e300 rough idle? air leak? help? - PeachParts Mercedes-Benz Forum

92497pmu · #1 10-02-2006, 11:07 AM

rough idle? air leak? glow plug? injectors? no fuel leaks anymore... help?

1998 e300 TD with 135k miles

Situation:
*On a cool morning, the car starts fine after normal glow
*immediately idles rough (probably 6 on a scale 1-10, definitely not normal)
*less rough when brake pressed and shifted in drive
*not too noticable while accelerating, normal driving... mixed city/ highway
*very rough again when let off accelerator approaching stop
*still rough again while braking, slowing to a stop
*not as bad at complete stop is reached (still in D, drive gear), but car will idle very rough if shifted into Park when stopped or Neutral (stopped or rolling Neutral)
*all symptoms remain the same for at least 15-20 minute commute
*less rough after 1/2 hour or more of driving, e.g a short road trip.
*car runs fine after long drive- no noticable shake, vibration or rough idle when hot or fully warmed up.
*Note, car reaches full 80c temp within 2-3 miles from home (5 min.)
*this rough idle/ vibration has been on/ off for nearly a year to varying extent
*no CEL or GP faults
*no known GP service or replacement to my knowledge (bought car @ 74k- now at 135k but no service book included)

Recently replaced:
*had a major fuel leak, replaced fuel delivery o-rings, copper washers
*also replaced plastic fuel lines at the same time (about 1k miles ago)
*recent fuel filter, air filter, oil change (unrelated, but thought I would mention.
*did NOT replace braided fuel return lines yet.

help please from e300 owners or others with similar problems
- getting more and more frustrated by the day.
Phil

TMAllison · #2 10-02-2006, 01:04 PM

I'm getting vibration from my belt tensioner assembly especially at cold idle. You might check the lower end of the tensioner pivot arm where the damper shock attaches and see if it is causing your vibration.

Could be a weak glow plug at start up with compression creating sufficient heat at operating temp to even idle out?

aklim · #3 10-02-2006, 01:50 PM

How about the Mass Air Meter, fi there is one. I noticed mine smoothed out a little when I cleaned it.

TMAllison · #4 10-02-2006, 02:12 PM

If MAF is malfunctioning should have code PO100 present, right? Its emmisions related.

My expirience with MAF problems is that it is pretty obvious somethings wrong as the turbo is off and the engine wont pull more than about 3k RPM.

aklim · #5 10-02-2006, 02:24 PM

I had a dead spot on my Ford Ranger but no CEL lights. Cleaned it and it went away.

david s poole · #6 10-02-2006, 04:12 PM

with 135k when were the injector nozzles last changed?

husk · #7 10-02-2006, 04:18 PM

There was a guy on here from new mexico that had a simliar problem, and found out it was due to the ECU Firmware. This could be your problem.

aklim · #8 10-02-2006, 06:10 PM

I had my injectors checked and 5 out of 6 passed. The 1 that failed had bad spray pattern and lower pop off pressure. The took it apart, cleaned it and life was good again. However, while the idle improved a little and so did power, accordig to the wife-o-meter, it is not significant like what the poster said. However, most of his injectors might be clogged or the prechambers might be curdded up.

psfred · #9 10-02-2006, 07:55 PM

Check engine mounts!

When they go bad, the glycol gel leaks out and the engine is mounted on undamped springs, bounces all over the place. Very roungh. You are at about the correct milage.

You should also check the condition of the serpentine belt and tensioner, idlers, and accessories -- a bad belt can slip and grab, shaking the car enough to think you have a dead cylinder and sound like a bad rod.

Peter

TMAllison · #10 10-02-2006, 09:28 PM

Motor mounts BTW should have a min of 13mm clearance from the metal lip of the mount to the frame crossmember. Easiest way to measure is with a bolt.

92497pmu · #11 10-11-2006, 09:46 AM

Thanks for the posts & suggestions, but I still have the damn vibration/ shudder...

