Hey friends, hope you’re all having a great summer!
I’ve been fighting a bit of a warm start issue that so far I haven’t quite nailed down. Hoping to lean on the experience of the group here, maybe help point me in the right direction.
Scenario 1 – Starts Great: When the engine is cool and the ambient temps are below about 25C (75F), it fires up right away on the turn of the key. This is true if the car has been sitting a day, or sitting for a month.
Scenario 2 – Rough Start: If the engine is cool, but the ambient temps get much warmer than 25C (75F), it doesn’t like to fire up right away and I need to give it some throttle input to get it started.
Scenario 3 – Starts Ok: When I’m driving and the engine is up to operating temp; if I stall the car it will usually start right back up with a twist of the key.
Scenario 4 – Rough Start: If I’ve been driving the car, it’s up to operating temperature and then it sits for a few hours, it doesn’t like to fire up and I need to give it some throttle input to get it started.
I hope the above information makes sense. I have the Service Manual and have referenced the Hard Start section to try and narrow down the issue. Here are a few ideas I’ve had and/or tried:
Fuel Pump Check Valve – Since the car will start fine even after sitting for long periods, I don’t believe the fuel is draining back to the tank.
Idle Air Control Valve (IAC) – The idle does hunt a little bit on first start, so I’ve wondered if this could be something. However, when driving the idle is stable and perfect.
Throttle Position Sensor (TPS) – Trying to figure out a way to measure the voltage of the sensor, so this is still an open item.
Coolant Temp Sensor – Reading the service manual, this is listed as a potential and given the connection with temperature I certainly wonder. That being said the temperature reading on dash has always seemed to be correct and quite accurate.
Bad Coil/Plug Wires/Timing – I’ve replaced the spark plugs, and the distributor cap and rotor so far. Perhaps the wires, coil or timing could be the issue?
Fuel Filter – Noting that I have not yet replaced this.
Throttle Body – On my todo list to clean this, but have not done it yet.
Emissions – The car is completely stock and as far as I have been able to check, all the vacuum lines and emissions items seems to be correctly connected.
It may also be worth noting that sometimes on a bad start the car will throw a Code 34. This is the MAF low air flow code, but can also be tripped for rough idle/start. I originally thought maybe this was the cause, but it might just be a symptom. Thanks in advance for your help! Any input is greatly appreciated. If there is anything above I’ve done incorrectly or should go back and check again, just let me know.
Thanks,
Josh
I’ve been fighting a bit of a warm start issue that so far I haven’t quite nailed down. Hoping to lean on the experience of the group here, maybe help point me in the right direction.
Scenario 1 – Starts Great: When the engine is cool and the ambient temps are below about 25C (75F), it fires up right away on the turn of the key. This is true if the car has been sitting a day, or sitting for a month.
Scenario 2 – Rough Start: If the engine is cool, but the ambient temps get much warmer than 25C (75F), it doesn’t like to fire up right away and I need to give it some throttle input to get it started.
Scenario 3 – Starts Ok: When I’m driving and the engine is up to operating temp; if I stall the car it will usually start right back up with a twist of the key.
Scenario 4 – Rough Start: If I’ve been driving the car, it’s up to operating temperature and then it sits for a few hours, it doesn’t like to fire up and I need to give it some throttle input to get it started.
I hope the above information makes sense. I have the Service Manual and have referenced the Hard Start section to try and narrow down the issue. Here are a few ideas I’ve had and/or tried:
Fuel Pump Check Valve – Since the car will start fine even after sitting for long periods, I don’t believe the fuel is draining back to the tank.
Idle Air Control Valve (IAC) – The idle does hunt a little bit on first start, so I’ve wondered if this could be something. However, when driving the idle is stable and perfect.
Throttle Position Sensor (TPS) – Trying to figure out a way to measure the voltage of the sensor, so this is still an open item.
Coolant Temp Sensor – Reading the service manual, this is listed as a potential and given the connection with temperature I certainly wonder. That being said the temperature reading on dash has always seemed to be correct and quite accurate.
Bad Coil/Plug Wires/Timing – I’ve replaced the spark plugs, and the distributor cap and rotor so far. Perhaps the wires, coil or timing could be the issue?
Fuel Filter – Noting that I have not yet replaced this.
Throttle Body – On my todo list to clean this, but have not done it yet.
Emissions – The car is completely stock and as far as I have been able to check, all the vacuum lines and emissions items seems to be correctly connected.
It may also be worth noting that sometimes on a bad start the car will throw a Code 34. This is the MAF low air flow code, but can also be tripped for rough idle/start. I originally thought maybe this was the cause, but it might just be a symptom. Thanks in advance for your help! Any input is greatly appreciated. If there is anything above I’ve done incorrectly or should go back and check again, just let me know.
Thanks,
Josh
