My 2001 Toyota Sienna (251000 miles) has a rattle when idling or coming to a stop. Several mechanics have told me it's motor mounts. I believe them. But, sometimes the rattle will come and go (yesterday I was eating lunch in a parking lot and I observed it again) when I just sitting there as the engine is deciding what RPM to be (could be because I cleared the codes to see if anything was fixed and it was relearning) it would rattle then not rattle. I attached my rented AutoZone scanner and discovered that the rattle goes away (or starts to) around 900 RPM. When my car is rattling away constantly at idle, the RPM is in the 700's. If I give it gas, the rattle will go away.
So my wonder is maybe my car is just idling too low. (Bad motor mounts aside.) Don't cars normally idle around 1000? If I somehow got the idle RPM to be 900 or 1000, then rattle at idle should go away when I idle and I can eat lunch in parking lots in peace without my foot on the gas. Then I could just not go 4 wheeling until I can figure out the motor mounts. Wouldn't a proper idle RPM be good for the car anyway? (Assuming what it's doing now isn't proper.)
Idle is like anywhere in the rage of 600-800 for most average cars. Could be anything from lifters going out to just a rattling heat shield compounded by bad mounts. You get any codes before erasing them?? Need a sound byte of the rattle to further diag.
I've had a 1130 forever, and when I was on my thousands of miles trip, there was a code for an intake gasket and the evap test finally finished and I had one for that. My notes for the codes went missing. I reset the codes because some of the codes I had been getting just disappeared on their own and I wanted to see if they would come back after a fresh start. The 1130 came back and the VVT code I fixed a while ago by cleaning that OCV also came back but then disappeared on its own. Today, the check engine light itself went off by itself while the only code it had when I checked last was 1130. I'm going to get the mounts fixed instead of trying to get fancy with the idle speed. Your numbers are where it is now so I suppose it's already correct anyway.
I'm going to try to get the mechanic to throw in a check on that 1130 sensor since he's going to be under there anyway. Maybe it just needs a little clean. I just can't do it myself because of the location of it being way behind the engine where I can't reach myself.
It sounds like your timing chain is on the way out.
