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GVR-4 Car runs rough, then doesn't?

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Nate355RS

Proven Member
446
50
Oct 25, 2012
Salem, Virginia
Occasionally when I start my car, hot or cold, it will run rough then after a few minutes it'll run smooth and all my power is back, almost like someone flipped a switch. This is on my 92 VR4.

While it was running rough I disconnected the injectors one at a time to see if idle changes. They all changed the idle, except on cylindar 3. After a few minutes the motor stated running smooth and I disconnected injector 3 and now the idle changes. I'm pretty sure it's a problem related to cylindar 3, just not sure what the problem is or how to fix it. And I'm confused why it only happens after start up, and once it smooths out I don't have any problems.

Just to cover a few bases, the motor has good compression, no boost leaks, and I've swapped to known good injectors and the problem didn't go away. The problem also happens in open and closed loop.
 
Base fuel pressure is good. What's the best way to check spark? I'm guessing I'll have to check it with the car running while it's running rough because the problem is intermittent.
 
You can buy a spark tester which allows you to see the spark. You basically plug it in between the plug and wire. It looks like a small plug wire. Anyways so you would do one at a time and have someone crank for you as you look. Or you can simply take off the wire and put a screw driver in the end and then ground it on a bolt and have someone crank while you look. Either way works I have the tester just cuz it's easier and less likely to get shocked LOL. Make sure to check all your grounds and connections. Make sure they are tight and no corrosion build up. Since you have link can you post a log of the issue happening?
 
I'll grab one tonight hopefully, and I'll check out that spark plug tester. What I don't get is how it runs so bad and then instantly gets better.
 
Post a log of it happening if you can would help the most. Sounds like either a fuel issue or spark. Have you changed the fuel filter lately or have old gas possibly. What injeectors are you using and are they setup right in link? Have you checked your coolant temp sensor, making sure it's working and plugged in properly?
 
I had an injector sticking open on me that would cause a hard start condition (would crank a while and run crappy for 1-3 minutes then it was fine) but it took me a few days to find it, It might be a long shot but run your car, let it sit overnight. then pull your spark plugs (AFTER it has been sitting! do not start it!) one by one and its very possible one could be coated with fuel or look very different from the rest. (I know you said you changed injectors but this still is an easy check) Or start it and let it run and as soon as the misfire clears up pull the spark plugs again and it should tell you if it was caused by a rich condition or a lean condition.

Good luck.
 
Finally caught it acting up and took a log. No check engine light, but I'm throwing code 0041 Injector circuit malfunction. When the car runs normally I don't get this code.

This was on a warm start coming back from my lunch break. It runs rough and lean through open and closed loop, up until the 180sec mark. Then the car backfired twice and started running smooth, which sounds like it's a stuck injector. But what's weird is I swapped injectors with another good running 4g63 and my Galant still had this problem.

I'm going to move the injectors around to see if the problem follows the injector or stays on 3. I'm betting it will stay on 3 but we'll see. Anything else I should check with the 41 error code?
 

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