Hard Start (E420) - Recent Tune Up, etc. - Page 2 - PeachParts Mercedes-Benz Forum

Holson Adi · #16 11-02-2004, 09:02 AM

Quote:

Originally Posted by merc300juno

I posted my own thread on E420 starting problems, then happened on yours regarding the same subject. I was wondering if you satisfactorily solved your 1995 E's starting problems with the R&R of the fuel pressure regulator, or if you are still dealing with it.

Those parts will come in today, and I will most probably install them tonight if I have the chance. However, it only fails to start once in a blue moon. But I'll definitely update it.

But, if you try to start your car right after the starter keeps cranking forever, does it fire up right away?

Gillly.

What does MAS Relay stand for? Mass Air?
Is it the green relay in the relay box?

Thanks

Gilly · #17 11-02-2004, 07:07 PM

MAS is a German acronym, no idea what it stands for. The common name for it (besides MAS) is Engine Systems Control Unit. This was quite common on the M104 124 chassis cars. It controls a few important functions, mainly AC compressor control, fuel pump control, and also the heater for the O2 sensor.
NOT to be confused with the mass airflow sensor. I don't normally abbreviate the mass airflow sensor "MAS" anyways, normally in MB literature, if it's abbreviated they use "MAF sensor" or simply MAF. As long as I'm thinking about it, on the V8 124 chassis they used a Base Module instead of a MAS.

Gilly

Holson Adi · #18 11-02-2004, 10:50 PM

I got the parts today

R&R'd the combo relay (fuel pump,etc.) and replaced the fuel pressure regulator.

Took me a few minutes to figure out how the regulator comes out

- but once I did it was easy.

Make sure you have something to compress one of these spring/ring/clip type of things - I used a pair of pliers but it was not too easy.

The fuel Pressure Regulator that was in there was a Mercedes unit and the replacement is a Bosch unit rated at 3.8bar.

Could that be it? I HOPE!

I started it cold twice and fired up perfectly and warm three times and all 3 times, it started without any drama.

If anybody knows any other things I should look at that don't cost too much - feel free to suggest.

Thanks again everyone

DangerMouse · #19 11-03-2004, 02:48 PM

Quote:

Originally Posted by Holson Adi

The fuel Pressure Regulator that was in there was a Mercedes unit and the replacement is a Bosch unit rated at 3.8bar.

Could that be it? I HOPE!

Holson,

I went through the same process with my 95 E420 shortly after purchase -- replaced the fuel pressure regulator as you did, with great results. Next on my list of minor r/r items are the ignition coils, which lose their effectiveness over time. If the engine still takes a while to turn over, this might be a good place to start looking (and relatively cheap to replace).

Regarding the sludge on the spark plug, I know what that is too: the spark plug ring on the valve cover seal is leaking. I do not believe you can remedy that without replacing the valve cover gasket (probably not a bad idea anyhow).

-DM

Holson Adi · #20 11-03-2004, 08:47 PM

Thanks for the reply DangerMouse

I will look into replacing the valve cover, that also means that I need some stronger Allen-head drivers as the L-keys feel like they are about to snap when i tried to undo the valve cover bolts..

Looked at Fastlane's list and it lists the ignition coil at $155 - it's not bad I guess. I might just buy it and replace it.

But which one do I need, it lists two:
Ignition Coil:Mounted on top of ABS hydraulic console
Ignition Coil:Mounted on side of ABS hydraulic console

and I never recall seeing it around or on the ABS Hydraulic Console...

Is it the ASR unit? or is there a separate ABS module?

Is it easy to replace?

DangerMouse · #21 11-03-2004, 09:27 PM

Quote:

Originally Posted by Holson Adi

But which one do I need, it lists two:
Ignition Coil:Mounted on top of ABS hydraulic console
Ignition Coil:Mounted on side of ABS hydraulic console

and I never recall seeing it around or on the ABS Hydraulic Console...

Is it easy to replace?

Holson,

There really are two coil packs for this engine, one for each cylinder bank. Unfortunately I cannot find an image of the engine to highlight the exact location (near the ABS unit, under the alarm horn, on the left side). They have a black plastic dust cover protecting the top of each unit.

The best way to locate them yourself is to trace the central lead from one of the distributor caps to the left side of the engine. Removing the left headlight should provide the most access, if you are comfortable with doing so. You will need a flat screwdriver to open the plastic covers and gain access to the coils.

There is no MB recommended service interval on coils, just to be clear. Intermitent coil problems tend to surface under high load (starting, hard acceleration) as they age.

-DM

Holson Adi · #22 11-04-2004, 10:32 AM

Thanks again DangerMouse,

Purchased the Ignition Coils :p

Must I really take the driver's side headlight to R&R the Ignition Coils?

Would you recommend disconnecting the battery before removing the Ignition Coils?

