Hello all,

A request for information and opinions on the ignition timing of a V6 motor 
run by a Bosch 7.0 ecu both the injectors and the plugs are feed from this 
i.e. no distributor. Its a 3 channel system i.e. the plugs and injectors 
fire twice per 4cycle. I have fitted a LPG system to this (the petrol is 
still there for starting from cold). It is said that a LPG system will work 
better by advancing the ignition by ten or eleven degrees. I have a Snap-on 
MT2500 scanner and it looks like I could advance the timing with it.

Supposing I can do this

(1) will the timing stay advanced or would the various sensors detect this 
and return it normal?

(2) if it did stay advanced on LPG what would happen when it was run on 
petrol would the sensors "knock sensor"? retard the timing if it picked up 
any rough running of the motor?

(3) would experimenting with a 10 deg adjustment do any permanent damage?

BTW the scanner says the ignition advances by about 35 deg when the motor is 
revved with no load.

George.

I was wrong I cant adjust the timing. Would it be possible to fool one of 
the sensors to get the same result?

George.


"George Gosbee"  wrote in message 
news:Wtiue.8136$y57.4334@fe1.news.blueyonder.co.uk...

> Hello all,
>
> A request for information and opinions on the ignition timing of a V6 
> motor run by a Bosch 7.0 ecu both the injectors and the plugs are feed 
> from this i.e. no distributor. Its a 3 channel system i.e. the plugs and 
> injectors fire twice per 4cycle. I have fitted a LPG system to this (the 
> petrol is still there for starting from cold). It is said that a LPG 
> system will work better by advancing the ignition by ten or eleven 
> degrees. I have a Snap-on MT2500 scanner and it looks like I could advance 
> the timing with it.
>
> Supposing I can do this
>
> (1) will the timing stay advanced or would the various sensors detect this 
> and return it normal?
>
> (2) if it did stay advanced on LPG what would happen when it was run on 
> petrol would the sensors "knock sensor"? retard the timing if it picked up 
> any rough running of the motor?
>
> (3) would experimenting with a 10 deg adjustment do any permanent damage?
>
> BTW the scanner says the ignition advances by about 35 deg when the motor 
> is revved with no load.
>
> George.
>
>
>
> 

"George Gosbee"  wrote in message 
news:jXiue.8226$y57.4774@fe1.news.blueyonder.co.uk...

>I was wrong I cant adjust the timing. Would it be possible to fool one of 
>the sensors to get the same result?
>
> George.


If the engines got a knock sensor, it should automatically adjust the 
timing.

Thanks for the reply.

It has and I have just tested it on petrol and lpg and get the same advance 
reading on both or are you saying the knock sensor will retard it if I 
manage to advance it for lpg?

George.


"Moray Cuthill"  wrote in message 
news:42b9eb6d@news.greennet.net...

>
> "George Gosbee"  wrote in message 
> news:jXiue.8226$y57.4774@fe1.news.blueyonder.co.uk...
>>I was wrong I cant adjust the timing. Would it be possible to fool one of 
>>the sensors to get the same result?
>>
>> George.
>
> If the engines got a knock sensor, it should automatically adjust the 
> timing.
> 

"George Gosbee"  wrote in message
news:M2kue.8438$y57.2757@fe1.news.blueyonder.co.uk...

> Thanks for the reply.
>
> It has and I have just tested it on petrol and lpg and get the same
advance
> reading on both or are you saying the knock sensor will retard it if I
> manage to advance it for lpg?
>


The ECU will start with a base timing figure, lets say for arguements sake-
10deg BTDC. It always tries to reach this figure but usually doesnt due to
engine pinking or knocking, which it reads through the knock sensor. When
this happens it will retard the timing a set amount (usually 2 degrees)
immediately for 4 crankshaft revolutions before trying to advance it back.

After a while the ECU will have stored what is the most advanced timing it
can get away with at various loads / temperatures / revs etc and rarely will
it get a 'i'm knocking' signal back from the KS.

Obviously for LPG , you may want a base timing figure which is more advanced
than the ECU's base figure, so in practive you will never reach this figure
as the ECU isnt programmed to pass it. The only way around this is a custom
map, a custom ECU or an RPI style timing advance interceptor, which when you
switch to LPG it gives you x amount of additional advance on whatever the
ECU is saying...

Tim..

"Tim.."  wrote in message 
news:d9cjt9$849$1@nwrdmz01.dmz.ncs.ea.ibs-infra.bt.com...

>
> "George Gosbee"  wrote in message
> news:M2kue.8438$y57.2757@fe1.news.blueyonder.co.uk...
>> Thanks for the reply.
>>
>> It has and I have just tested it on petrol and lpg and get the same
> advance
>> reading on both or are you saying the knock sensor will retard it if I
>> manage to advance it for lpg?
>>
>
> The ECU will start with a base timing figure, lets say for arguements 
> sake-
> 10deg BTDC. It always tries to reach this figure but usually doesnt due to
> engine pinking or knocking, which it reads through the knock sensor. When
> this happens it will retard the timing a set amount (usually 2 degrees)
> immediately for 4 crankshaft revolutions before trying to advance it back.
>
> After a while the ECU will have stored what is the most advanced timing it
> can get away with at various loads / temperatures / revs etc and rarely 
> will
> it get a 'i'm knocking' signal back from the KS.
>
> Obviously for LPG , you may want a base timing figure which is more 
> advanced
> than the ECU's base figure, so in practive you will never reach this 
> figure
> as the ECU isnt programmed to pass it. The only way around this is a 
> custom
> map, a custom ECU or an RPI style timing advance interceptor, which when 
> you
> switch to LPG it gives you x amount of additional advance on whatever the
> ECU is saying...
>
> Tim..
>
>

Thanks,

I agree the remapping would work but would be prohibitively expensive.

