NOAH WITH SHIVERS A 2001 Toyota Noah has recently had its 1AZ-FSE engine rebuilt at the garage. When cranked cold it will run for a few seconds and then sputter into silence. When hot, it seems to run fine. Weird, isnt it? Since it left the check engine light lit when it run and sounded to me like a timing-related issue, I got interested and found a lone code: P1656: Bank 1 OCV circuit malfunction. I immediately thought I was on to something. The code relates to the circuit that the ECM uses to operate the oil control valve which controls the VVT-i functionality of this engine. To view our description of how VVT-i operates, please follow this link: https://youtube/watch?v=N-yeDkEabgg. Musa and I examined this valve and found it to be within the manufacturers recommended resistance spec of 8Ω. Further investigations led us to discover that one of the wires that connects it to the ECM was damaged. We repaired it. The CEL now went out when the engine run and the code did not return when erased. However, the cold engine splutter soon after cranking still happens. Combing through the ECMs real time data revealed nothing to be obviously unusual to me except the positive short term fuel trims and negative long term fuel trims. I still think it somewhat related to timing on this engine. I convinced the team to take the covers off tomorrow to find out. A tooth or two retarded/advanced may be giving us a bloody nose. If you cared to ask why the engine seems to run fine when warm, I would explain that it could be due to the thinner oil now being pumped well enough through the OCV to allow VVT-i to somehow correct the problem enough to be unfelt.
Posted on: Sat, 22 Mar 2014 22:42:45 +0000
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