I have posted this on the LPG forum but thought I would post here too as normally someone knows what to do.
The LPG kit on my RR has started mucking about (it did it last week but I only remembered today when I went for a drive today).
Starting and running is fine but coming to a stop with the car in drive, the RPM drops to about 450-500 causing a slight stumble in the idle and it sits there. If I knock it in to neutral the RPM raises to 950 and it is happy again. No problem at all on petrol and regardless of the fuel it runs and drives fine.
I have tried turning the idle mixture screw up and it doesn't improve. Timing is spot on but moving it a few degrees in either direction doesn't make a difference. Checked for air leaks and none could be found, plugs all look good and I put a spare set of leads on which have not made a difference.
Any thoughts what to try next as running on unleaded at 9-16mpg is a bit expensive
LPG issue with idle in gear on an automatic box
LPG issue with idle in gear on an automatic box
Understeer: when you hit the wall with the front of the car.
Oversteer: when you hit the wall with the back of the car.
Horsepower: how fast you hit the wall.
Torque: how far you take the wall with you.
Oversteer: when you hit the wall with the back of the car.
Horsepower: how fast you hit the wall.
Torque: how far you take the wall with you.
Re: LPG issue with idle in gear on an automatic box
Does this make the thing difficult to drive or is it simply the fact that something has changed that concerns you, Terry? My train of thought is that, as long as the system remains free of leaks and is therefore safe, is there any real need to sacrifice the cheapness of running on gas between now and when you find someone who recognises this problem immediately and can suggest an effective cure.
Were it not for the fact that the idle doesn't drop on petrol I'd have blamed the transmission for this.
Were it not for the fact that the idle doesn't drop on petrol I'd have blamed the transmission for this.
J
"Home is where you park it", so the saying goes. That may yet come true..
"Home is where you park it", so the saying goes. That may yet come true..
Re: LPG issue with idle in gear on an automatic box
My two cents worth. If it was the same problem running on petrol I'd suspect a weak mixture, so I'd think the same running on LPG.
Currently over 35 years worth of fixing 35 boxes.
Hoping to reach 65 years worth of fixing 65 boxes.
Hoping to reach 65 years worth of fixing 65 boxes.
Re: LPG issue with idle in gear on an automatic box
It doesn't really affect the drivability however, the side effect of letting the engine idle at below 500rpm is the oil light flickers gently. There are a couple of threads on here where I have had fun with oil pressure problems in the past).
On petrol there is no problem at all (although I am used to problems first becoming apparent on LPG then appearing on the petrol system within a few miles). If it hadn't occurred in the same month as needing a new boiler and the PAS pump failing I would be worrying less.
I did try enriching the mixture a bit which I did by turning the idle screw out on the vaporiser. It didn't really make any difference until I had turned it out to the limit where the side effect is changeover from LPG - Petrol stalled the engine and Petrol - Gas revved it up to 2200rpm.
I think it's an excuse to upgrade to multi-point LPG later this year
Unfortunately I am working tomorrow so further fiddling is going to have to wait until next week. I can't remember when I last changed the LPG filter (possibly never) so I am going to pull that in the morning before heading to work to see if that is the issue.
On petrol there is no problem at all (although I am used to problems first becoming apparent on LPG then appearing on the petrol system within a few miles). If it hadn't occurred in the same month as needing a new boiler and the PAS pump failing I would be worrying less.
I did try enriching the mixture a bit which I did by turning the idle screw out on the vaporiser. It didn't really make any difference until I had turned it out to the limit where the side effect is changeover from LPG - Petrol stalled the engine and Petrol - Gas revved it up to 2200rpm.
I think it's an excuse to upgrade to multi-point LPG later this year
Unfortunately I am working tomorrow so further fiddling is going to have to wait until next week. I can't remember when I last changed the LPG filter (possibly never) so I am going to pull that in the morning before heading to work to see if that is the issue.
