Hello,
94 Accord LX
History:
Had intermittent shut down and no start condition approx 1.5 yrs ago. Finally, wouldn’t ever start and I troubleshot it and found a bad Ignition Control Module in the distributor. Replaced that and it worked great since that time.
Current problem:
Wont’ start at all now, although it began as an intermittent won’t start and sudden shutdown problem again this time…It turns over, has spark at plugs (tested by removing plug from block and jumpering the ground side to the chassis and turned key to start) and fuel is pumping to the fuel rail (removed banjo nut and turned over and watched fuel pump into a bucket when turning key to on) and very very briefly sounds like it wants to run…enough so that if I keep the key turned to start I hear that the engine is no longer being turned by the starter because it quickly seems start, but again very very very briefly. It has compression (not measured, but heard when turning over with plug removed). It throws a code 15 “Ignition Output Signal”. I did clear the codes first, so I’m sure this is a fresh code. It does not throw any other codes. While this current problem was still intermittent I replaced the Ignition Control Module as an educated quess due the my previous trouble 1.5 years ago. No luck. I don’t believe it’s a “water in the fuel” type problem since it began as an intermittent sudden shutdown problem and would run OK for a day or 2 in between problems. The injector resistor bank has correct resistance readings. I put a scope at the pin on top of each injector that leads to the ECM, thinking I should see some sort of pulsing signal firing the injectors as I attempt to start the car. When the key is turned on, I get a + steady DC signal, I’m thinking it was +5v but can’t recall, but didn’t see any pulsing signal. What are the chances that I have a bad ECM? The fact that I have spark, but get a code 15 confuses me. Any ideas??? Thanks, Jim
You have done some good troubleshooting.
Going by what you stated, the injectors are not turning on . Looking across the injector coil you should have seen pulses if they were. The problem may be due to the ECU shutting down the fuel delivery system since it doesn’t seem to see ignition pulses and is issueing the code. This is a safety feature. Perhaps there is a wiring connection problem that is causing this trouble. You may need to purchase a service manual to fix this. Having a manual will save you time and money and someone with your skills will really be able to use it.
One easy thing you could try doing to see if it is a fuel problem is to spray a small amount of starter fluid into the intake and see if tries to run then.
Thanks Cougar!
I’m going to try the starter fluid as you suggested. I’m working from a Haynes manual which I’ve found to be very helpful up to a point. I think what you’re saying is that the signals to the injectors may be shutting down as a safety feature due to the ECU either not seeing or thinking it’s not seeing ignition pulses…which would be the signal that comes from the ignition control module??? I’ll post my progress. Thanks, Jim
Look at the wiring diagrams (Yep, THOSE things) and see what the PGM-FI relay controls. This relay is on the underside of the dash and is problematic. You can also see: www.tegger.com/hondafaq/startproblems.html for more ideas.
Looks like it provides power to the injectors and fuel pump, iac & evap valves as well as the O2 sensor heater. Thanks, I’ll check that out.
Yes, voltage gets to the injectors but since the return side of the circuit is most likely controlled through the ECU, the circuit is basically open and no current is flowing. Current needs to flow through the injector coils to turn them on. Once the ECU sees the ignition pulses it will make the return connection to ground and turn on the injectors and you will see the pulses on the scope.
This is the way some Subaru systems work, which I am more familiar with, and assume Honda does this in a similar way.
That is exactly right.
Went out today and it fired right up. It wouldn’t start all day last Sunday when I was troubleshooting it. I need to figure exactly where the ECM is grounded to the chassis. Tegger.com said it’s usually on the thermostat housing, but I didn’t see it there. I recall one day when it wouldn’t start. After dropping the hood pretty hard to close it the car fired right up. I’m thinking I’m looking for an intermittent ground, connector or wire. Apparently ECM failures are rare per tegger.com. I did bench test the PGM-FI relay today, looking for a possible high resistance on possible dirty relay contacts, but they all have basically 0 resistance. Intermittent problem is going to drive me crazy for sure!
Saturday, 10:45 a.m. Won’t start. It’s 79 degrees outside here in Georgia. My daughter seems to think it has to do with being warm or hot weather. Another note on symptoms is that when turning the key from off to on to start it fires and runs for about 1 second. When trying to start again from the on position without going to off first the car doesn’t try to run at all. Only after turning the key all the way off, then on & start will it again run for 1 second before shutting down and throwing a code 15.
Found some high resistance readings when checking grounding from the frame to miscellaneous components throughout the car. Removed and cleaned the surfaces of the grounding lugs on the “battery to frame & block” ground cabling. Will have to see if my intermittent problem doesn’t come back.
Look back through the posts over the last few days. Honda start problems have been covered several times. To to those other web sites, also. They have some good stuff.
Been rooting through them and will continue. Thanks! It started up fine this a.m. I’m waiting the air temp top be 79 degrees, like it was yesterday when it wouldn’t start. I’m grasping at straws now since the problem has remained so intermittent with no rhyme or reason when it fails.
The problem is due to the ECU not seeing the ignition pulses for some reason and so it shuts down the fuel system and generates the error 15 code. The car starts briefly when you try to restart it but the ECU still sees the ignition problem and shuts it down again.
The problem could very well be a connection problem that makes trouble when the temperature gets warmer. This is common. The problem may also be something like a cam sensor having a problem. Subaru had a cam angle sensor in the distributor in an earlier model car and when it had trouble it would cause this same kind of thing. Look over your prints and see if you have a CAS sensor. You may need to replace it or have a bad connection to it. You may be able to prove it is bad by heating it up using a hair dryer.
Thanks Hellokit and Cougar for your help. I’m convinced I JUST found the problem…a cold solder joint on the PGM-FI relay. I re-visited Tegger.com (thanks hellokit) and rooted around about the PGM-FI relay, saw the symptoms and picture of the cold solder joint… http://www.tegger.com/hondafaq/mainrelayoperation/badmainrelay.html, and sure enough, found the same cold solder joint on the exact same pin as in the picture. Re-flowed the solder…now will wait and see, but after all the troubleshooting I’ve done, I’m thoroughly convinced I found the problem. I had already bench tested the relay and it worked just fine, but the intermittent problem was kicking my butt. THANKS to both of you for all your help! I can’t say enough about how much I appreciate it! Jim
Dang it! Daughter said it wouldn’t start this afternoon. I get home from work and it starts just fine. Ugggh!
Did you ever get this figured out? I’m having a similar issue with my 1994 accord ex
Hi! I did. It turned out to be my computer. Was lucky enough to have a friend that had access to a used one for me to try it before paying for it. A key symptom for me was it mostly occurred when the passenger cabin was really hot, after sitting in the Georgia sun for several hours. I finally realized that it always cranked up after I had the doors open for about 15 minutes while I was troubleshooting. It was very intermittent, so I was hesitant to throw money at a computer until my friend was able to offer that deal. Although I rarely use it, my 94 Accord is still running today.
Good luck. I’d love to hear what you discover as your solution.