Trans Sport Engine Missing(i Already Checked Under The Hood)

[SALVITORE597]

The Engine Misses On Start Up, Then If I Get It On The Road And Floor It, It Clears Up. If I Don't, It Will Continue To Miss.

I Put Some Fuel Injector Cleaner In The Tank And That Took Care Of The Problem For A Few Tank Fulls, Then It Came Back.

I Think I'm Looking At A Fuel Injector Replacement.
Has Anyone Replaced Them On This V6 Before?

[Slammerz]

Yes if it's the 3.4L SFI V6.

First figure out which injector is stuck, when it’s miss firing disconnect the spark plug wires one at a time until you find the one that doesn’t make engine run worse. (for the plugs on the rear bank you can disconnect the wires at the ignition module) (note: the factory wires have the cylinder # printer on them) Next swap the plug from that cylinder with another and make sure the problem doesn’t follow it.

Once you are sure which injector you need to replace get a new injector (about $100 ea.) and a set of intake plenum gaskets (I reused mine, but best to have them handy if you damage the old ones or they need to be replaced).

Plan on about 3-5 hours to do the work, if everything goes OK. (disconnect battery ) First remove the air filter box and intake tube from the radiator support back to the throttle body area. Then the plastic cover over the intake plenum and the front plug wires from the plug ends. Next start removing all the wires and hoses and cables that connect to either the Intake plenum or the throttle body (label them as you go ). You shouldn’t have to disconnect any fuel lines but there are a couple of coolant lines under the throttle body that are a real pain to get the clamps off of. You can remove the intake plenum with the throttle body flow meter etc. still attached to it. Finally start removing the bolts that hold the intake plenum in place, there is one at the back middle that you have to remove a sensor first to get at. This sensor attached to the bracket that also holds the back of the plastic plenum cover with 2 small bolts, the bolt heads face the back of the engine compartment. Once you get everything disconnected you should be able to remove the whole assembly.

Now disconnect the wires from the injectors and loosen the bolts holding the fuel rails in place. Next release the fuel pressure by removing the plastic cap from the back fuel rail and pressing in on the valve stem (it’s like a tire air valve) then remove the fuel rail and the injectors together. The injectors just push into the intake manifold and are held with O rings. On the fuel rail with side they have O rings and clips. It takes a little effort to get them loose I used a piece of wood to pry up on the rail a little to get the first on out. Make sure all the injectors still have the O rings on the intake side if not carefully recover them from the intake manifold. I knocked one down into the intake manifold and spent an hour with a flashlight mirror and coat hanger recovering it from around the intake valve (which luckily was closed). Remove the clip from the faulty injector and remove it from the Fuel Rail, again you have to pull at it pretty hard. Install the new injector into the fuel rail.
At this point I recommend you check the torque on the intake manifold bolts, they have history of getting loose and contributing to intake manifold gasket failures. If you think the gaskets might need to be replaced anytime soon now would be a good time to do it.
Finally put everything back together in the reverse order the injectors can be difficult to get back in (a little petroleum jelly on the O rings helps but don’t get any on the injector heads). I finally had to resort to a rubber mallet to get them seated all the way.
Other than that everything went pretty smoothly. Be careful not to kink the fuel lines and changing the fuel filter is probably a good idea at the same time.
One other note, I had to change my fuel pump shortly after the sticking injector became chronic (it was stuck all the time). Not sure if the injector was having more trouble opening because of low fuel pressure or not, 30-35psi vs. 40-45psi with a good pump.