Did that about 210k miles ago when the engine was rebuilt so it might need doing again but something I can chuck in the tank would be a lot easier. I think the most it has ever had in the tank since I've owned it is just under half a tank and that was only because I was setting off to drive across Europe and wasn't sure if I would be able to get LPG. As it turned out it is easier to find in Europe than here so I think that half a tank lasted the best part of a year!

However, one thought has just occurred to me. If I put something in the tank to clean the injectors, I'm going to have to run on petrol to let it do its stuff, so maybe taking them out will be cheaper and more effective......

Lpgc wrote:

It could be a petrol injector problem or could be the failed lambda sensor / learned fuel trims / less likely learned position for the IAV that's the problem?

First thing I did was reset the adaptive values in case that was the problem and it made no difference.

Or even something (Pitagora?) that's not connecting all the petrol injectors when it's running on petrol?

If that was the case it would be running on 7 when on petrol but it isn't. All cylinders are firing but the idle is lumpy rather than a consistent misfire.

I might give the stuff Dai recommends unless any has any better ideas.

As most of you know, my GEMS P38 runs on LPG. Unlike the later multipoint systems it has a single point so LPG enters just before the throttle body and the output from a lambda sensor adjusts a stepper motor valve in the LPG feed to keep the mixture correct. Because it doesn't slave off the petrol system, it can run on LPG from stone cold. It is set to change over at 1,100rpm on deceleration which means it starts on petrol, the revs rise initially and as they fall, it changes over and runs on LPG from that moment onwards. I keep some petrol in the tank for starting and in case I run out of LPG. Which I did a couple of days ago. My local Flogas charges 78p per litre and the two other filling stations nearby are £1.05 and £1.09 so I try to avoid them. I ran out of LPG a couple of days ago, so ran on petrol to Flogas but was too late, they had just closed. As I needed to use the car that evening, I bunged £20 of petrol in only to find it runs like a dog!

The idle on LPG is perfectly smooth but on petrol it is lumpy, accelerating up a slip road it could only just hold the same speed rather than accelerating as it would normally so seems down on power, although once I had got it up to cruising speed it felt normal. As I stopped at a roundabout, it stumbled and died but restarted without problem. The lumpiness clears once the revs are up to 1,000 rpm or so, so it is primarily an idle problem. As idle is controlled by the idle air valve, I gave that a clean (but thinking about it, that is still used when on LPG where there isn't a problem) and the petrol filter was replaced about 10k miles ago (I bought it when I first got the car 13 years and almost 300k miles ago and found it in the garage recently so decided to change it as I could). There is a separate 0-1V lambda sensor in the right bank exhaust downpipe solely used to drive the LPG system so the only part of the petrol injection system used by the LPG install is the throttle position sensor and that is only used to shut off the LPG on the overrun.

When running on LPG the petrol injectors are switched off but the fuel pump stays on and just circulates the fuel back to the tank. On petrol the RH bank lambda sensor switches as it should but the LH bank one stays pinned at 5V suggesting a lean mixture, yet the exhaust smells rich. Which means the only thing left would appear to be the injectors. My theory is that one of the LH bank injectors is partially clogged so the exhaust on that bank is showing as lean, the ECU is richening the mixture (Nanocom shows short term fuel trim on that bank pinned at +38.5%) but not all are getting their full quota of fuel so some cylinders are running lean while others are running rich. Hence me thinking the injectors could do with a clean. So the question is, has anyone used an injector cleaner, which one and did it make a noticeable difference? Or do I need to strip the injectors off and clean them for the rare occasion I actually run on petrol?

Marks could be signs of a liner leak but they could equally be slight distortion of the fire ring. One other thing I noticed is that the Elring logo and part number are still easily visible on the gasket which could suggest it has been apart before and wasn't torqued down fully. I assume it had stretch bolts rather than studs and doing the 90 degree turns can be a pain. You need a long bar so you can get enough grunt but then the bar hits against other things around it. If you put a long extension on the socket , it can twist when you are heaving on it so you don't get the full 90 degrees. Did they come out easily or did you need to use a breaker bar on them?

Gasket looks reasonable I'll agree but one of the fire rings is split and the stains on the head show a leak at one end. The pistons and combustion chambers aren't showing the normal steam cleaning you'd expect with coolant getting in although orange tip to the spark plugs is usually a sign that anti-freeze has been getting into the combustion chamber. It may be that you have a very slight leak around the outside of a liner, so it hasn't slipped but may be leaking. If that is the case, the options are a rebuild with top hat liners, or a dose of water glass in the coolant depending on how much mileage you do in it. The water glass will last for maybe 50k miles or so.

