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  #1  
Old 20th May 2006
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Default pinking (knocking)

APC solonoid connected: boost gauge only goes to half yellow. (still chatters on warm down & stops when brake pedal pressed)

disconnect APC solonoid: boost gauge goes to red line ok but engine starts pinking at half yellow - the same max boost spot as when solonoid connected. shouldn't it only pink higher up, much higher up?
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  #2  
Old 20th May 2006
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I don't know the details but you should be thinking about timing, vac advance/retard and fuel quality. Dunno what else...
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  #3  
Old 20th May 2006
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ta cd ( ) Yep, I've always associated pinking with advanced timing, but isn't that usually accompanied by quicker acceleration? & its a bit sluggish if anything
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  #4  
Old 20th May 2006
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Quote:
Originally Posted by Dean O
ta cd ( ) Yep, I've always associated pinking with advanced timing, but isn't that usually accompanied by quicker acceleration? & its a bit sluggish if anything
If the timing was *way* off, I would think it would become sluggish. IE: if it's too far advanced it would be pushing the piston back long before TDC which would kill power output.
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  #5  
Old 20th May 2006
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good point!
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  #6  
Old 21st May 2006
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Default Detonation

The only likely point not covered is fuel/air ratio too lean ??
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  #7  
Old 21st May 2006
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Quote:
Originally Posted by Saab Driver
The only likely point not covered is fuel/air ratio too lean ??
How do you test this?
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  #8  
Old 22nd May 2006
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Default Knock/Detonation

The AFR can be checked with an AFR Meter which all good auto workshops would have. This would be last on my list, after checking items previously mentioned,viz., octane rating of fuel, spark advance , engine temp , spark plugs of correct heat range. With ref to spark plugs make sure also pinging has not caused any physical damage. Wrong plugs may cause pre ignition leading to detonation ( pre ignition is an entirely different problem usually ).
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  #9  
Old 23rd May 2006
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Something's not right there - when the APC solenoid's disconnected the car should be restricted to base boost only. Has the wiring been monkeyed with?

If a previous owner's not been able to get the car to boost properly, then they have bodged it. It does sound like the APC box has been taken out of the equation.
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  #10  
Old 23rd May 2006
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I've misled everybody - sorry fellas
In light of Matthew's comments, I re-read my initial post & its plain wrong I'm afraid.
I did unplug the solonoid for a trial run in trying to get to the bottom of the warm down chattering BUT had reconnected it before
DISCONNECTING THE 3RD OUTLET PIPE (driver side) for the run that produced the pinking from 1/2 yellow thru to red border! - again, sorry.
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  #11  
Old 3rd July 2006
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sorry to drag this up again, but this problem remains 'as was' despite new engine fitted
could it be the solonoid itself that's faulty? could swap the one off me T16 if its worth it.
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  #12  
Old 3rd July 2006
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Have yo got another APC you can swap to see if it continues?

If it does then you've got to start with the pressure transducer really, it's under the dash but you can test it from the APC plug.
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  #13  
Old 3rd July 2006
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I'm having loads of trouble with the fueling on my 99T. I've got an air/fuel gauge to test it with.
I've changed the entire fuel system now and am thinking that perhaps all my fuel pumps are faulty
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Old 4th July 2006
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I'm beginning to think mine's running lean now as well
dunno whether having to unplug the CSI to get her to start is a separate issue, but I've noticed two successive mornings now that I have full boost UNTIL normal running temperature is reached & then it starts pinking about half way up the yellow & obviously won't then boost beyond that.
Tom, when yer finished with Si's gauge, will ya post it to me
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Old 4th July 2006
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Quote:
Originally Posted by Dean O
I'm beginning to think mine's running lean now as well
dunno whether having to unplug the CSI to get her to start is a separate issue, but I've noticed two successive mornings now that I have full boost UNTIL normal running temperature is reached & then it starts pinking about half way up the yellow & obviously won't then boost beyond that.
Tom, when yer finished with Si's gauge, will ya post it to me
That is exactly what mine was doing a week or so ago!

Then i started messing with the mixture to richen it and changing bits around (which made no difference). Now it has gone really lean like i said in my thread.

Sonnett1 said that he had found somewhere selling cheap bosch fuel pumps, but im still waiting for him to tell me where this place was so i can order one for myself!
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  #16  
Old 4th July 2006
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you mentioned yer fuel pump, Tom

again, dunno whether its significant but when I turn on the ignition, the pump 'priming' noise or is it the relay buzzing for a few seconds? whatever the noise is, it only happens maybe 50% of the time now, whereas I'm fairly sure it always used to be 100%.
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  #17  
Old 4th July 2006
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Does your vac advance capsule on the distributor work? That has an obvious effect on the timing when in boost. The other thing is to make sure your fuel pump has a good ground. Mine buzzed most of the time and completely stopped once grounds had been cleaned up. The quiet was quite eery at first
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  #18  
Old 4th July 2006
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don't spose you could advise me how to test the capsule, Orca just notice yours is a T8 special too

my fuel pump (assuming it's that which is supposed to make a noise when the ignition is 1st switched on) only buzzes for about 2 seconds then not at all, which I think is normal. the problem I'm having is that it no longer buzzes every time I turn on the ignition.
actually I have a working spare distributor so I'll swap that to test if the vaccuum advance is working

Last edited by Dean O; 4th July 2006 at 06:17 PM.
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  #19  
Old 4th July 2006
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Dean - you can take the vac advance/tard capsule off the dissy - its 2 screws.

To test if it retards under boost like it is supposed to, get the car running with a timing light on it then pump up the feed to the capsule with a foot pump. the timing should change.
I went through all this on mine first and it was working fine.

I dont think my pumps run when i turn the key either, though it used to. Mine is also very hard to start - I have to crank it once. then turn it off for a second and then crank it again to make it catch. wonder if it is all down to the pump?
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  #20  
Old 5th July 2006
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Quote:
Originally Posted by Dean O
don't spose you could advise me how to test the capsule, Orca
Their failure is simply that the diaphragm no longer seals the unit, so suction and pressure no longer actuates the arm. The simplest method is to remove the vac hose from the throttle end, block off the open holes, fire up the car and fire a timing gun at it. Apply suction to the hose connected to the capsule and see if the timing changes ... then pressure ...
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