Scion xD Drivetrain & Power Engine and transmission discussions...

STUMPED - chasing down rough idle problem

Old 02-24-2019, 08:26 PM
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Default STUMPED - chasing down rough idle problem

My 2009 xD automatic transmission (2ZR-FE) has been having some strange rough idle problems lately, and I haven't been able to chase it down. Hoping for some wisdom from you guys. I'm fairly familiar with working with cars, but this was has me stumped.


- Check Engine Light came on two months back, ODB-II shows P0301 code (cylinder 1 misfire). I did all of the following below, and then reset the CEL. The CEL has not come on since, but the rough idle still occurs (again most noticeable in Reverse).

Things I've Already Done

- Replaced all spark plugs (cylinder 1's plug looked pretty grimey).

- Checked all spark plug wires and coil packs

- Unplugged spark plug connector for each cylinder one at a time and verified engine RPM changed for all four (this also confirmed that all four coil packs seem to be operational)

- Verified fuel injectors were clean

- "Listened" to the fuel injectors to make sure they all clicked at the same rate (screwdriver method)

- changed air filter / cleaned MAF


- Does anyone know the nominal RPM for when it is in "Park" and "Drive"? I park ODB2 shows around 700RPM at idle, once I put it into Reverse or Drive, it drops to around 620RPM. Is this nominal?

- Does the rough idle in reverse indicative of anything?
jay.diem is offline  
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