( Timing chain, spark plugs, o2 sensors, Clutch etc etc ).The exhaust manifold
/ Precats have been replaced with a Toyosport Decat manifold, and the car has just the main cat present. The old precats showed damage a the tops, specially for the precat fed from cylinders 1 and 4 - those also were the worst damaged.Following the rebuild, it has basically gone straight in for a MOT and although it passes the Idle emissions test, at fast idle
( ~1500rpm ) the CO readings spike to ~ 0.5.The same Cat on another roadster recently passed a MOT so the CAT is OK.
OBD2 diagnostics at idle after the rebuild show the O2 sensors in the exhaust manifold are working OK and the output from the main cat is as you'd expect.
Any ideas what could be done to narrow down the problem.
Ideas so far as to possible causes : 1.
The ECU is still 'learning' as engine is effectively being run in so low ( below 4k ) revs and low to moderate load, and has only been driven abut 20 miles since the rebuild? However car does idle at ~800rpm indicating that the learning process has ended ...?2.
Coolant temp sensor : However Reporting coolant correctly3.
Maybe the car isn't running closed loop on fast idle, as it does at normal idle?4.
Possible problem with injectors? On rebuild, cylinders 1 and 4 were worst and showed evidence of running lean as exhaust values were blue. 5.
Possible marginal coil pack? However does run and idle smoothly without any lumpiness6.
Dirt on the MAF causing incorrect readings?Other ideas and suggestions as to how to diagnose are welcome
... !Ben
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