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Discussion Starter · #1 ·
I'm researching a problem for a friend, not my car (as you can probably guess). Being a Mustang guy, I know next to nothing about the Z. He had his injectors replaced little over 3000 miles ago at a ridiculous price. The shop that did the work (and took his money) is out of business. They have lasted less than 2 years of casual, good-weather driving. He over winters the car in the garage, always uses BP premium fuel, and doesn’t thrash it at all. Now he has injector problems again, can barely keep it running. He took it to a dealer for diagnostics and they identified two injectors as ‘bad’ (no details). I’ve replaced injectors on Mustangs and think I could probably do the work for him, but I can’t figure out exactly what parts he even needs. I’ve searched around and find listings for black dots, blue dots, etc. and can’t seem to get a straight answer for the correct injectors. I also don’t have any info on torque settings, etc. for whatever needs to come off to get to the injectors. My first inclination is to recommend we remove them all and ship them off to a professional cleaning service. If they are just clogged, no need to drop the big $$ on new or remanufactured injectors. So, I’m asking for general advice from folks that know these cars. What’s the deal with the secret code & colored dots? How do I know which to get, if we have to replace them? Are remanufactured as good as new, or should they be avoided? Is there a brand better than others (OEM vs. Bosch vs. others)? Can you help a brother out?

P.S. Would appreciate you don't hold the Mustang thing against me - an unwelcome visitor in your land. It's a Screaming Yellow Roush with a Kenne Bell 2.6L SC at 9psi. My next door neighbor has a Sentra with Turbonetics turbo and we get along just fine...
 

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Discussion Starter · #3 ·
It's NA, not a turbo car. In that case, I would assume it's not so complicated to get to the injectors, is that true? I've not even seen his car yet (about 50 miles from me), so I can't even guess how much stuff is piled on top of the engine. I don't think I'm up for the dremel method since it's not my car (don't want to screw the pooch on someone else's ride). Now I know the difference between Z31 & Z32 and the proper injector size (270cc), that's a good step forward. Does the plan of extraction & professional cleaning sound like a good approach to you? If I have to replace them, does the blue-dot / black-dot stuff I see all over the parts merchants indicate the injector size or something else? Is there a recommendation for manufacturer (OEM vs aftermarket)? Should he avoid refurbished injectors?

Thanks for the help...
 

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It's NA, not a turbo car. In that case, I would assume it's not so complicated to get to the injectors, is that true? I've not even seen his car yet (about 50 miles from me), so I can't even guess how much stuff is piled on top of the engine. I don't think I'm up for the dremel method since it's not my car (don't want to screw the pooch on someone else's ride). Now I know the difference between Z31 & Z32 and the proper injector size (270cc), that's a good step forward. Does the plan of extraction & professional cleaning sound like a good approach to you? If I have to replace them, does the blue-dot / black-dot stuff I see all over the parts merchants indicate the injector size or something else? Is there a recommendation for manufacturer (OEM vs aftermarket)? Should he avoid refurbished injectors?

Thanks for the help...
The dermal technique is a by far the easiest and quicker way to do the injector swap. I have done it to most of my injectors just make sure you don't take too much off the runners or you'll make a hole in the plenum. If you do remove the plenum to get too the injectors you'll have to replace a lot of little hoses that add up $(old and brittle) and takes a whole day to start and finish.

As for injectors always get OEM because they have been proven to be reliable while others have died in a short time of being installed. They also had a injector change in 94+ Z so make sure you give the correct year when ordering. I suggest ordering new for reliability but if you want used low mileage injectors are fine so long as you have them professionally cleaned like RC.

As for the dots I'll have to look it up? What year Z are you working on?
 

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Discussion Starter · #5 ·
Here's what I know about it so far. As I mentioned, I've not yet seen the actual car. It's a 1991 300zx 2+2 coupe (non-turbo). I know it's a V6 (duh), but that's about all he can tell me. One of these weekends (soon) I'm going to have to get over to his house to see the car & pop the hood. At this point I don't even know what it looks like under there. I'm hoping there is some more information in the owners manual and actually on the engine. Poking around the web I've seen seen several designations of engine styles (VG30, VG30ET, VG30DT) - is that something I need to identify? If so, I hope I can learn that from the engine itself of the owners manual.

I appreciate the help and patience. I obviously don't know anything about these cars. Just two weeks before he discovered the problem with the Z, his SUV had to have major work done on the front-end. It's been a bad spring for him. I just would like to help him out since he got stuck with such an expensive repair not that long ago. I even wonder if that shop did anything or just ripped him off. It's a shame they are out of business, I'd like to drag somebody across the counter by their shirt on his behalf...
 

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a 91 300ZX NA will have the VG30DE for an engine. If you are ordering injectors for the car, whether it be from a dealer (I go through courtesyparts.com alot) or an aftermarket source (there are a million, but ConceptZperformance.com has never failed me.) they I am sure will help you choose the right injectors. OEM is the way to go with an NA, if your friend is not planning on going crazy with it and building an All Motor monster of sorts, lol.

Either way, good luck and by all means, have fun!
As Sponge said (BTW, hi Sponge!) the dremel method is the easiest, but in the case of preventative maintenance, I like to pull the plenum. All depends on what your friend wished to do. With the pleunum pulled, it allows for alot of "cleaing" in the engine bay (water bypass, hose reroute, etc).
 
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