Lambda sensors

would like to know if he fixed it cant say we didnt try

It's a Prins system. As soon as I get the chance to start crawling around under the car I'll post what happens.

Just to repeat the story so far -

I took the car to a garage as it was lumpy on tickover and stank of unburnt fuel. They changed the MAF, HT leads and plugs but found no signal from O2 sensors. They swapped one but still got no signal so thought they might have been programmed out of the ECU for some reason. When I got the car back it ran and idled OK but was rich, especially on petrol.

After that I wasn't sure what to do (if anything) but after several weeks contemplation decided just to have both O2 sensors replaced. Now I get a signal from one but steady state no response from the other. Now the tickover is a bit lumpy though it runs fine; the tickover is slightly worse on petrol, but is not even on gas either.

So far in the 3 months I've had the car I've spent a coupe of grand on it (tyres, exhausts, ball joints, plugs, HT, service, Maf etc, etc). I'm not keeping the car much longer so won't be spending much more on it, but I would like to get it running properly.

on some systems like mine the gas rules the petrol so if the gas is running rich the fuel trims will be a back door out so first l would get the gas set up then put a simple code reader on it read the codes and eliminate them run it on petrol then gas and u will find it may set it self thats what l did, mine was terrible it back fired and allsorts put a code reader on it eliminated a list of codes like war and piece hey presto runs great, just check the gas on the lap top with the auto set up every 3 months or so and fuel consumption is good on petrol and gas and pulls well

The LPG system also monitors MAF and O2 sensors etc, I'm guessing all signals are relayed through the LPG ECU to the Engines ECU so this maybe where the problem lies, either the extra wiring or LPG ECU itself.

thats why l would check the lpg to see what that is doing mine was driving the petrol crazy that and the stupid air filter somebody had put on. but yes also get the codes read and eliminate the old ones mine was a list like war and piece hope he gets it sorted

I had a fiddle around with the plug underneath last night but no miraculous change.

I don't currently have any software or interface for any ECU, just a wireless OBD connector and a couple of phone apps. I have cleared the fault codes though (several times).

Where does the O2 lead go - I can see the plug underneath the car but no idea what happens to the leads where they disappear around the gearbox?

800jimbo said:

Where does the O2 lead go - I can see the plug underneath the car but no idea what happens to the leads where they disappear around the gearbox?

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Straight to the ECU

has the car done any proper running maybe needs to learn the new fuel trims some times it can take 80 miles if l run mine on gas all the time if i need to run it on petrol to the garage for gas it does run lumpy so l run to work which is about 35 miles and it back to norm so maybe a good run on petrol

grumpy52 said:

has the car done any proper running maybe needs to learn the new fuel trims some times it can take 80 miles if l run mine on gas all the time if i need to run it on petrol to the garage for gas it does run lumpy so l run to work which is about 35 miles and it back to norm so maybe a good run on petrol

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I normally do about 50 - 100 miles a day and recently did a full tank on petrol just to compare fuel economy which (for information) is a shade under 17mpg on petrol and a shade under 13mpg on gas for normal mixed driving.

on that basis its not a million miles away from being right . l would buy a interface lead for the gas and with a lap top do a auto tune if l dont keep on top of mine checking faults with torque app and checking the gas with the lap top it soon goes off tune, im looking at buying a blue tooth interface so l can tune it on gas on the move. but other than a nanocom to go further l think you have done all u can have u checked the wiring on the fuel temp sender mine was iffy l repaired it might b worth a try good luck

Hi guys sorry to pick up on an old thread. Just did the 'control technique' here in france, failed ! "pollution", my car 1999 4.6 HSE V8 only 20,000 miles !. Bought in Spain 2 years ago is a second car to my 1997 2.5 DSE, so not used very often. I changed the bits like fan belt and a service also changed spark plugs also a new petrol pump as the old one wasn't showing up on the gauge (very important on a V8) its in the tank, quite a job dropping the tank. Since then my impression is its 'missing' at low revs and tick over and not fireing. properly It passed the CT two years ago no problem. I noticed that the lambdas are not connected ? but it was running fine without them. Maybe their redundant.
Sooo whats causing the missfire that the CT picks up as a fail ? I'm going to change the leads to magnacor next but, I dont really think its them. The guy at the CT was very help and said in his opinion it is an air perol mixture issue. Yes changed the maf for a new bosch also, what next air-line petrol line lair leaks ? I dont get it. Passed the nano and got code very imprecise.

RovyCouple said:

Hi guys sorry to pick up on an old thread. Just did the 'control technique' here in france, failed ! "pollution", my car 1999 4.6 HSE V8 only 20,000 miles !. Bought in Spain 2 years ago is a second car to my 1997 2.5 DSE, so not used very often. I changed the bits like fan belt and a service also changed spark plugs also a new petrol pump as the old one wasn't showing up on the gauge (very important on a V8) its in the tank, quite a job dropping the tank. Since then my impression is its 'missing' at low revs and tick over and not fireing. properly It passed the CT two years ago no problem. I noticed that the lambdas are not connected ? but it was running fine without them. Maybe their redundant.
Sooo whats causing the missfire that the CT picks up as a fail ? I'm going to change the leads to magnacor next but, I dont really think its them. The guy at the CT was very help and said in his opinion it is an air perol mixture issue. Yes changed the maf for a new bosch also, what next air-line petrol line lair leaks ? I dont get it. Passed the nano and got code very imprecise.

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The lambda sensors are used in the control of fueling unless I am very much mistaken.

Plug them back in and see what happens, cos as ^^^^ needed for correct fuelling.

Low mileage car may pass without maybe but now yours isn’t and not run much.

maybe they are knackered and that’s why PO disconnect maybe.

What code did nanocom give surely it would throw an O2 sensor fault if they were unplugged?

J