V-AMG

Hey all,

I have a 1995 SL500 with serious misfiring issues. May be important to note that the car has been sitting for months at a time last few years. May have been driven 1,000 in last 4 years. Its at 84,000 miles now.

Here's how it goes:
Once in a blue moon, the car will run 100% without any issues for a full day, but majority of time, that's not the case. It starts well and runs well for about 5-10 mins and then the issues start. It starts misfiring at idle and just can't get through it. Its not drivable and I end up limping home last few times. Yesterday it stumbled and stalled upon taking off from a light and wouldn't restart so i ended up pushing it 5-6 blocks (this things heavy!). It just kept on popping very loudly out of the exhaust but no start. Finally after 30 mins when it cooled off, started up again and ran rough.

I recently replaced air, oil and fuel filters, did an engine and trans oil change. Checked the plugs and they look totally fine, BOSCH plugs. Wires all looks good. Not sure where to go next.

It's getting air and i assume the loud pops are unburnt fuel in the exhaust so i think its getting fuel too. So somethings off with the ignition.

Any suggestions? I have heard that 1995 specifically had some engine wiring issues. Any thoughts? I can't seem to get a clear on answer on what the offending harness is and its part #.

Any and all help is greatly appreciated!

Lee Wireless

Have your local MB dealer pull a VMI to see if the harnesses were replaced. If not replaced, I'm sure they are wasted. Pull your distributor caps and clean them along with the rotors. I use a Dremel tool with a small SS wheel to clean them. If they are in real bad shape, replace them. Do you have a check engine light?

bdnsmn

The distributor caps are the likely suspect. Cleaning the contacts are an easy fix, replacing is probably not necessary.

V-AMG

No check engine but likely because i try to drive, fail, then it sits for weeks/months and computer probably resets itself. Good news, I finally have a little time to devote to getting it back on the road.

Thinking about it some more today, it does run well once in a blue so i cant imagine its the harness. I feel like the harness issue would always be present, cant imagine it'd run well for first 10 mins then develop symptoms. Im starting to lean towards the distributors.

Here is what im planning to replace, items 23,20,17,14. Is there anything im missing? Do you happen to know what 38 and 5 are and if they should be replaced too?

Lee Wireless

I'd clean before replacing. Unless they are shot.

V-AMG

I bought all Bosch replacements from RMEuropean. Bought the caps, rotors, bowls and bowl gaskets for under $300. I'll tear into it and see what needs replacing then return the rest. Heard BERU may be better quality but i only found their cap. No rotor, bowl or gasket, so Bosch got my order (hopefully it'll be all right).

Lee Wireless,
What are thoughts on the harness? Should i buy it and have that ready too?

Car is parked nearly 2 hours away so when I go to it, i'd like to make sure I have everything i might need.

Thanks for the help and suggestions!

Lee Wireless

No. Go to the dealer and have them pull a Vehicle Maintenance Inquiry (VMI) and see if it was replaced under warranty like mine was. Their mechanic can quickly tell if yours is bad if they have no record of the change.

V-AMG

Made some good progress yesterday and i think the problem is solved.

Side-note: pulled the VMI and no harness replacement. We bought the car 5 years old so it the car would've been to new for the original owner to do it and we havent done it. VMI confirmed.

As mentioned, I bought caps and rotors to swap. Car's been sitting in a garage for 10 days without touched and when i took the caps off, full of condensation. Luckily no oil residue, but it was WET (see attached). The contacts were totally corroded too. Installed the new caps, rotors and bowl gaskets (very easy by the way - 1hr max) and voila! She fired right up and ran like a top. Drove for about an hour or two, shut off multiple times and no signs of misfire at all.

All in all, great success!

rich8566

Bravo!

Russell Ormerod

New caps and rotors!