General: 70: Lambda issue with LPG conversion

[JsR]

Originally Posted by cootuk

I thought gas fuel economy was lower, but makes up for it in terms of being about half the price of petrol....

Until Gordon (or his successor) has his way - after all, that's what happened with diesel...

[timh30]

I'm told with the latest lpg sgi systems fuel economy should be about 10% less than on petrol due to its lower calorific value. So I'm hoping for approx 27-28 mpg on gas which currently equates to 55mpg at petrol prices.

As I'm only currently running on the default map settings and having been testing the performance out on gas, hopefully that figure is achievable.

For anyone else thinking about getting a newer model car converted, I'd certainly investigate the lambda probe first and whether it is a normal 0-1v type as if it isn't (and the installer has not dealt with that type of car before) you could end up in the same 'try it and see' approach that I'm in - which is not only very time consuming but costly if you end up buying new lambda probes. If you/installer do suspect a faulty probe make sure that whoever you are buying the probe from knows exactly what they are talking about, I've made a lot of telephone calls and posts on this issue (here and on other forums) and most people had completely differing views as to what type it is.

[Chris_Rogers]

If you have doubt then the simple way is to get the manufactures part number from the proble itself (in/near the exhaust manifold) and work from that.
However I can assure you it's a Bosch wideband sensor.

[Chris_Rogers]

Originally Posted by cootuk

http://www.forparts.com/BoswidebandO2.htm

"The wideband oxygen sensor receives a reference voltage from the engine computer and generates a signal current that varies according to the fuel mixture.
When the air/fuel mixture is perfectly balanced at 14.7:1 (the stoichiometric ratio and lambda equals 2), the sensor produces no output current. When the air/fuel mixture is rich, the sensor produces a "negative" current that goes from zero to about 2.0 milliamps when lambda is 0.7 and the air/fuel ratio is near 11:1.
When the air/fuel mixture is lean, the sensor produces a "positive" current that goes from zero up to 1.5 milliamps as the mixture becomes almost air."

I thought I remembered something like that.

Typo?

"the stoichiometric ratio and lambda equals 2"

I think you will find Lambda equals 1 at stoichiometric ratio.

[entwisi]

I have a Prins kit on mine (2.5 LPT), initially they did have a few issues with getting teh lamba sensor set correctly. Its been fine now for about 8 months.

As for economy, I sit at ~80 on the motorway for about 40 miles of my 54 mile each way commute, I'm quite heavy footed for the rest of the journey as its a nice twisty A/B roads. At worst I get ~20 at best I get 23/4. I reckon if I was a good little boy I could get 25 without any major problems but then why drive a car like this and be a good boy

[timh30]

Just reading through those articles in detail suggests that the wideband sensor would have 5 wires. Mine only has 4 ! I'll have to try and read the part number off the probe and confirm exactly what it is (no doubt easier said than done).