Audi 80/Avant (B4)

Since 1991-1995 of release

Repair and car operation

Except engines of 66 kw

The detonation combustion arising if the ignition moment too far has been moved aside «ignition advancings», harms to the engine. A consequence of it are the overheat, damage of bearings and pistons.

But the engine works with the maximum capacity if «early ignition» that is if the engine works on the verge of a detonation is established as more as possible. This border of a detonation many factors (cause quality of fuel, adjournment on walls of chambers of combustion, etc.) so it cannot be fixed precisely. Therefore usually for ignition regulation it is necessary больший «a safety interval». Or "sentry" who defines, whether takes a place detonation combustion – regulation on a detonation.

Principle of action of regulation on a detonation

Combustion in cylinders is supervised by the so-called gauge of detonation combustion which is located at models with 4 and 5-cylinder engines at the left on the block of cylinders. Models with 6-cylinder engines are supplied by two sensor controls on the right and at the left above on the block of cylinders. The gauge of detonation combustion "feels", if at combustion in the cylinder there are non-uniform fluctuations instead of the usual uniform. It transfers this information further to the management block.

There there is a following: with signal receipt «detonating combustion at last ignition» following cylinders with normal combustion receive a spark still during the moment of ignition calculated earlier. But at that cylinder in which the detonation has been established, the ignition moment is displaced approximately on 3 °. And it occurs, it is necessary to notice, only at this unique cylinder. All the others work in a former mode.

If detonation combustion in the specified cylinder still remains, at a following working step the ignition moment is displaced for 3 °. And so it is possible to regulate to maximum 15 ° (calculated from the standard moment of ignition).

If in the corresponding cylinder now combustion proceeds normally after a while the ignition moment again moves in a direction of "early ignition». Adjustment occurs on 0,5 °, the break during many working steps before there is a repeated updating for 0,5 ° in a direction of "early ignition» then follows.

This process proceeds until initially planned moment of ignition or while the sensor control again will not inform on detonation combustion will be reached.

The gauge of detonation combustion

The slice is inserted into this gauge пьезокерамики, a material with which we are familiar on lighters (gives out a spark). Mechanical forces (a stretching, compression), influencing on пьезокерамику, are transformed by it to electric pressure. – arising because of detonation combustion – it is enough non-uniform fluctuations for sensor control activation. Important: the moment of an inhaling of the gauge of detonation combustion should make precisely 20 Н•м.