Fuel injector cups rubbing against supercharger flange, causing vacuum leak

I recently published a post about tracing vacuum leaks on my 1997 Tacoma 4x4 2.7L due to P0171.

In that post, I mentioned that I found a leak at my intake manifold with smoke testing and spraying carb cleaner.

Later, I learned that my cold air intake tube is the crucial leak causing most of my problems; however, that is an easy fix so let's set that aside for now.

I wanted an extra set of eyes on the vacuum leak near the intake manifold so I had my mechanic take a look.

He discovered that the fuel injector cups (in the cylinder head) are hard like plastic and rubbing against the supercharger flange, causing an intermittent leak.

I already purchased new fuel injector cups, o-rings, and grommets from LC Engineering.

I also purchased a beefy intake gasket. More on that below.

We are thinking of taking one of three approaches:

1. Shave off some material from the new fuel injector cups, allowing the supercharger flange to sit flush against the cups.
2. The above mentioned intake gasket is really thick, which will give additional distance between the supercharger flange and cylinder head. Shaving off material from the gasket near the fuel injectors therefore might work.
3. Grinding off some material from the supercharger flange near the fuel injector cups.
   1. This is obviously the least attractive option.

Has anyone else encountered this problem?

Can you suggest anything?

 

Those cups are already a pia to get in or out...

.....cant imagine making that more difficult........

 

I know, man, but it is what it is.

If anyone can help me out - it would mean a lot.

Right now, the most tempting option seems to be shaving down the gasket which I bought.

 

Yeah I really like the ideal of that gasket......hope it works out....

definitely do an update on down the line...

 

I'm more inclined to believe you just have a screwed up injector cup oring because a little bit of misalignment shouldn't cause it to leak. But if it was me I'd use the thick gasket and take a die grinder to the SC flange/gasket while it's mounted and keep test fitting the cup until it clears. And I would only do this if I had less than 1/8" to remove at any given point. If you have to clearance the cup and flange to make it safe then do that rather than take too much off the flange. My SC flange was identical to my OE intake and never touched anything and I used the PTFE LCE intake gasket.

 

Thanks, fellas. Y’all always respond.

Zane - I think we have the same idea re: how to approach the trimming process. Re: the o-rings, I ordered replacements. I am not really sure what to say or expect right now. My hope is that the new cups will be a little more pliable than the hardened OEM cups and, thus, not create a tiny gap for vacuum to escape. Maybe I won’t need to trim anything! Cross your fingers for me.

I will definitely leave updates.

 

TL;DR: fixed the vacuum intake leak by shaving the sides of the fuel injector cups and upgrading the fuel system.

Hey, fellas. Just following up.

The repair was finished last night; it consisted of: shaving the sides of some new fuel injector cups (the old ones were crushed badly), installing a thick thermal intake gasket, installing new injector seals and rings, and, for good measure, a new Walbro fuel pump with a check value and adjustable Turbosmart fuel pressure regulator with AN fittings and thermal sheathing along the fuel line at 45 PSI at WOT and ~35 PSI at idle.

The repair took a long time because of a few problems I ran into, namely the first pressure regulator I bought - stopped working. Second, the bolts holding my gas tank straps - were rusted badly. Additionally, the injector cups were, of course, painful to remove; however, the 3/4" tap trick mentioned on TW worked.

At WOT with boost at 5 PSI, the AFR reads between 10 and 10.5. Certainly rich; however, that's better than lean. The AFR stays at 13-13.5 for a few moments but abruptly slams into the aforementioned 10 to 10.5 region. Cruising around, the AFR fights for stoichiometrically center at 14.7. The fuel trims still feel a little high to me. Short term FT is between 0 and +5. Long term FT is about +15. That's 20 FT altogether, which is higher than normal. Given the fact that I have a supercharger, however, I am not entirely certain that is problematic. Lastly, the MAF roughly equals the engine displacement, which seems good.