cleaned fuel injectors...missing piece?
 

I bought a used set of 99 NB injectors (red) and sent them off to get cleaned at DW. I got them back but they are missing the black piece on the tip of the injector. I have been looking for a part number to buy one, but its no where to be found and its not part of the insulator package.

https://www.miataturbo.net/attachmen...ine=1327777237
(note the black piece missing from the cleaned injector on bottom)

What is it? Do I need it? If so, where do I buy it? Any help is appreciated.

btw, here is a link to "insulator" that I found:
http://parts.arlingtonmazda.com/prod...52d257%29.html

That would probably be called a "pintle cap." I'll check when I get home to see if my set of '01 injectors has them, can't remember. I can tell you that Mazda Motorsports doesn't show a pintle cap in the parts diagrams for a '99, just the insulator.

Email Deatschwerks and tell them what happened and they will likely send you one cheap or free. They usually put new ones on if you send injectors in to be cleaned so it probably came off.

Yeah, RC engineering replaced any bad ones on my cleaned injectors, so they should all have them, even if you sent them in with missing pintel caps. Actually I forget if they replace bad ones or just replace them all...

This is ridiculous! I will contact DW, but I can't say I am happy about this. Now my car has to sit around till I get new caps. The whole ------ point of getting another set of injectors was not to have any downtime. God, I need a second car.

---- I forgot, I have an appointment on Tuesday for a mount+balance and alignment.

I am thinking about running without the pintle caps. If I get a vacuum leak...well I will just deal with it then. Anyone else see another problem with running sans pintle caps?

I think you'll be alright. Some injectors just have the one seal. Pretty sure my 550s dont' have that cap.

I think a lot of guys are running around with broken or missing caps. Just be careful when installing. It's purpose is to protect the little tip in the middle.

My stock '99 injector pintle caps broke off when I removed my injectors. Just run them without...it'll be fine. My car has been running like that with no issues for months.

Good to hear, I still put it all together nicely tomorrow.

Car has ran fine so far. Doesn't seem like I have introduced any vacuum leaks, I still need to hook the gauge up to it just to be sure. Which is a good thing, because...

DW-Mark called me today. He informed me that the pintle caps are a non-serviceable item and that he cannot get them from anyone, not even Denso. I did find a denso pintle cap on a website for .89c that "looks" like the one on the injector, I may or may not try them depending on how the car behaves during the next week.

Good sign: my car started up faster than it ever has today. I didn't even crank it, I simply thought it and it fired right up ;)

My stock 94 injectors, and my RX-7 550s, are pintle style. My 01 injectors are of the Bosch disc type- 4 little holes in the nozzle instead of a single protruding pintle. Your 99s will be one or the other.

The reason pintle caps exist is to prevent or at least reduce the accumulation of baked-on fuel varnish and carbon gunk on the exposed part of the pintle, which affects spray pattern. The disc type injectors are far less prone to developing these deposits.

If your 99 injectors are disc type, I wouldn't worry about it. If you find another cap, great. If not, I might pull the other 3 just so everything is same-same across all cylinders. The insulator is the seal; it won't do any harm to verify with a gauge (or brake cleaner or propane around where the injector seats into the head) since you've R&R'ed the injectors, but absence of a pintle cap should not cause a vacuum leak.

If by chance yours are the pintle type, then it's marginally more important to find a cap. It's no big deal in the short term and people drive around with broken/missing ones all the time, but you don't want that one injector building up gunk over time and spraying differently than the others, or if it gets severe, leaning out one cylinder. It would take years to get this bad though.

It is the "better spray" pintle design (I guess its a disc type). a couple of holes in the tip and the tip is slightly recessed. I am not running any with a pintle cap, I figured if it has an effect, I would rather all 4 do it (since I figured worst thing is a vacuum leak, its much easier to find a huge vacuum leak than a tiny one, especially on the 99 intake manifold where the f'in injectors are burried under 15 lbs of aluminum and wire).

The weird thing is the "pintle cap" on here did nothing to block anything from the actual holes, it was more like a pintle "sleeve", only on the outside edge. I suspect its largest function was holding the insulator in place (something brainy mentioned) and to fill-in some of the space in the injector hole. Do you really think it does anything to prevent fuel varnish? and if so, how is that? I would appreciate a link or some info on this.

I suspect with-in the next 1-2 years, I will be megasquirted and on different injectors anyways as I move to light FI setup. Anyways, I don't seem to have a vacuum leak, my vacuum is still reading 25" as before (I know thats odd, but I have no idea why it is like that, maybe my gauge is inaccurate, I have a boost gauge I have been meaning to try out and see what the vacuum is on that).

I thought you had the other kind. Sorry.

No worries, It is informative, and it seems I am the only one who has posted about this. At least we got the answer from the horse's mouth here. Now people can search and get edjumacated. All for the price of monthly internets.

I have yet to figure out what the pintle cap on those injectors is good for. Like you said, it appears to have no purpose or function.
195500-4450. That's the part number for RX8 PNP's. They are the same in physical size as your stock '99 injectors, and can be had pretty cheap. I'm pretty sure they're 425cc, although I've seen them listed as 450's. Nobody really seems to know.
Just figured I'd throw that one in there as you did say you'd most likely upgrade injectors in the future. The way I see it, if you're taking bosch disc type injectors out...why would you put old school different shape pintle style injectors in? Maybe it's just me, but if I'm taking my 240cc bosch disc type injectors out...I'll put the same type, only larger cc injector in.

I don't know what the function of the cap is on a disc type injector either. The design is more resistant to gunk buildup in the first place, and the caps aren't close enough to physically protect the nozzle from anything really.

As for the cap's anti-varnish role on a pintle type injector, I read that in a brief technical article about the various injector types. I think I may have saved the link on my other computer, I'll try to dig it up.

Assuming these are the same 89-cent caps you found, it looks like they'll fit.
http://injector-rehab.com/shop/Denso...a-RX8-Cap.html

Tech article with explanations of injector types, pintle cap function, etc:
http://www.tomco-inc.com/Tech_Tips/ttt37.pdf

More articles are on their site here:
http://www.tomco-inc.com/techinfo.aspx

I was thinking of these:
http://injector-rehab.com/shop/Denso-Cap.html

Thanks for the articles, I will be reading them soon. BTW Scott, did you know we are using your car picture as a background logo at the bottom of the MFz page?? check it out:
http://www.miataforumz.com/

I was thinking the ones I posted since thirdgen says 99 injectors are the same physical size as RX8s. But I don't have your injectors sitting in front of me. The two caps look pretty different.

Yeah Brainey pointed it out to me a few months ago, right after he made it. Sooner or later I'll get around to making an account over there.