92 Q45: If a plug/injector/coil fails, should all be replaced?

[kdkrone]

In another thread, I had had an intermittent problem with missing on my '92 Q45. The missing, when it happened, would usually begin when I first started the car and would self-correct within a mile or two, if that far. All was then fine for a couple of weeks (I used Techron in one tank of gas and cleaned the engine), then beginning yesterday, the problem is now constant.

I will be taking the car in to have it looked at tomorrow; the issue may well be the plug, coil, and/or injector. If it is a problem with one of many of the same part, such as an injector, should one bite the bullet and replace them all, or just one at a time? Do they tend to have a lifespan or do they fail only occasionally?

ThanksKen K

[911/Q45]

Injectors are quite expensive($140ea) and they don't all fail at the same time, so it wouldn't make sense to replace all preventively. My car had one fail under warranty and 10 years later another one failed. Luck and fuel system maintenance seem to be equally at fault when they fail.

[kdkrone]

I would be interested to hear more about maintenance of the fuel system. What do you do to the fuel system?

Thanks

[elwesso]

Fuel system maintenace includes 2 primary things......

1. Replacing the fuel filter every 10-15k..... Prolongs fuel pump and injector life2. Doing rail flushes- What this does is a shop hooks the car up to a machine, which cleans out the injectors by putting on more pressure than the injectors ever see...... It clears out the little screens inside them.......

If its an injector thats bad, have someone test them.... If a bad one is under the plenum, re-arrange the injectors so that the bad ones arent under the plenum........

[kdkrone]

But if the injector is bad, why would you not replace it?

ThanksKen K

[elwesso]

Im saying some might be better than others..... IE, (i think) if the resistance is higher, that means its not as good, and is probably more prone to failure..... Not necessarily bad, but not perfect......

[911/Q45]

Some plenum phobic folks, when faced with a bad injector under the plenum, will replace all under there and leave old ones in the accessible spots.

[kdkrone]

Doesn't sound too unreasonable...

Ken