Yes but the HT coils are directly controlled by the ECU so cant see how an 
external device would advance the timing?

George.

"George Gosbee"  wrote in message
news:X2oue.9775$y57.4990@fe1.news.blueyonder.co.uk...

>
> "Tim.."  wrote in message
> news:d9cjt9$849$1@nwrdmz01.dmz.ncs.ea.ibs-infra.bt.com...
> >
> > "George Gosbee"  wrote in message
> > news:M2kue.8438$y57.2757@fe1.news.blueyonder.co.uk...
> >> Thanks for the reply.
> >>
> >> It has and I have just tested it on petrol and lpg and get the same
> > advance
> >> reading on both or are you saying the knock sensor will retard it if I
> >> manage to advance it for lpg?
> >>
> >
> > The ECU will start with a base timing figure, lets say for arguements
> > sake-
> > 10deg BTDC. It always tries to reach this figure but usually doesnt due
to
> > engine pinking or knocking, which it reads through the knock sensor.
When
> > this happens it will retard the timing a set amount (usually 2 degrees)
> > immediately for 4 crankshaft revolutions before trying to advance it
back.
> >
> > After a while the ECU will have stored what is the most advanced timing
it
> > can get away with at various loads / temperatures / revs etc and rarely
> > will
> > it get a 'i'm knocking' signal back from the KS.
> >
> > Obviously for LPG , you may want a base timing figure which is more
> > advanced
> > than the ECU's base figure, so in practive you will never reach this
> > figure
> > as the ECU isnt programmed to pass it. The only way around this is a
> > custom
> > map, a custom ECU or an RPI style timing advance interceptor, which when
> > you
> > switch to LPG it gives you x amount of additional advance on whatever
the
> > ECU is saying...
> >
> > Tim..
> >
> >
> Thanks,
>
> I agree the remapping would work but would be prohibitively expensive.
>
> Yes but the HT coils are directly controlled by the ECU so cant see how an
> external device would advance the timing?


RPI's device records timing advance on stroke 1 and lets it pass through. On
stroke 2 the device intercepts the timing signal, adds the programmed
advance then fires the coil. At the same time it checks to see if the
recorded signal on stroke 1 matches that on stroke 2. If not, it recomputes
an advance figure for stroke 3. etc etc etc.

Tim..

I can understand that.

On BRCs web site the modified feed to the coils is by way of the earth so 
will have to see how the earth is connected as it may be part of the coil 
mounting. The 3 coils surround the 3 front plugs with ht leads to the back 
3.

George.


"Tim.."  wrote in message 
news:d9dqna$7t7$1@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com...

>
> "George Gosbee"  wrote in message
> news:X2oue.9775$y57.4990@fe1.news.blueyonder.co.uk...
>>
>> "Tim.."  wrote in message
>> news:d9cjt9$849$1@nwrdmz01.dmz.ncs.ea.ibs-infra.bt.com...
>> >
>> > "George Gosbee"  wrote in message
>> > news:M2kue.8438$y57.2757@fe1.news.blueyonder.co.uk...
>> >> Thanks for the reply.
>> >>
>> >> It has and I have just tested it on petrol and lpg and get the same
>> > advance
>> >> reading on both or are you saying the knock sensor will retard it if I
>> >> manage to advance it for lpg?
>> >>
>> >
>> > The ECU will start with a base timing figure, lets say for arguements
>> > sake-
>> > 10deg BTDC. It always tries to reach this figure but usually doesnt due
> to
>> > engine pinking or knocking, which it reads through the knock sensor.
> When
>> > this happens it will retard the timing a set amount (usually 2 degrees)
>> > immediately for 4 crankshaft revolutions before trying to advance it
> back.
>> >
>> > After a while the ECU will have stored what is the most advanced timing
> it
>> > can get away with at various loads / temperatures / revs etc and rarely
>> > will
>> > it get a 'i'm knocking' signal back from the KS.
>> >
>> > Obviously for LPG , you may want a base timing figure which is more
>> > advanced
>> > than the ECU's base figure, so in practive you will never reach this
>> > figure
>> > as the ECU isnt programmed to pass it. The only way around this is a
>> > custom
>> > map, a custom ECU or an RPI style timing advance interceptor, which 
>> > when
>> > you
>> > switch to LPG it gives you x amount of additional advance on whatever
> the
>> > ECU is saying...
>> >
>> > Tim..
>> >
>> >
>> Thanks,
>>
>> I agree the remapping would work but would be prohibitively expensive.
>>
>> Yes but the HT coils are directly controlled by the ECU so cant see how 
>> an
>> external device would advance the timing?
>
> RPI's device records timing advance on stroke 1 and lets it pass through. 
> On
> stroke 2 the device intercepts the timing signal, adds the programmed
> advance then fires the coil. At the same time it checks to see if the
> recorded signal on stroke 1 matches that on stroke 2. If not, it 
> recomputes
> an advance figure for stroke 3. etc etc etc.
>
> Tim..
>
>