delete

 

Never heard of someone going the opposite way.

The WSM does make it sound like the '87+ cars can be either way, depending on the coding plug (and I assume) set of chips.

 

The US (1985 - 1986) and EURO/ROW (1984 - 1986) 25 pin LH fuel injection modules use the same printed circuit board [however there are different revisions of this board, changes over time], however, there are major differences.

The US LH [928.618.123.03 or .04] version supports lambda regulation (with O2 sensor) and idle speed regulation, and uses an 8039 microcontroller with an 8.388 MHz clock speed (nearly twice the speed of the Euro/ROW module). The EPROM contains the code for these features. The label color is blue or purple.

The Euro/ROW LH [928.618.123.00] circuit board does not have certain areas of the circuit board populated with components for idle speed regulation and lambda control. The microcontroller clock speed is 4.471 MHz. The easy way to tell if the 25 pin LH is a Euro/ROW module with no lambda regulation is the label color is black.

I have had several Euro LH customers who have had problems due to the use of improper fuel injectors. The 1984 US spec 928 used the L-Jetronic fuel injection system, and the resistance of the injectors was in the 1 Ohm range. The Euro/ROW 1984 uses the LH Jetronic fuel injection system, and the fuel injectors are in the 14 - 15 Ohm range. Many part shops only list US models in 1984, and the improper low resistance US-spec fuel injectors have been installed. The very low resistance causes too much current to flow and the LH injection module is damaged. So if you own a 1984 - 1986 Euro 928, always be sure that the correct fuel injectors are installed.

 

I'll second the NGK BPR6ES. Been running on them for 4 years with excellent results. Cheap too, my last set cost a little over $2 each.

Colin. 89GT.

 

Kevin,

That's some great info. Thanks for passing it along. I'll definitely be saving this one.

 

I recently switched to NGK simple copper also and I'm happy. But I haven't done any sort of testing.

 

You're now the 3rd person I've heard say that the Bosch copper plugs are the preferred in boosted applications.

 

I'v ementioned this in the past too. Boosted engines should use coper core plugs and IMO HGK makes the best copper plugs. Platinum (maybe even irridium) tipped plugs are a no no in a boosted engine. This is well known in the aftermarket SC/Turbo world.

 

When I first dynoed my twinscrew the shop manager suggested those for my application, i installed them the next day and say a significant improvement. Now I run them in all my 928s.

 

My last pressurized car (older Saab 900 turbo) thrived on NGK copper plugs, liked them better than the comparable Bosch for some reason. The only difference between them seemed to be useful life -- performance was identical when new.

Someplace I have an almost-new set of +4's for the S4. They wouldn't get past NOx testing, so copper Bosch plugs went back in and it passed OK. Gotta think there was a slight difference in combustion temps, but don't know why.

 

They don't work on high compression engines either. When they first came out I put them in my high compression 2.2liter 914. I was taking them back all the time (after 2 or three weeks) until they said they won't take them back anymore. Ran for a couple of years on a set of copper ones.