I had to rebuild the engine on this car because one of the nuts holding the piston rod to the crankshaft came loose. It didn’t come off, but loose enough that the rod and piston were slapping around. I replaced the crank, the one rod, put in new rings on all pistons, honed the cylinders, new bearings, had the head cleaned and new valve seals put in, new head gasket, cleaned out the EGR, cleaned out the intake. I didn’t have the head machined and I honed the cylinders by hand (VERY carefully). I replaced both O2 sensors along the way as well.
The engine holds compression, doesn’t seem to burn a drop of oil. Coolant is clean and staying at a constant level. The only thing that did happen is one of the teeth on the back timing belt pulley on the crank (teeth used with crank position sensor) broke off so I had to weld it back up and grind it to be exactly like it was before. I have pictures and it is the exact same gap and height, etc. so I don’t think that could be it.
Lately the shuttering at a stop light has gotten a little worse. Putting it in Neutral or Park at the light helps but you can definitely feel it where you could barely tell before. When I rebuilt the engine I put new plugs in. At this point, the engine has about 10k miles on it.
At this point, frustrated and wondering if it is worth it, I have these on my list of things to check:
1 - Motor Mount. I replaced the rear but the passenger side one isn’t great and I can see the engine move considerably when you put it in drive. Maybe the transmission one too. They are factory and at a 118k miles, they probably should be replaced anyway. Just not sure if that is the cause. Cost is about $50 for each mount (NAPA)
2 - Vacuum leak. I’ve done a cursory visual inspection and nothing seems out of whack. Need to check using other methods (some mentioned here).
3 - EGR Valve. It’s original, and although I have cleaned it, I guess it could be causing issues. Cost is about $210 (NAPA)
4 - Sensors. Throttle position, crank position, other? I’d prefer to test these some how instead of just randomly replacing as they aren’t cheap. Crankshaft - $70; Camshaft - $60; Knock - $160; FI Temp - $20; MAP - $300; Throttle Position - $95.
5 - Fuel injectors. Grasping at straws but it could be the issue or part of the issue I guess. $159 each.
I have done so much to this car at this point, and with a rebuilt engine that only has 10k on it, I don’t want to give up on it. But it’s getting to be a pain.
Are there easy ways to test the items above? Are there other things that might be causing this problem?