car makers.

[latief]

Do I need to Change the injector for this?

FYI ....no parts from Mercedes are available other than seals

[timmyr]

Hello to all, and thanks for the quick replys. i picked up the fuel injector seals(o-rings) from the dealer today. i plan on taking them to a local shop whhich specializes in Bosch fuel injection systems. i found out today that they have the replacement caps, and screens for my injectors. so now all i gotta do is pull em. hopefully it wont be that bad.

once again thanks to all for the good info.

tim

[ROGER E.]

Originally Posted by timmyr

Hello to all,

I have a 1993 300E M104 with 110,000 miles on it.
I have had trouble with constant rough starts for sometime now, and have finally decided to pull my fuel injectors to have a shop clean them for me using their ultrasonic cleaner. But before doing so, i decided to visit my local benz dealer to inquire about replacement parts for the injectors, however the guy there was very uncooperative, and i barely managed to get him to order the fuel injector O-rings(50USD for 12 ) for me. i am aware of the fuel injector service kits online(caps, spacers, o-rings, screens), and have ordered in the past, but wasn't very thrilled with the quality.

what i would like to know is : does the dealer carry any genuine benz fuel injector parts other than the O-rings? or if someone could at least let me know where i could find genuine fuel injector caps, spacers and screens for the particular fuel injectors found in my M104 engine, i would really appreciate it.

thanks,
tim

When I had the electric injectors rebuilt for my Porsche 944, they came back with new o-rings ready to reinstall. The rebuilder will know what you need.

Your injectors at that mileage definitely can cause idle problems. BTDT.

[timmyr]

I previously had fuel injector trouble on the aerostar at 120,000miles, but the symptoms were different. the aerostar lost a ton of power and really struggled uphill. as for the benz,it still pulls strong, however upon startup(hot/cold) it tends to really run rough for about the first 5-15 seconds, thereafter it runs perfect.
i built the code scanner lamp and kept getting a code 21, which idicates a missfire on cyl 1 & 6. i then erased the code 21 and swapped ignition components(spark plugs, wires , ignition coils) from the working cylinders one at a time, however the code 21 keeps coming back. And now recently, i have noticed that my engine oil level is at full although i usually keep it @ 1/2, and it kind of smells like gas. my guess is that i have a leaky injector.

i hope to do the job this friday or sat, and will post the results.

thanks for your help

tim

[duxthe1]

Leaking injectors are rare on those engines. From your description it sounds as if you have a leaking purge valve or fuel pressure regulator. Test the regulator by pulling off it's vacuum hose and looking for gas. If there is gas present at the vacuum nipple, replace the regulator. Check it a few times as they won't always leak consistently. You can check the purge valve with the engine idling by pulling off the line that goes to the tank and seeing if there is vacuum going through the valve when it is not cycling. It will cycle pretty soon after a start so you have to be quick to check it. If it starts cycling before you can check it, restart the engine and be quicker next time. If you get vacuum through the valve when it is not clicking from cycling, replace the valve.

Either of the above failing will put excess fuel or vapor in the intake that will need to clear out before the engine will run smoothly, approx 5 to 15 seconds.

[timmyr]

to duxthe1,

i have checked the fuel pressure reglator with engine running, numerous times. the vacuum line seems dry, and does not smell like gas, so i guess its ok.

the purge valve on the other hand, i have not checked, but will do so asap. should the engine be hot/ cold during the purge valve test? i thought that the purge valve isn't supposed to cycle at idle speeds, but i guess i'll have to look into that some more.

finally, what you are basically telling me is that, if the purge valve gets stuck open, there will be a constant vacuum applied to my purge canister and gas tank, and therefore result in lower MPG's and rough idle at startup, due to the constant feed of fuel/fuel vapors to the intake? is this correct?

thanks for the info will check it out today,
tim

[duxthe1]

When the purge valve sticks open, as the car sits pressure in the fuel tank vents into the intake manifold. With the intake full of fuel vapor it will run too rich on start up (often misfiring) until the vapor is cleared out of the intake manifold. I doubt that it would affect fuel mileage though.

[latief]

on the same topic: can a bad purge valve (stuck open) cause a rich running condition beyond the initial 15 seconds.....? my valve appears bad, and my exhaust smells like a rich running car....

thanks,

[timmyr]

yesterday i started up the car and did not notice any cycling done by the purge valve, so i removed it and blew on one end and found that it allows air to pass freely through it. i guess that it is stuck open. i did a little research and found claims that a purge valve can get gunked up from the fuel vapors, or may get messed up if it sucks up any rust debris from the charcoal canister. i'm hoping that its just gunk and that a bottle of carb cleaner might get her cycling again. will give it a try today.

would it be ok if i temporarily plug both hoses that go to the purge valve, and see if it cures my rough idle at startup?

thanks,
tim

[duxthe1]

Just plug the line going to the engine. You don't want to plug the tank side and have excess pressure cause another problem in the purge system. Once you've confirmed it has a problem, I'd just go ahead and replace it. It's not terribly expensive and you don't have to worry about it anytime in the near future. Otherwise you could end up futzing with it off and on until you do replace it.


Latief, yes a leaking valve can cause mixture problems, especially when stuck wide open. You may have other problems but the above advice applies to you as well.

[latief]

Originally Posted by duxthe1

Just plug the line going to the engine. You don't want to plug the tank side and have excess pressure cause another problem in the purge system. Once you've confirmed it has a problem, I'd just go ahead and replace it. It's not terribly expensive and you don't have to worry about it anytime in the near future. Otherwise you could end up futzing with it off and on until you do replace it.


Latief, yes a leaking valve can cause mixture problems, especially when stuck wide open. You may have other problems but the above advice applies to you as well.

thanks,

See my other post, will it cause fuel/fuel smell in the intake?

I appreciate the response

[duxthe1]

Fuel smell yes, fuel no. It's not abnormal for there to be a sticky oily accumulation in the lower part of the intake on the 104 engine. Unless you can get a sample and confirm it is thin with gas, it's a non issue.