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Hi guys new to the forum here, and having an issue with my Honda Civic Ex 1996 automatic. Car starts up fine, drives fine and after a few minutes, sometimes early as 5 minutes other days it'll take 10 min to do it, the engine surges, needle on the rpm gauge is bouncing up and down. At one point I pretty much lost power and the car just rolled, even while stepping on the gas. So I went thru the manual have been doing the troubleshooting, fuel injectors are fine, fuel pressure regulator has been replaced, fuel pump checks out, there's no intake leak, so my last thing to check says ECU or information sensor for defectiveness. I'm pretty sure that is the ECT sensor they are referring to. I don't even know if this will solve it and I'll have to pull it out to check it with a ohmmeter since I can't get it at its location. So my two questions are, if I can use a bolt to plug the hole from losing too much coolant, what size would it be? I don't feel like spending $30 on a new sensor if it's not needed. My second question is does anyone else have any insight to what this problem may be with my car in the event the ECT checks out or is replaced and the problem still exists? Thanks guys!

 
Rep Power: 211

Clean the IAC valve and it's screen gasket. Also clean the throttle body.
Other possibility is air in coolant system.
To get at the ECT remove the air intake hose for better access. The ECT is shown in this vid:

 
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I did a pressure test on the coolant system, no air is in it. ECT was changed still didn't fix it. The IAC was what I was looking at yesterday. I did perform the test to see the engine would pick up after unplugging the connector while running it passed, so not sure. I did see there is carbon build up over time from watching videos and stuff like that on the screen so it won't hurt to try it. Thanks for the advice. I'll keep you posted.

 
Rep Power: 211

Coolant system pressure test is used to find external leaks. Some use it to find internal leaks into the cylinder(s) and then pull the spark plugs and run a borocope into the cylinder(s) to look for coolant. Bleeding coolant system is different as it's goal is to bleed out unwanted air of the coolant system. Pockets of air in the coolant system can cause irradic idling and overheating.

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Ok guys so I fixed the surging problem. I flushed the coolant and bled all the air out that did the trick. However now the engine starts overheating when I'm accelerating pass a certain speed. I don't think it's a lack of coolant, I've already topped it off and I replaced the thermostat a few years back. Any advice guys? Thanks!