Replace clogged injectors in '93 300TT?

Pham ( snipped-for-privacy@NoBlok.net) wrote on Saturday 24 April 2004 12:25 am:

Your mechanic should have replaced them all at once. The labor to get to the injectors is a lot more than the cost of a single injector. And once you have the access to one injector, you can easily get to them all. I recently had Nissan replace all of them on my '90 TT, and it runs much smoother.

Now if I can only figure out a way to stop my wastegates from sticking....

Sounds like you just have bad luck? It's pretty rare for them to die and to have 2 die that close together is weird. BTW most can be changed without removing the intake manifold if you know how to do it.. $1000 is WAY too much for this job!

Well Thanks so much for the education, and I Will ask that they *all* be replaced ... BUT what/why clogs them? If it's sludge then I'd have thought that some solvent would dissolve the gook... or is it some mechanical (and irreversible) change... like the injectors droop or physically narrow ? or the blockage is insoluble?

From my experience they don't get "clogged", the stop working mechanically, i.e. the pintle get's stuck in it's bore or they electrically fail. They have a screen behind them to protect them and fuel washes over this screen to keep it clean so basically they are self cleaning. I guess your mechanic just calls any failed injector "clogged" to keep things simple for the customer. Most people never give stuff like this a second thought as to why it happened.

It's possible if the solenoid hasn't failed electrically to get them ultrasonically cleaned. They pump solvent though the injector, while pulsing the solenoid and subjecting the injector to ultrasonic vibrations. This breaks down the gum and varnish that makes the pintle valve stick. A new filter is often fitted at the same time. Few shops will do this as it means the car is stuck on their premises while the injectors are sent away to be cleaned. Quicker, warranty on new parts, don't have possibility that an injector is not recoverable

• more profit to just fit a new injector. So you either need a loan set (join a owners club and make some good friends?) and get them out yourself or have to take the car to an injection specialist with the cleaning equipment. There are on car processes using solvents but they just run the thing and hope, they don't verify the spray pattern or match flow rates.

Steve said that "Sounds like you just have bad luck? It's pretty rare for them to die and to have 2 die that close together is weird....."

If so... if the fact that one (or even two) have "clogged" doesn't alter odds that others will fail (any more than rolling snake eyes twice alters the chance they'll come up on next roll) is it still the smart move to replace them *all* instead of just the ones that are malfunctioning? THanks, Pham

Peter- Cool link! Gees I wish you were around here so I could know a real scientist was in on my car!

-P

One thing you might have going on is something wrong with the fuel. I had a

But yea to be sure it's fixed, you need to replace them all AND clean the tank etc. Also you need to know what's actually wrong with them. Are they electrically dead (open circuit), stuck pintel or "clogged" up.

Your mechanic should have asked if you wanted all of the injectors replaced since they are easily reached once all the intake runners are taken off of the engine. I just hag all my injectors changed (@152K miles). One of the injectors failed but my mechanic asked me if I wanted all of them changed since they were right there for them to reach and considering the milage on my car another injector could fail again. BTW you should also have the mechanic change the valve cover gaskets while he has everything off the engine. Injectors and gasket replacement cost me about $1740.