In the midst of my electrical nightmare I decided to take a break and change the plugs and air filter on my 86 240.
According to the owners manual the plug gap should be .024 to .028 for the BF230F motor.
I set the gap at .026 on every plug and then installed a new air filter, which the car badly needed. The problem is that now the car idles sort of rough (compared to before). The main thing that I've noticed is that the engine now seems to be seeking. It will idle perfecly for a few seconds and then will sort of stumble. I can give her some revs and she smooths right out but there is also some hesitation there that I don't remember having before hand. On a few occasions (when I first start the engine) it will even die if I don't give it some fuel. This is also something new since I put in the plugs and filter. Now I did check the old plugs (which looked too good to change by the way) and they were gapped at .035. I am wondering if that since this engine has 277,000 miles on her if I would be better off gapping the plugs to the wider setting. The plugs were not coated with oil but they did appear sort of blackened. I figure that means a rich fuel mixture but I'm pretty new at this.
One thought that I had is that .026 seems like a really tight setting for electronic ignition. I know on my van it's something like .060. Could someone please verify that this is the proper spark plug gap?
Also I was wondering if the computer might still be trying to adjust to the system improvements. As I said, the plugs looked really good butthe air filter was clogged. I held it up to full sunlight and couldn't see even a trace of light through it. Do computers adjust immediatly or do they take some time to sort all of the new readings out? I'm new at this so I really don't know.
As always, if anyone can give some guidance it would be greatly appreciated. Iam a total newbie at auto mechanics but this is one skill that I've always wanted to learn. Hope someone can give me some advice here.
Thanks in advance and thanks for such an excellent source of knowledge. As long as you all don't get sick of hearing from me, I expect to be picking your brains throughout this entire project.
Thanks a million,
Dave

 

Gap is supposed to be .28...

 

Sounds like it could be a fuel filter or dirty fuel injector. A 12-oz jug of Techron in the fuel tank probably wouldn't hurt.

I wouldn't use a plug gap narrower that .028, probably .030.

 

Hi guys,
Thanks for the replies...
I got to searching the web yesterday and found that Volvo has changed the recommended gap setting from .024-.028 to .028-.032. I changed the gap to .032 and the car is back to running fine.
Thanks again for the replies.
Dave