M104 Surge after Head Gasket - PeachParts Mercedes-Benz Forum

kiwi_bloke · #1 04-27-2009, 09:12 PM

Hi guys,

Just had the head gasket done on my 1996 E320.

Took it back due to an idle surge. The guy found a vaccuum leak and fixed it.

However now, it runs great. Just occasionally when changing from cruising, to coasting it will surge. It's not all the time only occasionally.

I understand it was only untill 95 wiring looms were affected. I think my motor is a 104. 999 xxxx so have ruled this out ?

I have a few suspisions. The valve on the front of the engine that controls vaccum to the EGR via two vaccum lines may have the lines switched - what should be where?

Additionally, my cruise control stopped working at the same time.

Arthur Dalton · #2 04-27-2009, 10:13 PM

Try this................\

95 E320 vacuum line question

POST #8

kiwi_bloke · #3 04-27-2009, 10:15 PM

Thanks.

Could this also be related to cruise control? Or am I grasping at straws?

Arthur Dalton · #4 04-27-2009, 10:17 PM

No connection...........

kiwi_bloke · #5 04-27-2009, 10:18 PM

Thanks,

Where should I start looking to diagnose cruise control - other than reading the codes. Ill get around to reading the codes at some stage.

Arthur Dalton · #6 04-27-2009, 10:19 PM

Fuses

kiwi_bloke · #7 04-30-2009, 02:38 AM

Ive taken the car back to the mechanic who did the work. Can't really be bothered hunting problems he created.

Any suggestions as to what may have caused this after doing the head gasket? Can someone verify if my 96 E320 was among the years with bad looms?

Arthur Dalton · #8 04-30-2009, 10:26 AM

That chassis was not known for the wire harness problem of the earlier 104s.
But your condition could be unmetered air bewteen the MAF and the intake. There are two comon places to check on a car that has had a gasket job.
The 2 places are :
The clamp where the intake air cross pipe meets the throttle valve assem..they forget to tighten that clamp b/c it is hidden once things go back together..it has to be gotten with an extra long screwdriver , accessed from the front.
The other is they forget to clip the little IAT sensor back into the same pipe.

And lastly, look for any vac leak sources/hose/etc..........

tinypanzer · #9 04-30-2009, 05:41 PM

Geez Arthur, it amazes me sometimes the level of specific knowledge you have....

kiwi_bloke · #10 05-01-2009, 12:09 AM

Ive just got the car back. They ran diagnostics on it.

Got the following:

006 Air MASS METER signal. Below lower limit.

Reset.

Reapeared.

Reset

Didnt reapear.

Does this automatically mean the Air meter is bad?

kiwi_bloke · #11 05-04-2009, 04:46 PM

I just replaced the MAS sensor. Runs great hot now. Runs great cold in the morning now. Surges, idles rough, and is "soft" to drive between 60 and 80C.

The rough running seems to have moved around temperature wise.

Not sure what's going on here. No codes. No Check eng light. No fuel in the fuel reg line. No vac leaks.

Adaption? I've only done 30 km since putting the part in. How long does it take to come back into line ?

tinypanzer · #12 05-04-2009, 05:06 PM

I dunno the answers to your questions, but it couldn't hurt to measure the resistance of your temperature sensor(s) and make sure they're in spec.

Another possibility is that your plugs got fouled out during the time your MAS sensor was out of whack. Couldn't hurt to pull them out and clean them up.

kiwi_bloke · #13 05-05-2009, 06:09 AM

Ok.

Ive replaced the MAF due to the initial code. I now have - MAF over upper limit, maf under lower limit, lambda over upper limit and lambda out of range.

Should I now replace the O2 sensor?

kiwi_bloke · #14 06-11-2009, 08:51 PM

I put everything back as it was, and decided to let the fault get worse so I could track it.

Heres what's happening now. Im getting the occasional stall at idle in gear. I get "Check battery charge" on the dash.

I connected a volt meter today accross the battery.

Get 12 not started.
13.1 idling
With all accesories on and idling it goes down to 11.6 after some driving.
Rev to 2000 rpm no accesories - between 13.2 and 13.5.

Battery sounds fine when starting, never goes flat.

Could this be the cause of all my problems ?

OzC36 · #15 06-14-2009, 10:20 AM

Dear Kiwi,

I have replaced the engine wiring harness on my 03/1996 C36 (M104). Only last week I helped a friend replace the engine wiring harness on his 12/1994 W124 220E. So I say the following based on some personal experience.

Mercedes wiring harnesses fitted on all Mercedes cars built between about 1992 and about 1997 were made using insulation that hardens with time but also rapidly degrades with high temperatures. So, at some time the engine wiring harnesses (due to engine bay temperatures) on all these affected cars must be replaced. You will not fix the problem by buying any number of new sensors, new MAFs, new computers etc, etc (I have been there and got the T-shirt).

You can easily check the condition of your engine wiring harness by looking for signs of disintegration, cracking and dust power (that was once insulation material). When changing the headgasket on the M104, the necessary physical manipulation of removing and replacing the engine wiring harness is almost guaranteed to cause engine problems due to shorting as the old temperature-affected insulation breaks down under stresses that it suffers. If your engine harness is showing the critical signs indicated above, then you must replace the harness with a new one (or have the old harness re-built with new wiring). When you buy a new harness, look to see the date of manufacture is not before 1998. The date is shown on a label along with the MB part number and attached to the earth lead.

Good luck..