Hi all, I'm new to the forum - looks like a great resource.

My 2002 RR (L322) with LPG (Lima) conversion has recently started experiencing a rough tickover when stationary or slow-moving.
It idles at about 650rpm, but the revs will drop; it will usually catch them and rev up to 1200, but often it just stalls. Sometimes it happens upon slow approach to a roundabout, which is tricky to negotiate without powered steering, powered brakes, or power.

I have looked at the Engine Breather Hoses which look fine from the outside (clean, not collapsed, fairly flexible).

I'm wondering about the MAF or the Accelerator Pedal Position Sensor.

Any suggestions (and costs) gratefully received.

Teddington, TW11
RR Mk3, 4.4 with LPG

are we talking the breather hoses at the back of the engine, they should be firm and not soft, i think you have an air leak, check the breathers and the vac pipes, have a good listen for any hissing.do you get any hissing when you take the petrol cap off. V8 facelift Range Rover Autobiography 22" wheels.
1976 Harley Davidson Iron Head Sportster

Does it do it on both Petrol and LPG? 5.0 supercharged autobiography
Gone-4.4 Vogue Lpg now unmapped
4.6 HSET Turbo Lpg mapped
Gone-Defender 90 200tdi
Gone - 3.9 Sprintex supercharged LPG
Gone - 3.9 Vogue LPG

Air flow meter.

If you buy a cheap ELM327 tool with software off ebay, you can plug it into the RR and read the engine data and codes. That will also include the readings from the airflow in terms of air flwo rate and air intake temp. If either are zero, then its gubbed.

No air flow reading wont throw an engine light - so its hard to tell without the OBD2 reader.

Sounds exactly the same as my symptoms I had recently. To cut it short. Buy genuine from the land rover dealer .... really .... dont even think about buying anything else.

http://www.fullfatrr.com/forum/topic10977.html V8 or else ...

Have you had the LPG serviced recently? I have this but not as bad. The LPG doesn't have as much bang and if it's tunning has slipped this can be caused. Mine does it when the AC compressor clutch is engaged. On petrol the ECU preempts this and over fuels to stop the dip in RPM on gas the dip is visible but hot as as bad as you have. Try on petrol with and without AC them again on gas with and without AC. [img]http://www.fuelly.com/driver/rob2529/range-rover[img/]
04, 4.4V8, Vogue Oslo Blue with LPG.
"You can sleep in your car, BUT you can't race your house!!!!"

If something can't be fixed with a hammer....... You have yourself an electrical fault!

Quote:

The LPG doesn't have as much bang and if it's tuning has slipped this can be caused.

See, I'm not so convinced that this happens so much with modern LPG installs. The sequential stuff ( as I understand it ) looks at the injector pulse timing of the petrol injectors, and then it creates an LPG injector pulse based on it. It'll may trim it slightly based on the O2 readings. Once that ratio is set between the petrol injector pulse and the LPG injector pulse ... what can go out of sync? LPG follows the petrol.

The petrol ECU runs completely unaware of whether its the petrol or lpg injectors throwing the fuel in. Any real fuel trimming gets done by the petrol ECU ... if it thinks the system is running rich, it'll back down the petrol injections till it reaches the correct air/fuel ratio .. and so the LPG will back down too.

My point is that bad running as described is still principly controlled by the petrol ECU, what it reads from sensors and the calculations it makes to create the petrol injector timing. For the sake of £20 to get an ODB2 reader, it really is worth it to find out what the engine is seeing.

My money is still on air flow meter  V8 or else ...

Thanks all.
I've ordered an ODB2 reader so will be able to check the air flow meter on Wednesday hopefully.

Symptoms are the same on LPG and on Petrol.
Equally, the same with AC on and AC off.

I'll have a listen to the breather hoses, but they did look good (clean, tight fitting and firm).

LPG system was serviced fairly recently; apparently some fairly major corrections to the settings were required then as the mix was much too lean and it was running hot. If only the RR temperature gauge told the truth, I might have picked that up myself...

I'll let you know what I can diagnose from the ODB2.

fisha wrote:

Quote:

The LPG doesn't have as much bang and if it's tuning has slipped this can be caused.

See, I'm not so convinced that this happens so much with modern LPG installs. The sequential stuff ( as I understand it ) looks at the injector pulse timing of the petrol injectors, and then it creates an LPG injector pulse based on it. It'll may trim it slightly based on the O2 readings. Once that ratio is set between the petrol injector pulse and the LPG injector pulse ... what can go out of sync? LPG follows the petrol.

The petrol ECU runs completely unaware of whether its the petrol or lpg injectors throwing the fuel in. Any real fuel trimming gets done by the petrol ECU ... if it thinks the system is running rich, it'll back down the petrol injections till it reaches the correct air/fuel ratio .. and so the LPG will back down too.

