About 2 weeks ago, my engine started vibrating periodically when it was turned on. It vibrates in spurts at random intervals; this issue happens when the car is in idle, and when I am driving it. I was doing some research and I thought maybe it was the spark plugs. When I put in new spark plugs, the vibrations went down to a minimum for a few days. Unfortunately the vibrations have become stronger again, and I think it might be the spark plug coils. I wanted to ask if anyone has any ideas as to what this might be?

 

Given the fact that a change of plugs helped somewhat, it seems that you might have temporarily strengthened a weak link in the chain. On that basis, I would tend to lean towards a bad coil myself. The usual test is the same as for a bad plug, unplug coils one by one and if there is no noticeable change when the bad one is disconnected, then that's the culprit.


But don't rule out plugs either. Much has been written on here regarding plug incompatibility, with poor running being reported after a plug change. A search will yield plenty of information. Likewise with replacement coils, apparently,there are plenty of "dodgy" ones out there.

 

clean fuel system including fuel injectors and fuel rails

 

On a somewhat related thread, my 4.0l motor runs fine, pulls well and generally purrs along nicely. However, whenever I'm on a motorway and can get up to 120kph/70mph I notice a slight rumble/vibration/miss if you know what I mean.


I realise this could be a multitude of things and is hard to diagnose, but the impression I get is maybe a bad spark or slight fuel starvation.


So, as part of my upcoming service this will be addressed with all the usual jobs, including a replacement fuel filter. But on the subject of cleaning the fuel system, are the readily available injector cleaner additives, poured into the fuel tank, any good or is it a snake oil of sorts? Has anybody used one and is there a recommended brand?


Thanks in advance.

 

sogood: I use Amsoil PI Performance Improver gas additive every 10,000 km in all my gasoline vehicles. My wife's 2005 Chrysler Pacifica was bought new, now has 270,000 km on it, and the engine runs runs like new. I've had excellent results using Amsoil products, and it gets delivered to my door. I like that.

AMSOIL P.i. Performance Improver Gasoline Additive

There doesn't seem to be any UK or Irish distributors that I can find on the Amsoil site, but here's the link to international sales:

http://www.amsoil.com/international/...tor/index.aspx

Honestly, you should order from a Canadian distributor. Our Canuck buck has sunk the fastest in it's history in the last few years, so now one Canadian dollar is 0.49 UK pounds or 0.67 Euros. You can use the exchange rates to your advantage!

 

Also make sure your plug wells are flooded with oil...


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