Tyres hit resonance at around 55-60mph so a rear wheel badly out of balance would cause it too.

mad-as wrote:

i could make it keep running if i pumped the throttle heaps but it would smoke out the shed in seconds

I bought a spares or repairs project P38 that was exactly the same. After pumping the throttle constantly, once running I could get it to run reasonably well. The pattern MAF sensors will usually work pretty well but if checked with an OBD reader, the airflow readings will be incorrect.

PC38 wrote:

I realise I should have put this in the electrikery section.

But then again, it's fuelling so that can leak....

Do you have an OBD reader that can show live values? If you do, check the lambda sensor and MAF outputs as it is, then disconnect the lambda sensors from the LPG system and see if it is the same. It may be that the LPG ECU is supplying a bias voltage.

The Zirconia sensors used on a GEMS work the opposite way round to the Titania sensors used on the Thor and most other cars, so 5V on a GEMS is lean with 0V being rich. That means it will be chucking more fuel in to try to get the voltage to come down. What diagnostics have you got? Anything that will show what airflow the MAF is reporting?

Compressor is faulty is one of the few error messages that actually says what it means. Your compressor is faulty.

A lot of people have had aftermarket height sensors fail in a matter of months so you may be another of them. I don't suppose you have the originals to put back in to try? It is almost as if you have two faults, one causing it to drop when left and another that causes the pump to not start. The fact that when one happens the other does too, would suggest the same fault but manifesting itself in two ways.

Real Steel (www.realsteel.co.uk) have ARP studs for £162 for the 10 stud set (which is what you need. Far better and much easier to use. Just torque them down to 65 ft/lb, none of this swinging on a breaker bar trying to get the 90 degree turn on them.

The RSW software also shows a fault that means nothing, so I assume it is the same as the Nanocom Unknown Fault. I think the RSW says something like 'Vehicle has moved'. My money would still be on an iffy height sensor though.

I got a pair cut at my local Timsons. Told them they used a BMW blank, which they didn't keep in stock but ordered in for me and cut them from my original on their machine. One worked but was a bit 'notchy' while the other one worked perfectly.. Cost me all of a tenner.

I had the opposite. When I first got my Classic, the reducer was in parallel and, as it was a single point system that would run on LPG from cold, the reducer would ice up within 300-400 yards of starting it. Changed that to series and never had another problem. When I got the P38, that was the same but I got the opposite. Reducer didn't freeze but at idle in traffic the heater output dropped to nothing. Again, changed it to series and never any more problems. I suppose the difference was which flowed easier, if it was the heater, the reducer would freeze, if it was the reducer, the heater went cold. Your theory that a more restrictive heater matrix would make sense, but I would have thought that would make it worse with them in parallel?

Thor heater pipework makes getting it neat harder than on a GEMS though.

There's no pump or any moving parts in there, just a coolant passage that heats it up. On a GEMS it is far easier, and tidier, to run the reducer in series with the heater rather than in parallel with Tees. Hose from the inlet manifold, through a bend to the reducer then out of the reducer to the pipe going to the heater. It gives a better flow through both the heater and reducer rather than it taking the path of least resistance and neither of them working at optimum. It also makes bleeding a lot easier.

StrangeRover wrote:

From what I understand 140,000 on a RV8 cam means they're usually a write off..

Only if it is totally neglected and never given an oil change. That looks nice and clean inside so has been serviced regularly. My original cam was still OK when the engine was rebuilt at 287k and the new one has now done a further 203k and still going strong.

I assume you all know what these are and what they do, but for those that don't, they plug into the RF receiver under the RH rear shelf and prevent stray RF from constantly waking the BeCM and flattening your battery. Marty has been working away for quite a while and some of the components he needed to build them were NLA so they haven't been available for quite a while. Well, the good news is, he has sourced the required components and has a limited number available now. They can be ordered through his website (http://p38webshop.co.uk/index.php?route=product/product&path=84&product_id=97) until the 20 or so he has are gone. So if you want one, get in quick.

Yes, one won't be locking and that is the faulty one.

That is an easy one and wants to be sorted asap before it locks you out and immobilises itself. It is caused by a dying microswitch in one of the front door latches. 3 of the 4 doors will lock, the one that doesn't is the faulty one.