She's Still 'Plodding' on O/S Bank...

Alright,

This has been brought up by me before and I have done much since, however, there is still an issue which is driving me nuts

Basically, when I just got the RR (98 P38 4.0 on Tartarini SGI) had new LPG injectors fitted/re-calibrated and WOW what a difference, however, the next day I did my usual 'new car service' which included new Britpart plugs (I know) with new 8mm HT Leads and she started to 'plod' (best word I can describe the noise) on the O/S (drivers) bank and performance was notably worse.

Now, I immediately reverted the plugs back to the Bosch ones, no difference, reverted the leads back to original, no difference, got new standard leads, no difference, changed the knock sensor (garage advice plus it looked melted) no difference and fitted NGK spark plugs (ones with V-grove) a bit better but not great.

So now I am thinking coil packs as could only be that? LPG man has looked at her since and re-calibrated again, with no difference and he thinks I am imagining it :lalala: however, he did say I should maybe remove the non-return valves from each of the LPG inlets in the mani as they are a 'old system', although this was by no means a suggestion at a cause.

On petrol there is no noise but performance matches LPG so don't think its LPG specific? Also I am not using water etc so think head gasket etc is ok (touch wood).

Here is a video I did to catch the sound, hope it is clear to people...

Range Rover P38 4.0 V8 on LPG Tartarini Strange So - YouTube

Many thanks in advance as always,

Diehard

Odd as it may seem, my 3.9 Classic developed an odd misfire type sound, but with no loss in performance of efficency....turned out to be a leaking exhaust manifold gasket....

Not saying that is what is wrong with yours, but yer never know....

Get hold of some spark plug test lights (they plug on to the sparkplugs and the HT lead then goes on top of that) when the spark fires, the lights flash...see if you get good flashes or if one is weaker/not functioning...

They are sold in packs of 4 usually, so do one bank at a time, or splash out and get 2 packs!!

Helped me diagnose a failed ignition amp on my Classic.

What model of Tartarini is fitted?.
I've got lead and software for TEC97,TEC99PRo,SFI,ETAGAS.
Cost me £40 for a generic set of systems, although there are probably specific kits available for Tartarini.

You need a new LPG man,he ought to know that the LAST thing you do is to trim an LPG system.If its not working 100% on petrol then it can only be worse on gas.And to be perfectly honest most people cant tell accurately if their engine is running properly - it needs checking with the correct gear to monitor fuel trims and misfire counts etc.
its no wonder so many people have problems with gas.....

True in most cases, but my RRC runs **** on petrol due to a faulty fuel pressure regulator which isn't made anymore. On lpg sweet as a nut.

The lpg software does however show some of the sensor readings from the main ecu, which can help in diagnosing problems.

Wookie said:

True in most cases, but my RRC runs **** on petrol due to a faulty fuel pressure regulator which isn't made anymore. On lpg sweet as a nut.

The lpg software does however show some of the sensor readings from the main ecu, which can help in diagnosing problems.

Click to expand...

Not so,your RRC is a basic system,not adaptive like Motronic5.2.1 or Gems.They need to set themselves up properly on petrol to set long term fuel AND igniton trims - its a world away from your sytem which is closer to forklift in operation.
Adaptive systems are far less tolerant of slight running faults - which the LPG man ought to bear in mind,shame so many seem to hit the "Autocal" icon and think thats good enough.

Saint.V8... Ow a new tool and a gadget too! Didn't know you could get them, I'll have some bought on payday, £16 for all eight so may as well... Could at least have a disco lol

Wookie - You have a PM

eightinavee - We had a tootle about in the RR with trims being monitored against the Tartarini program and I just trusted the guys knowledge to be honest... Think I'll try the testers first and see if the coils are ok and go from there, but you may well be right about getting a new guy

Just be careful with the noid lights - they are not infallible and are a very basic test.The gas man ought to be looking at the secondary HT waveforms on a scope via an inductive clamp on each plug lead - a few seconds looking at each one is real proof of the ignition systems health.
Should be done as a matter of course before the LPG connector is even thought about.