Understeer: when you hit the wall with the front of the car.
Oversteer: when you hit the wall with the back of the car.
Horsepower: how fast you hit the wall.
Torque: how far you take the wall with you.
Oversteer: when you hit the wall with the back of the car.
Horsepower: how fast you hit the wall.
Torque: how far you take the wall with you.
-
Richard Moss
- Posts: 425
- Joined: Wed Jan 05, 2011 5:09 pm
Re: LPG issue with idle in gear on an automatic box
Does your system have some sort of mixture compensation device on the LPG mixer? Usually on single-point these are a means of increasing LPG flow to augment the normal LPG idle control. If it has one they are usually mechanical (vacuum controlled) or electronic (using the coil wiring). If so, it could be maladjusted or faulty and adversely affecting the mixture, which would be more noticeable at idle than in normal running.
I've often found idling problems to be a consequence of a dirty mixer, throttle body or vapouriser. If the carb/throttle body idle control system is gunked up then it may be struggling to keep pace with the demands. Is the vapouriser clean inside? There is usually a valve to drain off the greasy "heavy ends" deposits inside. Is the vapouriser getting a good supply of warm coolant to prevent it freezing up? Are the spark plugs due for a change? LPG needs a good spark, as you know.
I've often found idling problems to be a consequence of a dirty mixer, throttle body or vapouriser. If the carb/throttle body idle control system is gunked up then it may be struggling to keep pace with the demands. Is the vapouriser clean inside? There is usually a valve to drain off the greasy "heavy ends" deposits inside. Is the vapouriser getting a good supply of warm coolant to prevent it freezing up? Are the spark plugs due for a change? LPG needs a good spark, as you know.
Re: LPG issue with idle in gear on an automatic box
I put in a new set of plugs first thing this morning (I didn't know there was a 6am on Sundays!). Went to work and back, the problem was still there but on getting home, pulling a couple of plugs shows that it is indeed running lean. There is a bypass screw on the vaporiser which is completely closed (as per the instructions). I have turned the idle screw out half a turn which hopefully will make a bit of a difference to that. The vaporiser is an OMVL R90 which has both top and bottom outlets for gas, following advice from lpgforum I pulled the cap off the bottom and YUCK, it was full of sludge. The cap was brim full and a large amount ran out on to the inner wing. OMG does that stuff stink! I have connected the gas outlet to the bottom connector now and blanked off the top one which (according to lpgforum) will allow the heavy ends to get burnt off in the engine. I won't get opportunity to go for a proper drive until next weekend but after a quick spin around the block, the car feels like it has more go now. It didn't get properly warm so I have no way to tell if the problem is fixed however, I ordered a service kit for the vaporiser from tinleytech so hopefully if the problem still exists, servicing that and fitting a new filter it will fix that. Hopefully that will be a cheap fix.
Understeer: when you hit the wall with the front of the car.
Oversteer: when you hit the wall with the back of the car.
Horsepower: how fast you hit the wall.
Torque: how far you take the wall with you.
Oversteer: when you hit the wall with the back of the car.
Horsepower: how fast you hit the wall.
Torque: how far you take the wall with you.
Re: LPG issue with idle in gear on an automatic box
Terry when was the last time you changed the fuel filter on the lpg system?
There is usually a filter between the vapourisor and the injector(s) these stop all that gunk
getting into the engine and fouling that up too!
That is the only thing I can add to what richard has said, Yes I have fitted and used a single
point lpg kit before as well as sequential (multipoint) kits to cars. How is the back fire valve
fitted on your RR setup? Or are you going through the intake manifolds or air boxes?
Sorry not been able to help previously, but been fighting the BT fiber optic gremlins
There is usually a filter between the vapourisor and the injector(s) these stop all that gunk
getting into the engine and fouling that up too!
