1993 Volvo 850 GLT will sometimes start & run for a couple of minutes, then rough idle & dies. Sometimes will not start but tries to fire.

If I take the coil wire off of the distributor cap & hold the coil wire end just above the distributor connection (which makes it produce a "hotter" spark) it starts & runs great. As soon as I reconnect the coil wire to distributor cap the engine coughs & dies.

I try to use OE or OEM parts, usually FCP Euro, when replacing things but ignition coil & distributor cap are pricey. Don't want to fork out all that cash for one or both if not needed.

Any idea what is causing my problem? Any good non-OE/OEM part suggestions?

Thanks

 

Sounds like you either have a bad coil wire or a weak coil. Did you replace the coil wire? did you test the primary and secondary resistances on the coil? There's not much that can fail inside the cap - you can scuff up the rotor and cap contacts to remove any corrosion and check for cracks before you decide to replace. As to brands Bosch is the OEM but FCP lists Meyle as after market for half the cost.

 

Thanks mt6127...did not check resistance, original coil & 5yr old coil wire... do you think there are any other than OEM coils & distributor caps that are just as good. I was in a pinch a few years ago with similar (not same) starting issue & distributor cap had "burn" marks, replaced with non-OEM cap. Fine until now.

 

I would replace the coil, distributor cap and rotor, and the plug and coil wires.......should fix the issue. Try ipdusa.com, fcpeuro.com or rockauto.com for OEM or similar parts.

 

Thanks

 

wires should be replaced at 5 years - there's actually a date code on the wires if you're curious. +1 on doing the "stage 0" tune up - wires, cap, rotor, coil, plugs with the coil. FCP/IPD also sells kits for some savings. Note when it comes to plugs, 850s are happiest with old school copper core plugs - no point to upgrade to iridium triple electrode etc. PS, when replacing the distributor cap/rotor, the easiest way to access the lower screw is to remove the intake air box. its possible to do it w/o removing but its a PITA... :-) I'd take the cap off with all the plug wires still on, then map the new wires/cap from there.

 

I experienced this a while back on another vehicle. I had a couple of plugs that would only run like that, NGK's, two of them. I'd never seen that before. I don't just randomly "replace everything". I carefully observed that these plugs were defective. Each one would spark if I held the wire off an inch or two. It was a long way. i don't really know how that could happen, but for $5, I got out of that problem.

In your case, if all five of your plugs are having this problem, then I might check to see how they were gapped. It's reasonable to think they're all gapped the same. If the coil is throwing a 50,000 volt spark when unplugged, then I'd be a little skeptical that it's bad, but I guess they're cheap.

The low voltage of the 850 ignition system has always been a curiosity to me. Spark gaps are the lowest of any car I've ever owned.

 

firebird...plugs replaced a couple of years ago, not a daily driver, it was running great until a couple of weeks ago. Appreciate the additional info. to add to my check list.