26 Reply by EriktheAwful (edited by EriktheAwful 2011-02-13 02:59 PM)

  • From: Choctaw, Oklahoma
  • Registered: 2009-11-12
  • Posts: 2,144

Re: Now what to ghettocharge?

Like he said, they're batch fired. You can use as few of the injectors as you like.

Or rather, they SHOULD be. From what I understand they were individually fired up until the injector recall of the late '90s. (For those who don't know, there are 2" hoses connecting the fuel injectors to the fuel rails, and according to Nissan they should be replaced every 60k miles, even though you have to drain the coolant and lift the intake plenum to get to them. Most owners didn't even know they existed until the car caught on fire.) When we performed the recall we replaced all the hoses, injector seals, fuel pressure regulator, and we cut the individual wires to the injectors and installed a harness on the #2 and #4 injector wires that branched the current to all the injectors. Some of the stuff we did was optional, but at the dealership I worked at we always did the full menu because it maximized the money we got for the job and because it helped cover our tails when a customer with a black-smoke belching 250k mile 300ZX got their car back and complained that it ran like new when he brought it to us and that we needed to fix it.

All that said, you can batch fire anywhere from two to six injectors straight off the ECU and not worry about it.

27 Reply by Crab Spirits (edited by Crab Spirits 2011-02-13 08:34 PM)

  • From: Romeoville, IL
  • Registered: 2009-12-12
  • Posts: 1,117

Re: Now what to ghettocharge?

My reasoning behind running an injector for each cylinder is because you would have to run the 1 injector upstream and I would think on some engines there could be distribution issues. Besides, you're going to have to trim the MAF signal down anyway since it would cause the injectors to max out as soon as it comes online, instead of progressive enrichment. There are easier ways of doing this, but I thought that this would be the most accurate method.

Erik, this should expand on what you are talking about.
http://www.az-zbum.com/information.inje … call.shtml

The Charnal House Geo MetSHO: Turning less laps than a regular Metro, the hard way!

1969 Subaru 360

Crab Spirits's Website

  • From: Choctaw, Oklahoma
  • Registered: 2009-11-12
  • Posts: 2,144

Re: Now what to ghettocharge?

MYTH: The Nissan dealer changed the ECU firing pattern.
FACT: The ECU is not touched during the injector work. Because of the condition of most of the cars that come in to get worked on, Nissan opted to install a new injector sub harness. Before the service campaign, the ECU had two firing modes, simultaneous and group. Simultaneous Injection mode means that all injectors fire at the same time. This mode is when the engine is over 3000 rpms, injection pulse duration is more than 6.5ms, or cylinder head temperature is below 60oC or 140oF. Group or Batch Injection mode means that the six injectors are divided into two groups. The groups are cylinders 1, 2, 3, and 4, 5, 6. These groups are fired once each engine cycle 180o opposite of each other. After the service campaign, the ECU still has both of these firing modes. The only difference is the groups. The new groups are 1, 3, 5 and 2, 4, 6.

So I understood it wrong. Engineers love keeping technicians in the dark. It helps them feel smarter.