[Diy_efi] direct injection

ScottyGrover at aol.com ScottyGrover
Fri Sep 9 04:15:23 UTC 2011

Thank you very much for the information.  I am designing a system for  an 
air-cooled, 2.7L flat six and haven't been able to get any co-operation from  
Delphi or from my local dealer (he says I don't need to know.)
I have studied the patents (Delphi and others) and have a good idea of the  
layout but I need the physical size (particularly the diameter) and the  
application (HP rating, engine size, and of course the part number.)
In a message dated 9/8/2011 7:46:41 P.M. Pacific Daylight Time,  
pmkls1 at yahoo.com writes:

I have  been a tech at GM dealerships since 2001. I don't have the 
slightest clue  about the other manufacturers using DI, but know a decent amount 
about the GM  systems. So far I haven't seen any common issues at all with the 
GM stuff. I  have seen a few injectors go bad and some issues with the high 
pressure pump  leaking fuel into the crankcase ( just like the old 
mechanical pumps did), but  nothing major or widespread overall. As far as the 
systems themselves go I  will give a detailed description of how they work etc. 
Currently, only the  Ecotec engines have DI versions, and all late model high 
feature v6 engines  (2.8, 3.0, 3.6) are DI. They all use an in-tank electric 
pump running at ~60  psi to send fuel up to the high pressure pump. The 
high pressure  pump is mounted on the engine, is driven off of a camshaft, and 
operates  exactly like the regular old mechanical fuel pumps do ( save for 
the pressure  output ). The entire system is a returnless system and
like most newer  vehicles has no serviceable fuel filter. The supply 
pressure is regulated by  the ecm and a fuel pump flow control module via a pwm 
signal to the electric  in-tank pump. The fuel pressure on the high pressure 
side of the system is  also controlled by the ecm too via an actuator mounted 
inside the high  pressure pump. The system operating pressures on the high 
pressure side are  500-800 psi at idle and around 2500 psi at max output 
iirc. From the high  pressure pump forward they use heavy stainless lines with 
flare and ball  connections and are supposed to be a one-time use deal. 
Anytime we take a line  loose it is supposed to be replaced, although I have 
reused several without  any leaks. There is also a fuel rail pressure sensor 
located on the fuel  injector rail to send pressure readings back to the ecm 
and there is no other  means of testing pressure on the high pressure side. 
The injectors look like  normal injectors on the fuel rail side and
use o-rings that appear to be  the same size or similar to that of regular 
fuel injectors( I still can't  figure out how the seals don't blow out at 
those pressures). The other end of  the fuel injector is very long and narrow 
and uses special teflon seals to  seal it into the cylinder head as they go 
directly into the combustion  chamber through the intake side of the 
cylinder head. Special tools are  required to install and size the teflon seals 
similar to the tools used for  non-cut teflon seals used in transmissions. 
There are also special tools  required to remove the injectors from the cylinder 
head as carbon will  quickly cause them to get stuck in the close-tolerance 
bores. Every time the  injectors are removed all of the seals have to be 
replaced. The injectors do  require a special high voltage driver, but I do 
not know the specs right now.  Overall, the systems operate like a regular 
sequential port system does and  are designed similar to a diesel
system. Both fuel economy and power are  improved on the engines GM is 
using DI on currently. The latest 3.6 in the  base camaro is up to something 
like 317hp now. As far as being able to fit DI  to any other engine, I suppose 
it may be possible on some engines. Even then  it would require significant 
cylinder head modification and some fabrication.  You would also have to use 
an ECM designed for DI and be able to modify the  calibrations and flash 
the ecm which I am unsure if that is possible  currently. Hope this answers a 
few questions.


-----  Original Message -----
From: Avery Nisbet <anisbet at gmail.com>
To:  Fred Cooke <fred.cooke at gmail.com>
Cc: ScottyGrover at aol.com;  diy_efi at diy-efi.org
Sent: Thursday, September 8, 2011 4:07 PM
Subject:  Re: [Diy_efi] direct injection

I have heard from VAG mechanics that  they still have trouble with
this. This is with the current TSFI engines  found in the audi's and VW
in the US.

Though TDI engines have been  around for years I only hear of them
clogging up the EGR system not the  intake ports.

I think most of this is due to EGR issues and dirty  air.  Where else
would any substance that would/could coke on the  intake port/valve
come from if you have DI.  The washing action of  Port injection
probably helped with badly designed EGR systems in the  past.

For DIY at home "testing" of DI, EGR systems could probably be  avoided.


On Thu, Sep 8, 2011 at 1:00 PM, Fred Cooke  <fred.cooke at gmail.com> wrote:
> Early examples, from at least  1998, perhaps earlier, are to be avoided as
> they are usually prone to  coking of the intake manifolds. Very bad 
coking -
> to the point of  blockage! The earlier cars had a lot of trouble in many
> areas and were  not reliable at all. If we're talking about DI. if we're
> talking about  BMW Piezo DI, I have no idea.
> On Fri, Sep 9, 2011 at 7:18 AM,  Avery Nisbet <anisbet at gmail.com> wrote:
>> A lot  the current car have these.
>> GM has been using them in  the eco-tec(FWD 4 cylinder) engine for a
>> while.  Im sure  there a few different injector styles.
>> The prices should come down  in a few years.  You may be able to find
>> specs by looking up  after market replacements.
>> The cruze should have these  depending on market.   The later model
>> year US market cobalts  had them too.
>> -Avery
>> 2011/9/8  Mike <niche at iinet.net.au>:
>> > All I know its pretty high  pressure, the latest bmw twin turbos use 
>> > with piezo  driven
>> > injectors that cost $2200+ (AUD) each !  But they  do get pretty
>> > reasonable
>> > fuel consumption  of
>> > around 6L/100Kms with sizable power on demand - straight  six 2 to 3L,
>> > seems like the next tech step but geesh does it  cost !
>> > regards
>> > Mike
>>  >
>> > At 02:48 AM 9/9/2011, ScottyGrover at aol.com  wrote:
>> >
>> > Has anyone done any work on this type  of fuel injection? I can't get 
>> > data from Delphi, even as  to the physical size (length, stem 
>> >
>>  > Scotty from Hollyweird
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