Misfire help!!!! Options

[sasrunner]

Thank you in advance!!! And sorry for the long 1st post!! My wife and I bought a 97 Celica St 7A-FE about 3 months ago for a little next to nothing. The car needed an alternator battery and all the maintenance stuff done to it(timing belt, water pump, plugs, plug wires cap and rotor, fuel filter, all new fluids) It had a stumble when we got it. Fiqured it needed the stuff mentioned and maybe some other stuff. So I took it to a Toyota mechanic friend who looked it over and diid some other work on it. He replaced the egr, egr vsv and modulator. Removed the intake plenum cover and decarboned the runners and passages. He also did a compression test, check valve clearance, fuel pressure, timing,valve timming, replaced and adjusted the TPS, cleaned the IAC valve and replaced #2 and #3 injector.Replaced #1 O2 sensor. All the parts replaced are Toyota OE except the injectors. They're NAPA remans. The car still misses when in gear and under load. It's always cylinder #3. We swapped injectors around the see if the miss moved. It didn't. The temperature sensor is in spec also. The plugs are normal grey after 1000 miles. The antifreeze is completely full. Also replaced the coil. He is going to parts warrenty the plug wires for me just in case I got a bad set from Toyota, which I doubt. I pulled the exhaust manifold this evening just to see if there was anything in the exhaust port. He is at a loss as I am as well. I suggested a fuel pump, but he said that it shouldn't be it as the miss is isolated to one cylinder. His suggestion is to replace the ecm with a used one to see if maybe the injector signal is getting screwd-up somehow. If it's still there he said we're pulling the head. Maybe be a funky valve or something wrong with the seat. He did say he wanted the check the valve springs before he jerked the head off. All in all it ain't that bad of miss. But my wifes driving it to save on gas and as of right now we got a total of $1500(including the car) and beer in it. Let me know if we're missing anything. All help is appreciated!!!

This post has been edited by sasrunner: Jul 31, 2013 - 9:38 PM

[Smaay]

double check the valve clearance. I had a 7A-FE come to me with a misfire in Cylinder 2. i changed the shim to bring it in spec, it ran fine for about 4 months and the misfire came back. I re-checked the clearance and it was tight again. I took off the head and replaced the valve. it was dishing really bad. new valve fixed the problem.

[sasrunner]

double check the valve clearance. I had a 7A-FE come to me with a misfire in Cylinder 2. i changed the shim to bring it in spec, it ran fine for about 4 months and the misfire came back. I re-checked the clearance and it was tight again. I took off the head and replaced the valve. it was dishing really bad. new valve fixed the problem.

Thanks man!!! I spoke with him earlier this evening and he said the same round about thing. He said he actually checked them with car warmed-up and should have done it cold. He said he was used to doing 22r's when they're hot and never thought twice when he did our car. So maybe and hopefully that's it. It's weird!! It's not like the car has a dead hole, it just occasionally stumbles in gear at idle. We're planning to drop it at the dealer he works at tommorow evening and let him work on it Saturday sometime. I'll post progress or failure.

[sasrunner]

Got it fixed!!!! The valve clearance was fine with the engine cold. They were right where they needed to be. Kinda a "go or no go spec." So my friend pulled the head. He gave me call Saturday afternoon to come by and check it out and help clean parts. He removed the valves on all cylinders and looked them all over. Cleaned them, checked the guides, replaced the valve seals, checked the springs for cracks and breaks. There was a small amount of carbon on the exhaust valves, but nothing major. The bore and pistons looked great. They all still had the crosshatch machine marks and no real amount of carbon at the top of the block. He had run Seafoam and GM upper cylinder cleaner through the motor a few weeks ago, so that's partly why there wasn't a whole lot of carbon in the combustion areas. He had removed the intake when he was going through the head and had it soaking in the parts washer. He said it had the typical gunk in the runners, but again nothing that should have caused a problem. I could tell he was getting frustrated so we took a break. He kept saying that it to be fuel delivery since it wasn't a typical dead cylinder miss. It was just kinda like having a 3 1/2 cylinder at times. So we went back and looked at the injectors again. He used his meter and measured the resistance again. All are good. Then by chance he looked at the holes in the back of the injectors. The fuel delivery side. The reman injectors from Napa looked alittle different. The seal or o-ring at the top seemed to be fatter. Like a restriction to feed the injector. After finding a magnifying glass he could see that the o-rings had little bits of skin from when they were molded still on them. Like the thin rubber that is on a brand new tire from the molding process. Hope that makes since. So he used used a xacto knife and small amounts of air to get them out. Sounds crazy, but it's running great. Of course what we can't understand is we had swapped #2 and #3 injectors(both remans) at one point and it still missed on cylinder 3. Like he said, it may justa been the right combination of poor fuel spray, carbon and intake sludge to make that particular cylinder run bad. I'm happy cause the wifes happy!!! And I know my buddy is thrilled to have this outta his hair.

[Smaay]

glad you figured it out. im surprised how easy it is to get the 7A head off with the engine in the car. I have done it twice now.