i'm thinking of buying a 740 volvo, it was parked for about a year, but started regularly, and then it just wouldent start, since i know the lady, i said if i could get it to start i would be intersted, and she could take some off the cost, so i messed with all the normal stuff, and found that it was getting gas and the distrubutor had spark, and there were NEW plugs in it. so i didnt even think to check them, but as time went on and i couldent find anything else wrong, i took them out and grounded them, turned it over and found that they sparked incredibly weakly, almost just a smoulder, even though new. so i had some old plugs laying around and i put them in and it started right up. the plugs i took out were new boshe supers, but made in india, the ones i put in were used boshe platnum, but made in germany, so i'm wondering could 4 plugs have been bad, or could something else make plugs go bad, and the problem is still there. i dont know of anything that would make plugs go bad, but if anyone does let me know cause if not i'm going to buy this car. thanks

Punkster - the quickest and easiest way to check your odd plugs would be to attach one of them into a plug wire on a friend's car and observe their spark.

If the spark is bad, the plug is bad. If the spark is good, you have your work cut out for you.

I suspect that the odd plugs are fouled from lack of exercise and possibly bad fuel. Fouled plugs can leak voltage to ground resulting in a poor spark.

If so, it's probably not that weird.
--
2 8s & 2 7s 600,000 miles total

Did you check the gap ?
If I remember correct the platinums or may be even all
plugs made in krautsland have the correct gap.
I am not sure about the indian ones.
--
GN Long Beach 745 1986

well i didnt acctually use a feeler guage, but they were brandnew plugs, i only swaped becasue i couldent figure out why they wernt sparking when i took them out and grounded them, and when compared to the very used platnums that i replaced them with just to see if there was a difference switched, by eye, the gaps were the same, i mean the plugs i took out looked great, thats why i'm so boggled by this, and wondering if there is anything that can make plugs go bad. but you may be right, something doesent seem right about boshe plugs being made in india, i just cant fathom 4 plugs being deffective or going bad, that and wondering if there is anything that can make plugs go bad. but you may be right

some more ideas:
1.) The thread : Some guys don't use the good antiseize stuff
which has also some conducting elements in it.
If they use some cheap antiseize on the thread it might be an insulator.
2.) The top head : Some plugs have the top (where the wires are going)
fixed and Bosch ,I think, has it removable as a little cap you can unscrew.
Now these little caps must be really tight !
3.) look inside the wires to make absolutely sure no cap is lost in the wire.
That is no joke. It happen to me when I bought my car. One wire was a little
"loose". The reason was the cap was separated from the plug.
4.) Maybe during the changing back and forth you touched/moved something.
If one or more of the plugwires have broken leads in some position there
is a spark in some other littlelittlebit different position no spark.
5.) Check the primary cable coil-distributor very carefull.
When you change the 4th plug you might touch that wire.
6.) The weak spark problem might be only the symptom. Maybe the platinum
plugs have a little bit better spark to start the engine. But the real
problem might still exist. In the moment I can only think about ignition sensor in the distributor, the amplifier and the coil. Speaking about the amplifier,
a bad ground at the fender affects the amplifier.
My car ran very unstable at idle until the distributor with the ignition sensor was changed. Now it has a stable 800 rpm. Before it was 900 +/- 200.
If I remember right the 90 model have sometimes computer problems. Ground?
Check the FAQ and the archive about Eprom upgrade.
Some other gurus might help you better than me in that.


--
GN Long Beach 745 1986

hummm, tell me more about this amplifier, i would like to check, that, because, i did have an extra coil laying around that i swaped in and it made no difference with the old plugs, i checked all the spark plug end caps, and they were good, and i thought maybe it was the ground but that seemed ok, although i dont know where that fender gound is, i just checked the ones on the engine and head. but i didnt touch anything before and after haveing changed the plugs, i mean i tried to start it: nothing changed 3 plugs started right up but choppy, replaced the last one, started and ran great. so i didn mess with anything inbetween, thats why i figured the plugs were the independant variable, but you never can be sure with volvo electronics.

As I said before I don't know so much either.
Pls Check the Haynes page 132 Ignition System EZ117K
and look for the amplifier number 133 also called
"Power Stage". Maybe I'm wrong.
I will go out to the car and look for that myself.
--
GN Long Beach 745 1986