1998 Honda Civic Random Stalling and Trouble Restarting
I have a 1998 Honda Civic CX, manual transmission with 113K miles (75% are freeway miles). It runs very smoothly and still gets 46 mpg. However, for the past six months it will occasionally stall while I am driving, at either freeway speeds or idling at a stop light. I used to be able to restart it immediately, but now it is sometimes is hard to restart and once wouldn't restart for several hours.
The CEL does not come on when it stalls and the car does not throw any trouble codes, either stored or pending. The battery was five years old so that was the first thing I replaced. I have subsequently changed the fuel filter, fuel pump relay, fuel pump and the ignition control module (OEM). After changing the ICU I didn't have any stalling for over five hundred miles but it sometimes did not start on the first crank as it usually does. But I still get random stalling every now and then. I still never have any trouble starting up my car first thing in the morning. I typically drive for 45 minutes and then park for 90 minutes. Then when I try to start up my car it sometimes stalls and/or cranks but does not start right away.
Also, something new happened recently. My OBDII scanner will power up but will sometimes say that it cannot communicate with my car. Sometimes is will run through the tests even if it says it cannot communicate with my car's computer. Other times it won't run any tests. I verified that the scanner is good by testing with another scanner. Is this a hint that my ECU is going bad? What is your professional opinion? Thanks for any help that anyone can give me.
Considering the car age and the symptoms, my guess would be the ECU.
Have you tried capturing data with a scan tool while driving and checking it for anything suspicious when the problem happens?
Check to make sure the battery terminals are tight and not corroded. I had a similar problem on my 1999 Accord, and shimming the battery terminals solved the problem. If all is tight, at least you can cross it off your list of things to check.
let us know how it goes!
I would monitor system voltage when it stalls
The only clue I have is that the electric signal to the spark plugs are very weak when my car won't start (as checked with a timing light)
Have you tried load testing your alternator? It might be something that simple. Hope so.
UPDATE: I swapped out the ECU but the stalling/hard starting recurred. So that wasn't the problem. I also replaced the coil with a new OEM coil and it ran great for two days. On the third day the the motor stalled while I was driving on the freeway. Now I'm extremely perplexed. Still no DTC (diagnostic trouble codes) being thrown.
The only clue I have is that the electric signal to the spark plugs are very weak when my car won't start (as checked with a timing light). I'm going to take apart the distributor, plug wires and inspect them carefully tomorrow. Anybody know if the crankshaft position sensor or the camshaft position sensor might cause stalling/ hard starting? I would have think that these sensors would throw a DTC if they were going bad. I'm all out of ideas; any suggestions would be appreciated. Thanks.