This is my first D-jet FI on a 914. My first 914 was a single carb and my second had the L-jet (which I liked because it was easy to manually adjust the air/fuel mixture).

First question:
In cleaning and detailing my engine, I noticed the housing on the fuel box simply came right off the _______ opening (sorry, I'm not a mechanic. Seems like a carb opening for air, but you guys will know from the pics). Shouldn't this be secured? Seems to me that a lot of air would be leaking from this. It sits on the housing, but not securely and not completely (off to the side a bit). I wrapped some Gorilla tape around it to secure it to see if it made a difference, but my car was driving shaky anyway, so I can't tell. Is this supposed to be secured or does it not matter? One mechanic told me not to worry about it. Seems like a poor design to me.

Click to view attachment

Click to view attachment


Second question:
Is there a way I can adjust the air/fuel mixture on a D-jet FI? On the L-jet, you can adjust it by the screw on top of the air box next to the air flow meter. The screw opens and closes a door allowing more or less air into the engine. Is there a way to adjust it on a D-jet FI? If so, can someone provide me with specific instructions on how to do so? Mind you, I'm not much of a mechanic, so I may or may not know certain parts you refer to. So if you could be specific (or provide pictures of yoru explanation), that would greatly help. I'd like to learn how to do as much on my own as I can. With my L-jet, it was easy. Haven't figured my way around the D-jet yet.

Its a "throttle body". Your airbox should latch down to a mount on 2 of your intake runners. Those latches pull it tight to the rubber gasket on the throttle body, which it appears you have.



There is a knob on the ECU but it only adjusts idle mix.

There is also an idle bleed screw on the throttle body, but it helps with idle speed.

the latches on the air box are fastened, but the rubber gasket doesn't pull tight and it's a bit offset. It doesn't fit over the opening either. I tried (TRIED) to fit it snug, but it just rests on top of it. Is it supposed to be secure with no air leak? Should I re-tape it to seal it up? Thanks!

So we're clear... Are the latches on the bottom of the box tight? when the whole assembly is clamped (box to runners, and lid to box) it should seal pretty well. Maybe you can adjust that sealing donut on the throttle body up a little bit.

Don't use tape, you shouldn't need a solution like that.

The latches aren't COMPLETELY tight. I can wiggle it a bit. I tried bending them in a bit to make them fit more snug. Need to find something to bend them in a bit better.

I don't know how to adjust the sealing around the throttle body. It's pretty much cut and dry. I took it off to try to bet better manageability with it, bending it to try to walk it's way around the inside of the opening on the air box. It's just too flush with it. The rubber donut is too big to fit inside of the opening.

I guess I will try to bend the latches again to see if it will clamp down more snug.

The metal mount across the intake runners that the box fastens to can get bent or even break.

BTW that seal won't cause bad running it is just letting a little unfiltered air into the the TB.

TB?

Throttle body... FI equivalent of a carburetor throat

ah, okay. didn't get the abbreviation right away.

I ran some seafoam in my engine and my gas tank just to keep system clean. Any suggested treatment or maintenance I need to periodically do on the FI?

Do yourself and everyone else here a favor and read brad Anders webpages on the D-jet. Go over it a few times to be sure you understand and it will be easy.

D-bible

http://members.rennlist.com/pbanders/DjetParts.htm

That's the D-jet bible!

You're showing a rubber sleeve that is clamped over the throttle body. The sleeve should be attached to the top of the air cleaner. Looks like yours is not. There is a channel in the throat of the air cleaner that the edge of the rubber sleeve fits into.

I had one come apart when I forgot to loosen the clamp that holds the sleeve onto the throttle body. I couldn't get the sleeve back into the channel very easily, so I just swapped for another top from my parts stash. (Because I'm lazy.)

--DD

If I've read it through once I've done it 20 times not to mention the numerous times I've referenced segments of it! The more you read it the easier it gets. In a year you'll be an expert.

DD is spot on. The air box to TB rubber coupler has ripped free from its channel which it was originally glued.
Yes it will cause a air leak unless you can secure it back in place so that repetitive removals of the Air box - AFTER you loosen the securing clamp,
dont cause it to come free again.

there is a factory clamp on the rubber sleeve..
I also think the sleeve may have been glued into one side from the factory...


and it takes special tools (a wide band air fuel meter) to adjust the air to fuel ratio...

not easy
most have never done it.

if you read the anders site
do all of the component tests on the MPS
if it holds vacuum and everything tests good, you shouldn't have to make adjustments on a stock motor.

richening it a tiny bit is a good thing, but again you will have to have a wideband meter to do that.

Mine isn't glued to the box, it's clamped to the TB. When everything (box and lid) is latched, it pulls tight to the rubber seal.

Thanks, guys! I haven't been able to get online for a few days so I haven't been able to reply until now.

Yeah, it seems that rubber seal is supposed to fit in the opening of the air box. I just can't seem to get it in there though. It's such a tight fit...almost flush. Any suggestions on how to get it back in there?

Tell me this, in your pic above showing the gap.... Are you pulling the box up to demonstrate how loose it is? Or is that gap always there?

I'm holding it up so you can see exactly what I'm referring to. But it just sits on it, unsecured and slightly offset. It's supposed to be fitted into it, but it's such a tight fit I cannot get it in.

I removed the clamp and rubber piece to try to get a better angle to fit it. It seems to be just slightly too big to fit inside the opening. Maybe its expanded and I need a NOS?

There are two of the over center clamps on the bottom of the air box. one in front, and one in the rear. They clamp the entire box to a bracket that bolts to the intake runners. Pop those two clamps loose and remove the whole box. The one in front is easy to get to, They one is the back has to be done by "feel". Then remove the rubber seal from the throttle body and install it on the air box. Then set the box back on the throttle body centering the rubber on the TB. When everything sets properly, pop the two clamps back on. While you have the air filter box off, you can see the bracket on the intake runners. It should run parallel with the centerline of the engine case. Looks like the bracket might be crooked causeing the misalignment at the TB.

I did that already. Didn't make a difference. :/