16 replies to this topic

[Brandon]

I've seen/heard about 'blueprinted' injectors (matching spray pattern & flow across all 4) or does saving a couple hundred worth the time of sending yours in?
Obvious considerations if any of my submitted injectors end up beyond repair/adjustment/cleaning.

Good source for these matched sets?

I'm doing this with the intent of having this side of the combustion process up to snuff before heading to the dyno post-FPR installation & exhaust.

TIA!
Brandon

[Keith Novak]

I send mine to Miatacage.

Before

Inj # CC/Min Pattern
1 245 Good
2 232 Dripping
3 244 Good
4 239 Dripping

After
Inj # CC/Min Pattern
1 251 Excellent
2 249 Excellent
3 251 Excellent
4 250 Excellent

$100 I believe. They ones I've sent start looking like hell and come back clean with all new rubber bits and the numbers come out looking consistently about like what I posted.

(note: formatting in the typing screen looks better than the post.

[Alberto]

Plenty of good places to get injectors cleaned. I don't remember reading about issues with Miata injector cleaning companies. I'd probably go regional.
Injector.com is in CT
RCEng.com is in CA
WitchHunter.com is in WA
Advanced-autosports.com in WI

Many of the RX7 guys, including myself, have used Witch Hunter. Their o-rings seem better / less prone to failure or fitment issues on the RX7. Haven't heard about any such issue with the Miata but I haven't researched it much.

Also, Advanced Autosports offers a great injector exchange program. Send in yours and get a set of cleaned injectors back. No waiting. And you know we all love Dave and all the great advice he gives on here!
http://www.advanced-...13c04b0985efdf2

[FTodaro]

How often is it recommended to have them done. I did mine two years ago?

[Panic Motorsports]

It can also save you time and frustration on the dyno chasing a lean condition. We had a customer blow one up, obviously lean. Sent the injectors out, imagine that, one bad one. Peace of mind is worth the $100 you'll spend getting them serviced.

[LarryKing]

Stewart Engines in Indy - great service.

[William Keeling]

who i use http://www.injectorrx.com/

[Glenn]

It can also save you time and frustration on the dyno chasing a lean condition. We had a customer blow one up, obviously lean. Sent the injectors out, imagine that, one bad one. Peace of mind is worth the $100 you'll spend getting them serviced.

What Steve said! This is especially true if you are tweeking the A/F to the very limit.

[Jim Drago]

Dave At Advanced Autosports is also doing them and is a site sponsor. I use him on my stuff. he typically has a set ready, so he will send the day you order in most cases and you sent yours back
Jim

[Brandon]

Marren looks to be the winner here - close by (CT) and reasonable on pricing for the service overall.

Next question: buying another set of used injectors and sending in all 8? 2 junkyard sets and send in all 12?
At that point you're up to $300 worth of investment in parts/services so...I see on MSP they're $100+/injector.

What's been the outcome of new stock/factory items? Good/bad/indifferent? Other thoughts?

[davew]

I have had my injector cleaning machine about a year. I have done a couple sets of Camero injectors and 1 set of Honda injectors. So I am not an expert by any means. But I have done about 600 Miata injectors.

Nothing is servicable on the inside. You can not adjust or disassemble them. The filter and seals are the only replacable parts.

The cleaning procedure is a 4 step process.
1- pretest the injector for impedence, flow rate and spray pattern under multiple speeds and conditions.
2- ultra sonic cleaning of the injectors in a heated ultra sonic bath while pulsing the injector at different speeds.
3- Back flush the injector with solvent in the reverse direction
4- retest using the same sequence as in step 1

I have seen injectors that would not even flow during the first step, clean up and have perfect spray patterns after cleaning.
If they don't look good after 1 cleaning, I reclean. If the still look bad, I toss them. I expect that there must be a rust pit someplace inside that causes the poor spray pattern.
Once cleaned, Miata injectors are very equal. Usually within 1-2 cc's on any test.

What surprised me is that clean injectors flow less fuel than dirty ones. I assume it has to do with deposits slowing the pintle from closing as well and as quickly.

If you have not cleaned your injectors, do them when time permits. Especially before a dyno tune. I expect that they only need a cleaning every few years.

I hope this helps
Dave

[Brandon]

Dave,
Interesting you noted the issue about dirty injectors flowing more than clean ones - I must have the worst-mileage NA1.8 in the nation as I ran out of fuel in a 45 minute (mixed-class) race with 1-1.5 laps remaining (babied it the entire way around - the checker flew BEHIND me for the leaders as I passed S/F so *WHEW*!). Put nearly 6 gallons into it (drained just under a gallon from the earlier 30 minute qualifier then added 5 gallons) and there was nothing/zilch/zippo left when I made it back to the paddock.

But, I'm on my 3rd season with this engine (with a 4th season of DEs) and I've never done a FI service so I wouldn't be surprised if I'm dripping/using more fuel than 'normal'.
In fact, the plugs I took out from last season were dark brown (not light tan but not black/sooty from burned oil) which indicates a way, way, way too rich AFR and could quite possibly be the reason for my poor mileage. Hence the dyno questions earlier too.

So what's your take on sending in 8 total injectors with the idea/understanding there may be a few that aren't good/worth returning?
Good idea/bad idea?

You may be the recipient of a set from Jersey....
Thanks,
Brandon

[William Keeling]

I have only had 3 sets done -- but have never had one that did not clean up -- and a few flowed 0 to start

[davew]

It can't hurt. But I have only had a handfull of injectors that would not clean up.

Dave

[fotostars]

Or you can DIY following this. This is what I've done before my last dyno tune with the new AFPR installed. Pretty happy with the results:

[Keith Novak]

Keep a couple extra o-rings on hand. I've nicked them on a couple of occasions getting them in the fuel rail. Doesn't take much to cause them to leak. I also keep a couple of those plastic insulators handy that go between the fuel rail and the head. When you accidentally knock one out of place they always seem to fall somewhere nearly impossible to find.

[trimless]

I use silicone on those fuel rail isolators to keep them in place after loosing a few, they are hard to find after knocking them off for sure.