W124 300E Coupe

[GH421]

I borrowed my mates 300E coupe for the lovely weather and the pillarless windows..beautiful car, all merc drivers turn to look at it.

Anyway there's been a problem with the car and I hope one of you techs can help me.

The car won't rev past 4000RPM. In first gear I floored it and it went to 4000RPM and changed gear to second. Once it hit 4000rpm the car jerked violently as if it was about to fall apart!!! So I took my foot off the throttle and the car changed into third. Did the same again and at 4000rpm it was jerking

Does anyone have any idea what this could be? It's the 2.6 Variant.

 

[Howard]

Don't think they ever made a 260 coupe , certainly not in the UK ..

Sounds like a different engine has been fitted ?

 

[Adam230K]

I think you're car has the 3 Litre straight six, could be wrong though. It sounds like its in limp mode... you'd have to get it diagnosed... i'm only assuming this cuz i have a w202 (same era) and if that happened to me, i'd be thinking along those lines.

 

[Benzowner]

Don't think they ever made a 260 coupe , certainly not in the UK ..

Sounds like a different engine has been fitted ?

If they have fitted a 2.6 litre to replace a 3 litre, it it possible the torque coverter is not compatible? I was told back in the 80/90's, torque converters on mercs were engine size specific.

 

[Howard]

Don't think w124s have a limp mode .... no MAF on that era of car ( 300E )

 

[aka$h]

Don't think w124s have a limp mode .... no MAF on that era of car ( 300E )

They do have a metering unit, if you take the air filter off, you see a flap, there is a sensor attached to that, to calculate volume of air.

 

[janner]

They all have a rev limiter at 4000rpm in neutral. Maybe the limiter thinks it's in neutral when it's actually in gear?

 

[Howard]

They do have a metering unit, if you take the air filter off, you see a flap, there is a sensor attached to that, to calculate volume of air.

Ah ok , i never knew that .

Do they have a limp mode also , like you see on modern MB's when the MAF fails , it goes into limp ?

 

[Adam230K]

limp mode can be triggered for a number of reasons, and i think this is independent of the MAF.

If his gearbox has some fault codes registered or something, it could trigger limp mode. Would be nice if someone with more knowledge than us come along and shed some light on this .

 

[GH421]

The logbook states 2.6CC engine and the car is a 300e

Never could figure out what size the engine is. That car is one juicy Bleep!!!

full tank gives about 270-280 miles if lucky!

anyway back to the point

it's a 1990 G Reg could there be corrosion with the electrics?

 

[Roger Jones]

There's no 2.6 Coupé or CE listed in MB's own Technical data passenger cars (October 1993) manual -- something odd about the car or the logbook. If it's a 1990 car, the wiring looms should pre-date the degradation that affected the "environmentally friendly" stuff that came in just a year or two later.

Unless the driver has a very heavy right foot or is doing lots of short trips (or both), he should be getting comfortably more than 300 miles out of a tankful.

Stick the VIN into the Russian site and you will find out which engine the car has:

http://old.mbclub.ru/mb/vin/?lng=eng

 

[Howard]

I'm still sure that the w124 doesn't have a limp mode .

 

[GH421]

sorry guys my mistake

the car had an engine conversion from a 260

apparently a few mechanics guessed it to be a wiring problem

 

[Roger Jones]

From a 260? There never was a 260CE/coupé. You say "the car is a 300e", so presumably it has four doors and not two, and is therefore a saloon.

 

[bolide]

If the car is pillarless it's a Coupe. If it's a 260 or 300 it's pre-facelift with the 12-valve engine and it doesn't have a MAF or limp-home mode nor does it have mapped injection / ignition like the later cars. There's no electronics in the gearbox and there is no conventional ECU - it has the EZL ignition box instead, plus a coil & distributor

I'd try and establish exactly when (gears, revs, hot/cold, etc) the problem occurs and then seek specialist advice. It might be a gearbox / torque convertor problem or it might be HT-related

Or the 260 engine may be running with the wrong EZL module?

Nick Froome
www.w124.co.uk

 

[GH421]

The engine is from a 2.6 merc. No Idea which one. It's a straight 6 12 valve however and there is an airflow sensor.

The problem is 4000rpm - hot or cold. Would a star machine be able to tell the problem?

Cheers Nick and the rest of the gang

 

[janner]

Has the car ever worked since the engine swap? What year is it?
This is what I would check (in order)...

1) Rear ABS sensors and leads around the diff. The engine may have the 4000rpm limiter which prevents damage to the torque converter when revved in neutral or park. The rear ABS sensors tell the limiter to disengage when the car is moving.

2) Fuel pump relay.

3) Spark plug wires and coil.