The Lambda sensor replacement in another post came about as Philip was having trouble with his Zavoli LPG system, either not switching over to gas or getting switched over then flipping straight back as though there was no gas present.

I've not had much time of late to get involved, but I did fit the new Lambda sensors today while he was working inside. Then I told him to give it a run after we had checked that both Lambda were working, which they were.

That cured that fault, but we still had this switching on and off problem.

I've got the Zavoli software on the laptop and the lead to plug into the ECU, so we went out for a drive, him driving and me in the passenger seat with the laptop.

First thing I noticed was that on mine, I am on gas within a hundred yards or so at this time of year, everything is already warm so it flips over after a couple of junctions, while we were 2.5 miles out of town and his still wasn't going over.

We did a 5-mile run and it did flip over once, but I couldn't force it manually and it didn't like it at all.

When we got back, I plugged the laptop into mine, and immediately we could see that he had no temperature readings for vapouriser water and gas (post-vapouriser) even though both were obviously hot. Mine ran at 75 Dec C and 40 Deg C by the side of the road.

Twiddling the wires to the two sensors brought an immediate change on the screen, the vapouriser went up to 70 Deg C and the gas up to 40 Deg C.

It looks like we have a damaged wire on one sensor and the other has either road salt in the lead-out or just a damaged sensor.

That makes sense, as the display shows -40 Deg C with no sensor functioning, so not surprising that it didn't want to change over to gas.

I'm going over to Tinley Tech in the morning and pick up a pair of sensors.

Thanks to Peter Feacey of Energyshift who gave us time on the phone to talk through what we thought (correctly) was the problem.

We need it back on the road as we have both engines going to the Tibenham show on Sunday, and Philip is taking one of them.

Peter

This is one of those situations where it is good to have notes,(I have a leather bound black book...) of good data recorded.When there is a problem you can then look back and see where the fault is.If a temp reading is fairly obviously out then its easy,but - just as an example, with a Thor injected v8 like yours where Mafs often die slowly without logging a fault,its not always easy to see whats wrong.

Agree on the notes and MAF's, plus too many buy the cheapie MAF copies off ebay which invariably don't work properly, just as easy to buy a Bosch one and do it right.

Got the sensors from Tinley tech this morning, they aren't far away from us, wires broken inside the heat shrink on one and a repair on the other one had failed.

Changed them both and it's a good 'un

Peter

Carrying on from the Lambda and Temperature sensors renewal, we got to the main issue, which is what I would describe as a 'bad stumble' on LPG.

It doesn't do it on petrol, it doesn't do it on LPG if the laptop is reading the LPG ECU.

It isn't a single misfire, it seems as though the ECU is 'confused'.

Backing off the throttle gets it running again for a while but then it returns.

We have not reproduced it with the laptop online and watching the parameters, despite a lot of mileage today.

We do have a bearing going in either the alternator or aircon pump, it is quite 'mechanical' so we are starting to wonder if there is enough vibration going into the block to affect the knock sensors?

Going to pull the belt off tomorrow and run with my belt (No aircon on mine) to see if we can isolate the noise. It sounds aircon pump but doesn't stop with the pump off, so maybe the alternator front bearing, although it doesn't sound fast enough.

Water pump isn't that old, but we have a new spare one just in case.

Pleased to get the Lambdas and LPG sensors sorted properly, but a bit p*ssed off to have this weird problem coming up.

Peter

May be worth doing an adaptive reset,if the engine has run a while with bad feedback from the oxygen sensors,the long term trims might be far enough off for the injector pulse widths to have narrowed right down.
I don't think mechanical noise from elsewhere would upset the knock sensors,even if it could all it would do is back the timing off on a few cylinders over a few firing strokes - probably not even enough for you to notice any difference.
What are the oxy sensors reading whilst the engine is faulting ?

Just back from Tibenham, Philip ran the laptop both ways to hold the ECU stable, and as long as it is plugged in and online nothing happens.

I'm going to open the ECU up tomorrow and have a look to see if we have condensate inside the enclosure or whatever.

Then we'll get Hawkeye involved as well.

Peter

Got into the ECU this morning, it uses a low drop-out LM2397ET5.0 regulator, which is surface soldered to the board, and one of the adjacent capacitors looks overheated.

Our theory is that the 5V control supply is down, but when we plug in the laptop it can get 5.0V from the USB supply which lifts the control rail in the ECU.

We changed the dodgy-looking cap but no effect, a new regulator is next, and we swapped my ECU for his and it runs fine. Ordered new regulator from RS, will be here tomorrow. New ECU is £350

Quite a nice board, mixture of mainly surface mount stuff with through-hole relays for the injector change-over function and a big power relay for power on/off.

Watch this space.

Peter

No improvement, we've got a new ECU on the way.

Peter

what a zavoli??..OR am i confused and you talking petrol ecu??in which case opps..

why??(if gas)

send it back and go buy a king from tinley at 170 with many more functions..(same aeb manufactor..but so much better, come with loom etc)

dont forget too one can turn off the diagnostic fault control on the gas ecu..so if it detects a fault it still works..with it on it shuts down..

Thanks, Zen, Zavoli is the LPG ECU. It definitely had a fault within the ECU, fitted new one and set it up, away it went.

Took both engines up to Driffield at the weekend, Philip was towing about 2 tons, I had the big trailer on at 3.5 tons, both D2's went well. Filled up at Doncaster, 100 miles for 45 litres on mine, not too bad for what is a pretty hilly run.

I've also got the latest software from Pete Feacey for the Zavoli ECI (It's an AEB, as are most of the market) so we can do some fine trimming this week.

Here are our two engines on the Saturday, it was a nice day, but Sunday was a real shocker:



Peter