Looking for help...

I seem to be getting a pulsing or fluttering in RPM's when accelerating in 4th and 5th gear (auto trans).Seems to be at lower RPM (1500-3000 approx) when the engine might be slightly undergeared (lugging). Does not occur in any other gears, does not seem to occur at higher RPM. There is a faint, but noticable pulsing of acceleration as the RPM's go up and down by maybe a couple hundred RPM. About 80k miles on the motor, 2001 E320.

Fuel filter was replaced about a year ago, as was the air mass sensor. Problem does not seem to be related to those fixes.

Any ideas? I hope it's an easy fix, not a tranny replacement or something catastrophic.

Thanks for your replies!

 

I'll keep this post on my priority list.Need to get my teens settled down for the night
In the morning we can go over some things and possible causes and solutions.Probably not the trans or major item,so rest easy.It will get figured out
ohlord

 

Thanks Ohlord!

 

Step 1.
Is Service History up to date. i.e. Air cleaner change, spark plug change at recommended mileages.etc.
Next
See if any DTC diagnostic codes have been set.

Let us know where this gets us to.
Stuart

 

Hi Stuart:

Service - current, filters, etc, but don't think plugs have ever been changed. Probably a good thing to do regardless...
DTC Codes - like a check engine light or malfunction warning? No malfunctions or lightsreported. Do I need to run something manually for this, and how do I do it?

Please advise...

Thank you!!!

Thanks.

 

CEL / MIL (Engine Warning Light) only comes on when certain DTC's are set.

To read DTC's you need a scanner. It appears that many garages in the USA will scan for you at no cost on the offchance youy will get them to fix whatever is found.
Basically you plug a small computer into a socket just below the dash and it gives a health check on the engine and trans.
Scanners can be bought on the internet and the job takes about two mins once you know what you are doing.
If you go this route ask some questions as to what sort of scanner to buy.

Plug change point differs model to model, and market to market.

I believe the change point in the UK on the V6 M112 engine is 70k miles so changing the plugs maybe a good idea but may not resolve the problem.

The V6 M112 has 12 plugs! Straightforward to change but access is restricted and takes quite a while (so expensive at a garage) to complete.

Stuart

 

Hi Stuart,

I think that you are knowledgeable...

I have a 97 E420,which had the engine light on right after I started the car last night in the rain. It was running rough and the shaking becoming less after it warmed up. The smell of the exhaust seemed to be on the rich side.

Do you know the possible causes?

Also, do you think that the INNOVA OBD2 code reader can read my car?

Thanks in advance!

Regards,

William

 

OK.
97 E 420.
Unfortunately I don't have any specific experience.

Thanks for your vote of confidence. Misplaced?

Scanner type depends on diagnostic plug available.
97 is in the transition period so not sure if it is the "X pin" MB socket or the now standard OBDII 16 pin socket.
It will be located either under the hood in the electronics box adjacent to the firewall (likely to be an MB socket) or alternatively under the dash in which case it will likely be a 16 OBDII. It is quite possible that the socket under the dash has a cover over it.

I suspect that you are going toi find that it is the "special" MB socket.

Any OBDII scanner will work on a vehicle with OBDII socket however different scanners give different functionality.
In general the more you pay the more feature you get.

Prior to the OBDII standard each manufacturer had proprietary standards with respect to sockets and coding and getting the correct reader is more complex and you may be forced to go for the simplest type namely blinking LED. Only provides limited information.

Best to get the codes read for free from one of the many "shops" that do so if you are in the States. Ohlord knows all about this.

You need the codes to determine "What Next".

Since the yellow CEL is ON it is advising that a code has been set because "something" does not meet spec. The code will give a clue as to what.

JFI Have you inspected to see whether the electrical harness insulation across the top of the engine is in good shape?



Stuart

 

M119's hate water,it seems that you may have run into a puddle and soaked the top side of the engine.Spray some wd40 down eack plug rescess and make sure the connectors are pushed on fully.M119's also hate being pressure washed so remember that if you ever decide to give it a bath.
centec scanner 94169 states is a great little scanner if someone can send you one works on all 96 and up obd2 systems.
Some good diy's for the m119 420 engine on www.mercedesshop.com
resource section diy's.