P38 Randomly Judders and stalls at Idle

This site contains affiliate links for which LandyZone may be compensated if you make a purchase.

CJMoore

Member
Posts
56
Location
Nievre, Bourgogne, France
Hello, I wonder if anyone can help please as I am at my wits end. My P38 Vogue (2002) has started (some two or so months now) to occasionally judder when standing still, after starting, when sat at traffic lights or junctions etc etc. Basically any time it is at a stand still, or going very slowly. It’s not every time, but it is getting more often, and has gone from weekly to every couple of days. I have taken it to two different garages and it behaved beautifully for them . We have run diagnostics and nothing showing up. It’s a dual fuel and we live in France. I am at the point where I daren't drive it as i am worried it’s just going to stop! I have searched for hours for this and have found a few threads, but nothing that came to anything. Can anyone help please?
 
Hello, I wonder if anyone can help please as I am at my wits end. My P38 Vogue (2002) has started (some two or so months now) to occasionally judder when standing still, after starting, when sat at traffic lights or junctions etc etc. Basically any time it is at a stand still, or going very slowly. It’s not every time, but it is getting more often, and has gone from weekly to every couple of days. I have taken it to two different garages and it behaved beautifully for them . We have run diagnostics and nothing showing up. It’s a dual fuel and we live in France. I am at the point where I daren't drive it as i am worried it’s just going to stop! I have searched for hours for this and have found a few threads, but nothing that came to anything. Can anyone help please?
Right place, at last ;)
Whether it is a 2.5 Doozle or 4.X Petrol jobby would be really great to know.
So when it does this juddering what are the Revs?
Have you had it on proper P38 specific diagnostics? Were there any error codes? Standard OBD2 readers won't get you much info from a P38.
 
Last edited:
Yay right place. Thank you.
It’s dual fuel: LPG/Petrol
Juddering starts (randomly not every time) a couple of seconds after turning key, or when at stop for junction etc. Revs pulse low, between 2-4 lines from bottom/rest
No not on computer diagnostics, just the small machine.
 
Yay right place. Thank you.
It’s dual fuel: LPG/Petrol
Juddering starts (randomly not every time) a couple of seconds after turning key, or when at stop for junction etc. Revs pulse low, between 2-4 lines from bottom/rest
No not on computer diagnostics, just the small machine.
A great start, you really need this on proper diagnostics (Nanocom or nearest equivalent).
If it does it immediately after initial start, then is it running on petrol at that time?
Does it have exactly the same behaviour when running under LPG as when running under petrol?
My dual fuel 4.6 HSE P38 would "hesitate" on idle and each time it was diagnosed to a failed Plug HT lead or the associated coil-pack.
You really need to get it on P38 specific diagnostics to get all the codes read.
 
I’m sorry if I’m not very mechanically minded. I’ve had the car for 10 years and we have worked through many of the usual issues, this one just has us stumped. We live in very Rural France and it’s not possible to find anyone for detailed diagnostic. When we first arrived here 5 years ago we took it to the French Land Rover dealership and they were utterly useless.
Yes it’s running on petrol, the nearest GPL (French name for LPG ;-) ) is 45 minutes away so running it on GPL is rare. It is primarily run on petrol, last time for GPL was about 4 months ago.
The plug HT leads were replaced ten months ago and the coil pack was changed about 4 months ago. The car ran so much better after a brand new coil pack but now this is happening.
 
Isn't there 2 coil packs on the thor engine?
I also seem to remember someone offering to rent out nanocom with a decent deposit but can't remember who.
There are some members in France but not sure what they have and if they're close.
I would certainly look at coil packs again as they can and do fail intermittently.
 
2002 Thor so might get lucky on engine codes with an ELM327 reader connected to Torque or similar. We have members in France, check the LZIR map.

