Isuzu 4HL1, Workshop Manual

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Engine Control System 1A-255
9 ECM
VIM 1. Install Tech 2 and display the data list.
2. If the data does not appear or the displayed data is
incorrect, perform the "On-Board Diagnostic (OBD) System
Check".
D: Engine mechanical system
1 Valve clearance 1. Using tools, measure and adjust the valve clearance. (Refer
to "Functional Check" in "Engine Mechanical".)
2 Compression 1. Using tools, measure the compression. (Refer to "Functional
Check" in "Engine Mechanical".)
2. If the measured value is incorrect, fact-find the compression
leak and repair or replace the faulty portion(s).
3 Glow plug 1. Using a tester, measure the resistance of the glow plug.
2. If the measured value is incorrect, check the circuit between
glow relay and glow plug, as well as glow plug.
4 Fuel filter / pipe / tank Perform the visual check according to the following
procedures.
• Check the fuel system for air bleed. (Bleed the air as
necessary. Refer to "Functional Check" in "Fuel System".)
• Check the fuel filter for excessive contamination and choke.
• Check the pipe for damage, collapse, and choke.
• Check the fuel tank for contamination with dust.
• Check the feed pipe in the fuel tank for foreign materials.
5 Air cleaner, intake pipe Perform the visual check according to the following
procedures.
• Check the air cleaner for excessive contamination and
choke.
• Check the pipe for damage, collapse, and poor assembling.
6 Ring gear Perform the visual check according to the following
procedures.
• Check the gear teeth for chipping.
• Check for cause(s) that prevent gear rotation.
• Check the gear for correct engagement.
7 Catalyst 1. Check the catalyst for internal damage sound.
8 CKP sensor
CMP sensor 1. If non-OEM parts are installed, turn off all the powers and
reconfirm the symptom. If OEM parts resolve the symptom,
the cause lies in noises from the non-OEM parts. Report the
fact to the customer.
2. Check the sensors are firmly fixed.
9 Mechanical timing
Pump mount condition 1. Check the service history to identify the pump was removed
in the past.
2. If a removal was recorded, check the pump has correctly
been installed. (Refer to "Supply Pump" in "Fuel System".)
10 Rotary parts in pump assembly 1. With the pump running, check the assembly for fuel leak
and unusual sounds.
11 Valve timing 1. Check the service history to identify the camshaft was
removed in the past.
2. If a removal was recorded, check the camshaft has correctly
been installed. (Refer to "Camshaft Assembly" in "Engine
Mechanical".)
12 Fuel 1. Drain the currently charged fuel completely.
2. Fill new (and appropriate) fuel.