Sc not running smooth any more .... please help

daz911 · 05-02-2002, 02:35 PM

I helped a friend change the spark plugs on his 83 SC, - I have the tool - he didn't ! I haven't changed mine yet but didn't think it would cause problems .... famous last words !!

We changed the right side, started the car no problems ... changed the left side, it started but sounded a little rough almost like it was missing - we checked the leads were fitted properly - o.k. then thought that it could be a dodgy plug so we changed this side again, - still the same ! - you can here it sparking when it's running - but couldn't see any!

What did we do wrong? Is it dodgy plugs? Wires? - is there a simple way to test the plugs or wires without expensive equipment?

We have used bosch W3CC plugs with a 7 mm gap - bentley says 7-8mm is fine.

Now the car is stranded in front of my garage - he didn't want to drive it ... any help would be great

Thanks

Daz

pbs911 · pbs911's Garage

Is it possible that you switched the plug wires?

pwd72s · 05-02-2002, 02:57 PM

"you can here it sparking when it's running - but couldn't see any!"

You might try looking after dark...easier to see if there is a short due to bad wiring or connector...if you can hear a spark but not see it? Might be just that.

makaio · 05-02-2002, 03:08 PM

Like PBS said, do you have a crossed wire? Where did you buy your plugs from? The reason I ask is, on my old dodge truck, I went through 3 sets of plugs from Kragen, before I got 8 good plugs.

daz911 · 05-02-2002, 03:19 PM

PBS - the wires are tight it seems impossible to cross them, we did thing about it but couldn't change them around anyway.

I bought the plugs from an independant supplier - we have already gone through 12 !!!!!!
Is there a way to tell the good ones so that we don't waste any?

Thanks for the input ..

Daz

pbs911 · pbs911's Garage

How did you pull the plugs wires off? It is possible that you separated the core of the plug wire from the connector and it is no longer sending spark to the plug. Since the old plugs did not cause this "miss" did you try the old plugs again? If you did, and the miss is still present, I would bet the wires are crossed or you pulled on the plug wire, separating the connections.

I am also confused about your statement that "you can here it sparking when it's running - but couldn't see any!" Can you explain what this means.

Have a beer and go back and take a look. its the simple things that drive ya nuts.

Doug Zielke · 05-02-2002, 03:52 PM

Are you really sure you have the plug connectors pushed firmly onto the plug terminal??
The Beru connectors seat at different angles depending on the cylinder, and sometimes they feel connected when they are not.
You should feel them snap in when properly connected. Also, sometimes the fitting inside the Beru has deformed and will not make good contact with the plug.

Argo · 05-02-2002, 06:41 PM

If it's running on 5 cylinders, you could pull each of the left side plug wires in turn and see if it still starts with that wire disconnected. If it doesn't start with a particular wire disconnected, that wire/plug is probably good. If it starts with a particular wire/plug disconnected and runs (ragged like before) then that wire or plug is probably the culprit. Might help to narrow down the possible problem area.

Argo
88 Targa

911jon · 05-03-2002, 01:59 AM

Has to be bad plug/wire/contact.

Use a logical process of elimination to determine which of these is guilty!

Disconnect plug leads in turn to locate problem cylinder, then replace that plug first (most likely problem if your leads were OK before plug change). If not this, try dielectic grease to promote contact and check fit. If all else fails you may have to consider the lead.