Just as many of the Hondas before mine, I've run into the issue where if I run the car for awhile (say driving home) and stop for gas, the car struggles to start.

I have read about the "main relay" issue, but I'm not sure my vehicle has a "main relay" as they changed the design in 2001.

Any help on this?

Txgreasemonkey? Help a fellow Texan, a Galvestonian! :)

Thoughts:

. Replace platinum spark plugs (NGK only), if they have 35,000 miles on them:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-46563-5.html#post617111

It wouldn't surprise me if replacing the plugs solved the problem--try this first.

. Test/replace the Engine Coolant Temperature (ECT) Sensor, which affects fuel injector pulse width. The ECT Sensor is a temperature dependent resistor (thermistor), whose resistance decreases as the engine coolant temperature increases. It provides a richer mixture when cold, leaner mixture when hot. Your ECT Sensor may be flooding the engine, when you stop and the engine temperature increases.

I agree with you that there is no infamous main relay on your Civic.

Thoughts:

. Replace platinum spark plugs (NGK only), if they have 35,000 miles on them:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-46563-5.html#post617111

It wouldn't surprise me if replacing the plugs solved the problem--try this first.

. Test/replace the Engine Coolant Temperature (ECT) Sensor, which affects fuel injector pulse width. The ECT Sensor is a temperature dependant resistor (thermistor), whose resistance decreases as the engine coolant temperature increases. It provides a richer mixture when cold, leaner mixture when hot. Your ECT Sensor may be flooding the engine, when you stop and the engine temperature increases.

I agree with you that there is no infamous main relay on your Civic.

Well, the plugs are relatively new (5,000 miles) and the problem has been going on for about 25,000 miles. I'll look into the ECT sensor.

Have any codes been thrown?

No, there are no codes.

It's important to periodically remove the Idle Air Control Valve and clean it with brake cleaner. While doing this, I also clean the throttle plate, upper and lower ports, and replace the air filter.

Since you live near the oil capitol of the world, I presume you use synthetic engine oil in your Civic. If you don't, you should. These engines perform best with synthetics and develop fewer emission system and starting related problems.

I've been using synthetic since I got it with 35,000 miles. Now it's at 187,500 mi and this is my only real complaint.

I'll clean the IACV first and see if that takes care of it.

Be sure to clean the throttle body and ports, as well. A lot of dirt can accumulate around the upper port. Just remove the air intake for access. Easy job.

This link may help:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-46563-7.html#post1054149

Also, check for any vacuum leaks. Ensure all emission hoses are in good shape and that the PCV Valve has been changed in the last 60,000 miles.

Several final thoughts:

. Disconnect the negative battery cable for 10 seconds to reset the ECM--record any radio codes first. This will force the computer to relearn some basic information on how you drive and eliminate any information that interferes with basic algorithms.

. Add fuel injector cleaner; e.g. Shell Regane or Chevron Techron.

. Focus on the Crankshaft Position Sensor, if the problem persists. Serious starting problems with your generation Civic usually involve the ECM, Crankshaft Position Sensor, and coil-on-plugs. Because of the location of CP Sensors, they can be problematic.

Keep me posted.