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Start Quantity Control, Basic Function - GF07.08-P-1052A
Engine 139, 176, 177, 254, 256, 260, 264, 274, 279, 282
Overview
This document contains information on:
- General
- Function requirements
- Function
- Cold start enrichment
- Post-start enrichment
- Warm-up enrichment
General
To achieve stable and smooth engine running, the fuel/air mixture is enriched via the combustion engine control unit.
The following enrichment phases are decided from:
- Cold start
- Post-start phase
- Warming-up phase
Function requirements
- Engine management ON (circuit 87M)
- Engine in operation
Function
Cold start enrichment
In order to facilitate the engine starting procedure, an additional quantity of fuel is injected during the starting procedure. To do this, the combustion engine control unit calculates the required injection duration of the injection valves for starting mixture enrichment. The higher the coolant temperature, the shorter the injection duration calculated by the combustion engine control unit. In order to compensate for the reduced start quantity for a lower battery voltage, the combustion engine control unit extends the injection duration.
Post-start enrichment
In order to ensure that the engine continues to run perfectly, the fuel condensing in the cold cylinder barrels is compensated for by the post-start enrichment. To do this, the combustion engine control unit calculates the injection duration of the injection valves and extends it.
Warm-up enrichment
The quantity of fuel condensed in the still cold cylinder barrels is compensated for by the warm-up enrichment. The injection duration of the injection valves is extended by the combustion engine control unit.
To provide additional heating of the combustion chambers, exhaust gas recirculation is activated during the warm-up phase.
The lambda control monitors the injection duration as soon as this is enabled.
| Function schematics | |||
| Function schematic for start quantity control | Engine 260 in model 118, 177, 247 Engine 264 in model 167 | PE07.70-P-2500-97A | |
| Engine 282 in model 118, 177, 247 | PE07.70-P-2500-97B | ||
| Engine 176, 177 in model 167 Engine 177 in model 290 as of model year 2021 | PE07.70-P-2500-97C | ||
| Engine 139 in model 118, 177, 247 | PE07.70-P-2500-97D | ||
| Engine 254 in model 206, 214, 236, 254 Engine 256 in model 214, 223, 236 | PE07.70-P-2500-97E | ||
| Engine 176 in model 223 | PE07.70-P-2500-97F | ||
| Engine 177 in model 192, 223, 232 | PE07.70-P-2500-97G | ||
| Engine 139 in model 192, 206, 232, 236, 254 | PE07.70-P-2500-97H | ||
| Engine 279 in model 223 | PE07.70-P-2500-97I | ||
| Engine 274 in model 213 as of model year 2021 | PE07.70-P-2500-97J | ||
| Additional basic functions | |||
| Combustion engine control unit, basic function | GF07.08-P-9890A | ||
| Basic function of injection valve | GF07.03-P-2001A |
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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