injectors and fuel distributors

[jchip]

I found this interesting. Had a persistant miss at idle so after checking all the usual suspects, I brought my 91 420 SEL (199K) to my favorite independant MB mechanic for a diagnosis. While discussing the possibilities of it being injectors or the dreaded fuel distributor, my mechanic told me that he doubted it was either. He said in his 20 odd years as a MB independant mechanic, he probably had only had to replace 2 or 3 fuel distributors. He also said that he replaces injectors so rarely, that he doesn't even stock them. This seemed to conflict with all the recommendations I read on this thread when it comes to the typical rough idle problem that seems so widespread. He said most dealers are very quick to replace these components but usually find something else as the culprit along the way. Sure enough, he located a small vacuum leak that corrected the problem. His experiance is that age related problems with vacuum hoses and plug wires are usually the cause of rough idle problems unless you have been using a poor grade of gas such as Exxon (lots of dye in their gas that leaves a sticky red tar.)

J.Chip

[stevebfl]

He is right of course, unless you have a bad injector (bg).

We also replace very few injectors and even fewer fuel distributors (maybe 1-2 distributors a year). We have a differential flow tester and diagnosis is just a matter of time.