Bad Injectors
 

Any easy way to tell if fuel injectors are bad or plugged? My '88 300ce Idles rough and starts hard when warm likes it's flooded. Could all or one of the injectors be leaking and flooding the car?

Although it's strange, when the a/c is ON it actually idles pretty good.

bad injectors
 

Hi John

I have an 89 300ce with 153k kms. I have similar symptoms in an otherwise perfect car.

Starts well when cold but starts and dies when warm unless a bit of throttle is used.

Like you I notice that it can be rough on warm start up like it is missing a cylinder or two for the first few seconds.

My indie tells me I need new injectors. After proving everything else in the fuel system including adjusting the EHA which has transformed the driveability to 'as-new' this is the only thing left that makes sense for remaining symptoms.

It seems like the old injectors can leak down which in effect floods the engine. You are right that it is probably one or two cylinders. When additional throttle is used the engine has the air to burn it off.

The injectors for this engine a reasonably cheap and it is a reasonable DIY job.

Please let me know if you make the change.

89 300CE

big blue is right.. Just as an aside, MB rates their injectors to have a service life of about 100,000 miles before they fall off. I just pulled a set from a very well maintained SEC w/ a little over 100K. All but one of the injectors had a poor spray pattern.

Let me know if I can help in any way!

Jonathan

Poor injector spray pattern is a much different problem than leaking ones. The throttle blipping that helps the problem makes me think that the idle air control valve may be suspect. The A/C helping the idle is another clue (I think the A/C being on opens the idle air valve a bit more than normal idle).

Before spending whatever criminal prices Bosch is charging for injectors these days, try cleaning the Idle Air Control Valve. Replacement might do the trick if cleaning doesn't.

Hope this helps.

Troy
1995 E420 93k

or, do as I did and replace the air idle valve w/ a plumbers valve..Works great:)

http://www.mbnz.org/forums/forums/thread-view.asp?tid=1208630&posts=12&fid=11

Jonathan

Great
 

I found a place in Arizona that cleans the injectors and replaces the seals. Supossed to make them like new, for not too much money. I'll replace the ICV and see what difference that makes before doing the injectors. Is it easy to take them out?

I was having a similar problem in my 89 'E. I purchased a $100 fuel injector pressure test kit and discovered that my system was perfect and after 45 minutes there was zero leakdown.

I ended up discovering some vacuum leaks, giving it a tune up, setting the Lambda, cleaning the ICV, and resetting the camshaft timing. The car runs alot better and has much more power, but still sometimes needs a little pedal when starting warm, although to a much lesser degree now.

While the pressure tester didn't solve the problem, it saved me considerable time and money replacing the injectors...

Robert

Jonathan, that's unbelievable. For us non-plumbers out here, could you please specify exactly what to ask for when looking for the valve? thanks.

I had the same symptoms on my 560SL (hard warm starts) and I landed up replacing all 8 injectors and the associated air tubes that feed them from the ICV and that fixed it finally (after tinkering with a bunch of other things). The car performs like new again now.