Neif

When fuel injectors become worn and old, does fuel delivery and performance slowly decline? Or do they run the same until the day they completely die?

I'm wondering if there's any sense in replacing fuel injectors while they're all still working, even though they are old.

Thanks!

dgeesaman

iTrader: (10)

Many things can happen, both gradual, intermittent, and sudden.

Worst case, they stick closed or open, dumping fuel or starving fuel. Or they leak externally onto the engine. This happens on occasion with RX-7s, but I dunno if it happens much on Maximas.

You can also get gradual degradation from varnish buildup or dirt. This happens to pretty much every car, and I think its worse if the car sits for periods of time without fuel stabilizers.

If you're concerned about it, send them out to a place like Marren Injection, RC Engineering, Witchunter Performance, etc. They will test them, ultrasonically clean them, and test them again to verify the effectiveness. It runs between $25-50/injector. This is the most effective treatment by far (except brand new injectors, of course), and it usually restores performance completely. Second most effective is those in-car flush procedures, and a distant third is a tank additive like Techron.

Dave

Neif

Hmm thanks, I think I'll ask my local shops what kind of fuel injector cleaning / testing service they offer.

By the way, what is the difference between the in-car flush procedure, and the tank additive? I know places like Jiffy Lube offer a "Fuel system flush" but it sounded like BS to me, as well as the tank additives.

maxgtr2000

iTrader: (29)

I would run fuel injection cleaner every once in a while to keep them up to par. If you can't sleep at night Deatschwerk.com does injector testing and cleaning. I just got a set done for $60 with the org discount.You get a flow test sheet and everthing detailed for each injector.

dgeesaman

iTrader: (10)

The tank additive means there is some extra detergents in the fuel for one tank of gas. I guess if you religiously run a Techron every 10 tanks it might help in the long run, but it won't work many miracles.

The flush means they disconnect the fuel rail from the fuel lines and run 100% cleaning solution through the injectors and rail for a little while. This is far more effective than a diluted fuel additive, but it will not give any direct information on the before/after of the injectors.

I found a local shop that did ultrasonic cleaning, but they could not run the before/after test. It turns out the injectors were still in sorry shape, and I spent most of this summer in frustration trying to pinpoint the problem. (This was with my RX-7). Moral of the story - the ultrasonic cleaning is best, but be sure it's done properly and you get full test data.

Dave

njmodi

iTrader: (4)

Dave - for this type of fuel service, where do the chemicals that pass through the injectors end up? or are the injectors expected to be closed? i.e. so nothing enters the combustion chambers?