Cannot Clear Check Engine Light - Apparently?

[EViS]

I have a Romano system fitted in my 2004 4.6l V8. Not knowing how well the previous owner had maintained the system and with a CEL appearing due to both banks running too lean (P1071 and P1074), I sent the truck over to a local LPG specialist for a once-over and to stop the CEL from lighting up.

Apparently the system was "way off" and he spent a day tuning the system "feathering it throughout the rev's" in the shop and driving it up and down an A road. However, although he's confident that the system is now running as well it can be, he could not prevent the CEL light from illuminating as the "vaporiser does not have mechanical dials/screws for fine adjustment".

Is this all plausible? Although the system seems to be working, other than a rough idle (only on LPG), the CEL bugs me that long term damage is being done due to a too lean mixture...

[LPGC]

Doesn't seem to me the person supposedly sorting the problem has done a very good job..

If there was a problem with the vaporiser - why didn't he advise you that a new vaporiser was required? The excuse of too low a pressure sounds implausible anyway.

Where did you go?

Simon

[EViS]

I should have mentioned that he did suggest a new vaporiser, however at circa £300 (I recall him saying), he doesn't think it's worth it.

I'd rather not name the shop but suffice to say they do get recommended a fair bit on various forums, at least for being local in the area if nothing else.

[Tubbs]

Sometimes. Unless you reset the adaptivity it can stay well off. Even if the s/t trim is right. The long term will switch the mil on because it hasn't got a lot of room for manoeuvre. Maybe he didn't have the right tool. What is it ? An x5 ?

[EViS]

It's an F150. By "right tool", I presume you are referring to the software. Is this manufacture specific?

[Tubbs]

They arnet generally a problem child tbh. Pretty straightforward.

[EViS]

They arnet generally a problem child tbh. Pretty straightforward.

Does it make a difference (to the LPG tuning) if there is a SuperChips programme installed?

And should it be possible to fine tune without the screw dials on the vaporiser? Or are they pretty fundamental as I do see them mentioned a fair bit around the forums?

[LPGC]

What is it ? An x5 ?

2004 4.6V8 had me thinking it was likely a Valvetronic X5 too mate!

Being a 2004 Ford, then, it may not have a fuel return and may need one to be fitted.. If this is the case, until a fuel return is fitted you can expect problems. With a code reader plugged into the vehicle's OBD socket showing live data, does the OBD reader show any info on petrol fuel pressure? If so, a fuel return should be fitted - Or you can 'cheat' and add a constant petrol addition of 1ms but this will mean the vehicle uses petrol while running on gas, by far the easiest way of getting around the problem though!

Aftermarket petrol ECU tuning chips can cause problems if the fueling map in the chip doesn't really suit the engine. To confirm this would involve a drive on petrol watching the fuel trims and high load mixture. There are little gains to be made from fitting an aftermarket tuning chip to any petrol engine that doesn't have a turbo / supercharger in any case. I wouldn't bother fitting a superchip to any normally aspirated petrol engine that hasn't also been fitted with aftermarket engine parts such as a cam change, manifolds change, etc. Fitting a tuning chip can b****r up the fueling map if the chip doesn't suit the engine, though I doubt the Superchip is making much difference in this case. As said, drive on petrol and see what the trims and mixture are doing.

With few provisos (injector nozzle size and pressure within anything like the correct range), up to a point, an installer should be able to make differences to the tuning of the LPG system particularly at low engine loads.

Simon

[LPGC]

Where in the world are you Elvis (sorry EViS)? hehe...

Simon

[EViS]

I'm in Surrey, Simon. Thank you very much for that detailed reply. How would I know if the truck has a fuel return? It's an 04-08 f150. I don't have a detailed OBD reader, only the SuperChips computer which will read codes and clear them.

[LPGC]

Welcome to replies mate..

I've outlined what is perhaps the easiest way to check for a fuel return above (using an OBD scanner that shows live data) - That way you don't even need to lift the bonnet...

