MOT / CO / Hydrocarbons!
Discussion
Well well well, Thunderpants passed its MOT with no issues. Just a wee advisory to get it tuned and the HC's are way high..so how do I do that.. I know the best thing is gonna be to put it in to someone but there is no one round here I can trust with my old car..
I've adjusted the CO via the AFM (Hotwire), using the correct voltage method, set to 1.25volts and it runs nice, but the MOT man claims I'm not burning fuel efficiently..
So great news all round. Just the CO/HC
Si
I've adjusted the CO via the AFM (Hotwire), using the correct voltage method, set to 1.25volts and it runs nice, but the MOT man claims I'm not burning fuel efficiently..
So great news all round. Just the CO/HC
Si
Did the garage not offer to adjust the mixture whilst it was there. I just mot'd my 350i last week and the tester was happy to let me adjust the emissions whilst it was on the gas analyser. First time using that garage and I have never met the guy before so I thought that was really decent.
Pull the dipstick and smell the end (no that's not a euphamism Zig!) if it smells of petrol you've got petrolly oil which won't help, someimes an oil change before the MOT will sort that out.
As for how to cure it in the long run well don't do short trips and make sure it's not too rich on wide throttle so check the connectons for the engine temperature sensor and that it's on nominal ohms when engine hot, and check he throttle pot operation.
As for how to cure it in the long run well don't do short trips and make sure it's not too rich on wide throttle so check the connectons for the engine temperature sensor and that it's on nominal ohms when engine hot, and check he throttle pot operation.
The relationship between Hydrocarbons and CO.
Hydrocarbons are unburnt stuff.
Depending on your CO it is possible to actually raise your CO and see a reduction in the hydrocarbons (often quite a lot)
The reason for this is, if you encounter a lean miss your hydrocarbons will double.
I'm guessing as you passed the MOT they are not too bad and the guy was just adding an FYI. So.....assuming your co is low (ish) slight enriching could bring down the hydrocarbons.
But you do need a gas meter like a gunsen sitting in the passenger seat.
A static sun tune would work.
Lean miss....OK Zig your turn
Hydrocarbons are unburnt stuff.
Depending on your CO it is possible to actually raise your CO and see a reduction in the hydrocarbons (often quite a lot)
The reason for this is, if you encounter a lean miss your hydrocarbons will double.
I'm guessing as you passed the MOT they are not too bad and the guy was just adding an FYI. So.....assuming your co is low (ish) slight enriching could bring down the hydrocarbons.
But you do need a gas meter like a gunsen sitting in the passenger seat.
A static sun tune would work.
Lean miss....OK Zig your turn
jeff m2 said:
The relationship between Hydrocarbons and CO.
Hydrocarbons are unburnt stuff.
Depending on your CO it is possible to actually raise your CO and see a reduction in the hydrocarbons (often quite a lot)
The reason for this is, if you encounter a lean miss your hydrocarbons will double.
I'm guessing as you passed the MOT they are not too bad and the guy was just adding an FYI. So.....assuming your co is low (ish) slight enriching could bring down the hydrocarbons.
But you do need a gas meter like a gunsen sitting in the passenger seat.
A static sun tune would work.
Lean miss....OK Zig your turn
Lean miss?Hydrocarbons are unburnt stuff.
Depending on your CO it is possible to actually raise your CO and see a reduction in the hydrocarbons (often quite a lot)
The reason for this is, if you encounter a lean miss your hydrocarbons will double.
I'm guessing as you passed the MOT they are not too bad and the guy was just adding an FYI. So.....assuming your co is low (ish) slight enriching could bring down the hydrocarbons.
But you do need a gas meter like a gunsen sitting in the passenger seat.
A static sun tune would work.
Lean miss....OK Zig your turn
And if hydrocarbons are unburnt stuff, how does enriching the mixture bring the figure down?
PoleDriver said:
jeff m2 said:
The relationship between Hydrocarbons and CO.
Hydrocarbons are unburnt stuff.
Depending on your CO it is possible to actually raise your CO and see a reduction in the hydrocarbons (often quite a lot)
The reason for this is, if you encounter a lean miss your hydrocarbons will double.
I'm guessing as you passed the MOT they are not too bad and the guy was just adding an FYI. So.....assuming your co is low (ish) slight enriching could bring down the hydrocarbons.
But you do need a gas meter like a gunsen sitting in the passenger seat.
A static sun tune would work.
Lean miss....OK Zig your turn
Lean miss?Hydrocarbons are unburnt stuff.
Depending on your CO it is possible to actually raise your CO and see a reduction in the hydrocarbons (often quite a lot)
The reason for this is, if you encounter a lean miss your hydrocarbons will double.
I'm guessing as you passed the MOT they are not too bad and the guy was just adding an FYI. So.....assuming your co is low (ish) slight enriching could bring down the hydrocarbons.
But you do need a gas meter like a gunsen sitting in the passenger seat.
A static sun tune would work.
Lean miss....OK Zig your turn
And if hydrocarbons are unburnt stuff, how does enriching the mixture bring the figure down?
jeff m2 said:
PoleDriver said:
jeff m2 said:
The relationship between Hydrocarbons and CO.
Hydrocarbons are unburnt stuff.
