Missfiring under load and after 3000 rpm

[paulshellnicbeth]

Hi all,

Struggling with my 68 280SL, it's a UK car now resident in Charlotte. Car starts fine, cold or otherwise, but as soon as hot, miss-fires either under load or after 2800 rpm. It feels like it's flooding. Has new plugs and injectors. Not sure about the CSV or much else. Ideally would be great if there was a local (to Charlotte) garage that could take care. It was my fathers car, and he always blocked off the fuel line to the CSV, I have unplugged, and checked the value and think it's fine. I tried adjusting the timing, but makes no difference.

[Cees Klumper]

It could be the opposite of flooding: fuel starvation. I recommend checking fuel pressure and flow first.

[Paul99]

I had this once, it was my Coil giving up. I thought of fuel, even changed the fuel pump - no difference. ..... Fine initially and as the coil heated up, had the same issue.  Worth trying a coil if you have a spare.

[Cees Klumper]

x2 on the coil, would check that also

[mdsalemi]

Welcome, Paul!  There are a few of us in the greater Charlotte area (and more outstate NC) with Pagodas.

One thing at a time. What's the integrity of your wire set? Has this been checked? You should have copper core wires, and they should be clean. Moisture and grease, dirt, etc. on the outside of the wires can cause misfiring. It's happened to me on other cars. If you have a carbon core wire set (you should not) these can also break down internally.

Ditto on the coil. While rare they can and do go bad on occasion. I've had that happen as well. I do have a spare coil if you need to check something different.

Do you have conventional ignition or have you converted? Always a possibility of something there too. Once you've gone through the electrics then onto the fuel. As Cees has mentioned it could be fuel starvation at higher RPMS, and this could be caused by an actual fuel pump problem OR wiring to the fuel pump. I've had that happen too, on my Pagoda.

[rwmastel]

paulshellnicbeth,

I don't know your experience level with general DIY car maintenance & repair, or how long you've been working on this Pagoda.  Just test everything you can so you are dealing with facts.  Fuel pressure and flow rates can be tested, for example.  A CSV can be tested for leaking under pressure.  Electrical relays can be tested.  Don't make any assumptions.  Be logical about troubleshooting process.  You can get a lot of very detailed help from this forum.