Misfire at Idle Only

Swedjen2

Well-known member
Sep 12, 2018
552
111
California
I have a '04 D2, about 10K on a rebuilt engine - D&D (the outfit in Michigan) machined the original block, added top-hat liners, Wedgeshop cam, just about everything else new- coils, injectors, plugs, O2 sensors, wires, etc.
It's an SAI engine, (Calif. vehicle)
If I let the vehicle idle much longer than a few minutes, it'll start throwing the P0300 thru P0308 codes. Ususally does cyl. 1, 8, 6, 2 first, then the rest after a few more minutes of idling.
I usually put it in neutral at a stop, then press the throttle to get it just above idle - I can go weeks with no codes as long as it doesn't sit and idle at whatever the stock idle speed is.
The P.O. had similar symptom but it also ran rough during regular driving, after the rebuild. I suspect the P.O and P.P.O - who also had CEL lights and rough running issues - used regular gas most of the time. I've been running 91 octane since I bought it and no issues or codes above idle.
The P.O. also sent the ECU to Mark Adams/Tornado in the U.K. for remapping. I can't tell if that actually did anything since I have not driven a stock 'O4.
Appreciate any suggestions or insight you might have on this issue.

Thanks