98 E300 cold, low fuel, rocky idle
 

Does anyone have a similar experience or can shed any light on the following:

On a "cool" morning, 50/60 or so after a previous. warm day...

Fuel in tank is approx. 1/4

Temperature of engine is not warmed up yet ..5 minutes of driving....temp gauge shows "midway" perhaps

At stop light or similar, idling gets VERY rough and engine will stall. Only way to prevent stall is to use accelerator for a "high idle" at 1000 rpm or better. Hard to control brake, accel in this matter in, say, a parking lot. Car will stall unless high idle until temp gauge shows 80 degrees -- fully warmed up.

Feels like this is moisture somewhere, but my question is how to get rid of it.

This has now happened three or four times with the above scenario.

:confused:

thx and best

How are the fuel filters? Maybe the strainer?

I recall reading something about this in this forum, but don't remember the resolution. Fuel metering from the computer, perhaps, but I'm guessing.

Try a few searches. I know it's here.

Also could be your fuel hoses to the shutoff valve that are leaking

Its not anything "B" service related
 

This problem began shortly after the last "B" service....

so do I just start replacing stuff?

If it was the fuel filters, then woudn't that affect the idle of the car regardless of circumstance or environment?

Well, my 99 E300 stared hard in the mornings. Ran fine after that but starting hard. Turned out to the the fuel lines that leaked and had air coming in. As to your strainer, maybe, after some fuel runs thru it, it clears the blockage a little? Those are things I would start out with since they are cheap. However, since you have done a B service, I would wonder if you had the mileage for a fuel filter replacement.

This model has a fuel heater mounted near the injection pump, and the computer controls the flow to it. If you have a leaking plastic fuel line going to or from the heater (very likely) that would explain why you have rough running cold and fine when hot. The fittings on these lines get very brittle and will leak with the slightest provocation.

Rick, thanks so much for your reply. Wouldn't a leaking fuel line result in lower miles per tank....I've seen zero decline in miles per tank or mpg.....

thx

It could be sucking air in but not leaking any fuel out. Start the enigne and watch for bubbles in the those translucent plastic lines. If they have gotten too dark brown for you to see through them, then they should be replaced anyway.

My car was sucking air but not leaking fuel. Mileage was about normal. Cold starts were not good! Check the plastic fuel lines.

any further updates here?
 

Quote:

Originally Posted by 98E300man (Post 1190131) Does anyone have a similar experience or can shed any light on the following: On a "cool" morning, 50/60 or so after a previous. warm day... Fuel in tank is approx. 1/4 Temperature of engine is not warmed up yet ..5 minutes of driving....temp gauge shows "midway" perhaps At stop light or similar, idling gets VERY rough and engine will stall. Only way to prevent stall is to use accelerator for a "high idle" at 1000 rpm or better. Hard to control brake, accel in this matter in, say, a parking lot. Car will stall unless high idle until temp gauge shows 80 degrees -- fully warmed up. Feels like this is moisture somewhere, but my question is how to get rid of it. This has now happened three or four times with the above scenario. :confused: thx and best

I have a rough idle problem also.
I recently had a huge fuel leak - see forum
http://www.peachparts.com/shopforum/diesel-discussion/105291-99-e300td-injector-pump-leak.html

I replaced the following:
*6 delivery valve o-rings & copper washers
*most of the fuel lines (couldn't access one under intake manifold #119 & Phil forgot to ship the longer one from shutoff valve #83)
see pic


Present situation:
*Car starts fine
*seems to idle very rough when cool or cold (I notice door shake visibly and change rattle in ashtray)
*rough idle goes away when in gear and as I accelerate (still cold motor)
*rough idle is very strong again as I brake or stop
*overall mileage is about normal 27-28 mpg (maybe a little reduced, only on 1st tank)
*rough idle is usually less bad when motor is warm/ hot
*no visible leaks anymore, very little/ no air in fuel lines- it's been 600 miles since previous repairs.


***car sometimes seems to "skip" almost sounds like it's missing a cylinder... sometimes @ stop but not always, with a warm/ hot motor***
>>> I have no idea what this is, but this one worries me the most<<<


Questions? Help? Advice?
1. could I have gotten dirt or debris in one of the delivery valves and plugged it?
2. How could I check this?
3. Is it something else or different (air in line, leaky/ bad plastic fuel hose or o-ring)
4. I saw a thread on Lubro moly diesel purge or purging injectors with biodiesel. Is this my best next step? A good PM? or just something else to worry me?

Thanks in advance
Phil

update as requested
 

It turned out to be the fuel lines as was suggested in this forum.....not fuel going OUT, but air coming IN. I replaced all the fuel lines and voila no more problemo.

probably a good idea to do anyway at 100k miles. Note, also a good idea to do at glow-plug-replacement time, since the manifold has to be removed in both cases.

How about the injectors? Mine idles smoother since I took them out and had them tested. One of them failed because of poor spray pattern and lower pop off pressure. Clean them all out and they now are smoother and better acceleration. Also removed the MAF SENSOR, not the housing only. Took the sensor out, cleaned it with electronic cleaner and then washed out the MAF housing. Also helps a bit.

IMO, with the risk of having to remove the head when the plug gets stuck, I would take the plugs out, clean the threads and anti-sieze the hell out of the entire portion of the plug that gets screwed in the head. Not the tip of course. When I took them out after 60K, they came out nice. The copper colored antisieze on the body told me that none of the exhaust fumes are leaking into the body area. I would do this every couple years. Also every 100K, check the injectors. Not just run diesel purge. DP cannot check if they are clogged or unclog them if it is really clogged. DP might be good PM but not as a cure, IMO