I have a 1991 300d 2.5 diesel and last night, when I started it it the car sounded almost like a gasoline car that was misfiring. I hit the gas and it brought it back to the normal idle. It is not a vibration probelm such as a worn belt shock tentioner or motor mounts. I am assuming that it is fule realted. I am due for new fuel filters in about 5,000 miles, but I am going to change them early. Logic would tell me that it may be a clogged injector, but they are all new (about 2,000 miles ago). If it was a fuel problem, then why after I hit the gas it clears up? It starts up instantly, but just idles funny?
What do you think?

Hello CJ,

So have you worked on the manifold and cleaning job that we talked about a while back?

Reguards to your current problem, I have a similar problem, but mine only happens when starting cold and a lot of shaking, etc. involved.

I would say change BOTH filters first. How often does this happen again? If the injectors are so new, then I wouldnt suspect them to be the prob.

I have not pulled the intake for cleaning yet. I clean the tiny drip mark off and it takes about 3 months to "sweet". I think for now I will leave it. The idle problem has only happend 2 times from a cold start. I am going to change the filters Monday night, I have to pick them up at my buddies shop. How goes your Benz? I had a crazy problem, here is the link to what my problem was.
Talk to you later.

Fuse keeps blowing for front power windows

Donny,
Where are you???

Check your glow plugs. Mine does that when one is bad.



1995 S-350 135,000 miles

Oldsouth,
Thank you for the suggestion, but they are all good. The car fires up instantly, it just idles funny until you give it gas.

I echo oldsouth's suggestion.

Even though the engine may start easily, and the glow system appears to be working properly, I suspect that your problem is glow plug related. Are they the original plugs? If so, they have served a useful life.

Try letting the car "glow" for an extra 20-30 seconds prior to starting. I suspect one of the glow plugs may be covered in a sheath of carbon and, as such, is unable to properly heat the pre-chamber in which it is housed. Assuming this helps your cold starting, you can check the resistance of each glow plug to ensure proper operation. As with most things diesel related, an Italian Tune-up can't hurt!

__________________
Chris

'04 ML500 - 53k, Inspiration Edition, Desert Silver
'11 Audi A4 Avant - Brilliant Black
'87 300SDL sold
'99 C280 Sport sold
'85 190E 2.3 sold

How do you "hit the gas" in a diesel?

P E H

From my undestanding the glow plugs only help the car start up, not actually help it run. The car starts up instantly, it just idles funny. If one of the glow plugs was going south, I was under the impression that the glow plug light would come on? If I start the car and then hit the gas and let it run for about 10 seonds, then shut it off, and then start it up, it does not idle funny. I do not think it is a glow plug problem.I am not sure if this makes a difference or not in determining the problem, but if hit the gas once, before cranking the car, it does not have that funny idle. It is beginning to sound more like a fuel problem.
What are your thoughts?

If one plug isn't working properly, the engine will start on the rest of the cylinders, but the bad plug cylinder won't contribute until it has reached its proper operating temperature, i.e. uneven running for a few seconds. It sounds like this is the problem, I wouldn't change filters until you have checked out the glow plugs.

__________________
'76 240D-Sold
'78 240D-Sold
'85 300 SD, 165K-Sold
'88 300 TE, 165K-Sold
'64 Porsche 356C Cabriolet- under restoration
'86 560SL 124K Miles-Sold
'94 320E Wagon, 74K Miles-128K Miles JUNKED
'06 E350 Wagon, 84K Miles
07 SL550, 14K Miles

I thought the glow plug light would indicate a bad plug? If I "prime" the car and start it, the car runs fine. It is my understanding that the glow plugs heat up the chamber to help the car start, as opposed top help the car actually run.

I may very well be wrong but I thought on a diesel that if you pushed down the accelerator pedel without the engine running, this did nothing. It does not prime anything because no fuel in being injected into anything. Do a resistance test on the glow plugs, won't take but 5 minutes.

CJ,

The glow plug light will indicate when a glow plug has FAILED. I suspect that one has not yet failed but, more likely, is covered in a sheath of carbon which is not allowing the plug to adequately pre-heat the chamber. Allowing the glow process to cycle longer WILL help initial starting when the engine is cold.

The symptoms you indicate are common when glow plugs begin reaching the end of their useful life.

__________________
Chris

'04 ML500 - 53k, Inspiration Edition, Desert Silver
'11 Audi A4 Avant - Brilliant Black
'87 300SDL sold
'99 C280 Sport sold
'85 190E 2.3 sold

Oldsouth,
I appreciate your insight and will certainly take your advice. Can you explain exactly how to perform this test?
Thanks for your persistence in helping me with this problem.

First get a ohm meter--if you don't have one you can get one at wall-mart or true value for about $10. Find where the glow plug wires plug into the relay at and unplug them. Take your ohm meter and connect one end to ground or chassis and the other ent to each wire going to the gloplugs one at the time. If the meter swings all the way indicating there is no resistance, then that glow plug is good. Resistance indicates the plug is bad. Hope this helps. By the way the harness has numbers on the connector to indicate which wire goes to which cylinder.