Dreaming of 8 degrees BTDC
Discussion
Is my car unique in not being able to run more the 3 degrees BTDC before it pinks like hell ?
Co is 3%, cool plugs, new wires, 80 degrees running temp and running super unleaded.
Is there access to the distributor weights ?
Losing 5 degrees probably equal to a few BHP.
Any suggestions ?
Cheers Keith
Co is 3%, cool plugs, new wires, 80 degrees running temp and running super unleaded.
Is there access to the distributor weights ?
Losing 5 degrees probably equal to a few BHP.
Any suggestions ?
Cheers Keith
Hi Keith
Pinking is often due to a lean mixture, not just ignition timing. However there are several possible causes of this - all of which require a bit more investigation. Assuming your car is standard and in good condition, here's some possibles:
1) fuel pressure too low - check regulator
2) fuel pressure dropping off under full load due to blocked filter, or dodgy pump
3) dodgy ECU
4) timing marks in wrong place?
5) dirty injectors
Sometimes the timing marks are nearly eight degrees out! If the crank pulley has ever been loose then the keyway can fret, and even bigger errors are then possible.
Over the last two years the number of cars I see with injector problems has rocketed, due to apparent changes in the fuel formulation about two years back.
Injector problems cause pinking for two different reasons. Either the flow is less for affected injectors, or the spray pattern is wrong.
If the injector produces a jet instead of an atomised cone, the the mixture will appear weak since only some of the fuel burns (slowly at that).
Injector problems are indicated if you take the car for a good blast, then kill the engine without letting it idle (easier on the rollers). If you then whip out the plugs, they should all look exactly the same. If they are different colours then this may be the tree to bark up!
>> Edited by Mark Adams on Monday 2nd September 10:59
Pinking is often due to a lean mixture, not just ignition timing. However there are several possible causes of this - all of which require a bit more investigation. Assuming your car is standard and in good condition, here's some possibles:
1) fuel pressure too low - check regulator
2) fuel pressure dropping off under full load due to blocked filter, or dodgy pump
3) dodgy ECU
4) timing marks in wrong place?
5) dirty injectors
Sometimes the timing marks are nearly eight degrees out! If the crank pulley has ever been loose then the keyway can fret, and even bigger errors are then possible.
Over the last two years the number of cars I see with injector problems has rocketed, due to apparent changes in the fuel formulation about two years back.
Injector problems cause pinking for two different reasons. Either the flow is less for affected injectors, or the spray pattern is wrong.
If the injector produces a jet instead of an atomised cone, the the mixture will appear weak since only some of the fuel burns (slowly at that).
Injector problems are indicated if you take the car for a good blast, then kill the engine without letting it idle (easier on the rollers). If you then whip out the plugs, they should all look exactly the same. If they are different colours then this may be the tree to bark up!
>> Edited by Mark Adams on Monday 2nd September 10:59
The injectors are the easiest parts to check, so I would probably start with them. It is also worth verifying that your timing marks are accurate, although you do need specialist equipment to be spot-on (try V8 developments on 01775 750000).
ECUs are easier to check by swapping with another known good vehicle, and making sure that the fault moves to the other car. I can test and remanufacture them, but there is obviously a charge for the service.
Obviously I have to be careful what I say in order not to be guilty of blatant on-line advertising! If you want to e-mail or call me I can fill you in on the details!
Tel: 01694 720 144
Mob: 07798 582 390
ECUs are easier to check by swapping with another known good vehicle, and making sure that the fault moves to the other car. I can test and remanufacture them, but there is obviously a charge for the service.
Obviously I have to be careful what I say in order not to be guilty of blatant on-line advertising! If you want to e-mail or call me I can fill you in on the details!
Tel: 01694 720 144
Mob: 07798 582 390
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