Background:

1991 civic si hatchback
b18c5
toda spec C camshafts
toda sports injection kit (individual throttle bodies)
custom hytech header
car is converted to obd2b but I have a harness to run an obd1 p28 w/ crome pro
car was retuned over the summer and has been running fine

I haven't driven the car very often since autox season is over.

The battery has gotten very low a couple of times just because the car sat for 2 weeks without running (miata battery).

I went to drive the car on saturday, and the battery was too low to crank the car so I jumped it off.

Now it drove fine for 10 or so miles, but all of a sudden the check engine light came on and the car started running really crappy. The car wouldn't stay running without me holding it at 1/2 throttle - it almost felt like it was runninig on 3 cylinders or something..... that's the only way I can describe it.
(I remember having injector #1 wiring come disconnected before once when I had adaptor clips on there and it felt very similar but that issue actually shows a CEL code to trace by flashes. I have since spliced and soldered the injector wiring and know it to be solid.)

I pulled off to an empty parking lot to check and see what was going on.
First thing I jumped the service connector and it still showed a solid CEL. Turning the key off and back on reset the CEL, but if I put the jumper in again it shows solid.

It wouldn't restart (battery was too low again) so I pulled the spark plugs and replaced them, then checked fuel pressure and spark. Injectors were firing (I can touch the nozzles by putting my finger in the itb inlets).

So I jumped the car off and drove it back home. I had the issue pop up one more time when I started to drive back home. But with a restart I was able to drive again without issue. I hesitate to drive it anywhere else until I can figure out wtf happened. This has happened 3x now. At first I thought maybe my crome chip wasn't seated correctly in the zif socket, but I double-checked and it's fine.

I read several threads in the archives, but none have the same issue as mine. One says possible main relay issue - but the car drives fine until the CEL pops on and then it drives like ***..... huge power loss and I noticed black smoke (rich) when the CEL comes on. I put my trickle charger on the battery overnight so hopefully that will help.

If not, I'm wondering if a low battery or alternator on the way out could cause this issue? Or is it possible it's a main relay (I'm using the 2000 itr wiring and relays).
This motor has 4x,xxx miles on it.

Thanks in advance for any advice you can give. I'm kind of at a loss without a code to trace.....

 

As far as I know, a solid CEL indicates that the problem lies within the ECU. Perhaps try burning a new chip, or try a different ECU.

 

I would point to the ecu itself. But its very strange how you drove for 10 miles and then had the problem come up.

Sounds to me like your car runs in close loop mode on start up then switches to open loop when the o2 warms. Maybe a sensor is causeing the ecu to go on the fritz.

 

funny thing. i haven't changed a thing. i charged the battery overnight and went and drove the car without any issue whatsoever........ makes me think it was the battery.

 

pull the jumper out of j1 and see if it goes back to the stock p28 program.then go from there.do u do the solder work your self?im wondering if some solder broke lose on the board?open the ecu and post some pic so i can see what it looks like.

 

A solid cel with the SCS connector shorted means that there are no stored codes. A solid CEL during ignition start up is an ECU problem.

Where this seems like an intermittent problem. Start checking your ground and power wires starting at the battery and work your way out from there. Look for any corrosion or bad connections. Check your new relay wiring and make sure there are no loose connections.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GhostAccord &raquo;</TD></TR><TR><TD CLASS="quote">A solid cel with the SCS connector shorted means that there are no stored codes. A solid CEL during ignition start up is an ECU problem.</TD></TR></TABLE>

hum? thats good to know ill have to remeber that!

 

[QUOTE=GhostAccord;32388708]A solid cel with the SCS connector shorted means that there are no stored codes. A solid CEL during ignition start up is an ECU problem.

Where this seems like an intermittent problem. Start checking your ground and power wires starting at the battery and work your way out from there. Look for any corrosion or bad connections. Check your new relay wiring and make sure there are no loose connections.[/QUOT

my civic had an issue with the map sensor connector. But there was no cel at on position or while car running, only threw a code when i jumped the scs. Error code 3 = map sensor. When i fixed the issue- the error code went away. But now instead of an error code- cel stays solid when scs is jumped and goes away when i take jumper out. Car starts and runs fine except some rough idling(intermittently revs high then low for about 30seconds).

is the cel staying solid only when scs is jumped mean theres nothing wrong?