Hey TGO. Here's something I learned the hard way. I bought a set of Bosch 3rd Gen injectors for my 91 Z28. Spent 3 days trying to get them installed without having massive leaks on the top of the injectors at the fuel rail. Uninstalled and reinstalled them at least 8 times and each time a different one (or more than one) would have a huge leak. I was SOOOOO sure I was doing it correctly. I would flip the fuel rails upside down, lube the o-rings with a little dish soap and insert the injectors into the fuel rails. At this point I had what looked like a dead cockroach with the injectors sticking upwards. Then I would flip it over and slip the bottoms of the injectors into the intake manifold and tighten down the rails. Over and over again I would get massive leaks. This was on a Saturday so I couldn't call SouthBay til Monday. All I could do was re-visit their website and see if there were any clues. ......... Well whadya know. It clearly says right on the ordering page to install the injectors into the MANIFOLD first. Who knew? I was a little skeptical about how much this one tiny detail could make any difference. Without saying much else I will just say that they ALL sealed perfectly on the first try. The moral of the story is not to be a dead cockroach and read the freak'n instructions instead!!

 

Who needs stinking instructions? We don't need no stinking instructions! LOL!
Glad you got them sealed. Maybe someone will benefit from this!

 

I had always installed them rails first, and tightened them down with no problems. Then I saw Southbay said manifold first, so when I installed the Southbay injectors, I did manifold first. Hasn't run yet, so we'll see. Can't see why it matters, but you're not the first person to have issues when doing it backwards. Oh well, thanks for posting up!

 

We have been telling people for years to install the bosch lll's into the intake manifold first. Every order that goes out gets a note in the box as to how to install them because 99% of the time if they're installed into the fuel rail first they will leak! Has to do with the alignment during installation. It's not only our injectors it's with all the bosch lll injectors.

 

The injectors are slightly shorter than stock so you have to becareful there with how its setup. I trim down the tpi rail mounts to make up for the difference but still install into base first

 

Every set I have installed all leak, no matter which way I do it.

I gave up, no more of those. It's the o-rings, after I change them the leaks go away.

Two much work.

 

We have an acronym at work for when people continuously try to do something and it doesn't work - RTFM. Stands for Read The F*****G Manual. Works every time.

 

I just ordered my set..and will remember your errors when installing mine....I'm sure hoping I'm not throwing tools around after starting car for first time afterwards!

 

My car desperately needs new injectors and I was/am ready to buy the Southbay ones but there is a member here who was saying that the injectors dont flow like the OEM ones do and it was causing serious tuning issues with his car. I cant remember the details but the thread had some good info in it. Basically, the Southbay injectors were not a direct swap plug and play swap. I called Southbay about it but really didnt get any technical answer so Im just sitting here trying to decide what my options are for new injectors.


Update, here is the thread. Can someone shed some light on this please? My car is basically stock but it needs new injectors. I really dont have the resources to tune and retune this car simply because I replaced injectors.
https://www.thirdgen.org/forums/diy-...ctors-not.html

 

Bottled..Holy hell..I just ordered a set..and am gonna do the job myself....I can only hope that if I go thru all the jazz of doing this, that these will not dissapoint....My car runs fine now, but thesemultecs were done in 02/03..So I am only doing this to improve what I already have.....Now I'm a tad nervous of my results....

 

Hopefully Southbay can chime in here with a detail explanation to this

 

Nothing too much to be worried about. Swapping injectors creates a leak risk because you're installing 16 new o-rings that need to seal properly (both sides of the injector). Follow installation instructions for best results.

That being said, I did the job in 3-4 hours and none of my injectors leaked first go. Maybe I was lucky, but I did have a second set of hands and was very careful seating everything.

You'll be fine. He was just posting to be informative.

BOTTLEDZ28: They work fine without tuning but I was running just a tad lean. Scott Hansen expanded the injector pulse width a bit (I think) on my tune to sort that out. They ran fine drop in, though. I have a feeling some of the cars that don't run right with them have some other issues causing them not to respond properly. They're not that different from stock to cause any MAJOR notable issue. I'd still do a datalog and tune for best results.

 

So with regards to fitment. Our bosch lll's are not any different from others out there. The problem that we came upon years ago was that they are an "oring" or 1/4 to 1/8" shorter than the stock multecs and they were leaking from the rail. If an injector leaks from the rail side it does not mean there is something wrong with the injector. It's an installation/oring issue. If an injector is bad it's going to leak from the bottom. At the time the way we corrected the problem was to add an additional oring to the bottom. It acted as a spacer/washer. We decided to take it a step further and after 6 months to a year of testing and development we designed a custom oring and a custom adapter that fits onto the bottom of the injectors which has since solved the height/fitment issue. To be used with STOCK INTAKES ONLY! We then found that people were still having problems with leakage from the rail. It turns out that installing them into the intake manifold first and then the rail solved the problem 99.9% of the time. Our guess is that it has to do with the alignment.
As far as having to tune the car with these injectors...I have to say that over the years we have sold literally thousands of these injectors and never had a problem or a complaint about performance. If there were any problems we never heard about them. This issue is new to us and only mentioned on the forum. The best i can do is to do some research to see what i come up with. These injectors are a direct replacement for the stock.
I hope this helps for now.

