Air duct of a new type of ONS engine equipped with fuel injection
A – elastic tube, B – mounting hole, C – mounting clamp
Crank mechanism
Pistons
Since February 1987 (code 7В02) in ONS 1.6 dm³ engines and since September 1986 (code 6J15) in ONS 2.0 dm³ engines, the offset of the piston pin axis relative to the piston axis has been reduced from 0.8 mm to 0.6 mm. New pistons cannot be installed with old connecting rods and vice versa.
Fuel system
Since May 1987 (manufacturing date code "HL") some adjustment data of Weber two-chamber carburetors intended for ONS 2.0 dm³ engines have been changed - the deviation of the air damper when the vacuum regulator starts to operate in all Weber 85 HF carburetors is 8 mm.
Since January 1988 (manufacture date code "JB"), a new type of air duct has been installed in petrol injection engines.
Since May 1988, cars with the 1.8 dm³ ONS engine have been equipped with a new Pierburg carburetor with the designation 85 HF 9510 KS. Its distinguishing feature is a yellow dot on the enrichment valve.
Adjustment data of carburetor 85 HF 9510 KS
| Diffuser diameter: | |
| - 1st chamber | 23 mm |
| - 2nd chamber | 26 mm |
| Main fuel jet: | |
| - 1st chamber | 102,5 |
| - 2nd chamber | 102,5 |
| Idle fuel jet | 45 |
| Idle air jet | 120 |
| Idle speed | 875±25 rpm. |
| CO content | 1,25 % |
| Air damper deflection | 4 mm |
| Throttle mixture damper stroke (dashpot) | 1.6 – 2.4 mm |
Since July 1988 (production date code "JG"), the ONS 1.6 dm³ engines have used a new carburettor type 84 HF 9510 DB with an electromagnetic valve that shuts off the fuel supply after the ignition is switched off to prevent spontaneous ignition.
Adjustment data of carburetor 84 HF 9510 DB
Idle speed: 875±20 rpm.
CO content: 1%.
The remaining adjustment data are the same as in the Weber 84 HF 9510 CA two-chamber carburetor.
Other information concerning the technical characteristics, adjustment and repair of ONS engines can be found in subsection 4.1 and subsection 3.1.3.1.