Emulate injectors - how?

Dodge Durango 99 5.9L, converted to run on LPG (single point). When running
on LPG injectors are disconnected to prevent them from working (or rather
the common positive lead is routed thru resistor so that voltage drop on
injectors is insufficient for them to operate), and naturally PCM complains
about open injector circuits. Alldata is pretty vague about P0201-P0208
codes, and only says "if induction kick is not detected PCM will set the
code". Apparently it checks not just for correct resistance but also for the
'inductive kick'.

Anybody knows how to properly emulate injectors on this engine?

Peter

Why don't you just disconnect the fuel pump and let the injectors operate
normally.

--
If at first you don't succeed, you're not cut out for skydiving


"Peter" > wrote in message
...
> Dodge Durango 99 5.9L, converted to run on LPG (single point). When
running
> on LPG injectors are disconnected to prevent them from working (or rather
> the common positive lead is routed thru resistor so that voltage drop on
> injectors is insufficient for them to operate), and naturally PCM
complains
> about open injector circuits. Alldata is pretty vague about P0201-P0208
> codes, and only says "if induction kick is not detected PCM will set the
> code". Apparently it checks not just for correct resistance but also for
the
> 'inductive kick'.
>
> Anybody knows how to properly emulate injectors on this engine?
>
> Peter
>
>
>

On Thu, 2 Jun 2005, TBone wrote:

> Why don't you just disconnect the fuel pump and let the injectors operate
> normally.

I'm not sure that'd be wise. Many injector designs depend on fuel flow to
cool the solenoid windings (i.e., to prevent them overheating and
cooking).

>> Why don't you just disconnect the fuel pump and let the injectors operate
>> normally.
>
> I'm not sure that'd be wise. Many injector designs depend on fuel flow to
> cool the solenoid windings (i.e., to prevent them overheating and
> cooking).

I'm not sure it's a good idea, too. Fuel pumps are designed to work
continuously, and disconnecting it could be yet another reason for CEL to
come on.

Peter

"Peter" > wrote in message
...
> >> Why don't you just disconnect the fuel pump and let the injectors
operate
> >> normally.
> >
> > I'm not sure that'd be wise. Many injector designs depend on fuel flow
to
> > cool the solenoid windings (i.e., to prevent them overheating and
> > cooking).
>
> I'm not sure it's a good idea, too. Fuel pumps are designed to work
> continuously, and disconnecting it could be yet another reason for CEL to
> come on.


While it is possible that the fuel injectors may overheat, the CEL will not
be set by the fuel pump being disconnected.

--
If at first you don't succeed, you're not cut out for skydiving

In message >, TBone
> writes
>
>
>"Peter" > wrote in message
...
>> >> Why don't you just disconnect the fuel pump and let the injectors
>operate
>> >> normally.
>> >
>> > I'm not sure that'd be wise. Many injector designs depend on fuel flow
>to
>> > cool the solenoid windings (i.e., to prevent them overheating and
>> > cooking).
>>
>> I'm not sure it's a good idea, too. Fuel pumps are designed to work
>> continuously, and disconnecting it could be yet another reason for CEL to
>> come on.
>
>
>While it is possible that the fuel injectors may overheat, the CEL will not
>be set by the fuel pump being disconnected.
>
There may be a fuel pressure sensor which would be triggered IIRC late
Volvo's have one. Incidentally my fuel pump does not run continuously.
There is a pressure switch on the rail which controls it. If you listen
you can hear the pump start up then after a few seconds switch off when
first switching on the ignition. I run my LR 4.0 litre V8 with injectors
running and pump off and have done so for 50k+ miles. Switch back to
petrol and absolutely no problem. We did this on the advice of a
technical consultant in this field who advised us that these injectors
do not rely on petrol for any form of cooling or lubrication. However I
don't recall whether he was actually referring to "all" injectors.
--
hugh
Reply to address is valid at the time of posting

On or around Thu, 02 Jun 2005 20:06:19 GMT, "TBone" >
enlightened us thusly:

>
>
>"Peter" > wrote in message
...
>> >> Why don't you just disconnect the fuel pump and let the injectors
>operate
>> >> normally.
>> >
>> > I'm not sure that'd be wise. Many injector designs depend on fuel flow
>to
>> > cool the solenoid windings (i.e., to prevent them overheating and
>> > cooking).
>>
>> I'm not sure it's a good idea, too. Fuel pumps are designed to work
>> continuously, and disconnecting it could be yet another reason for CEL to
>> come on.
>
>
>While it is possible that the fuel injectors may overheat, the CEL will not
>be set by the fuel pump being disconnected.

