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pinking (knocking)

3K views 58 replies 11 participants last post by  Dean O 
#1 ·
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? :confused:
 
#4 ·
Dean O said:
ta cd ( :lol: ) Yep, I've always associated pinking with advanced timing, but isn't that usually accompanied by quicker acceleration? & its a bit sluggish if anything :confused:
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.
 
#8 ·
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 ).
 
#9 ·
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 ·
I've misled everybody - sorry fellas ;oops:
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.
 
#14 ·
I'm beginning to think mine's running lean now as well :roll:
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 :lol:
 
#15 ·
Dean O said:
I'm beginning to think mine's running lean now as well :roll:
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 :lol:
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!
 
#16 ·
you mentioned yer fuel pump, Tom :confused:

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%.
 
#17 ·
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 :eek:
 
#18 · (Edited)
don't spose you could advise me how to test the capsule, Orca ;) just notice yours is a T8 special too :cool:

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 :)
 
#19 ·
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?
 
#20 ·
Dean O said:
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 ...
 
#22 ·
the rotor arm doesnt move, its bits underneath it that do. If you remove the dust shield you can see them moving.
On the 99t dissy there are 4 contacts that turn with the rotor arm. there are also 4 contacts in the base plate in the dissy. when the vac acvance/retard moves it moves these contacts effectively changing the timing.
 
#23 ·
mmm, ain't had a timing gun for nearly 30 years :confused:
it goes like a rocket for the 1st 5 mins so wouldn't that rule out a dodgy diaphragm? I think its an unlikely solution because I'd already swapped distributors in trying to cure what turned out to be a jammed turbo, & there was no discernible difference in running between the two. I'm going to replace all the vac lines after reswapping the dizzy.
 
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