Depending on your CO it is possible to actually raise your CO and see a reduction in the hydrocarbons (often quite a lot)
The reason for this is, if you encounter a lean miss your hydrocarbons will double.
I'm guessing as you passed the MOT they are not too bad and the guy was just adding an FYI. So.....assuming your co is low (ish) slight enriching could bring down the hydrocarbons.
But you do need a gas meter like a gunsen sitting in the passenger seat.
A static sun tune would work.
Lean miss....OK Zig your turn
Lean miss?Hydrocarbons are unburnt stuff.
Depending on your CO it is possible to actually raise your CO and see a reduction in the hydrocarbons (often quite a lot)
The reason for this is, if you encounter a lean miss your hydrocarbons will double.
I'm guessing as you passed the MOT they are not too bad and the guy was just adding an FYI. So.....assuming your co is low (ish) slight enriching could bring down the hydrocarbons.
But you do need a gas meter like a gunsen sitting in the passenger seat.
A static sun tune would work.
Lean miss....OK Zig your turn
And if hydrocarbons are unburnt stuff, how does enriching the mixture bring the figure down?
) rather than masking the problem by over-richening throughout the range and causing other problems? (Carbon fouling, fuel costs, unburnt fuel in oil etc.) Mixtures that are too lean - do not burn..
There are essentially 2 fuel systems on the Rover V8 Injection system
Idle
and main power
Idle can be adjusted by the idle co trim screw on the airflow meter
Main power - well it's fixed and not really designed to be changed - so before
any other changes you should check that the rest of the system is not causing
the problems :
Ignition system
Fuel system (air leaks) etc
The two possible ways to alter the main fueling are as follows :
Fuel pressure - this can be adjusted up or down (may require an adjustable fuel pressure regulator)
Air flow meter (flapper) base setting - the dial under the meter can be adjusted either way (up down).
But - in general it should be correct and the issue will be another problem.
What ever you do - mark the starting point, so that you can always go back for both adjustments.
There are essentially 2 fuel systems on the Rover V8 Injection system
Idle
and main power
Idle can be adjusted by the idle co trim screw on the airflow meter
Main power - well it's fixed and not really designed to be changed - so before
any other changes you should check that the rest of the system is not causing
the problems :
Ignition system
Fuel system (air leaks) etc
The two possible ways to alter the main fueling are as follows :
Fuel pressure - this can be adjusted up or down (may require an adjustable fuel pressure regulator)
Air flow meter (flapper) base setting - the dial under the meter can be adjusted either way (up down).
But - in general it should be correct and the issue will be another problem.
What ever you do - mark the starting point, so that you can always go back for both adjustments.
I spoke to TVR today who said the Hydrocarbon figure quoted was not an issue on an old Rover V8, they said in a certain range it was fine, if in excess of that then its an issue. I was advised to put some good quality injector engine cleaner through the system in the meantime and when I'm back from my hols I'm gonna book it in for a good tune up... Its still going and sounding like a good'un!
Old cars eh.
Old cars eh.
Often an oil change, new plugs and clean air filter will keep it running in the sweet spot.
No need to start tinkering when the basics have not been done.
One big issue is we often do not do many miles each year and so do not think any kind
of service is needed..
Plugs rust, injectors get sticky etc..
No need to start tinkering when the basics have not been done.
One big issue is we often do not do many miles each year and so do not think any kind
of service is needed..
Plugs rust, injectors get sticky etc..
I agree, I as I've only recently got it running after a long spell of head scratching and parts replacing...
Oil, plugs etc all new... I've put additive in tonight and will take it for a right good run at the weekend...
I think that's been the big issue, lack of use and the fact it's not ran or run properly since last Oct..
Si
Oil, plugs etc all new... I've put additive in tonight and will take it for a right good run at the weekend...
I think that's been the big issue, lack of use and the fact it's not ran or run properly since last Oct..
Si
Might add the old Range Rover Classic with Rover V8 improved on its combustion last night.
As a test I bought a new ignition coil and tried swapping it in. And idle smoothness improved a lot as did the reduction of smelly exhaust.
So apparently the old coil was not up to producing a strong enough spark with the power supply voltage at idle. Could be in combination with the old engine being weak in compression a stronger ignition pivoted things over to a more regular combustion.
As a test I bought a new ignition coil and tried swapping it in. And idle smoothness improved a lot as did the reduction of smelly exhaust.
So apparently the old coil was not up to producing a strong enough spark with the power supply voltage at idle. Could be in combination with the old engine being weak in compression a stronger ignition pivoted things over to a more regular combustion.
After reading this thread I'm glad I took my 280i (yes I know different engine) for a run to the Hants TVRCC meet 2 weeks before the MOT and gave the cobwebs a blow out.
You may have seen the other thread I started that shows how low my CO and HC are I couldn't believe it (If I didn't know this engine had produced such good results in the past I'd swear they put another car on the tester...lol)
I have had this engine close to passing the CAT test levels before...Must mean my engine is running quite well?
You may have seen the other thread I started that shows how low my CO and HC are I couldn't believe it (If I didn't know this engine had produced such good results in the past I'd swear they put another car on the tester...lol)
I have had this engine close to passing the CAT test levels before...Must mean my engine is running quite well?
Edited by wedgeinald on Wednesday 26th March 11:22
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