On Saturday here's my captain's log...
*Removed intake manifold per Lightman's thread for GP replacement- thanks!
*replaced 6 Glo plugs (no issues- Thank God, use a reamer & never seeze)
*cleaned black gunky jiz from intake manifold and intake runners
*replaced the 2 remaining plastic fuel lines (couldn't reach before)
*replaced fuel filter
*replaced air filter
*re-assemble everything above in about 5 hours total (2 hrs for cleaning)
*motor mounts "look" ok. Not collapsed or leaking any stuff.

Shakedown drive.
Still shudders when motor is cool
Mileage is still low 2-3 mpg below normal.

Arrrrrrgh...

#12 10-11-2006, 12:36 PM

I'm the guy with the car in New Mexico. I had the car in a shop for three days with similar symptoms: cold start OK, accelleration, normal running OK,
all fuel leaks cured, new filter, prefilter, clean diesel, no codes, good engine mounts new tensioner, belt, idler wheel, tensioner shock, new alternator,good glow plugs, everything working on car, good battery--still runs rough when at operating temp and only when in neutral or park. Shift into drive or reverse and it idles smoothly. Shop said POSSIBLE ECM problem but no way to tell ie. start throwing parts at it. The car was running well overall so I've been driving it until yesterday when all of a sudden it died at cruise with apparent fuel starvation. I pulled over, turned off the key, waited
five minutes and presto--restart and running as normal for ten miles. The same thing happened again five times until it limped into the airport parking lot where it now sits. Finally the CEL came on, so we finally have something to work with.
All of this started last month with leaking o-rings on the injector pump and has really stumped everyone. I called the local MB dealer and asked the parts manager how many ECMs and injection pumps they have sold for these cars
and the answer was 0, so he thought it was unlikely to be either of these two items especially due to the intermittent occurrence.
We shall know more later since I'm taking it to yet another shop today.

Steve

not very impressed with the repairability of this model

husk · #13 10-11-2006, 03:06 PM

So you didnt replace the ECM?Did you try the K40 relay? There was an article on here which stated that the ECM Harness could become "stretched" out and ruin the internal parts of the ECM. I will try to locate the thread.

92497pmu · #14 10-13-2006, 06:56 PM

Quote:

Originally Posted by steve hutson

I'm the guy with the car in New Mexico. I had the car in a shop for three days with similar symptoms: cold start OK, accelleration, normal running OK,
.......

All of this started last month with leaking o-rings on the injector pump and has really stumped everyone. I called the local MB dealer and asked the parts manager how many ECMs and injection pumps they have sold for these cars
and the answer was 0, so he thought it was unlikely to be either of these two items especially due to the intermittent occurrence.
We shall know more later since I'm taking it to yet another shop today.

Steve

not very impressed with the repairability of this model

... me either.

This weekend it's getting colder. Frost this morning. Just had 2 feet of snow in Buffalo NY 5 hrs west of here...(those poor sorry f@$#@#s- I feel bad for them)

I kinda gotta get this fixed before it gets too cold here too and I don't think the cold is going to help this. The e300 was shaking like a biatch this morning to the point of rattling the sunroof!!

Can I run it without a serpentine belt? (for a minute?)
to see if the vibration is caused by belt slip/ stuck pulley somewhere.

The vibration frequency seems not like an engine miss (seems like longer freq of the belt making one full revolution) but just as harsh...

Also, the shift thing bugs me
*Rough in Park
*Rough in Neutral
*Rough as you brake to a stop.
*Roughness fades if you shift from P or N into gear and as I accelerate.
*Could this have anything to do with my "maintenance free, permanently filled transmission" or torque converter?

Somedays I get sick of throwing $ at this...

Phil

TMAllison · #15 10-13-2006, 11:07 PM

You can slip the belt off the tensioner pulley and then rotate each pulley by hand to see if there are bad bearing somewhere.

I cant think of anything that would be damaged by running for 30 secs without belt but cannot state with certainty that is the case. Obviously the waterpump would not be turning so one would not want to do that for long. Belts do break w/o doing irrepairable harm......

If you do run engine with belt off it ought to set off CEL with codes for alt/batt charge and AC related codes pretty quickly. Those codes should clear themselves after the third cold start if they do not occur again.

The safest bet is to rotate by hand......