85 Euro QV - slight miss after sitting for a few months.

Note: I'm not a technician and have no long-term experience on this. But, I'll throw this out there.

I changed from old plugs to BPR7EIX about a month ago. I believe they were Champions, but I didn't measure the gap. Car did smell like it was running rich, more than seemed normal. Anyway, when I went to install the new plugs, I noticed also that the gap was around .030-ish. I researched this a lot, and read that these plugs aren't supposed to be adjusted; IE, the .030 gap is perfectly fine - because it's iridium, not platinum. I saw a couple other Fchat posters were already doing the same with fine results.

So I went with it. On the first weekend out, I had a singular backfire after a 70 mi drive (scared the heck out of me.) But on arriving home, I also found a plug wire was loose, so I pushed it back down. Since then, 300-400 miles and perfect engine behavior. And my garage no longer smells like the inside of a gas can for days. Hope this helps somehow.

 

Two more ideas:

- Plugs torqued to spec? (I highly doubt this is the problem. Just tossing it in)
- Since it's been sitting awhile, possibly an injector needs cleaning?

 

I thought you might.

 

500 grit sandpaper

 

FWIW, I don't have experience with iridium plugs but I tried Platinum plugs in my carb two valve 308 and the car ran like crap right out of the box with misfiring. I put standard plugs back in and it was fine after that. If others are having good results with these high tech plugs that's great. I'm just letting you know what I experienced.

 

what happens above 3000rpm ?

if the miss is gone, check extenders ! (also the connections wire/extender/plug)


you can also try to isolate the missing cylinder

 

If you are already inside the cap, you should measure the resistance from the contact in the cap to the clip in the extender that connects to the spark plug for each wire to see if there are any issues in that chain (and the coil-to-cap wires too). The stock spark plug wires are not zero resistance so the resistance will be more for the longer wires, but getting a reading of infinite ohms for any would be a bad thing.

 

As stated above check the spark plug extenders. They plug into the end of the spark plug wires and protrude thru the valve covers to the spark plugs. They will have some resistance on QV models. A few thousand ohms as I recall. I had several bad ones. Measured open. I switched to the 328 version which have no resistance. The 328 versions are very slightly longer, but will still work if you want to go that route.

 

My 83QV is also experiencing an issue with new plugs. I did belts, tensoner bearings, brakes, oil, air filter, wires, caps and rotors and rebuilt the water pump and a few other things.

So I figured after 16 years and 27K miles why not put in new plugs. Put in the iridium BPR7EIX gapped at 27. 6 out of 8 extenders had a crack from the top half way down. Changed them today and the car runs like crap. I'm going to pull the plugs Monday and have a look. Car has a very slight miss last week on the way to Ct, before changing plugs and extenders. You can't make it up. Had the champions in and the car always ran perfect.

 

I'm pretty sure the extenders are all the same for 308s. Got them from the same place I bought them last time.

 

Hello,
make sure the fuel plunger is loose and squishy
remove all plugs and use heat lamps to dry out all cylinders to for sure dry
new Bosch plugs ,,for me
Sunoco Race gas
new fuel filter
Italian tuneup