rockandrollstar
Member
- Posts
- 45
- Location
- Devon
I would suggest you need to get an oscilloscope on the lambda sensors and see i one or more is working correctly. That will tell you if its a sensor or if the fuelling is causing your high co.
Pinking... but high CO at MOT?!?
- Thread starter Frostycab
- Start date
This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
Frostycab
Active Member
- Posts
- 173
- Location
- Duns, Scottish Borders
Think a lad at work has an oscilloscope. Time to go googling and see how to test these buggers!
Diesel Do
Well-Known Member
- Posts
- 5,212
- Location
- Nottingham
Just been hunting around. Found this on the RPI website!
Almost all used Rover V8 engines that have covered in excess of 70,000 miles will be suffering, or beginning to suffer, from worn camshaft, lifters and a stretched timing chain. This is normal with the V8 because these engines are amongst the most forgiving.
The result is a gradual decrease of engine efficiency and economy that goes quite unnoticed to start with, this is due to the fact that although you have eight cylinders, the major loss of efficiency, in only in one or two of them (typical of a worn camshaft), may not be apparent until they have perhaps failed completely, as the remaining good cylinders will mask the power loss effectively until severe enough to make replacement unavoidable. However, if left this long, many other engine components will have suffered due to this, and can lead to an engine's condition being far too bad for an inexpensive overhaul.
Why unnoticed? With the hydraulic tappets taking up the clearance as things wear away, by the time you get to hear them, they are already very worn. The initial problem will be a gradual loss of power over a few thousand miles. Also, you will notice the need for changes in carburetor and ignition settings to cope with the excessive emissions produced, seemingly from the engine as a whole but more likely the individual cylinders that are suffering the most camshaft wear (causing loss of full or correct valve lift).
This change in emissions (High CO and HC) is why most mechanics would be incorrect when they advise that your carburetion or ignition is in need of attention, when in fact the problem is more likely to be camshaft wear, along with erratic ignition and cam timing due to the timing chain stretch.
Not saying that this is definitely the cause but the bottom paragraph reads very true. Everyone saying fuelling or timing! To be fair it appears to refer to the earlier version but it still shares the basics. I've used them in the past for ignition stuff, they're very helpful and may be worth giving a ring.
Almost all used Rover V8 engines that have covered in excess of 70,000 miles will be suffering, or beginning to suffer, from worn camshaft, lifters and a stretched timing chain. This is normal with the V8 because these engines are amongst the most forgiving.
The result is a gradual decrease of engine efficiency and economy that goes quite unnoticed to start with, this is due to the fact that although you have eight cylinders, the major loss of efficiency, in only in one or two of them (typical of a worn camshaft), may not be apparent until they have perhaps failed completely, as the remaining good cylinders will mask the power loss effectively until severe enough to make replacement unavoidable. However, if left this long, many other engine components will have suffered due to this, and can lead to an engine's condition being far too bad for an inexpensive overhaul.
Why unnoticed? With the hydraulic tappets taking up the clearance as things wear away, by the time you get to hear them, they are already very worn. The initial problem will be a gradual loss of power over a few thousand miles. Also, you will notice the need for changes in carburetor and ignition settings to cope with the excessive emissions produced, seemingly from the engine as a whole but more likely the individual cylinders that are suffering the most camshaft wear (causing loss of full or correct valve lift).
This change in emissions (High CO and HC) is why most mechanics would be incorrect when they advise that your carburetion or ignition is in need of attention, when in fact the problem is more likely to be camshaft wear, along with erratic ignition and cam timing due to the timing chain stretch.
Not saying that this is definitely the cause but the bottom paragraph reads very true. Everyone saying fuelling or timing! To be fair it appears to refer to the earlier version but it still shares the basics. I've used them in the past for ignition stuff, they're very helpful and may be worth giving a ring.
Frostycab
Active Member
- Posts
- 173
- Location
- Duns, Scottish Borders
Mines bang on 75k as well! Could be worth looking into to be honest. I'll have to break the timing light out and see if there are any old fashioned marks for me to check!
Rick-the-Pick
Active Member
- Posts
- 782
- Location
- Hove, Sussex.
You really need to get diagnostics on your vehicle. Else you're just guessing.
Frostycab
Active Member
- Posts
- 173
- Location
- Duns, Scottish Borders
Sadly the guy I know locally who has a MSV faultmate is on holiday... the inconsiderate swine! 
Diesel Do
Well-Known Member
- Posts
- 5,212
- Location
- Nottingham
Agree completely. Only issue is that if it is mechanical the diagnostics will tell you the symptoms not necessarily the cause. That would be fuelling and ignition! Doh. So computer and investigation work for me!
Frostycab
Active Member
- Posts
- 173
- Location
- Duns, Scottish Borders
Well, made a little progress today.
Despite getting called out with my work I managed to get the Fuel pressure reg changed over. took it for a drive and the pinking is greatly improved! I'm guessing that its either adapting to the new MAF or the pressure reg has helped.
Thankfully my mate is back from holiday so maight get a change to finally get it scanned and got my hands on an oscilascoope to check the lamdba... when work isn't dragging me out!
Despite getting called out with my work I managed to get the Fuel pressure reg changed over. took it for a drive and the pinking is greatly improved! I'm guessing that its either adapting to the new MAF or the pressure reg has helped.
Thankfully my mate is back from holiday so maight get a change to finally get it scanned and got my hands on an oscilascoope to check the lamdba... when work isn't dragging me out!
