ASR problem resolved - by 4 cable ties

[LeaUK]

I've just spent half an hour typing this once before but IE decided to disappear along with all my tapping - so this one is a slightly shortened version!

Background:

My car has recently been lighting the ASR indicator more and more frequently and this Saturday morning enough was enough - three times in 20 minutes!!

To cut a long story short (for my car) it's all down to the accelerator cable. After 10 or so years of service the outer sheath had finally given way and had snapped at the tightening collet. Not only had it snapped, it would occasionally get stuck-out a little, after the accelerator pedal was returned to idle.

This is exactly what the ASR control circuit protects against and so thinks it's a genuine fault. The moral to the story - those of you with ASR light problems check your accelerator bowden cable setup and especially look for a broken outer sheath.

The arrows below show where the break occurred and of course my temporary fix and confirmation technique (4 ties ):



Here's a little more of the accelerator linkage mechanism.



FYI - the throttle linkage testing and setup procedure is available at AllDataDIY and has allowed me (this afternoon) to set my cable to exactly as it left the manufacturer's. Full step by step instructions - even a 'sparky' like me could follow it!!



Naturally a new cable is on it's way

Enjoy
Lea

[LeaUK]

Still using the cable ties and no ASR lights ever again

[billwrb]

Hi! What's "alldatadiy"? How does one get to it?

[LeaUK]

Hi Bill

AllDataDIY is an online web based service that provides an extremely comprehensive, car specific, repair information service. It has an abundance of info including schematics, component descriptions, operational flow diagrams, TSBs and much more.

I have been joined for 4 months or so and still haven't managed to review the whole site - there's just so much info.

Well worth the annual subscription of $15 or so


Lea

[LeaUK]

Uhm, just thought I'd update this post with my latest findings. There I was literally about to order a new wiring loom and brand new ETA see: http://www.peachparts.com/shopforum/mercedes-benz-sl-discussion-forum/227406-engine-harness-replacement-92-93-500sl.html#post1907838

BUT, I also suffer with reoccurring distributor cap issues causing horrendous misfire and power loss after around 15 minutes. Normally last around 10 minutes then disappears. My normal resolution is to take the caps off and remove the tracking lines which go across contacts and give the contacts a clean up, which normally resolves the miss-firing for another few months. Yes I could change them and as they're 5 years old and probably need it now but cash is tight at the moment and they are 100GBP each.

However, this time I made a significant effort and scraped and removed ALL the corrosion off the copper contacts using a Stanley blade and wet and dry. Engine was perfect after...nothing new.

Now, what is new is that my reoccurring recent ASR light issue, guaranteed to light at 20 minutes use hasn't reared its head at all, even after the whole weekend of driving!? YES, now that is interesting.

So I'm wondering if there is a misfire detection system that can also illuminate this light?

I was literally going to shift 1500GBP in replacing the ETA and Engine loom, and all I needed was a good distributor cap clean!

And the reason I've linked this update to this thread is that if I can recall correctly, I replaced the caps when I carried out the tie wrap mod... would seem to suggest misfire recognition?

Any thoughts?

Lea

[LeaUK]

Well, it's definitely distributor caps. After just 2 months of cleaning them I got my first ASR light again! Panic; is it ETA, wiring loom or do the caps just need another spruce?

Stripped them down, re-cleaned (including the square center pin this time), and voila, no ASR again!

I'm not sure of the mechanism as to why the ASR is triggered on misfire, however it's clear that for the LH Engine it is.

One can also surmise that because the caps are +5 years and that the copper contacts are quite concave now where they have worn, the spark has to travel further. Under these circumstances this causes greater carbon deposits and so carbon is built up at a faster rate than non concave contacts would. Hence only 2 months before reclean is required.

Everything suggests it's now really time to change them - so off to the dealer for a parts price check!

Lea

[LeaUK]

The caps are now obsolete from the two biggest ignition suppliers in the UK. However I found these can still be purchased from www.ignitionparts.co.uk at 47% less than Benz...Not sure the quality though but they are supplied with a '3 year warrantee' ;-)