 

Why is this? Aftermarket manifolds (the few that exist) were designed around the stock injectors.

I fully expect them to work fine with my Accel SuperRam lower manifold. If they don't, I'll be quite cross...

 

This may sound stupid, but I've always had the best luck (no problems) with the blue OEM o-rings. The aftermarket ones always seemed slightly thinner, & I would have intermittent sealing problems. switched to OEM exclusively and the problem disappeared. Just my experience.

 

Why be cross? It's posted on this forum and all over my website and even my ebay listings that if you have an aftermarket intake to let us know.
If they are ordered over the phone our first question is whether or not everything is stock
It has to do with the design of the adapters. They were fitted for stock intakes.
We've been selling them this way for over 5 years maybe longer and thousands later.

 

What exactly needs to differ for use with aftermarket intakes?

The various manifolds were designed to work fine with the stock Multitec injectors, so I'm unsure why 'stock replacements' should differ. I'm running a stock manifold now but that is changing within a month.

Is there a height difference that needs to be accounted for?

 

That's correct, however the adapter does not seat the same in the openings of the aftermarket intakes. Most aftermarket intakes require a standard length injector. The adapter gives it additional height so they sit too high into the rail. What kind of intake are you switching to?

 

The lower manifold is a Edelbrock 3860, paired with a SuperRam plenum and runners.

 

ok so you're going to need the standard length injectors. No adapter.

 

Like i said above, i cut the rail mounts down a tiny bit and installed into manifold first. Didnt have a leak. But one injector eventually stuck open so i had to replace it. This time one different injector is leaking at the rail side. Ugh it can be frustrating working with tpi

I did this on a stock manifold and a tpis bigmouth

 

Any knowledge on if the FIRST TPI intake changes the injector height or anything? I believe it was designed also with stock injector types in mind.

 

I guess I will now have 2 sets of b3's on the shelf. Maybe I'll start giving them out as party gifts.

 

you can use a washer to elevate the rail, or send yours in and we'll be more than happy to exchange them for you

 

This just happened to me when I finally got around to installing my DIII's I ordered last year...I did install them in the rail first. unfortunately already put all the runner bolts back in and torqued them before checking, ONE injector spraying fuel everywhere from the rail side DOH. I think if they had a spot for the C-clips to hold them in place like the OEM d2's this would not happen, as it stands there is side to side and up and down play since they are only held in once both the rail and the manifold are sandwiching them.. Time to tear everything down again and try again tomorrow intake first, worst part is getting the fuel line bracket in the front off.

 

the reason why it's leaking from the rail is because they need to be installed into the intake first and then the rail. You do not need the clips as you have at least 43lb of pressure holding them in place

 

I will absolutely vouch for what South Bay is saying here. I attempted to install a set 5 times without carefully reading the instructions. They installed perfectly on the FIRST attempt after following their instructions. Be sure to lube the o-rings with some dish soap too.

 

I just wanted to add to this that if you upgrade to an aftermarket intake (TPIS, Edelbrock etc.) you do not need to replace your Bosch 3's that were modified to fit the stock intake base, if you use a washer/s the approximate thickness of an injector O-ring under each fuel rail pedestal your old Bosch 3's will fit properly. Without doing this they would not fit correctly (too tight) and leaked fuel. The only issue I had with this mod was I had to grind a small amount off the bottom of the plenum near my Holley AFPR in back and in the front right near where the fuel rail crosses over but this is to expected when mixing aftermarket parts. Just to be safe I replaced the top fuel injector O-rings on each one before re-installing. I have ran the car several times after doing this and no trouble so far..

 

Yeah this was my mistake here, I incorrectly installed into the rail first, I wasn't trying to insinuate that there was a problem with the injector, I was just detailing my experience with the install. The clips keep the OEM injectors in the correct placement, but obviously If I followed directions it wouldn't have been an issue. I used fresh 5w30 oil to lube the O rings, hope that's OK.

 

thankfully tonight I was able to pull the fuel rail off and seat the injectors in the intake first without taking the runners off again, once I had them all seated in the intake firmly I pressed the rail into place, I could tell they were too deep in the rail the first time. Pressurized three times, no leaks! Also removed my alternator this time instead of fighting with the fuel lines, made it SO much easier.