00M6SSLS1
New Member
- Joined
- Apr 22, 2011
- Messages
- 3
- Reaction score
- 0
- Points
- 0
- Vehicle Year
- 1999
- Make / Model
- Mazda
- Engine Size
- 2.5L
- Transmission
- Manual
Hello Everyone,
I'm trying to diagnose a rough idle condition on my dad's 1999 Mazda, B2500.
It's a 2.5L, inline 4 cylinder.
This truck will start with no problem, but will begin to idle poorly after 20-30
seconds. It will also stall if the throttle is slammed shut. Very weak power
overall.
The Haynes manual is far from helpful, there are no specs for compression,
or camshaft dial-in.
I suspect the cam has jumped at least a tooth because the compression is
reading 198-210 PSIg across all four cylinders. According to some forums,
this is about 30-40 PSI too high. My guess is the cam has advanced itself,
or the previous owner did some engine work and did not install it properly.
If anyone can confirm the compression readings for this engine, and also
indicate how to tell the camshaft gear position I would really appreciate it.
Some other measurements taken:
- fuel pressure 70 PSI at idle
- 02 sensors are both responding and crossing from 100 mV to 800 mV
- No DTC codes are present when ODBII port is scanned
- TPS reads fine and responds when probed
- IAT and ECT are working and read the same when starting the motor
- Electronic ignition timing (read by scanner) says 19 degrees (advance)
Fuel injectors have 12 volts and pusle with the engine cranked.
New wires and plugs (all 8 plugs)
New fuel injectors
New IAC valve
EGR valve checked and functional. Have also blocked it off for a test
No apparent vaccum leaks. Hoses look good and are tight fitting.
Thank you in advance for any tips!
I'm trying to diagnose a rough idle condition on my dad's 1999 Mazda, B2500.
It's a 2.5L, inline 4 cylinder.
This truck will start with no problem, but will begin to idle poorly after 20-30
seconds. It will also stall if the throttle is slammed shut. Very weak power
overall.
The Haynes manual is far from helpful, there are no specs for compression,
or camshaft dial-in.
I suspect the cam has jumped at least a tooth because the compression is
reading 198-210 PSIg across all four cylinders. According to some forums,
this is about 30-40 PSI too high. My guess is the cam has advanced itself,
or the previous owner did some engine work and did not install it properly.
If anyone can confirm the compression readings for this engine, and also
indicate how to tell the camshaft gear position I would really appreciate it.
Some other measurements taken:
- fuel pressure 70 PSI at idle
- 02 sensors are both responding and crossing from 100 mV to 800 mV
- No DTC codes are present when ODBII port is scanned
- TPS reads fine and responds when probed
- IAT and ECT are working and read the same when starting the motor
- Electronic ignition timing (read by scanner) says 19 degrees (advance)
Fuel injectors have 12 volts and pusle with the engine cranked.
New wires and plugs (all 8 plugs)
New fuel injectors
New IAC valve
EGR valve checked and functional. Have also blocked it off for a test
No apparent vaccum leaks. Hoses look good and are tight fitting.
Thank you in advance for any tips!
Last edited: