RaceCarBldr

Okay, so I just bought this 1994 civic EX coupe. It's an EJ, d16z6. Automatic (I know, I know!!) I needed a car in a pinch and it was cheap. Ran perfectly fine for the last month.

One day, I run it though the car wash, I get out of the car wash tunnel and put the pedal down HARD making a hard right turn. After spinning the tires a bit, I return to driving normally. about two minutes later, at idle I notice car starts shaking. I give it a little gas and it struggles to idle up. I have an aftermarket muffler, so its easy to hear that there is a misfire. My car went from sounding like a Honda to sounding like a WRX... you would think that is cool, right? NO! Suddenly it is running at about 75% power.

So I figure, dead cylinder, right? I park it, keep the engine running (since I don't know if it will start again), pop the hood and check all my connections. Spark plug wires, check. Air intake, check. Sensors/Wires, check. Nothing seems to be out of the ordinary. So I finish lugging it home. I turn the car off, restart it, same. Runs like is had multiple misfire or dead cylinder. Throughout all this I have no check engine light on (yes, it works!).

I shut the car off again. Pull all the plug wires, they seem fine. I pull the plugs, they seem fine. I try to restart the car, now it won't run at all! So I pull the cap and rotor. Rotor is worn down, contacts in the cap look worn. I learn from my cousin (previous owner) last tune up was about 3 years ago. He didn't drive the car much. About 5k-10k miles per year.

So I go buy new plugs, wires, cap and rotor. Still won't start. I test the coil, it's bad. No spark. So I go buy an Accel SuperCoil (it was cheaper than stock LOL). Car starts. Idles smooth at 1500 RPMs for, I would say, up to 2 minutes. Then starts misfiring again. Engine is shaking, it will rev, but with hesitation. Misfire is very inconsistent. Seems random. When in gear and driving, still weak, still sounds like a WRX (still not cool!)

So I do so research and learn the igniter may be bad. Nobody sells the igniter separately, so I put in a whole new distributor. HALLELUJAH! It starts and idles smooth! REV REV REV!!! ...then there it is again. Same as before. So my next thought is timing belt jumped. I check the timing, it is dead on! But I decide to mess with it anyway. Advance... no change. Retard... WORSE! After some YouTube research, I pull the timing cover, set it to TDC. Everything looks okay... except the cam pulley is just a little off. The bottom line on the cam pulley lines up perfectly with indicator, but my video says it should be just a hair to the right. So i loosen the tensioner, pull the belt. turn cam pulley one tooth counter-clockwise and reattach the belt. I fire it up, and BAM!! Car is running PERFECT! AGAIN!! And again.. there was a delay.. no longer than two minutes later, it starts misfiring AGAIN!!

So by now, it is safe to say that on a cold start, the car runs perfectly fine. But once it starts generating some heat, it begins misfiring. Again, through all of this no check engine light. During every part replacement, i disconnected the battery and removed the ECM fuse so that the computer could start fresh and learn new parts.

My last and final thought is a Throttle Position Sensor (TPS). The reason I hesitate on buying one is because it's $40 and not a return-able part. I am also skeptical because I did at one point unplug TPS and engine ran and drove good, even with check engine light on. When I plugged back in, CEL stayed on and still ran good. So I disconnect battery, reset computer, and restart engine. Check engine light is off again and engine running rough again. So I unplug TPS again to see if same thing happens. It doesn't. Engine still running rough. So maybe that was a fluke? I am at a complete loss here guys. I cannot think of any reason this should all be happening.. All I know is that somehow, hammering the gas while making a hard right out of a car wash got this snowball rolling. Maybe it was a coincidence though...

I would appreciate any input you guys have, or if anyone has had a similar experience with an inexplicable issue like this one?

civic402lx

Have you check injectors for clog or leaks? May need a good cleaning.

mk378

Did you actually check for dead cylinders? Warm up until it starts to misfire then unplug the fuel injectors one at a time. Do not unplug the spark plugs while the engine is running, that is prone to blow the coil.

Generalized misfiring when the ECU goes "closed loop" (engine warmed up and all sensors working so no CEL) could be a lean condition such as low fuel pressure.

RaceCarBldr

Okay, so I will try warming engine and unplugging fuel injectors 1 at a time. I will also pull the fuel rail and injectors and check for clog. Thanks guys. Will update when done.

RaceCarBldr

Actually I just remembered... don't know if this counts, but I did pull the plugs and hold a lighter over cylinders one at a time while cranking engine. Got fire from every one of them.

NotARaCist

iTrader: (1)

That's...an interesting way to test for fuel. Not exactly something I would recommend anyone do. Test your spark. Get an HEI tester, and use it. You should see white, or blue white spark at all four. If you don't, then you have defective parts in your ignition system and need to further diagnose. After you re-set timing, did you check the timing again after it started acting up again? You could have a stretched belt that jumped again.

mk378

Yes I missed that. If your timing belt ever skips, that will damage the teeth and you need to put a new one on.

Nedrobmas

Yeah man, I think In having your same problem. It happened on the way to the gas station, gas on E, filled up 10.6gal/11.9gal, rpms dropped real low as if it was going die. Filled up, still a problem for about 10min & 10mi, went away. Came back Randomly, so I thought fuel related. Checked plugs, they were rounded off, changed fuel filter first and ran seafoam through it, changed plugs & wires and still get the problem randomly , usually right after start-up and a mile in morning temps. Still looking for patterns and other factors.

The last I did before this happened was changed the distributor o-ring closes to the engine. Also when I wash the car, I do get a little soap & water in the muffler tip. When I looked inside it, there were rust peelings but not sure if its related to the problem. Was there anything you or previous owner did before the problem occur?

Nedrobmas

I forgot to mention after new plugs, battery was changed because of age and corrosion along with ground & starter cables, then weld the muffler because of crack where end(tail) joins the muffler. Anything similar to you?

RaceCarBldr

Ok, so unplugged the injectors one at a time. Cylinder 4 3 and 2 engine nearly dies when unplugged. Cylinder 1 had no change. So I swapped injectors one 1 and 2. Problem did not move to cylinder 2, it stayed on 1. So what now? Injector is not bad, but something causing cylinder 1 injector to fail..?

mk378

That means that cylinder 1 is dead, and the problem is not the injector. Next step should be a compression test to see if there is a mechanical failure. You can also take the spark plugs out, inspect for obvious plug problem like broken or fouled out, and swap them around.

Remember you need all of fuel, compression, and spark to fire a cylinder.

RaceCarBldr

So the problem has been solved. One of the new plugs was defective. When I pulled it out to do another compression test, noticed the porcelain was not secure to the base. Went to parts store and warrantied plug, car runs great! Thank you to everyone who put in suggestions! By the way, just wondering wherr the compression should be. On cold engine I got 90psi closed throttle crank all cylinders, open throttle they averaged 130 within 5 psi. From what I read on other threads a lot of other folks are getting 150-180 on compression tests...

NotARaCist

iTrader: (1)

Your engine needs to be warm with the throttle fully opened to do a proper compression test. New spec is something like 170, IIRC, but as long as you're above 100, you're fine.