w124 280 TE engine problems....help!

[IMD]

Hi all,

I am thinking of purchasing a 280 TE, 1993 model. The car is a 1993 model, with about 140000 miles on, with a full MBSH up until about 130000.

It has a rough idle problem, which I know is a common problem. It apparently sits at 500 or so revs, then often erratically jumps to 1000 and back when stationary. It also stalls on the odd occasion whilst doing so, but starts first time.

Now, from looking at the forum, might it be a MAF / MAS problem or might it be a wiring loom issue. All other electrics work and it runs smoothly when driving.

It also has a non functioning kickdown. Could this be related, or is this just a kickdown button / cable problem?

Your help would be much appreciated.

Thanks

Ian

 

[bolide]

Rough idle is normally the throttle body and they do improve with cleaning, I believe. If it's a loom issue you might get misfiring under load, popping & banging & general odd behaviour

Lack of kickdown is pretty common and is normally related to the adjustment of the throttle & kickdown cables

There are a couple of good W124 experts in & around Brighton

Nick Froome
www.w124.co.uk

 

[Vlad]

I would go with the throttle body as a starter...common problem on the M104 280 and 320 engine and its easy to clean...tends to get ignored at services which is why they tend to play up now that they are getting on a bit

 

[IMD]

Thanks guys, I'm tempted to buy the car and if I do, I'll work on this throttle body first. I was worried that the loom might be on it's way out, however the car performs well at all other times, just erratic idle and odd stalling when stationary.

Any other ideas would be appreciated. Ian

 

[Vlad]

It would also be an idea to replace the Over Voltage Protection relay that sits up behind the battery and to the right of the ECU's...very easy to replace once you have taken the battery out.

They suffer from dry solder joints internally and are a common cause of stalls for no apparent reason....if its still on the original relay, its well past its best.

Secondly despite the loom seeming to be OK, I would still recommend that you take the spark plug cover off the engine and where the loom joins the cap that fits onto the coil pack, take a rasor blade and carefully slice open the thin cosmetic outer sheath of the insulation on the wiring loom....this will expose the main wiring of the loom.....its highly likely to be breaking down and crumbling if its not had a new harness fitted.

If you don't fancy shelling out for a new harness (£600) then its advisable at least to have the badly effected areas (its at its worst under the spark plug cover as it gets maximum heat) cut out and new wires spliced in. You can buy new coil pack caps as individual items and they cost very little.....its well worth doing as a short in the harness will fry the coil packs, ECU and wiring harness.....cost of repacement £2000+

 

[kth286]

As VLAD, if the loom as not been fixed it WILL need doing.

You WILL NOT GET ANY WARNING.

One day you will go to start it and it will blown a coil (only one if you are lucky).

At the same time it COULD blow the ECU.

Ask Vlad and I how we know.

I presume you are into car DIY, if not you need a very experienced honest tech that is into these cars and at an affordable rate.

 

[Dave Lewis]

As Vlad and Kth286 - it's not worth replacing anything, or trying any fault finding (apart from throttle body), until the loom is replaced or found to have been done already. And the whole engine loom is vulnerable, not just the bit under the coil cover. Mine went without warning and took out all 3 coils and the ECU, in one of the last W124s made