400SE Still pinking...
Discussion
I know this has been mentioned before but I would really like to cure this long standing problem. The timing has been backed up to about -12 degrees (off the end of timing marks)Car ticks over smoothly but only pinks loudly when warm. I have noticed of late that when the outside ambient temp is lower it seems to improve? Overall performance seem "ordinary" but picks up after 3500 to 4000 rpm. I have nothing to compare this too so may be normal? I have tried various fuels and additives with no change as well as an ACT carbon fibre trumpet upgrade. I am satisfied that there are no air leaks on the vacuum plumbing as well as the advance and retard tube on the dizzy. This is also working when testing by sucking the tube and seeing the mechanism working. The blackbox has been looked at by Mark Adams as well as at rolling road test which indicates that the car is performing reasonably well but the pinking only manifests itself under road driving conditions when hot and under load.
It has been mentioned that I may need to back off the timing even more but I am a little cautious. Any help or suggestions would be gratefully recieved!
It has been mentioned that I may need to back off the timing even more but I am a little cautious. Any help or suggestions would be gratefully recieved!Dear Jack,
Have had similar problems with my 450SE. Mine tends to pink when hot ie when in slow moving traffic around town and when ambient air temps are over 20 degrees C. I reduced the pinking by using Optimax initially, then I changed the air inlet hose from the filter to the plenum from the black reinforced fabric thing, to a Samco hose supplied by Tim from ACT. This has reduced the pinking but not eliminated it. If I take her for a blast in winter, then I have no pinking problems at all and the car goes much better. In summer as long as I am moving at above 40 then heat build up is not much of an issue and she hardly pinks at all until you get into slow traffic or stop start, when airflow is reduced and the heat builds up again. When you start moving again it can take quite a few miles of motoring to cool the intake system down and pinking reduce.
Hope this helps
Nige'
Have had similar problems with my 450SE. Mine tends to pink when hot ie when in slow moving traffic around town and when ambient air temps are over 20 degrees C. I reduced the pinking by using Optimax initially, then I changed the air inlet hose from the filter to the plenum from the black reinforced fabric thing, to a Samco hose supplied by Tim from ACT. This has reduced the pinking but not eliminated it. If I take her for a blast in winter, then I have no pinking problems at all and the car goes much better. In summer as long as I am moving at above 40 then heat build up is not much of an issue and she hardly pinks at all until you get into slow traffic or stop start, when airflow is reduced and the heat builds up again. When you start moving again it can take quite a few miles of motoring to cool the intake system down and pinking reduce.
Hope this helps
Nige'
Could be the heads have carboned up, the wrong head gaskets have been fitted and thus the compression ratio has been increased and hence the problem, or TVR went mad when making the engine and you have a CR of around 13.5 to 1. All of these have caused pinking on exotic wedges before now.
Steve
www.tvrbooks.co.uk
Steve
www.tvrbooks.co.uk
Fuel pressure ok? If you have a rising rate type check it, or install one.....
Probably your monster likes a lot of fuel, and not supplying enough can cause these symptoms (lean running) as well.
Installing a rising rate fuel pressure regulator improved things on my standard 350i. Although it was not as bad as yours, and I was looking for an improvement as well.
Rob
Probably your monster likes a lot of fuel, and not supplying enough can cause these symptoms (lean running) as well.
Installing a rising rate fuel pressure regulator improved things on my standard 350i. Although it was not as bad as yours, and I was looking for an improvement as well.
Rob
It seems to me that most of the causes have already been covered.
I think you can pretty much ignore air leaks in terms of pinking, because leaks only matter at part load when there is a lot of manifold depression.
Similarly, if there is any doubt about the vac advance, disconnect the vac line. It should have no effect at full load anyway.
One problem with clockwork igition timing is that the mechanism isn't always consistent. If the spark timing is varying significantly, you might find that some sparks are arriving too early and provoking pinking. Once it has started, hot spots cause by the pinking would be enough to keep it going. I don't have any experience of checking for this so I don't know how you would go about it other than a timing strobe on a rolling road, braver man than me required to hold it though!
