Fuel Injector replacement

[Yimu]

Hey guys, my number 7 injector is dead a couple days ago for 94 Q45, the dealer asked to change alll 8 injectors due to balance of fuel pressure which is really really pricy. Was wondering is this nessesary? And how can i replace injectors by myself? Can anyone help with some detail steps?thanx

[goody90q45]

The dealer would love to sell you 8 injectors at about $160/ea while he's charging you $100/hr+ on labor to remove your plenum to replace one bad injector.

Ohm the injectors yourself with a digital volt meter. It is the only tool you will need for this check. The connector you are looking for is in a cluster of three on the PS adjacent to the plenum. Detailed instructions and pics are at Q45.org. It will take you all of 5 minutes.

While you are there read up on what's involved in removing the plenum to get to the injectors and then decide whether it's something you want to do or pay a mechanic for. Get back to us with the injector ohm readings and we'll compare them to what the dealer wants to replace. Lot's of people on this board have experience with injectors and will give you some great input. Good luck.

BTW- Do you work for McMasterCarr?

[autotech43]

Be careful when taking ohm meter readings in consideration for diagnosing fuel injectors. I have seen where fuel injectors ohm out with the proper resistance and still be faulty. You are only checking the electrical part of the injector not the mechanical part. There are many readings dealers can check with consult and give you an accurate diagnose.

[Jesda]

#7 is a pain.

You have to remove the plenum (and all hoses attached to it) to get to the injector. You'll end up replace the brittle and old hoses while you're there.

Once the plenum is off, removal is the easy part. You use an impact screwdriver to remove the screws and then pliers to twist the injector out, making sure to remove both o-rings.

Then, you put new o-rings on the new injector, lube the o-rings with grease or oil, and insert it. Then, you reattach the metal cap and two screws. Preferably, you replace the screws with ones that have non-philips heads.

More details are available in older threads. "Tangalora" has some pictures in her threads.

[Aus94Q45]

Not to rain on the parade but here is what you should do:

1. if they have not been done, replace all of the under plenum hoses.2. the rear fuel rail hoses3. check and replace the injectors as needed.4. replace the injector O-rings -- at this age some are bound to start leaking5. relace the knock sensors and harness6. clean out the plenum, tb, and iacs

Sounds like a lot, but these are all identified maintenence issues that you can knock out all at once with the plenum removal, or deal with over and over as nagging piece-meal problems. I did all of these to my '94 -- unfortunately bit by bit with three plenum removals. Had I done it all at once I would have been ahead of the game. Since the last round (knock sensors and o-rings) the car has never run better -- true improvement.

You can do all of this in a weekend.

Now if I can just get the transmission and motor mounts replaced it would be super smooth.

[sdkhalsa]

If you decide to do this yourself, one of the best sources for injectors is Jo at Scottsdale Infinity web site: http://www.trademotion.com/par...l=Q45

The thing to remember is that it is a time consuming, expensive job to do the plenum, and if you cheap-out on the parts it will force you to repeat the process. In my experience with a 94'Q, 100K, it will probably be necessary to pull the plenum two or even three times during my projected ownership of tthe car. If you can time the routine replacement of parts, such as knock sensors, hoses, harnesses, etc.it makes life with the Q much more pleasant.

[Q451990]

I agree with everything Aus94Q45 said, except for #4. I think you invite a lot of added expense and pain if you attempt to remove these injectors without replacing them. Especially on a 90-93 without aftermarket support on the pintile plastic caps. Perhaps someone has come up with a better way to remove the injectors than I have, but they are easy to destroy while trying to get them out of the rail.

I can't say that I have ever heard of an OEM installed injector o-ring leaking... not to say that it isn't possible or hasn't happened - but I haven't heard of it. As far as someone (even techs.) pinching an o-ring during replacement - it's not that uncommon.

Heath

[pito11213]

I remember when I changed my fuel injectors in an autozone parking lot. It took many hours and alot of cursing and sweat. The screws are guaranteed to strip. Be very careful.

The tops of the injectors are almost guaranteed to break because they are brittle when you start to twist the injector out of there.

The pintle on the early Q are probably going to crack if you are not careful.

Pull the plenum off. Do not try to prop it up with a piece of wood as you will regret this. That is unless you have the garage space to just pull back and relax when you get frustrated and believe me you will be frustrated.

[DebbiQ]

Whoa there guys. I have replaced two or three injectors, as you know some of these can be accessed without touching the plenum. I did one propping the plenum up out of the way, no problem. Admittedly most of the hoses had been done not long before, so maybe wiggling the plenum out of the way is not a great idea. Also we had one injector clear itself when we changed to Chevron fuel exclusively, have not had a proble with it in over 18 months.

[Jesda]

If it were 1, 2, or 8 that were bad (accessible without plenum removal), I would have suggested installing used ones, sending them to DeutschWerks (NICO sponsor) for recapping and cleaning.

Also, buy brand new injector harnesses. As you remove yours, there's a darn good chance the brittle plastic will crumble in your hands.