P38A Pinking Under Load

PastyMuncher83 · May 16, 2016

How do all,

My 2001 4.6 Thor has started linking really bad under load. It has a 12 month old LPG system fitted but does it on petrol or gas.
Not long after the LPG was fitted I replaced both coils, new plugs and fitted 2 new coils.
I've pulled only 2 fault codes with me cheap eBay generic OBD reader, hoping they would be cam/crankshaft sensor related but no.-
P1319 - misfire detected at low fuel level.
P0112 - IAT Sensor 1 low input.

Other than the 2 cam and the crankshaft sensor going wrong what else could cause it to pink? Hopefully not a stretched timing chain! Could the MAF or wrong plugs cause this?

Saint.V8 · May 16, 2016

Poss plugs....timing chains rarely stretch to a point of timing issues on the Rover V8's.

I'd be tempted to have the fuel trims reset, then see how she goes after a good few miles for the fuel trims to reset themselves.

wammers · May 16, 2016

Pinking should not be possible on LPG it is far to high an octane for pre ignition. IAT sensor is in MAF sensor so the MAF could be your problem. When running on LPG the ignition should be advanced considerably by the control module as LPG takes much longer to burn than petrol. On petrol that advance should be reduced. So the LPG controller could also be a problem not reducing advance on petrol. But look at the MAF first.

tomcat59alan · May 17, 2016

Remember when we had to do a de-coke to stop pinking Tony? For you youngsters, the carbon build up on the head would glow and cause pre-ignition.

wammers · May 17, 2016

tomcat59alan said:
Remember when we had to do a de-coke to stop pinking Tony? For you youngsters, the carbon build up on the head would glow and cause pre-ignition.

Yep remember it well. Happy days.

martynv8 · May 17, 2016

I get this sometimes if under load (up hill) from cold on unleaded. I put it down to the higher compression i have though. Never a problem on LPG due to octane level. I had my fuel trims reset which improved it somewhat. It never happened for about 6 months after the new engine & I would guess it could be carbon build-up on the piston crowns & heads upping the compression a little more?

PastyMuncher83 · May 17, 2016

Thanks for that, my gas system does have advance the timing when running LPG, have a few questions!-

Could a faulty MAF even cause pinking?

Is there anyway to bench test the MAF, I don't really want to spent £150 on a new one to find it makes no difference.

I only have basic OBD diagnostics so regarding the fuel trims would an overnight battery disconnect achieve the same as having them reset?

Thanks

Grrrrrr · May 17, 2016

martynv8 said:
I get this sometimes if under load (up hill) from cold on unleaded. I put it down to the higher compression i have though. Never a problem on LPG due to octane level. I had my fuel trims reset which improved it somewhat. It never happened for about 6 months after the new engine & I would guess it could be carbon build-up on the piston crowns & heads upping the compression a little more?

I thought LPG was much cleaner burning? So should be less carbon? The oil colour is certainly cleaner than the petrol. And if you want to see really dirty oil take a look at my diesel after a few days of running.

biketeacherdave · May 17, 2016

no no ur all wrong its the evap thingy its give a sounds just like pinking il look up the part number and post a pic its a 20 quid part or just clean it. usually only does it from cold and or under high load conditions

Grrrrrr · May 17, 2016

biketeacherdave said:
no no ur all wrong its the evap thingy its give a sounds just like pinking il look up the part number and post a pic its a 20 quid part or just clean it. usually only does it from cold and or under high load conditions

Now you're starting to sound like Wammers.

No, no, you're all wrong, you bunch of useless f*ck-knuckles. You couldn't arrange a f*ck-up in a whore-house and deserve to be pinned on an ant's nest covered in jam. No go and buy a new vap.

tomcat59alan · May 17, 2016

Grrrrrr said:
Now you're starting to sound like Wammers.

No, no, you're all wrong, you bunch of useless f*ck-knuckles. You couldn't arrange a f*ck-up in a whore-house and deserve to be pinned on an ant's nest covered in jam. No go and buy a new vap.