My point is that bad running as described is still principly controlled by the petrol ECU, what it reads from sensors and the calculations it makes to create the petrol injector timing. For the sake of £20 to get an ODB2 reader, it really is worth it to find out what the engine is seeing.

My money is still on air flow meter

I don't know the full ins and outs of LPG software but I'm not agreeing with this 100% (but could be very wrong). When I've had issues Andy (LPG tech) has plugged the laptop in and I've seen the graphs produced while the LPG has been in a learning cycle. Now he can adjust these to get the two graphs to match using what I can only assume as a trim type setting. Now if the petrol cycle had changed as they are a learning system you could find the LPG was slightly out due to the petrol adjusting. If that makes sense  [img]http://www.fuelly.com/driver/rob2529/range-rover[img/]
04, 4.4V8, Vogue Oslo Blue with LPG.
"You can sleep in your car, BUT you can't race your house!!!!"

If something can't be fixed with a hammer....... You have yourself an electrical fault!

fisha wrote:

Quote:

The LPG doesn't have as much bang and if it's tuning has slipped this can be caused.

See, I'm not so convinced that this happens so much with modern LPG installs. The sequential stuff ( as I understand it ) looks at the injector pulse timing of the petrol injectors, and then it creates an LPG injector pulse based on it. It'll may trim it slightly based on the O2 readings. Once that ratio is set between the petrol injector pulse and the LPG injector pulse ... what can go out of sync? LPG follows the petrol.

The petrol ECU runs completely unaware of whether its the petrol or lpg injectors throwing the fuel in. Any real fuel trimming gets done by the petrol ECU ... if it thinks the system is running rich, it'll back down the petrol injections till it reaches the correct air/fuel ratio .. and so the LPG will back down too.

My point is that bad running as described is still principly controlled by the petrol ECU, what it reads from sensors and the calculations it makes to create the petrol injector timing. For the sake of £20 to get an ODB2 reader, it really is worth it to find out what the engine is seeing.

My money is still on air flow meter

+1 What he said  Stolen / Gone: 2006MY Supercharged LPG Autobiography - Zambezi Silver with Sand/Jet/Jet Oxford Leather.....

OK, I got my new OBD2 to work after some port configuration trouble.

Fault Codes:
P0140 Oxygen sensor circuit no activity Bank 1 Sensor 2
P0443 Evaporative emission control system purge control valve circuit malfunction

Brief google searching elsewhere suggests that the Oxygen sensor shouldn't have any effect on the running of the engine. The Evaporative emission business could affect the engine running, but it doesn't quite help diagnose the problem.

No apparent fault with the airflow, pressure or temperature, so looks like those are ruled out.

Thanks for your help so far!

Tomorrow I shall attempt to remove the EVAP Purge Valve and see if it is working properly.
If it has failed in the open position then that might be the cause of my worries.
If not, then I've no idea...

Just because no fault is shown for the air mass meter it doesn't always mean it's not knackered. Beg or borrow one to try if your other route fails and if you need a new one make sure it's OEM.

Jonno 5.0 supercharged autobiography
Gone-4.4 Vogue Lpg now unmapped
4.6 HSET Turbo Lpg mapped
Gone-Defender 90 200tdi
Gone - 3.9 Sprintex supercharged LPG
Gone - 3.9 Vogue LPG

With the engine running look at the live values of the air flow and inlet temp.

Then blip the throttle, you should see the air flow change accordingly.

Errors are part of the diagnosis, but so are the live values too. V8 or else ...

Latest update:
Last night I tried to disconnect the EVAP Purge Valve. I got the electrical connector and fuel tank (in) pipe off, but I couldn't remove the engine side (out) pipe.
I wanted to test if the valve was stuck open or not, so I tried blowing through it but couldn't. Not conclusive, but suggests that the valve solenoid is closed.
Refitted valve.

Connected to OBD2 and started the engine.
Original 2 fault codes displayed as before (P0443 and P0140)

Blipped the throttle as suggested - the Mass Air Flow sensor values were responsive.

I reset the codes so I can check if they reappear in a few days. Also opened and closed the petrol cap.
Took the car for a drive and on the whole the revs seemed a bit smoother. Maybe this is going to turn into an intermittent fault...

For future reference, an EVAP purge valve has to be ordered via the dealer (not indie parts supplier) and costs around £55 inc VAT. I haven't ordered one yet.

Latest update:
Having made six trips totalling 150 miles, often with long periods in stationary traffic, the car has been behaving itself.
Rough idle cured and no stalling.

It's early days and the problem may reappear, but so far I can only put it down to:
1. disconnecting and squeezing a few pipes therefore dislodging something.
2. disconnecting and reconnecting the Purge Valve electrical connection, thereby improving the connection.
3. releasing the vacuum in the fuel tank via the filler cap.

Whichever way, I'm a happy man at present.

Next issue, the steering feels like it's wandering just a little (tyres are properly inflated). It might just be my hypochondria...