This upgrade was more of a preference than a necessity. While self tuning the car for knock detection i noticed some inconsistency’s at varied boost levels. Id sometimes hear pinging, sometimes not. Every inspection of the cylinders and spark plugs turned up nothing of significance to be found. Was it knock or was it engine noise? its hard to be sure. The yellow top 555cc injectors I have been using were advertised as genuine JECs, but they did come from ebay and were under $100 shipped for all 6, Highly suspicious. I also did have a incident in 2019 with cylinder 2 detonating with one of the yellow tops that I later determined was a flow variation between all the injectors.
Another part of the equation is the fuel I’m using. I pumped out 3/4 of the fuel in the car in May because the fuel was from October 2025. I put in new 91octane fuel from a gas station I never got to. Maybe that fuel was bad? maybe the mixture of old fuel and new fuel was enough to lower the octane? nether the less I was hearing pinging at timing and boost ranges I wasn’t last year and Id feel more comfortable knowing the injectors were quality and measured professionally.
I decided on Deatschweks 550cc Nissan Injectors. At 43.5PSI of fuel pressure they are effectively 637cc injectors. They feature a special atomizing metal pintle cap that requires more fuel rail modification, otherwise they are drop in for fuel rails already modified for Nissan injectors. A very beneficial thing about these injectors is accurate pulse width and deadtime settings witch im documenting here that may be helpful for anyone using these same injectors. I already did the conversions for these settings into Megasquirt 3 using 1.6 version deadtime settings.
For comparison sake, these yellow tops are similar to what I purchased off eBay. I actually purchased 2 sets of 6 and they all function and measured exactly. The durability of these injectors remains to be known. They worked, but side feed injectors, specifically Nissan side feed do a have a reputation of failure and inconsistency’s. If your on a budget they are defiantly worth trying.
The DW injectors are much more realistic for pricing and while they hurt the budget they are guaranteed. Nowhere online are they pictured with the metal pintle cap, they also had the same filter cups as the yellow top injectors pictured above. Maybe my set was a fluke or they haven’t updated images ever.
What is the required modification?
This modification can be done in a fixture on the mill or a drill press. A mill is pictured here, but I did use it in drill press mode without a fixture because it was faster then setting up each bore with a center finder.
The metal pintle cap on the DW injectors is larger then the OEM pintle cap and it cannot be removed. I tried removing them at the peril of destroying $700 injectors, they simply will not pull off. I decided cutting them off would be the absolute last resort. Instead I have few junk fuel rails that I ruined in my process of fuel rail modifications in 2019 that I would test modify for these injectors.
Depicted in the drawing is an already modified fuel rail injector bore. Notice the narrow untouched pintle bore at the bottom.
Depicted in the drawing is a DW modified fuel injector bore.
Increasing Pintle Bore:
The pintle bore will need to be bored to slightly oversized of 10mm. 10mm alone is too tight a fit the injector is incredibly difficult to get in or back out. I used a 10mm drill bit for this process on the Mill/Drill and afterwards I put the 10mm drill into a hand drill and ran it thru the bore by hand ( holding straight as possible) this imprecision of doing it by hand was enough to make the injector slide in and out perfectly.
Depth Chamfering Pintle Bore:
A 11.5mm -12mm chamfer needs to be bored a the top of the pintle bore approx. 2-3mm into the bore. Being I used a drill press to do this chamfer, measuring was not as important as being consistent. On my test fuel rails I chamfered the bore and test fit the injector until fully seated into the bore. Once this was accomplished I dead stopped my Mill/Drill press and chamfered all bores on the fuel rails Id use.
Im aware this is not the correct way to do this, but I did not have nor want to purchase a 12mm reamer to complete this job.
Below is the finished fuel rails with injectors installed and the pintle cap seated perfectly. This position allows just enough clearance to seat inside of the manifold injector seals.
These DW Injectors were very pleasant to configure with all the technical data on them. With them the engine runs very precisely, no idle hunting or inconstant AFRs at idle. Its just rock solid and very responsive. However this did not help the original issue of random pinging at varied boost levels.
Below is the injector pulse width and deadtime for these injectors.
After this fuel injector upgrade I decided to convert the fuel rails to dual feed, witch Ill later document.
