The SL has been off the road for the last 9 months and due to work/race commitments I just didn't have time to deal with it.
So feeling suitably guilty for the last few weeks I set about it swapping a load of parts and getting it ready for MOT.
All new brakes were fitted pads/discs/handbrake, Brake fluid change' New tyres, oil & filters etc . As it was low on fuel I put about 2 gallons in from a local Total station (where I always fuel) to be sure it would have enough to get to the test and on to the workshop for the finishing touches.
All through this I had it running/ticking over with its usual Swiss watch reliability. So I booked it in for MOT this morning and set off and for the first couple of miles it was absolutely fine - then the gremlin struck
It started to missfire slightly under light load but cleared if I gave it a little throttle. Thinking it might be a bit of damp in the ign system somewhere I continued to the MOT hoping it would clear.
The 5 mile journey turned into an absolute nightmare. Every time I came to a halt it would miss slightly - but any attempt to pull away resulted in it cutting out. having been caught at a set of lights on a major roundabout for 9 changes of the lights I finally got it moving and it was fine until the next roundabout. Another 3 sets of lights and I was finally at petrol station (to add another couple of gallons just in case) prior to the MOT station. At the test station I went through a load of underbonnet checks looking for air leaks etc before it was time for the test.
Although it took about 10 mins to start it having cranked it at least 20 times amazingly it flew through the MOT. Although the car must have relented because the idle behaved just long enough to get a cat test pass
Outside I ran it for about an hour waiting for Eddie to escort me back to the workshop just in case and I went through everything again.
After idling and driving around the yard for an hour it started to clear slowly. It then covered the 25 miles to the workshop with a slightly rough cruise which felt slightly similar to out of balance rear tyres and hasn't been as bad but it still certainly isn't right. The couple of times I gave it some full throttle to try and clear it Eddie reckons he smelt it overfuelling
I have a feeling this is fuel distributor or and old fuel/filter issue. However I would be grateful for any advice if they have seen a similar situation. Modern EFi systems I can deal with - but mechanical K-Jet is really stretching my memory here! If the car hadn't been so incredibly reliable over the last 8 years I may have had to understand it better and it might had been less taxing. But I literally have had to do nothing to it bar changing normal service items.
To recap
Symptoms
Will start when cold and run no problem
once warm feels "rough" as if it has a cylinder out or is overfuelling
will tick over with a an occasional very slightly lumpy idle but has problems pulling away from stationary without stalling
Once moving rough running returns
Possibly heavily overfuelling at 70% + throttle
Checked
All vacuum hoses and connections around the fuel distributor
OVP relay fuse and relay connections (no spare relay to try)
All relays under the bonnet for signs of any corrosion and secure fitment
The longer it ran the better it became but even after 3 hours it wasn't right!
Any ideas appreciated - but I probably wont see the car again now until Tuesday due to work commitments. At this point I will swap plugs, leads, distributor cap and rotor arm as these have been on for nearly 3 years and were due replacement anyway.
Cheers
Mark
So feeling suitably guilty for the last few weeks I set about it swapping a load of parts and getting it ready for MOT.
All new brakes were fitted pads/discs/handbrake, Brake fluid change' New tyres, oil & filters etc . As it was low on fuel I put about 2 gallons in from a local Total station (where I always fuel) to be sure it would have enough to get to the test and on to the workshop for the finishing touches.
All through this I had it running/ticking over with its usual Swiss watch reliability. So I booked it in for MOT this morning and set off and for the first couple of miles it was absolutely fine - then the gremlin struck
It started to missfire slightly under light load but cleared if I gave it a little throttle. Thinking it might be a bit of damp in the ign system somewhere I continued to the MOT hoping it would clear.
The 5 mile journey turned into an absolute nightmare. Every time I came to a halt it would miss slightly - but any attempt to pull away resulted in it cutting out. having been caught at a set of lights on a major roundabout for 9 changes of the lights I finally got it moving and it was fine until the next roundabout. Another 3 sets of lights and I was finally at petrol station (to add another couple of gallons just in case) prior to the MOT station. At the test station I went through a load of underbonnet checks looking for air leaks etc before it was time for the test.
Although it took about 10 mins to start it having cranked it at least 20 times amazingly it flew through the MOT. Although the car must have relented because the idle behaved just long enough to get a cat test pass
Outside I ran it for about an hour waiting for Eddie to escort me back to the workshop just in case and I went through everything again.
After idling and driving around the yard for an hour it started to clear slowly. It then covered the 25 miles to the workshop with a slightly rough cruise which felt slightly similar to out of balance rear tyres and hasn't been as bad but it still certainly isn't right. The couple of times I gave it some full throttle to try and clear it Eddie reckons he smelt it overfuelling
I have a feeling this is fuel distributor or and old fuel/filter issue. However I would be grateful for any advice if they have seen a similar situation. Modern EFi systems I can deal with - but mechanical K-Jet is really stretching my memory here! If the car hadn't been so incredibly reliable over the last 8 years I may have had to understand it better and it might had been less taxing. But I literally have had to do nothing to it bar changing normal service items.
To recap
Symptoms
Will start when cold and run no problem
once warm feels "rough" as if it has a cylinder out or is overfuelling
will tick over with a an occasional very slightly lumpy idle but has problems pulling away from stationary without stalling
Once moving rough running returns
Possibly heavily overfuelling at 70% + throttle
Checked
All vacuum hoses and connections around the fuel distributor
OVP relay fuse and relay connections (no spare relay to try)
All relays under the bonnet for signs of any corrosion and secure fitment
The longer it ran the better it became but even after 3 hours it wasn't right!
Any ideas appreciated - but I probably wont see the car again now until Tuesday due to work commitments. At this point I will swap plugs, leads, distributor cap and rotor arm as these have been on for nearly 3 years and were due replacement anyway.
Cheers
Mark