Don't sit on the fence mate, tell it how it is.

biketeacherdave · May 17, 2016

evap purge vale new it would pop in my head i just needed the proper support cheers grrrrrrr

wammers · May 17, 2016

Grrrrrr said:
Now you're starting to sound like Wammers.

No, no, you're all wrong, you bunch of useless f*ck-knuckles. You couldn't arrange a f*ck-up in a whore-house and deserve to be pinned on an ant's nest covered in jam. No go and buy a new vap.

I say, steady on old chap.

PastyMuncher83 · May 17, 2016

biketeacherdave said:
no no ur all wrong its the evap thingy its give a sounds just like pinking il look up the part number and post a pic its a 20 quid part or just clean it. usually only does it from cold and or under high load conditions

Haha I love this forum, sounds like this could be the cause thankfully. All the noise of pinking with none of the fault codes.

Thanks biketeacherdave, from mr.f*ck knuckle

wammers · May 17, 2016

PastyMuncher83 said:
Haha I love this forum, sounds like this could be the cause thankfully. All the noise of pinking with none of the fault codes.

Thanks biketeacherdave, from mr.f*ck knuckle

Well you do have a couple of fault codes if your OBDII reader can be believed. Whether they are related to the Evap valve clattering i don't know. Prefer to keep as far away from nasty petrol engines as i can these days.

PastyMuncher83 · May 17, 2016

wammers said:
Well you do have a couple of fault codes if your OBDII reader can be believed. Whether they are related to the Evap valve clattering i don't know. Prefer to keep as far away from nasty petrol engines as i can these days.

Oh dear Wammers if I didn't need to depend on your fountain of p38 knowledge, promoting those oil burners would be fighting talk ;/

I've only had one and it was a classic with the VM so am understandably against them.

But I have noticed the MAF fitted is one of those pattern/no brand types. There must be a reason why the Bosch is £150 and these ones £30.
I did the hilly billy tune up test and unplugged the MAF with the engine running and it cut out so it must be doing something?!

wammers · May 17, 2016

PastyMuncher83 said:
Oh dear Wammers if I didn't need to depend on your fountain of p38 knowledge, promoting those oil burners would be fighting talk ;/

I've only had one and it was a classic with the VM so am understandably against them.

But I have noticed the MAF fitted is one of those pattern/no brand types. There must be a reason why the Bosch is £150 and these ones £30.
I did the hilly billy tune up test and unplugged the MAF with the engine running and it cut out so it must be doing something?!

Unplug it then start the engine, see if it runs any better. There are several scenarios regarding MAFs it depends which part of it is duff.

tomcat59alan · May 17, 2016

PastyMuncher83 said:
Oh dear Wammers if I didn't need to depend on your fountain of p38 knowledge, promoting those oil burners would be fighting talk ;/

I've only had one and it was a classic with the VM so am understandably against them.

But I have noticed the MAF fitted is one of those pattern/no brand types. There must be a reason why the Bosch is £150 and these ones £30.
I did the hilly billy tune up test and unplugged the MAF with the engine running and it cut out so it must be doing something?!

Now't wrong with the VM as long as it never overheated and you cracked the heads. I believe there was a mod you could do but too late for mine, it overheated towing the tin tent in France during the summer, about 13 years ago. The rad blocked with butterflies and moths (there was a plague that year) , but it still got us back home. Four cracked heads and picked up on one cylinder.It used to pull like a train by the way.

PastyMuncher83 · May 18, 2016

Mine was the 2.5 turbo it did pull well but the pins and needles I would get from the vibrations sitting in traffic at tick over began to irritate me!

PastyMuncher83 · May 18, 2016

I can't find anyone selling new purge valves only second hand ones. Anyone got an ideas where to source one-

Part no. wtv100150

P38A Pinking Under Load

Active Member

Dyed-in-the-wool 100% RR Junkie

No longer with us, RIP

Well-Known Member

No longer with us, RIP

Well-Known Member

Active Member

Technician, Bodgit & Scarper Ltd

Well-Known Member

Technician, Bodgit & Scarper Ltd

Well-Known Member

Well-Known Member

No longer with us, RIP

Active Member

No longer with us, RIP

Active Member

No longer with us, RIP

Well-Known Member

Active Member

Active Member

Similar threads