Bench cleaning injectors?

[Highway Q45]

Well the verdict is in, #4 injector has to replaced. While the plenum from Hell is off, should I have the other 7 injectors and fuel rails professionally cleaned? If so, any idea what it costs? I'm going to be tanking the plenum, hand cleaning the TB,IAC, and EGR. Is there any benefit to carefully wiping the runner bodies. I have a pretty good idea of all the hoses and gaskets I should replace.

[Highway Q45]

After testing this morning the verdict is in, #4 injector has to replaced. While the plenum is off, should I:

1. Have the other 7 injectors and fuel rails professionally cleaned? If so, any idea what it costs? 2. Is there any added benefit or danger to carefully solvent wiping the runner bodies? 3. Is resealing the valve covers (slight leak) any easier at this time with the plenum off the car?

Thanks to this Forum I have a pretty good idea of all the removal procedures and hose kits and gaskets I should replace. I'm going to be tanking the plenum, hand cleaning the TB,IAC, and EGR. I'm trying not to break the bank here but don't want to miss a window of opportunity for easily accessible maintenance. Thanks to everyone for the help offered so far.Steve

[Q451990]

I doubt the results of having the injectors bench cleaned would be much better than a pressurized rail flush - but it would make sense that they could be cleaned better while off of the car - maybe someone else will have better information on this...

I've never replaced rocker cover seals with the plenum off, but you would save some duplication of labor (e.g. removing throttle body, fuel lines, breather hose, etc.) As far as actually bolting and removing the covers, there's probably not much difference unless you're taking the lower plenum runners off too (which isn't necessary).

As far as cleaning the runners - yes that's a good idea, as long as you don't flood the cylinders with the solvent.

Heath

[Chally]

Depending on how good the rail flush is, as to weather the bench clean will benefit.

I personally would get them all checked while I could. Can do no harm. (if done properly)

[Highway Q45]

Thanks Guys. While the Q is disemboweled I'll have some more time to do a few more things while I'm waiting for parts from Joe. I would hate to tackle that plenum without the valueable info archived at this forum, talk about an intimidating task. I wish I was about 7 inches taller, I even thought of pulling the front wheels and lowering the front to gain better access but my jack stands are too tall. I'll check prices on the injector cleaning/testing Tuesday and see if it's worth the effort and $$$.Steve

[911/Q45]

Get a set of those platform soles that all the kids are wearing!

[Highway Q45]

911,Great shoe idea. I guess it's payback time for that earlier comment I made about first flipping your Q over when that bolt dropped into one of your runners! Misery loves company. I do wish I understood more about what causes sudden injector failure...it just seems that with an electro-mechanical device there would be some kind of warning. Has anyone known of any injectors that have just gotten worse but not failed in the closed position? Maybe the resistance has been climbing all along but minimal fuel was still being supplied and one rough cylinder isn't as noticeable as total fuel starvation. Who knows, the results are still the same. I add a can of Techron about every oil change but I'm not sure it helps much when my wife drives so many short cycle trips around town. Dennis supplied some good info on what these "cold" trips do to injectors, throw in oxygenated fuels and it can't be good for an engine. What a way to spend a holiday weekend. Steve

[911/Q45]

I think it's an electrical continuity thing. Mine failed at start up and the CEL came on, revved it a little and it cleared, then the next time I started it failed for good.

[Eswift]

im going to bump this up, maybe someone more knowledgeable will reply.

i believe cleaning/balancing per injectors costs between $20 -30 each, so you can figure ball park from there.

the professional cleaning isnt whats important, as you can do this yourself with a host of solvents. its the balancing and flow testing that you are paying for.

they should give you a printout of the results for each injector, showing comparative flowrates achieved and other variables.

[Highway Q45]

Eswift,Actually this is the copy of a double post. I was trying to edit and somehow it came up twice. Some earlier posts were made to the other copy.

You mention cleaning injectors at home...sounds good to me. Have you done it before and if so what solvent(s) did you use? I wonder if I could add simple fittings with an old fuel rail, use a pressure pot/compressor with solvent and hit it with 13 volts. I'm not sure how long a duty cycle the injector could take but they are used to WOT, so 5-10 sec. bursts shouldn't hurt anything. I'm always looking for ways to stretch my Q dollars. Yeah the power balance/flow data would be nice but adds more than I'm able to spend at the moment. It ran flawless until the injector failure so it's a crap shoot on the other 7 units. The original injectors replaced by recall 50k ago.

Thanks for the idea, I'll look into it some more.

[Q45tech]

The Q45 370 cc injector never exceeds 55% duty cycle in WOT at any load or rpm:370 cc = 35 lbs x 0.55 x 2= 38.5 HP per injector x 8= 308 HP.

The important trick is to supply slightly more than the peak normal pressure of 43.4 psi......50 no more than 60 psi to help flush the 1-5 micron sceens.

[Eswift]

you could definitely do it at home, and i think any kind of mineral spirit would work relatively well.

if you want more detailed info on making your own little bench to clean injectors on, try http://www.twinturbo.net. several guys there have done the exact same thing with considerable success.

do a search with the terms: "injector" and "bench" and you should come up with some good stuff.

im sure if you posted specific questions about it, you would get some good, experienced replies.

not that you dont get experienced replies at nico, just that these 300zx guys are pretty crazy and know all kinds of great tricks.

good luck!

[Highway Q45]

Thanks for all the great leads and specs. The twinturbo site is down at the moment so I'll check it out later and see what I can come up with. I figured someone had done this before. I even thought of brazing up the proper fittings to an old Binks paint spray gun I don't use anymore. It already has a tank for the solvent and a regulator to keep the air pressure under control. I'll have to see if it can take 50 psi though. I did find a shop in town that will do it for $10/injector which is pretty tempting. This place also is a supplier for injectors so I have some concerns regarding unbiased results. I suppose I'll just put the 7 cleaned units in there original locations unless some look way out of norm; those will go into the 1 & 2 spots. I can't do any power balance test until it's back together anyway so it's the best I can do with available time and limited Q dollars.

Thanks Again,Steve