It would be useful to get hold of a wideband lambda sensor and see whether it's running lean. This might show up problems with the fuel pressure regulator, air flow meter, fuel pump and so on.
Don't place too much faith on the timing marks on the front pulley, unless you have verified them by measuring the actual position of #1 TDC.
If the engine has been running rich it might be coked up. This would encourage detonation. Increasing the fuelling is one trick to prevent detonation so this might be a bit of a catch 22 situation. Short of stripping the engine for a decoke, the only solution I know for this is to add water injection for a few thousand miles. This would probably fix the detonation too, but the science behind water injection is bleeding complex so doing this properly is quite a challenge. In any case, it should be possible to cure the detonation without resorting to water injection, so I wouldn't consider this as anything more than a way to spring clean the insides of your engine.
If the engine is running very high compression it will burn faster so it will need less advance, it will also be more vulnerable to pinking and require higher octane fuel.
Have you go the right grade plugs in? If these are overheating that would encourage detonation. You should be able to see signs of this on the plugs if so.
It would be useful to measure the air intake termperatures and see if the pinking occurs because the temperature has crept up. The obvious solution if so would be to improve the cold air intake.
At least you can get some consolation from the cold weather, you won't need to worry about this particular problem for a few months!
I think you can pretty much ignore air leaks in terms of pinking, because leaks only matter at part load when there is a lot of manifold depression.
Similarly, if there is any doubt about the vac advance, disconnect the vac line. It should have no effect at full load anyway.
One problem with clockwork igition timing is that the mechanism isn't always consistent. If the spark timing is varying significantly, you might find that some sparks are arriving too early and provoking pinking. Once it has started, hot spots cause by the pinking would be enough to keep it going. I don't have any experience of checking for this so I don't know how you would go about it other than a timing strobe on a rolling road, braver man than me required to hold it though!
It would be useful to get hold of a wideband lambda sensor and see whether it's running lean. This might show up problems with the fuel pressure regulator, air flow meter, fuel pump and so on.
Don't place too much faith on the timing marks on the front pulley, unless you have verified them by measuring the actual position of #1 TDC.
If the engine has been running rich it might be coked up. This would encourage detonation. Increasing the fuelling is one trick to prevent detonation so this might be a bit of a catch 22 situation. Short of stripping the engine for a decoke, the only solution I know for this is to add water injection for a few thousand miles. This would probably fix the detonation too, but the science behind water injection is bleeding complex so doing this properly is quite a challenge. In any case, it should be possible to cure the detonation without resorting to water injection, so I wouldn't consider this as anything more than a way to spring clean the insides of your engine.
If the engine is running very high compression it will burn faster so it will need less advance, it will also be more vulnerable to pinking and require higher octane fuel.
Have you go the right grade plugs in? If these are overheating that would encourage detonation. You should be able to see signs of this on the plugs if so.
It would be useful to measure the air intake termperatures and see if the pinking occurs because the temperature has crept up. The obvious solution if so would be to improve the cold air intake.
At least you can get some consolation from the cold weather, you won't need to worry about this particular problem for a few months!
Air leaks are important as they bypass the MAF meter and introduce 'false' air into the inlet/engine which doesn't add extra fuel to compensate.
Tighten the rocker covers down as well as the inlet manifold bolts. Then check all the hoses which connect to the plenum. Also spray some carb start around various flanges/connections and see if the revs increase. Oh check all of the above as well
Boosted.
Tighten the rocker covers down as well as the inlet manifold bolts. Then check all the hoses which connect to the plenum. Also spray some carb start around various flanges/connections and see if the revs increase. Oh check all of the above as well
Boosted.
alot of the early wedgies sorry i dont know the age of yours? the engines were built by nck and generaly used a high duration 234 camshaft, which ran fine on compresion ratios of 10-1 and higher with no pinking, however because of drivability and mot emision laws a lot of these cams were replaced with mild cams which cant handle high cr
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