Fuel Injectors...Clean, Replace?

Question

Greetings,My 95 S320 has been acting up lately especially during warm starts.It appears that fuel is leaking down into the cylinders making it hardto start when the engine has been off for 15 minutes to a couple ofhours.  The cold start is ok but I think it's getting worse as is theidle which seems to have a slight fluctuation while in gear at a stoplight.I tried a couple of tanks of techron treated premium fuel with noimprovement.The car only has around 70,000 miles on it and I thought it was oddfor the injectors to fail so soon.Am I missing anything?Can they be cleaned, rebuilt??Or should I just replace them?Thanks for any ideas,Bob

T.G. Lambach · Accepted Answer

I've owned a '97 E320 since new (same 104 engine as S320).

At about 18K it began to have a delayed hot start - no start until I stepped on the accelerator, then immediate start. At 18 K the dealer checked the fuel system's pressure - nothing found.

The problem is worst between .5 to 3 hours after hot shut down; cold start is fine. The owners manual even tells one to step on the throttle if the engine doesn't fire after 4 seconds. Now, at 37K miles, it's worse. Otherwise the engine runs PERFECTLY!

I, too, have tried fuel injector cleaners but so far there's no change. The exhaust reeks of unburned fuel when I start the engine - hot or cold. #6 spark plug was wet when I changed them at 30K miles.

The Bosch ME manual describes most modes of operation - except starting. Thanks a lot.

I'm considering removing the injectors and having them tested and ultrasonically cleaned but cleaning doesn't repair an injector that simply leaks due to rust on its plunger. Perhaps the test will find one or more that needs to be replaced. i.e.

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Its frustrating because the engine runs very well otherwise - but when I look at it there are various ananomous boxes attached to the intake manifold that I know nothing about - perhaps one of them......

Martin Joseph · Answer

Look for vacuum leaks.  especially in the air intake system?Good Luck,Marty

fred_emmerichnospam · Answer

Its a fuel delivery problem, not injectors. Replace injectors as a lastresort.  What are the chances more than one go bad at the same time?  Ifyou check the spray patterns on injectors, you would be shocked. Newinjectors spray with crappy patterns.  So the pattern isn't telling thewhole story. Try everything else first, unless the

Fuel Injectors...Clean, Replace?

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