I'm having some leaking issues with my Bosch 1680s that seat in an S4 LIM on my secondary fuel rail. Under boost they blow some fuel out the bottom area. I have S5 pintle caps on them and want to replace the caps and lower grommets. There are different part numbers for the S4 and S5 grommets and pintle caps (Fuel Injection Parts). I've been told I have to run S5 pintle caps on the Bosch injectors.

Do I match the grommets to the pintle cap or LIM? If I match them to the pintle caps I'd need S5 grommets. If I match them to the LIM I'd need S4 grommets.

 

Match it to the pintel caps and you should be ok. The difference between pintel caps is width. Grommets should be the same overall width, just a different inner diameter. So any grommet should seat in any LIM in theory.