Look at your plugs; You need to install something there that doesn't require super-high-voltage to fire. The car originally called for copper plugs (NGK, Denso, whatever) with a relatively tiny spark plug gap. Platinum and iridium plugs cause a lot of problems with coils just as a general rule, where the coil was never designed for that. I am not talking about the 2000 T5 specifically, but Volvos that I work on seem to me to have a curiously low-voltage ignition. A 2nd possibility is you may need to pay more money for a better coil. Just maybe. Finally, I would say make sure you blow all the water out of those plug wells. I'm sure you figured that out already.


P.S. I may be wrong about what was originally in there. If it was platinum originally, and you go that route, just make sure the gap is not at all bigger than specified.

 

My experience is that the coils cannot survive a douse in water. I have repeatedly pulled the coils off before washing the engine and then blow out the plug wells with compressed air.

For whatever reason, the design of the coils is such that there is open space where water can come in. The Volvo coils are not totally encapsulated in plastic like others.

Replace whatever coils you got wet.

 

Ok thanks guys for youré advice. I replaced the twol that weren't working with secondhand ones I bought, it ran on all 5 cylinders for a few minutes, took it for a run, and it began to splutter then ran 3 cylinders again. I left it overnight had a play with it, started it and it ran fine, with the secondhand ones. The engine mount near the cam belt needs replacing, just thought the engine mount may be causing the engine computer to shut down cylinders, to make run a bit smoother, does this sound like a possibility?

 

The mount will not effect the engine computer. My advice to you is to start with new coils. Also, as suggested by the other senior member, replace all of the spark plugs. We nearly always use the Denso brand plug which is inexpensive and works well.

Here are the plugs: https://www.rockauto.com/en/moreinfo...434016&jsn=374

Here are the ignition coils: https://www.ebay.com/itm/New-Ignitio...72.m2749.l2649

Before doing any more diagnostics, start with good ignition coils and plugs.

 

Ok thankyou for the sound advice Tony. I didn't think that the engine mounts would upset the ecu, but I had to rule it out by asking. I'm in Australia, parts are easy to come by here, its the postage that's a bit costly, prices for parts are more expensive here, but we have a much smaller population than in the us. so we pay more.

 

Thankyou to firebirdparts for your help as well, it is very helpful, and logical. Lfovlov40 (Tony from Australia)

 

Good luck! Sounds like you might have had some water down in there still.

 

Hi, just an update, I changed the spark plugs and coils, its running on 4 cylinders, under initial acceleration it hesitate a bit, seems to run on 2 or 3 cylinders, then runs on 4 cylinders. I'm thinking the oxygen sensor maybe faulty, can anyone help. Tony from Australia

 

Check your wiring under the cover and you will find that you may need to run new wiring to the coils the heat after such a long time melts the plastic on the wiring and fuses them altogether. Therefore shorting out coils. I only found this out on mine, as a purple wire, which is the Cooling fan trigger wire, goes to the 5th coil. So it must tell the fans that the engine is running.
I'm new at Volvo but am a Euro Mechanic.

 

Hi, thanks Martin, I had my mechanic fix it, their was water in the ecu wiring. Replaced 2 of the coil packs with second hand ones. It also had a faulty oxygen sensor, and had the diagnostics cleared. It cost me $300 all up, but is actually going better than when I bought a month ago, and is using less fuel. You do have a point about the wiring getting hot and melting or making the flexible wiring shield brittle. I'll just have to keep an eye on it, but I'm very happy now