having issues with my 99 civic ex. while driving accelerator temporarily goes out. once car is started back up it is fine. this happened 4 times in the last month. now, car wont start periodically. engine threw out p0420 code. fuel pump is pumping gas. (not sure if its enough pressure, havent checked it). could it be catalytic converter or o2 sensor? i've also heard coolant temp sensor could cause problems at start up. it turns over fine, and sputters a little like it is trying to start, but wont. had an extra distributer cap, so i threw it on for the hell of it. did nothing. took hose off intake manifold to look or buildup. didnt look too bad. plugged wires back into it, and put hose back on, and it fired right up....for one day. next morning took a few minutes and some cranking to get it running. ran fine all day. next morning, wont start. I don't want to change cat converter if its something simple like a sensor. any ideas?

 

That's an O2 sensor code, so start there, at the very least the O2 sensors will be dirty and clogged up, maybe you could pull them and clean a little more life into it/them, does not cost you anything but some time and effort, if that does not work, maybe time to replace it/them, [it's a sensor, sensors go bad].

A bad ECT sensor symptoms are, [normally] easy starting when engine is cold, but harder when warm, poor gas mileage, boggy when warm, exhaust stinks of fuel, [running rich].

Before you do anything, you need to know what is missing, no or low fuel pressure, no or poor spark, test for those.

Just buy and permanently mount a FPG, handy to have in place anyway.

Unless you have or can borrow one, buy or rent an HEI spark tester....



And check the spark. 94

 

hmm, what else have you checked?

 

Just bought new o2 sensors. getting ready to put on. bought some starting fluid just to see if i could get it started.(it had been sitting for 3 days). before using starting fluid, i turned the key. started right up. i cleared the 0420 code. drove it around. code not back yet. hopefully thats the problem. driving it anywhere is a gamble. dont know if it will start up.

 

Hope that fix your problems. Good luck!