Anyone local with Diag/reset box of tricks?

Hi,
On the scrounge for help with my P38a 4.6HSE.
Runs like petrol is going out of fashion, have checked MAF (all OK at all revs) and new aftermarket Lambda's fitted.

(See thread http://www.landyzone.co.uk/lz/f10/sooty-lambdas-petrol-wont-lpg-284134.html for details).

Forget the LPG part, that's separate and for another time.
I am confused why the OBD tells me one Lambda is at 0.45 v and the other bank is at 0.95v. It has been suggested that the fuel "trims" need resetting and that diag tools are needed to do this.

Why oh why don't cars have CMOS resets like PC's? ;-)

I am in the Southend-on-Sea/Basildon area, anyone remotely close to me that can help, or must I pay a specialist garage?

I don't mind paying anyone, but since I retired and dropped to pension income I 'd rather not pay for the overheads of a business too! LOL.

Regards,

Dan.

iv got some diag on the pc but i cant get down to you this side of the eeek end

Those sensors should be a varying voltage, rather than fixed value. You need to check the voltage range (easier at low revs). They should both cover the same Min-Max. Very unlikely they will both read the same value at same time.

OXYGEN SENSORS

Pete

Tis a shame, I was over that way on Saturday - could have chucked the diag gear in the boot.

Thanks all respondents, I appreciate all the posts.
I will have another look at the reported values, I think though that even on Real-Time Data the Sensors are showing fixed values of 0.45v & 0.95v consistently (which doesn't seem right to me).

Regards,

Dan.

Just seen this thread aswell as your other one.

Mentioned in the other one about having a genuine Bosch MAF... Also this extends to the Lambda sensors. They should 'flip/flop' between about 0.1v and 0.8v ish under normal running - so if they've frozen and you are getting 0.45v and 0.95v all the time, then it's basically constantly telling the ECU that one bank is running bang on lambda, and the other is running rich all the time.

Again - same as with the MAF - the Bosch systems seem to be calibrated so tightly that anything other than genuine Bosch O2 sensors just don't seem to work properly (as you found out with the first set only lasting 3 months)

Again - I have just recently swapped my O2's out for a new set of Bosch ones, due to lumpy running at idle, to the point of misfiring - but only on a hot restart. Initially I was only getting misfire codes on cylinder 4, but over time it got worse, and it became all of bank 2 that was throwing codes.

2 Genuine Bosch sensors later (£55 inc VAT from Island 4x4... and free overnight shipping! I figured if one had quit, then the other wasn't too far behind) and she's now running sweetly again and the rough running at idle, on a hot start is gone completely.

Again, the GEMS systems that use the 'wide band' sensors which are 0-5V seem to be a lot more lenient and happy on aftermarket O2 sensors, but sadly not the Bosch ones!

I think if you swap the O2's out for some Genuine Bosch ones, and the same with the MAF (again Island 4x4 was the cheapest I found for the MAF) I think you will find that most of your issues will disappear pretty quickly - even without an adaptive values reset.

I know it's a lot more expensive to get the genuine Bosch parts, but the difference I found is night and day - and learnt my lesson with the MAF - hence I didn't even bother trying cheaper O2 sensors.. It just wasn't worth spending money on cheap ones to then just have to spend out again on the proper ones.

The LPG system slaves off the petrol system, so if the petrol system isn't running right, then the LPG system won't either. Most LPG systems (even the later multipoint ones) don't make their own adaptations as they run - some of them have the option to, but I've never seen it enabled - as then you end up with the LPG ECU fighting the petrol ECU... one will trim itself, then the other will trim, and so on and so forth. So they are generally set up so the LPG system just slaves off the petrol system. So if the petrol ECU is running out of whack, then the LPG will too.

Hope this helps.
Marty

Thanks Marty,

The latest ones fitted are specifically for this model RR (according to the seller)
and are part number MHK100940 (although the ad also said "Intermotor") which is a confusion in terms I think.

The ones my LR repairer had put on (that I suspected had failed and probably have not) are indeed Bosch (I just cleaned one up with contact cleaner and compared it to the picture in the online Bosch catalogue and it is deffo a Bosch original) so they should NOT have failed, but they are totally sooted up after only 3 months. I think the system is just shagged and without a proper diag tool on it I am stumped.

Time to spend yet more money on this hunk-of-junk.

If the MAF is showing more air flow than is going in and it's running rich, then that would blacken the O2 sensors pretty quickly..

If the original replacements were indeed Bosch, then they definitely shouldn't have failed in 3 months... I would be checking and tracing all the wiring for the O2 sensors... if could be possible that the LPG system has been connected to the O2 sensors (some off them use them just for the self-tuning part) and the wiring has been damaged, or the join has gone and corroded or failed altogether so that it's giving strange readings back to the ECU.

On mine, they had tapped into the O2 sensors down under the vehicle, and one side wasn't even soldered together - it was just wires twisted together and then insulation tape over the top... Needless to say I re-did them with solder!!

Without being able to see it/or the live data from Nanocom etc - it's a bit hard to diagnose remotely!

MHK100940 is the part number for the sensors, yes - Intermotor is just a manufacturer. I am not sure on what they are like for quality compared to Bosch, or Britpart/Bearmach etc.