I've heard warnings against firing electronic injectors with no fuel, as
well.

you need an injector emulator. I don't know where you get one, but there
are such things as many of the more modern cars need 'em.

'course, if the computer is putting a warning light on, you could just
remove the bulb...

--
Austin Shackles. www.ddol-las.fsnet.co.uk my opinions are just that
Beyond the horizon of the place we lived when we were young / In a world
of magnets and miracles / Our thoughts strayed constantly and without
boundary / The ringing of the Division bell had begun. Pink Floyd (1994)

Peter wrote:

> Dodge Durango 99 5.9L, converted to run on LPG (single point). When running
> on LPG injectors are disconnected to prevent them from working (or rather
> the common positive lead is routed thru resistor so that voltage drop on
> injectors is insufficient for them to operate), and naturally PCM complains
> about open injector circuits. Alldata is pretty vague about P0201-P0208
> codes, and only says "if induction kick is not detected PCM will set the
> code". Apparently it checks not just for correct resistance but also for the
> 'inductive kick'.
>
> Anybody knows how to properly emulate injectors on this engine?
>
> Peter

If it were me, I'd probably just ignore the check-engine light :-)

But I wonder if you could wind a set of 8 iron-core electromagnets to be
the same inductance as a fuel injector, and then have the LPG system cut
over to the bank of "dummy" injectors. The fact that they don't have a
moving pintle might affect the waveform a bit, but I bet it wouldn't be
enough to trip the computer. It would add a lot of complexity since you
would have to put in 8 relays to switch over from the real injectors to
the dummies, intstead of a single relay to cut in the resistor on the
common side.

>> Dodge Durango 99 5.9L, converted to run on LPG (single point). When
>> running on LPG injectors are disconnected to prevent them from working
>> (or rather the common positive lead is routed thru resistor so that
>> voltage drop on injectors is insufficient for them to operate), and
>> naturally PCM complains about open injector circuits. Alldata is pretty
>> vague about P0201-P0208 codes, and only says "if induction kick is not
>> detected PCM will set the code". Apparently it checks not just for
>> correct resistance but also for the 'inductive kick'.
>>
>> Anybody knows how to properly emulate injectors on this engine?
>>
> If it were me, I'd probably just ignore the check-engine light :-)

I've considered that ;-) However this way I may miss other reasons CEL is on

> But I wonder if you could wind a set of 8 iron-core electromagnets to be
> the same inductance as a fuel injector, and then have the LPG system cut

I don't know what is the injector inductance. Alldata only specifies
resistance of 12 ohms

> over to the bank of "dummy" injectors. The fact that they don't have a
> moving pintle might affect the waveform a bit, but I bet it wouldn't be
> enough to trip the computer. It would add a lot of complexity since you
> would have to put in 8 relays to switch over from the real injectors to
> the dummies, intstead of a single relay to cut in the resistor on the
> common side.

Yep, 8 relays it is. I've considered it, but this would mean ungainly bundle
of wires, relays and coils of unknown inductance (or injectors from
junkyard). Are there relays that will switch 4/8 separate circuits?

Peter

On 02/06/2005 21:23 Peter wrote:

>>over to the bank of "dummy" injectors. The fact that they don't have a
>>moving pintle might affect the waveform a bit, but I bet it wouldn't be
>>enough to trip the computer. It would add a lot of complexity since you
>>would have to put in 8 relays to switch over from the real injectors to
>>the dummies, intstead of a single relay to cut in the resistor on the
>>common side.
>
>
> Yep, 8 relays it is. I've considered it, but this would mean ungainly bundle
> of wires, relays and coils of unknown inductance (or injectors from
> junkyard). Are there relays that will switch 4/8 separate circuits?

You can get 4-pole double-throw relays, can't remember where I seen them
but I definitely came across them as I was going to use it as part of a
car-phone kit with the two front speakers (two wires in each being
switched hence the 4-pole required). Never seen an 8-pole, but it would
be pretty huge packaging wise - the 4PDT has 14 pins!

Paul.