ANYONE that knows their SR20's

[luke91]

I have a blacktop S13 SR20 in my '91 240.  I finished the swap about two months ago, and have been driving it ever since.  A couple nights ago, I was driving home from a friends house, when the car completely died.  Nothing worked.  Not even flashers, or lights.  I pulled over, and just as I did, the battery terminals exploded (in the trunk).  I disconnected what was left of them, and called a tow truck.  
The next day, I surveyed the damage, and noticed that the battery cable (+) was totally melted, as were the terminals.  I also determined the cause of the short to be the connection to the positive side of the alternator.  The nut holding it on had come off, and it must have grounded to something else.  I screwed it back on, and replaced the battery cable with some thicker 2 gauge.  I checked all other wires and grounds to see if they had fried, or came loose.  Everything seemed fine, so i decided to put it on the road again.  Here's where it gets interesting...
I drove approximately 15 miles to a friends house, got gas, and drove another 15 miles to the local racetrack.  Everything seemed fine.  As I was parking, I noticed that the engine was idling on three cylinders, but when I gave it gas, it cleared up.  I thought this was weird, but thought nothing of it.  When I left, the problem was still happening, only now it was worse.  After about 5 minutes, the car was running on three cylinders, and would not clear up.  I pulled over, disconnected the battery for a few minutes, and looked under the hood.  Nothing was out of the ordinary, so I hooked up the battery, and hit the road.  Everything was good again, although I would feel an occasional misfire every once in a while, which is still out of the ordinary.  By the time I got to my house, it had gotten worse, but not to the point it had earlier.  
The next day, today, I drove out to run a few errands, and everything seemed fine, until the car warmed up, then it started misfiring again - bad.  It would consistently run on three cylinders, and sometimes even two.  I shut it off, disconnected the battery, and  waited a few minutes. just like I had the night before.  When I reconnected the battery and tried again, it still ran on on only 3 cylinders.  I have absolutely no idea what is going on here.  I think I might have damaged something when everything shorted out the other night, but I don't know what.  
The misfire sounds exactly like hitting the speed limiter.  Only it happens at all RPM's, in all gears.  Sometimes the car will straighten out and run on all four cylinders, but only for a few seconds at a time.  I don't get it.  Anyone that can help - I need it.  Thanks
--luke

[luke91]

Someone's gotta be able to help me out, here...

[YellowS14]

ok, well how do you know its only running on 3 cyl(just feel, or did you check someting else?)

id see if you can figure out which cyl isnt running, play with the wires, see if anything changes, if not check the plugs, the bad cyl may look different

from there check the wires assoc with that cyl, then using a multimeter check for signal....

id also check your injectors, see if there getting signal

were there any terminals that have anything to do with ignition that were close to the damage caused my the short circut?


did you check if you threw codes?

Troy

[luke91]

Well, here's what I found out today...
The first thing I did was start the engine.  It started on three cylinders and continued to run on three cylinders consistently.  Next, I unplugged each injector, one by one, to see if one of the cylinders wasn't firing, and to rule out a timing problem.  When I unplugged the first cylinder, there was no change in idle, but when I unplugged each of the other ones, the engine vibrated and the idle dropped.  Now I know, for sure, that the engine is running on three cylinders, and that the problem is in cylinder number one.
Next, I switched the injectors from cylinders number 1 and 2 with each other to see if the problem is a bad injector.  I preformed the same test as above, and the results were the same.  When I disconnected cylinder number 1, there was no change, but when I disconnected each of the other cylinders, the engine ran on two cylinders.  Clearly there is nothing wrong with the injectors.  

The next test was to see if an ignition component had gone bad.  I pulled each plug, one by one, attached it to it's corresponding coil pack, grounded it, and started the engine.  Each one sparked regularly.  Now I know there isn't anything wrong with the ignition system.  

So here's what I learned for sure:
cylinder number 1 is not firing
all Injectors are good
all spark plugs are good
all coil packs are good
all ignition system components are good.  

My next step is to test the voltage in cylinder number 1's injector plug.  I am almost 100% sure that's were the problem will be.  If so, I'll pull the entire wiring harness, unwrap it, and test each wire for continuity.  Any suggestions would really help, here.  Any.
--luke

[DuffMan]

Could be, but also try switching or replacing the spark plug. Just because you see a spark doesn't neccessarily mean its working properly all the time.

[luke91]

I did.  No dice.  Thanks anyway.  
--luke

[camppain]

to really rule out the injectors ohm them out then move on

after that i would check cap and rotor

[luke91]

Well, I checked all of the injectors, themselves, and they all spray.  I also took an ohm meter to the injector plugs and saw that all are getting power except number 1.  So now I know that's what the problem is.  Great.  Now what do I do to fix it?  Tomarrow I'm going to pull the entire wiring harness, unwrap it, and see what I can find.  I'll check that plug for continuity, and if it's there, then I guess my ECU is bad?  I dunno.  
The motor is a RWD blacktop S13 SR20, so there's no distributer.  There is a cam angle sensor, and I'm pretty sure it's OK, since all plugs are sparking.  
I've never had this problem before.  Until a few days ago, the car never misfired at all, and had absolutely no signs of hesitation.  Hopefully, this is the result of some damaged wiring or ground.  I'll post again tomarrow and let you know what I've found.  
--luke

[luke91]

I'll be willing to bet that almost everyone who looks at this thread is discouraged by the size of the origional post, and moves on to find a smaller one.  That would explain the large number of views and the small number of replies.  That's too bad.  Anyway, I haven't gotten a chance to tear into the harness, yet, but I'll post the results when I get a chance.
--luke

[MFDoomSTYLE]

im having the same problem man... damnit..

[DrtyRat]

Just a little late on the post huh?

[fliprayzin240sx]

Well check the harness and another thing im thinking is that since you shorted shiet out...have you checked all the grounds to the engine??? You could have melted some of those too...

[mrmephistopheles]

Originally Posted by MFDoomSTYLE

im having the same problem man... damnit..

Good of you to chime in on a 3year old thread.