RangeRovers.net Forum banner

21 - 37 of 37 Posts

·
Registered
1995-2002 Range Rover P38A
Joined
·
99 Posts
Discussion Starter #22
The suppressor is, according to RAVE, fitted adjacent to the coil mounting bracket (p49 of the fuel system)

Appreciate the advice on fuel levels for that code, plenty of fuel in the tank though, over quarter. I know the LPG system is very closely linked to the petrol system, but surely a petrol supply/pressure issue wouldn't affect how the engine runs on LPG?

I've checked the long term fuel trims and they are both fairly low numbers, ie not maxed out one way or the other.

I've just read somewhere else i should try driving with the MAF unplugged, and not just see if there is a change in idle, so I'm off to do that now
 

·
Registered
1995-2002 Range Rover P38A
Joined
·
99 Posts
Discussion Starter #23
Ok, been out with the MAF unplugged, that did seem to be better! Although I'm not sure if that was wishful thinking or not as it didn't seem to get any worse when i plugged it back in. Either way I've given the sensor and the connector a clean.

I have found something though!! I had the torque app running while i was driving and noticed volts at the OBD port was alternating between 14.4 and 11.9. Not sure what the cause can be but that can't be good!? There was no dash light on and volts across the battery terminals was a steady 14.0 which, while isn't great, certainly shows a steady charge so I to be an alternator issue
 

·
Registered
Joined
·
1,539 Posts
The suppressor is, according to RAVE, fitted adjacent to the coil mounting bracket (p49 of the fuel system)
You're right it is. Never noticed it before but I would think if it was to blame it wouldn't affect just a couple of cylinders but all of them.
Appreciate the advice on fuel levels for that code, plenty of fuel in the tank though, over quarter. I know the LPG system is very closely linked to the petrol system, but surely a petrol supply/pressure issue wouldn't affect how the engine runs on LPG?
It wouldn't but if a misfire is detected when low on fuel then it is always possible that the ECU assumes the two are linked and flags that particular code.

Not sure you will be able to get it to run, let alone drive, with the MAF disconnected
 

·
Registered
1995-2002 Range Rover P38A
Joined
·
99 Posts
Discussion Starter #25
Right, done some more testing. Think the odd voltage reading was an old OBD adapter. Out a new one in and it seemed stable.
Definitely driving better with the MAF unplugged. Seems you need to stop/start the engine after plugging it back in for the computer to use it.
Torque app shows a healthy amount of air flow, that rises and falls with the throttle as you'd expect, so next I'm going to check for air leaks. Again!
 

·
Registered
1995-2002 Range Rover P38A
Joined
·
99 Posts
Discussion Starter #26
Hi, finally got round to putting new bosch coil packs on, did improve things a little bit but I'm still getting a misfire but not registering an error code for either a general misfire or or a specific cylinder.

I'm really stuck now, no idea how to proceed, good compression, new coils plugs and leads. Same on lpg and petrol, so not specific to one fuel issue.

Where do i go from here?
 

·
Registered
1995-2002 Range Rover P38A
Joined
·
99 Posts
Discussion Starter #27
Ok time for another update! With engine at idle I'm seeing a nice regular spark on cylinder 1 as a benchmark, say 2 per second, ish. Move to number 3 and I'm seeing intermittent sparks, sometimes once a second or less, sometimes around 4 per second. The same goes for cylinder 3 (2&3 on the same coil pair)

Does that mean a problem with the ecu? Or a problem with the wires between the ecu and the coil?

I'm on new bosch coils, I've swapped plugs and new leads. I've moved leads and plugs to make sure the problem doesn't follow

Thanks
 

·
Registered
Joined
·
1,539 Posts
Have you swapped coil packs to see if the problem moves with the coils? I know they are new but it would be worth a check. Or, if you have a scope (even one of these cheapy USB ones), look at the incoming pulses from the ECU to the coils and compare cylinders. However, faulty wiring or ECU would be unlikely to affect 2 cylinders and particularly the two on one shared coil so it is still pointing towards a coil problem.
 

·
Registered
1995-2002 Range Rover P38A
Joined
·
99 Posts
Discussion Starter #30
The plugs are new and i checked the gap when i put them in. They have only done a few miles while I've been trying to get to the bottom of this. I've swapped them round too, but I've not swapped the coils yet. I'll get to it again next week and swap the coils, I'll also try putting in the old one i think is good in place of the suspect new one. I'll update again in a few days! Thanks everyone for your patience and advice

I've not got any kind of scope. But maybe i need to look at getting one. Any suggestions?
 

·
Registered
1995-2002 Range Rover P38A
Joined
·
99 Posts
Discussion Starter #32
Cheers for the suggestion, I've already closed the gap some as per another thread on the forum, because of the LPG. I don't recall the measurement off the top of my head but 0.5mm seems very narrow?
 

·
Registered
Joined
·
1,539 Posts
It is, old school 25 thou which is about 0.8mm is recommended for standard plugs when running on LPG. LPG needs a better spark, or at least petrol will run OK with a weak spark, but as the misfire is on both fuels, then that is pretty much irrelevant
 

·
Registered
1995-2002 Range Rover P38A
Joined
·
99 Posts
Discussion Starter #34
Ok time for another update and i think this is the last one!! I took the new coils off, replaced the new one that was having issues with the old one that didn't seem to have issues and i think that's cured it! No pops or bangs on petrol or LPG!!

Took it for a drive and actually got to 70mph!!

I can now bother to fix the exhaust manifold leak and check the rest of the exhaust system for holes and leaks etc

Next job is to take it for a decent run to get the plugs settled, see what colour they look when i pull them out.

Thanks everyone again for your patience and advice!! I feel like it's been a difficult journey pushing me down the right route
 

·
Registered
1995-2002 Range Rover P38A
Joined
·
99 Posts
Discussion Starter #35
Aaaagh!!!!

It was running better because I'd left a plug lead off!!!

Connected the lead and it's back to normal, no power, popping, etc

I've not had chance to pull the plug and earth it to see how that runs, but given compression is ok, must it be an injector related problem after all?
 

·
Registered
1995-2002 Range Rover P38A
Joined
·
99 Posts
Discussion Starter #36
Just remembered, sorry, it can't be a bad/leaking petrol injector - some time ago, while it was switched over to lpg, I pulled the fuse for the petrol pump but there was no change 😞
 

·
Registered
1995-2002 Range Rover P38A
Joined
·
758 Posts
Been following this thread, I’m thinking it’s nothing to do with the coils, I’m wondering if everyone is so fixated on the coil problem, have you looked at other options, air leaks ect, sensors ect, it’s easy to chase a fault and get fixated on one part, I’ve had many diagnostics that have been wrong, diagnostic computers are set to read and say xyz has gone wrong, but there not always right.
try some simple things like spraying wd40 round the inlet and see if engine note changes, quick, simple and illiminates things.
 
21 - 37 of 37 Posts
Top