Anyone mention MAF yet?
 
when I did my HG's on my 4.6 Thor, I replaced the coil backs, as I was there. one lasted all of a month. it was intermotor brand not the OEM bosch. luckily I kept the OEM bosch, still on it, and its been fine. the thor uses a redundant spark so it sparks twice, one for mixture ignition, the other, well redundant.

what coil pack went on ? no reason to say that hasn't failed ?
when were the plugs last changed ? I go through a set of plugs every year as LPG does eat them


air, fuel, spark. the v8 doesn't manifest a non sparking cylinder well as the other 7 cover it well.

if you unplug the maf does that make a change ? bang the cats with your fist, does it rattle or tap it with a rubber mallet. a broken down cat will choke the engine easily. it kind of sounds from your description that could be a cause. also the O2 sensors. order an ELm 327 cable (a couple of quid) off ebay and download some software to look at the live run data. if you get stuck finding the software let me know and i'll send you a link to my dropbox with it

MAF, O2 and cylinder sparking should be able to be seen from that

look at the sparking of the HT leads. could indicate a failed HT lead.

also check for any vac leaks from deteriorated rubber piping.. as wild stab in the dark I would guess and its a pure guess the cat broken down and starting to block the exhaust

if its not throwing fault codes, its something that
 
Isn't there 2 coil packs on the thor engine?
I also seem to remember someone offering to rent out nanocom with a decent deposit but can't remember who.
There are some members in France but not sure what they have and if they're close.
I would certainly look at coil packs again as they can and do fail intermittently.
Thanks, yes there are two coil pack and we replaced both. We buy most of the parts from Island4x4 as it’s hard to get them here.
 
Last edited:
when I did my HG's on my 4.6 Thor, I replaced the coil backs, as I was there. one lasted all of a month. it was intermotor brand not the OEM bosch. luckily I kept the OEM bosch, still on it, and its been fine. the thor uses a redundant spark so it sparks twice, one for mixture ignition, the other, well redundant. Thanks for your reply, I’ve answered below. Also the engine is BOSCH.

what coil pack went on ? no reason to say that hasn't failed ?
when were the plugs last changed ? I go through a set of plugs every year as LPG does eat them

Just changed plugs and from memory it was Bosch coil pack x 2.



air, fuel, spark. the v8 doesn't manifest a non sparking cylinder well as the other 7 cover it well.

if you unplug the maf does that make a change ?

We will test that today. The problem is that problem is intermittent.

bang the cats with your fist, does it rattle or tap it with a rubber mallet. a broken down cat will choke the engine easily. it kind of sounds from your description that could be a cause. also the O2 sensors.

Just changed cat and sensors in last 3 months

order an ELm 327 cable (a couple of quid) off ebay and download some software to look at the live run data. if you get stuck finding the software let me know and i'll send you a link to my dropbox with it

I will do that..... does the software have a name I could google search for it?

MAF, O2 and cylinder sparking should be able to be seen from that

look at the sparking of the HT leads. could indicate a failed HT lead.

The ht leads are new but we felt of poor quality. The last time the problem occurred we took leads off and back on again to ensure a firm connection on plugs. The problem disappeared for a few days. Will repeat exercise today. We will also do fault check again.

also check for any vac leaks from deteriorated rubber piping.. as wild stab in the dark I would guess and its a pure guess the cat broken down and starting to block the exhaust

As above, changed in last 3 months.

if its not throwing fault codes, its something that
 
2002 Thor so might get lucky on engine codes with an ELM327 reader connected to Torque or similar. We have members in France, check the LZIR map.

Anyone mention MAF yet?

Thanks, we changed that within the last year and it made a difference to the running of the car definitely. Thank you for the map ‘heads up’. There is a person 2 hours away from us....Beasties Shed it says.
 
Last edited:
Don't let any banter put you off. The folks on here are tremendously helpful and there is wealth of knowledge to be mined from the collective that is LZ.
If you methodically go through the suggestions and keep up a dialogue of what's been done/not-yet-done the folks will help get you to a fix or an understanding of what the fix needs to be.
The P38 is a persnickety beast to fault-find but the guys on here are experienced & tenacious. Don't be put off.
 

It comes in a handy presentation case !

What I forgot to finish off was if it's not logging a fault code it's something un monitored.

The coil packs I had that failed were from island too if I recall. not their fault they don't manufacturer.. and Its the cost difference between Bosch OEM and pattern parts.

Get an ELM327 cable off eBay it's about £6. let me know and I'll send you a link to a full version generic software to clear minor codes and see run data
 
Back
Top