That is the only thing I can add to what richard has said, Yes I have fitted and used a single
point lpg kit before as well as sequential (multipoint) kits to cars. How is the back fire valve
fitted on your RR setup? Or are you going through the intake manifolds or air boxes?
Sorry not been able to help previously, but been fighting the BT fiber optic gremlins
I'm Diabetic,& disabled BUT!! NOT DEAD YET!!
Re: LPG issue with idle in gear on an automatic box
'Evening Aaron,
I don't think I have ever changed the LPG filter however I did pull it out and it made no difference. I have ordered a new one as part of the service kit for my vaporiser so will bung that in at the weekend.
The vaporiser (via a power valve) is plumbed in just before the butterfly in the intake plenum. I have had a few LPG kits although they have all been single point. I think this is the only one I have had for long enough for it to need a service. (Quick bit of mental maths, I have done almost 50,000 miles in this car and I don't think I have ever changed the LPG filter. Add that to however many miles the previous owner did and it is a seriously long lived filter! Mind you I have replaced the vaporiser and the engine in that time). I have never changed the (petrol) fuel filter either but that is because it is a lump of rust that has welded itself to the fuel lines and I don't want to replace those.
I was looking at a replacement front end kit but a decent multi-point one is £700 so that can wait until I am feeling flush. I resent buying parts that cost as much as the whole car did!
Hopefully cleaning the heavy ends out and taking it for a run then re-calibrating the system has sorted the problem (it did turn the full power setting up by 5%). I'll slap the service kit I have on the vaporiser on Saturday. (SWMBO is going out so I can make use of the kitchen table. don't tell her!)
I don't think I have ever changed the LPG filter however I did pull it out and it made no difference. I have ordered a new one as part of the service kit for my vaporiser so will bung that in at the weekend.
The vaporiser (via a power valve) is plumbed in just before the butterfly in the intake plenum. I have had a few LPG kits although they have all been single point. I think this is the only one I have had for long enough for it to need a service. (Quick bit of mental maths, I have done almost 50,000 miles in this car and I don't think I have ever changed the LPG filter. Add that to however many miles the previous owner did and it is a seriously long lived filter! Mind you I have replaced the vaporiser and the engine in that time). I have never changed the (petrol) fuel filter either but that is because it is a lump of rust that has welded itself to the fuel lines and I don't want to replace those.
I was looking at a replacement front end kit but a decent multi-point one is £700 so that can wait until I am feeling flush. I resent buying parts that cost as much as the whole car did!
Hopefully cleaning the heavy ends out and taking it for a run then re-calibrating the system has sorted the problem (it did turn the full power setting up by 5%). I'll slap the service kit I have on the vaporiser on Saturday. (SWMBO is going out so I can make use of the kitchen table. don't tell her!)
Understeer: when you hit the wall with the front of the car.
Oversteer: when you hit the wall with the back of the car.
Horsepower: how fast you hit the wall.
Torque: how far you take the wall with you.
Oversteer: when you hit the wall with the back of the car.
Horsepower: how fast you hit the wall.
Torque: how far you take the wall with you.
Re: LPG issue with idle in gear on an automatic box
Terry it all depends on where you look for the kits, and £700 IS OTT!!!
This a link to a 6 clinder kit I have book marked but the site has the ohers listed
http://www.lpgshop.co.uk/6cyl-mini-kit- ... omvl-rail/
This a link to a 6 clinder kit I have book marked but the site has the ohers listed
http://www.lpgshop.co.uk/6cyl-mini-kit- ... omvl-rail/
I'm Diabetic,& disabled BUT!! NOT DEAD YET!!
Re: LPG issue with idle in gear on an automatic box
If you wanted to be an uber skrimper, a second hand kit?
http://www.ebay.co.uk/itm/lpg-gas-kit-d ... 1c3c27052d
http://www.ebay.co.uk/itm/lpg-gas-kit-d ... 1c3c27052d
I'm Diabetic,& disabled BUT!! NOT DEAD YET!!