Or you can do a physical check - Vehicles with a factory fitted fuel return will have 2 pipes to the petrol tank not including the evap pipe (purpose of evap pipe is to allow petrol tank vapour to be burned off in the engine, so no HC's escape to atmosphere when you remove the petrol filler cap) . If a vehicle has a factory fitted fuel return it will have a mechanical pressure regulator, usually but not always fitted on the petrol injector fuel rail.

You're a bit far from me in Surrey, Tubbs will be closer if you struggle.

Simon

[EViS]

I was recommended another installer who I visited a couple weeks back. He too could not clear the CEL. I was by his side the entire time so know he worked quite hard trying to find the symptom.

He spent the best part of an hour trying to get the fuel compensation down to around 5% at idle. We then went for a drive where he kept tinkering. However, as soon as I opened up the throttle (doing around 40mph at the time), the fuel compensation shot up to 20%+. He couldn't get this down.

Back in the workshop, he checked the emissions which confirmed that the system continuously runs lean. I forgot to ask whether this would be an MOT failure?

He also wasn't too sure why his Romano software had greyed out the 'Lambda 2' sensor - could it be a faulty sensor OR the ECU is just too old to measure both sensors?

He is hiring a newer model ECU from Romano which can supposedly provide more details on individual cylinders and injectors. He will temporarily hook this up to see if there is anything else that can be found as faulty.

Interestingly, he too said that his gut feeling is that upping the pressure (from I *think* 1.2bar to 1.5bar) may be the likely cure, although impossible on the vaporiser I have. Short of that, it would be a case of ripping out the entire front end and starting again. The latter seems a little excessive to me, but what are your guy's opinions?

[LPGC]

Being a 2004 Ford, then, it may not have a fuel return and may need one to be fitted

First thing should be to find out about the above..

Back in the workshop, he checked the emissions which confirmed that the system continuously runs lean. I forgot to ask whether this would be an MOT failure?

Maybe, maybe not. Less likely to fail emissions running lean than rich. Regardless, you want the mixture to be correct, a lean mixture will probably cause it to be less economical and could damage the engine. What was mixture like running on petrol?

He also wasn't too sure why his Romano software had greyed out the 'Lambda 2' sensor - could it be a faulty sensor OR the ECU is just too old to measure both sensors? They are all capable of measuring both sensors... This could be just a case of the second lambda being set as not connected in the software but it's doubtful the installer wouldn't realise that!

Can you see the injection pulse durations for both banks of cylinders (should be 2 boxes for petrol injection pulse time and 2 boxes for gas injector pulse time)?

He is hiring a newer model ECU

Really? A strange thing to do!

Simon

[Tubbs]

Or it's just set up on one lambda. Or it's bust.
Either way. Sounds like the bloke is yanking your chain to me. Odd behaviour.
Did he mention a fuel return ? It's pretty easy to spot if it's required. Personally I've never had to fit one.

[rossko]

Back in the workshop, he checked the emissions which confirmed that the system continuously runs lean. I forgot to ask whether this would be an MOT failure?

No on rwo counts: you don't have to have it MoT'd on gas, this is either/or with the petrol option at your choice. Also the test is at idle, which your man has apparently sorted out.

He is hiring a newer model ECU from Romano which can supposedly provide more details on individual cylinders and injectors. He will temporarily hook this up to see if there is anything else that can be found as faulty.

I expect he wants to exercise individual injectors; this can show up oddities like one (or two) poorly injectors or hosework that are difficult to pick out when the problems are not apparent at idle, and you only have whole-bank diagnostic readings from sensors.
'Hiring an ECU' is an unusual course, but the logic is sound; especially if he has seen some other clue or other.

Barring an actual failure found, running at a higher pressure is likely to be part of the eventual outcome. But there is a risk that will not be enough alone, and better injectors are also needed. By this stage it is flogging a dead horse, and a new front end (with warranty etc.) becomes a more sensible course. The difficult part is knowing when to drop the horse before you spend too much in finding out if it is dead or not.

Sound reasonable to me. A general bash-everyone-else attitude is very apparent in this forum recently, but pirates are actually few and far between.