Re: pinging fix - old message rehashed

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: I have done a decent amount of research regarding distributors and timing (mainly on my '79 320i that has a vaccuum retard and advance distributor also). If my understanding of these instructions are correct then they do OPPOSITE of what is desired. : Vaccuum retard allows you have have an advanced mechanic setting for timing and at idle the timing is backed off for a smoother and lower emissions idle. As you first accelerate the vaccuum retard goes away quickly allowing a decently advanced timing. : This description also displays a common misunderstanding of how vacuum advance works. At part throttle (crusing) the vaccuum is high and the timing is advanced by the vaccuum adv for better mileage etc. At full throttle, the vaccuum is low so you get LESS vaccuum advance (i.e. the timing reverts back to the mechanical/centrif. weights setting). : So if the vaccuum retard is disconnected and the timing reset to get the same idle speed the base timing has now been retarded in order to get the idle speed down. By connecting the retard diaphram to the advance vaccuum port you are now retarding timing during part throttle/crusing situations but at full throttle not doing much since the vaccuum decreases. So my take is that by following these instructions you have retarded your base timing and screwed up the advance curve completely. The only up side is that the engine should feel stronger at low RPMs because of the RETARDED timing but just die at high RPM. In short these instructions are incorrect. : : Walt Barie : '80 528i : '82 320i : '79 320i : : : Found an old message I had posted to the digest - thought it might be of use to someone. Samir. : : : : From: gofast@ix.netcom.com : : Subject: e12 pinging : : Date: Mon, 15 Sep 1997 19:30:20 -0500 (CDT) : : Next Article (by Author): <E36>IAA midas@vortex.is (Torfi Asgeirsson) : : Previous Article (by Author): smooth driving :-)) "Vida J Morkunas" : : Articles sorted by: [Date] [Author] [Subject] : : : Mine does it too (I have a 9.5:1 pistons in my 530i). I've been fighting this for a year or so, and have just begun to : : understand whats going on. I dont have much time, so I'm going to give a short reply, with a suggestion. We can communitcate : : more later. Many thanks to eric tangen, the alfa digest, and the DIY_EFI digest for the many lessons and discussions on : : ignition over the past year. : : You dont need to do all this injector cleaning. The pinging is probably due to a change in gas formulation. Running valve : : cleaners throught the system wont hurt, though. : : Pinging occurs when there is too much advance. You have a euro engine, thus high compression. Therefore you need less : : advance at higher revs. Or, more octane. Advance is cheap hp at low rpms, though. : : What kind of distributor do you have? The one with both vacuum advance and retard? Do the following with a warm engine: : : - - Disconnect both vacuum and retard lines from the distributor, and block them with golf tees. : : - - The line to the retard came from below the throttle body, right? : : This line gets vacuum at idle, goes away when revved. : : - - The line to the advance came from the top drivers side of the TB? : : This line gets no vacuum at idle, gets vacuum when revved. : : - - Start engine. Loosen nuts and rotate distributor clockwise till you get to the right idle speed. I have no idea what the : : new timing setting will be. : : - - Then connect the formerly-advance vacuum line to the retard cannister on the distributor. : : - - dont connect anything to the advance cannister on the distributor. : : Heres what you are doing. Formerly, you had retarded the engine at idle relative to the dynamic timing setting in the book, : : via the cannister on the distributor. When the car revs, that vacuum goes away, and the retards stops fighting the : : mechanical advance, allowing for increasing advance with rpms. At higher rpms, the advance cannister kicks in to give : : yet more advance. : : Now, you have changed the timing of the car, to give max mechanical advance at a lower rpm, so your car will get a shot in : : the pants with this setting. And as the rpms increase, the timing will get retarded, hopefully reducing the liklihood of : : pinging. : : I just did this last week, and my car is flying! so will yours, I hope. I have moved the pinging to 5000 rpms from 3500 rpm. : : You can also widen the spark plug gap, and try a hotter ignition. I just got an MSD which I will be adding soon. I am using : : 0.030 for the plug gap, but am going to try 0.035. : : Let me know how it works. : : Everyone with a euro l-jet car should try this. : : Samir.

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