Nick86

iTrader: (1)

Hey there,
I'm in the process of adding a Microtech to my '86 N/A and at the same time have decided to replace the injectors. I picked up a new set of Siemens injectors but there seems to be a problem when I go to install them - they are slightly too long... but the actual physical size is the same as stock.

Here's a pic of the old (right) and new (left) injectors side by side.



The problem seems to be at the top collar. On the stock injector it has a rubber ring while that same area on the new one is hard plastic - you can see it here:



Has anyone had this before?? These are supposed to be a direct replacement for stock. The only thing I can think is that I am not supposed to use the plastic "air bleeds" (diffusers) that you need with stock. Is that possible?

Is there something I need to do that will fix this issue - or do I need to return the injectors? I have this feeling that I am missing something simple!

Thanks for all the input!

Nick

RotaryRocket88

iTrader: (7)

Not only is the top different, but the bottom seal sits lower too. I can't see how you'll be able to get these to fit with the stock rails. If you pull out the plastic diffusers, the top will probably not go far enough into the rail to seal.

arghx

iTrader: (3)

you may get a vacuum leak from those injectors if the pintle cap doesn't seal to the manifold. I've been through that before. If it's too long, raise the height of the fuel rail by adding an extra washer or two as a spacer. I went through a big mess trying to get Bosch 1680cc injectors to fit in my T2.

The other thing you can try is removing the pintle cap and grommet from your factory injector (it is possible, you need a vice or something like that) and install them on the bottom of the new injector. Bosch injectors have a lower o-ring, I had to remove that and install an s5 pintle cap to make it seal properly.

Aaron Cake

iTrader: (1)

If you can space up the bottom, you can Dremel off the plastic collar.

Nick86

iTrader: (1)

Thanks!

I had thought about shimming the fuel rail to make up the difference in height, but that just seems like an invitation for fuel leaks.

Using the dremel to reduce that collar is also an option - especially when on the store's website they talk about custom milling of injectors for Rx7's. That said, I want to be sure I have the "right" injectors before I start chewing them up.

Are the fuel rails for a TII and an N/A the same on an S4? I was under the impression they were, but could it be that they are not and these are specifically for a TII? Grasping at straws, I know....

arghx

iTrader: (3)

explain to me again why you bought new injectors for your nonturbo? all you needed to do was get the stock ones cleaned. if you really want new ones, just get new ones from Denso so you get OEM fitment

Nick86

iTrader: (1)

I had the old ones cleaned but they were the original ones from 1986 and had a less than stellar report even post cleaning. As such, buying new ones was a no-brainer.

The Siemens ones were supposed to be a direct OEM Fitment which is why I went with them. Had I known they would not be the same, I'd have gone with Densos. I've emailed the place where I bought them to see what they say!

RotaryRocket88

iTrader: (7)

The portion of the rail that the injector slides into is the same, but the rails themselves are not.

Just get some new densos, or some cheap used ones and clean them. There are plenty 20+ year old stock injectors that will be fine once sent out for cleaning. Not sure why yours are sub-par. My 550cc primarys for example have perfect flow rates post-cleaning.

Nick86

iTrader: (1)

Yeah, that's more what I was talking about - the TII vs N/A injectors are physically the same size/shape, so it's not as if I got TII injectors instead of N/A ones.

I guess there are a thousand reasons why my injectors were so deficient - anything from mileage to the climate I live in, to fuel quality to time. Whatever the sequence of events were that led to it... here I am! lol I knew they weren't great, but I did expect them to be good after a cleaning. Oh Well.

I've spent a lot of time and money on this car recently (and especially over the years! lol) putting in a Microtech etc, so I am unwilling to go to all that trouble only to throw in a set of "cheap used ones", even if they have been cleaned, as my first option to fix this. If that's what I have to do in the end, fine - but I'd rather have new ones.