[Gmecm] [Diy_efi] direct injection
Phillip Kuhn
pmkls1
Wed Sep 28 03:32:24 UTC 2011
???? Just an fyi before I type my reply, I sent that last e-mail out last thursday and it just went through. For some reason my emails sent to the list are taking forever to get through.
?
???? David, I believe that you are correct in your assumption because I am sure that the engineers are trying to get the engines to run on as lean a mixture as possible. To jump slightly off topic for a second .?The very unrealistic demands regarding auto manufacturers increasing their CAFE ratings is placing a large strain on the auto makers, more specifically the engineers. They are resorting to unconventional means and pushing limits to try to squeeze every last mpg out of every car that they can.? Right now a decent portion of driveability complaints that we see are actually considered "normal operation". The root cause of those complaints is how the ecm and tcm are programmed to operate, which of course are aimed at improving fuel economy. Having said that, I am sure that the DI engines are running pretty lean.
?
???? Milano Guy, I'm not sure if there is any available information that I haven't disclosed. If you have any specific questions I can do my best to answer. Honestly, we have had very little DI specific issues to date so I don't know much past the layout and operation of the systems. I forgot that the only 2 injectors that we have replaced at my shop were not the problem with the respective vehicles either and were just replaced as a shot in the dark. The only actual fuel system issues we have seen from the DI systems was the high pressure pump leaking fuel into the crankcase and causing the vehicle to set rich codes. This was on the 2.4 Ecotec engines only. The only other issues would be due to the DI, but not actually the DI itself. There have been issues with the 3.6 v6 engines developing excessive carbon deposits on the intake valves and actually causing the valves to stick at low RPM's resulting in intermittent misfires.? That issue is common
enough nationwide to result in a bulletin being released, but overall is still rare and can be at least partially attributed to the maintenance and driving habits of the owners. Other than that and some updated calibrations the systems in the GM vehicles seem to be operating well. One complaint that we see a lot would be the ticking noise you can hear from the pump and injectors which is absolutely normal. There is a significant amount of noise dampening material used around the pump and injectors and you can still easily hear the ticking, especially when the engine is cold. This is of course due to the pressures the system operates at along with the way that the pump operates in respect to the commanded fuel pressure. Which, again, this is completely normal, but for those unfamiliar with DI vehicles it "seems" like an engine problem that causes them to believe that the engine has an issue. Glad that I can contribute to the list for a change. And did
everyone get the e-mail that I sent out with links to the photos I took of some DI components ?
?
Phil
________________________________
From: David Allen <davida1 at hiwaay.net>
To: Phillip Kuhn <pmkls1 at yahoo.com>
Sent: Tuesday, September 27, 2011 5:23 AM
Subject: Re: [Diy_efi] direct injection
Interesting information, and it does make
sense.
?
Our natural gas engines have a system where an
enriched fuel/air mix is held near the spark plug and less rich in the remainder
of the chamber. It allows for cleanly and completely burning mixtures that would
otherwise be too lean to ignite of the mixture was completely
blended.
?
I bet GM is doing the same thing by the placement
of the fuel spray and the shape of the chamber.
?
David
----- Original Message -----
>From: Phillip Kuhn
>To: ScottyGrover at aol.com
>Cc: Do It Yourself fuel injection
>Sent: Thursday, September 22, 2011 9:39 PM
>Subject: Re: [Diy_efi] direct injection
>
>
>I know that this topic has gone kind of cold, but I spoke with a field engineer that came to the shop today and he had some information I thought I would share with you. When I told him about your inquiry and the information that I had been unable to obtain he also had some additional information that I was unaware of as well. He told me that the injector placement was critical and that was one of the major obstacles that took GM engineers some time to overcome. Evidently, the location of the injector in the combustion chamber and more importantly where the spray is focused is crucial to the engine performing properly. Since they were modifying existing?engine designs with the intention of making as few major modifications to the cylinder heads as possible it was quite difficult to get the injectors spraying fuel into the right part of the cylinder for the engines to run right. As a matter of fact I have replaced a cylinder head on a DI
3.6 v6 recently.?I noticed the injector actually came in through the side of the combustion chamber ( this was probably due to the only available location to mount the injectors ) and the top of the piston and combustion chambers were very specifically shaped. They were profiled so that the fuel spray focused into a recess in the middle of the combustion chamber directly under the spark plug. I am guessing that this was to get the flame to start in the middle of the chamber and spread outward in a controlled manner. Anyhow, I thought this information was important enough to pass on. Don't get me wrong, I would love for you to successfully utilize a DI system on your project and anyone else for that matter. I just want to provide enough info so as to aid in this being completed successfully without running into so many obstacles that anyone who attempts this will not give up. I also don't want to see someone ruin a possibly rare and/or
expensive cylinder head just to mount the injector and find out that the rest of the project is too difficult to complete. Good luck and feel free to ask anymore questions that come to mind.
>?
>Phil
>
>
>
>________________________________
>From: "ScottyGrover at aol.com" <ScottyGrover at aol.com>
>To: diy_efi at diy-efi.org
>Sent: Friday, September 9, 2011 12:15 AM
>Subject: Re: [Diy_efi] direct injection
>
>
>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.)
>
>Scotty
>
>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.
>>
>>Phil
>>
>>-----
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.
>>
>>-Avery
>>
>>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 this
>>>> >
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 any
>>>>
> data from Delphi, even as to the physical size (length, stem
diameter.)
>>>> >
>>>> > Scotty from
Hollyweird
>>>> >
_______________________________________________
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mailing list
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>>>> >
http://lists.diy-efi.org/mailman/listinfo/diy_efi
>>>>
>
>>>> >
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>>>>
>
>>>> >
>>>>
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list
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