View Full Version : SR20DET misfiring problems

11-05-2002, 10:04 PM
Just when I thought everything was under control...

I was driving back from a friend's house one night when all of a sudden, POP!!! The car completely dies. I mean completely. Nothing - no electrical. I had it towed to my house.

The next day, I found that the positive battery cable was completely fried, and both terminals on the battery blew up. Later on I realized that the positive terminal to the alternator had come loose and grounded somewhere, causing a short. I replaced the positive battery wire, replaced the terminals, and re-connected the alternator. Everything ran fine again - for about 6 hours...

Later that day, I drove about 30 miles to the racetrack without any problems. As I was parking, I noticed the car was idling on three cylinders. When I gave it gas, it cleared up. I wasn't concerned.

When I left the track, and drove for about 20 miles without any problems. Then the misfiring started. The car started firing on three cylinders, irradically. At first it was only under light to moderate throttle, but it quickly got to the point where the misfire was constant. I drove the remaining 10 miles to my garage on three cylinders

The day after (day 3), I tested some things and here's what I found:
Cylinder no. 1 was not firing. All the other cylinders fired consistently.
It's not the coilpacks. I switched them and no. 1 still wouldn't fire.
It's not the spark plugs. Same test.
It's not the injectors. Same test.
Finally I used a multimeter and determined that the plug to cylinder no. 1's fuel injector was not getting power.
I pulled the harness, and checked every connection. No dice. It's not a wire or ground.
I visually checked the ECU, and nothing looked out of the ordinary (burned, melted, etc.). It's not a fuse, either.

I believe the problem to be in the Ignitor chip, or Cam angle sensor, but I don't know how to test them. I do not know the chain of command for the fuel/spark system, so I don't know what would be causing this problem. Any suggestions? The engine is an S13 blacktop type 2 ('97-98). This one's past me.



11-06-2002, 01:43 AM
C'mon, I know there are plenty of briliant minds with the experience to help me out. I posted this on Zilvia, and they told me to come here!!


11-06-2002, 12:54 PM
</font><blockquote><font class="small[/img]In reply to:</font><hr />
here's what I found:
Cylinder no. 1 was not firing. All the other cylinders fired consistently.


i forget what color or what pin location, but injector harness should worm its way uninterrupted, iirc, to the ecu.
did you test for continuity on wire between the #1 injector plug and corresponding ecu pin?

11-06-2002, 10:00 PM
Yes, I checked all continuity in the engine harness.

What I didn't check was continuity is the lower harness (connection the transmission with the alternator, started, fuse box, etc.). Do you think the problem could be there?

Is there any way to manually test the ECU, ignitor, oe CAS?


11-06-2002, 10:41 PM
There's no way the CAS could affect the firing of only ONE cylinder.

Easiest way to check the ECU is replace it with a "known good" ECU if you've got a friend with one...


11-06-2002, 10:44 PM
are u sure that the little metal pins inside the injector clip arent bent. I had that problem with my sohc ****box but it shouldnt matter what motor. One of the pins was bent and it wasnt making contact with the pin on the injector. It had power and continuity and the injector was good so it took me months to figure out that was the problem.

11-06-2002, 10:55 PM
</font><blockquote><font class="small[/img]In reply to:</font><hr />
Is there any way to manually test


remove your c.a.s. from cylinder head.
reconnect the c.a.s. harness to c.a.s.
place c.a.s. upside down on your cam cover.

check you're in neutral.
turn ignition key to "on".

when you turn the c.a.s. gear with your hand, you will hear your injectors click.
at the same pace, your ignition coils should throw sparks.

if you remove the coilpacks, insert a plug or bolt and have the protruding metallic object set close to cam cover or intake manifold, you will see sparks. (keep sparks away from injectors if you have leaky seals, and fix the leak!)

from what you have already told us, you should see four sparks and you will probably hear clicks from #2~#4 injectors.

what would this excersise yield? not a whole lot, unless you conduct further tests while someone twiddles the c.a.s. gear.

and yes, there is a possibiity that you fried up your ecu.
have you checked for d.t.c.? (diagnostic trouble codes)

i don't think your igniter chip and rest of the ignition department has much influence on your injector issue.

11-07-2002, 02:35 PM
OK, well, thanks for the info on that test. I will try that.

I manually checked the wiring harness with a multimeter, and made certain that the metal prongs inside the plugs were not bent.

I looked inside the ECU, and nothing seemed burned, melted, or damaged in any way. Could it still be f-ed up?

Also, my engine is unique. It is an S13 blcktop from a '97 or '98. The ECU is slightly different (two pins) than other S13's. I don't know of anyone that has a late model S13 like me. I'm sure they exist, but I don't know them. So swapping ECU's just to check mine probably isn't going to happen.

Thanks for the help. I'm going tto check some things over the weekend, and I'll let you know what I find, so make sure to check back. If you think of anything else, please let me know.

Thanks for taking the time to help me with this problem, I really mean it.


11-07-2002, 04:35 PM
you're welcome.

correct me if i am wrong, the signal wire for #1 injector is white/black? and leads to pin #101 @ ecu?

if that wire shows continuity; and there is continuity betweeen the ground terminal at #1 injector coupler and chassis; and when you twiddle the c.a.s. in formentioned "test" and you get no signal out of the ecu pin, your problem is beyond your wires, and likely to be ecu related.

check other pins, such as #103 (green/black), #110 (yellow/black) for injector signals right there at the coupler, if you get something out of them and nothing from #101,,,,

good luck

11-07-2002, 08:57 PM
Just FYI heres a link for all the ecu pins. http://www.datnet.org/new/techinfo/page1.html If you look around on this site theres also the S14 manual in english you can download.

11-08-2002, 03:33 AM
well, i'm home and i dug out my jdm fsm on s14 along with the schematics for jdm s14; i must correct my 0.5assed recollection of the injector harness.

each injector receives power via red wire which branch off into four injectors from one red wire.
just where the injector harness is coupled into the 8-pin coupler, the power supply wire changes to color R/L which is red/blue.
if the #2~#4 injectors are receiving power, then problem might be between the branching point to the #1 injector.

if the power distribution is not the problem, then the signal wire for the #1 injector, which is white/black, might be the culprit.

the fsm, even the english version, contains trouble shooting guide. there is a section on injector circuit.
it's way too late for me to translate and describe the procedure, but, it's never too late for any sr-owner to download a copy for the sake of having a reference.