Thanks in advance!

merc300juno · #23 11-04-2004, 11:42 PM

I will be taking my hard-starting E420 to Hartmann Motors in Portland, OR next week. In discussing my problem, Pat Hartmann suggested (in addition to installing a pressure gauge on the fuel rail) looking at the alarm system for electrical faults. When describing my hard-starting occurrences, Pat asked my if after unsuccessful attempts, did I remove my key and reinsert it to attempt another start. I said, "excuse me?" Then he described situations that relate to faults in the ignition system (caused presumably by wear), where the proper signals do not reach the alarm system, essentially preventing the ignition system from energizing. This is way beyond me, so I'm going to bite on having the Merc scoped. Apparently they have a scope similar to those one sees at larger dealerships. Anyway, Im preparing to get financially hosed as this E420 is my wife's daily driver. I'll give more feedback if it seems relatable to E420 starting problems posted by others.

joiseygal · #24 11-05-2004, 09:22 AM

Quote:

Originally Posted by Holson Adi

Ok,

this is getting on my nerves. Over summer, the car started acting up. Whenever I leave the car and the engine is warm, upon coming back, chances are I could crank forever and nothing would happen.

When that happens, sometimes it might seem like it's going to fire but it doesn't. Other times it just cranks to no end.

If I give up and crank it again, it fires up as if nothing ever happened.

Power is good, mileage is good, everything else is fine. Never a problem when the engine is cold though.

Mind you, it does not happen all the time.

The spark plugs, distributor rotors, caps are recent - say about a year ago or 10,000 miles.

Over summer when it started acting up, the dealer replaced the crankshaft position sensor and shimmed it as per MB's suggestion. They also claimed that they could not replicate the problem.

Upon taking the car back, I stopped for gas. When I tried to fire it up, it just kept cranking. But! The second time I tried (right after), it fired up like it would normally.

It did it again a while back, and in the past two days it failed to fire up three times.

The wiring harness is new too.

Any ideas?

Plug wires maybe? or should I try replacing the spark plugs anyhow? I do have 8 Bosch Supers doing nothing on the shelves somewhere.

Fuel Pump? Fuel Pump Relay of some sort maybe?

Any suggestions will be great. The car is obviously going back to the dealer that tried to fix it. What a waste of money it was!

I have the same problem on my car, just replaced the spark plugs....

I also hearing the clicking/tapping sounds around the ABS / climate control?? try to figure out if any relay?? anyone help?

Holson Adi · #25 11-08-2004, 02:44 AM

Not the best day ever,

the car failed to start again..so the fuel pressure regulator and the relay wasn't the culprit.

Haven't installed the Ignition Coil - got to taking the headlight out but I still think they are pretty tough to get to.

Any tips as to what I need to remove?

Gilly · #26 11-08-2004, 08:18 AM

I still think you're pulling at straws. When it doesn't start, remove the cap from the test port and use something like a small screwdriver and push in on the schrader valve core and see if there is pressure in the rail. Could still be the pump itself, or maybe an electrical problem (such as control over the fuel relay, not the relay itself) keeping the pump from working. It is easy to see if you have pressure in the rail. Some have also said that 119's can get rotten harnesses like the 104 engine 124's.
Gilly

Gilly · #27 11-08-2004, 08:20 AM

In short, you should have the engine ready to be able to check fuel (at least rudimentary checking at the port as I suggested) and also check for spark. May be difficult to check for spark solo, but it CAN be done.

Gilly

DangerMouse · #28 11-08-2004, 11:59 PM

Holson, sorry to hear the car is still having problems. You should be able to access the top of the coils without removing the alarm horn, but it is listed in the service manual as one of the steps. Unless you have corrosion or physical damage, I would not expect it to completely resolve the hard starting problem.

I agree with Gilly regarding fuel/electrical checks and the harness -- in addition to the fuel pressure, check the condition of ignition wires and the main harness itself. The harness is one of the weak points of the M119, and you *will* end up replacing it sometime during the life of the vehicle. The big V8 generates a lot of heat, so the wire insulation breaks down with age. The harness in my car literally crumbled when I replaced it last year.

You should set a demarc time after which a mechanic is called in, to preserve your wallet and sanity ;-) There are lot of minor items to check that cannot be done over the Internet - fuel system leaks, fuel filter, battery output, condition of the fuel pump relay, etc. It may be worth the $75 diagnostic fee to have someone tell you "dirty fuel filter" instead of spending $750 on minor parts. But everyone's threshold is different.

Good luck,
-DM

#29 09-11-2005, 07:57 AM

I have a 98 E320 that started actiung this way last week is the advise advisable o that engine as well?
Thanks
Bob

Larry Delor · #30 01-29-2006, 10:03 PM

What ever became of the hard start dilemma?

Mine has been acting up lately...Starts great when cold, but once warm, I have to step a little on the accellerator pedal to make it run.

This evening it had the worst case yet... It acted like it was almost running....but, as soon as I let go of the ignition key, it would die. During the third attempt, I thought I heard something click or turn on... as if a second fuel pump decided to fire up....weird either way.

thanks!

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