Hi all,
I'm dealing with a rough idle and I can really use some help and advice.
To begin with, my Evo is a 2010 SE and it's completely stock. I’m logging with Evoscan and a tactrix 2.0 cable using the the MUT III ECU setting.
The issue started when I was checking lash adjuster clearances and I managed to drop one of the valve cover bolts onto the valve tappet on the exhaust side and I didn’t notice. I checked the clearances on half of the engine and when I turned the engine over to check the other half, I turned it pretty hard by hand without thinking. The stray bolt marred the side of one of the cam lobes and basically bent at 90 degree angle, but didn’t seem to do any real damage to anything else. Just glad they are aluminum. The scratch on the cam lobe was above any contact points, so it seemed like everything was ok. So, I put everything back together.
When I started the car it had a rough idle with a lot of popping in the exhaust. It basically sounds like a Harley at idle. I suspect valve overlap, or something like that. The RPMs fluctuate between 1.5k and 1.25k, periodically dipping down to 750 at which point it sounds like it comes close to stalling before jumping back up. It throws a P0017 CEL which is an “Crankshaft/camshaft (exhaust) position sensor phase problem". So, I figure I did more damage than I had originally thought, so I replaced the cam sensor which didn’t help. I also noticed that unplugging the exhaust sensor didn’t make any difference. Running down the list of problems associated with this code, I’ve checked the timing belt tension and position and that looked fine. Pulled out the oil control solenoid and bench tested it. That checked out. Changed the oil, partly just to make sure there were no metal flakes in it. That was fine. Running down the list, the next thing to check out is the VVT sprocket and the crankshaft position sensor. I doubt it’s the crank sensor and before I remove the cam shaft to check the VVT, I wanted to compare my VVT values at idle to a good set. I did notice that the exhaust side fluctuates at idle along with the movement in RPMs, so I’d like to know what’s going on there.
I attached my log which includes the VVT readings and a few other measurements. Two things I noticed were that the VVT readings oscillated between 51 and 57 (degrees) for the most part. The reading would drop into the high 40s after a little while, 15 seconds or so, and then move up into the low 60s before settling down again. This seems to track with fluctuations in the RPMs as well. When I eased into the throttle, it would drop to -14, with a drop in RPM until I gave it more throttle. Then it comes back up to normal readings and the RPM rises. I don’t know if this is normal or not. The drop in RPM certainly isn’t. This is where a healthy idle would be nice to see. The other oddity I saw was that the exhaust VVT tracked perfectly with the intake VVT. Maybe this is normal under no load, but again I can’t be sure without a comparison. Another possibility is that the VVT values could be the target values rather than the actual values. I'm not sure what the readings are in MUT III. I understand that a patched ROM will allow both values to be displayed. Is there a preferred ROM to use?
If anyone has any advice or sees anything of note in the log that I should look at, please let me know. I want to get back on the road!
Thanks for the help,
Scott
I'm dealing with a rough idle and I can really use some help and advice.
To begin with, my Evo is a 2010 SE and it's completely stock. I’m logging with Evoscan and a tactrix 2.0 cable using the the MUT III ECU setting.
The issue started when I was checking lash adjuster clearances and I managed to drop one of the valve cover bolts onto the valve tappet on the exhaust side and I didn’t notice. I checked the clearances on half of the engine and when I turned the engine over to check the other half, I turned it pretty hard by hand without thinking. The stray bolt marred the side of one of the cam lobes and basically bent at 90 degree angle, but didn’t seem to do any real damage to anything else. Just glad they are aluminum. The scratch on the cam lobe was above any contact points, so it seemed like everything was ok. So, I put everything back together.
When I started the car it had a rough idle with a lot of popping in the exhaust. It basically sounds like a Harley at idle. I suspect valve overlap, or something like that. The RPMs fluctuate between 1.5k and 1.25k, periodically dipping down to 750 at which point it sounds like it comes close to stalling before jumping back up. It throws a P0017 CEL which is an “Crankshaft/camshaft (exhaust) position sensor phase problem". So, I figure I did more damage than I had originally thought, so I replaced the cam sensor which didn’t help. I also noticed that unplugging the exhaust sensor didn’t make any difference. Running down the list of problems associated with this code, I’ve checked the timing belt tension and position and that looked fine. Pulled out the oil control solenoid and bench tested it. That checked out. Changed the oil, partly just to make sure there were no metal flakes in it. That was fine. Running down the list, the next thing to check out is the VVT sprocket and the crankshaft position sensor. I doubt it’s the crank sensor and before I remove the cam shaft to check the VVT, I wanted to compare my VVT values at idle to a good set. I did notice that the exhaust side fluctuates at idle along with the movement in RPMs, so I’d like to know what’s going on there.
I attached my log which includes the VVT readings and a few other measurements. Two things I noticed were that the VVT readings oscillated between 51 and 57 (degrees) for the most part. The reading would drop into the high 40s after a little while, 15 seconds or so, and then move up into the low 60s before settling down again. This seems to track with fluctuations in the RPMs as well. When I eased into the throttle, it would drop to -14, with a drop in RPM until I gave it more throttle. Then it comes back up to normal readings and the RPM rises. I don’t know if this is normal or not. The drop in RPM certainly isn’t. This is where a healthy idle would be nice to see. The other oddity I saw was that the exhaust VVT tracked perfectly with the intake VVT. Maybe this is normal under no load, but again I can’t be sure without a comparison. Another possibility is that the VVT values could be the target values rather than the actual values. I'm not sure what the readings are in MUT III. I understand that a patched ROM will allow both values to be displayed. Is there a preferred ROM to use?
If anyone has any advice or sees anything of note in the log that I should look at, please let me know. I want to get back on the road!
Thanks for the help,
Scott