Hi All,
This vehicle starts and idles well with no DTC's stored.
On the road though it is a flat as the proverbial pancake with very poor torque.The upstream lambda sensor keeps switching until WOT when it pegs rich.
At idle the lambda sensor switches well but the MAP is steady at about 60kPa where I would expect about 45kPa. The MAP sensor has been checked against my vacuum gauge.
Snap throttle naturally brings the MAP up to atmospheric and on the overrun it drops down to approximately 24kPa before returning up to 60kPa.
Dropping the exhaust manifold off (I could not get the lambda sensor out to open up the exhaust that way) improves the figure only very slightly to perhaps 58kPa so I think the catalyst is ok. On snap throttle there seems to be plenty of life in the exhaust, it doesn't seem restricted.
Sorry I have not done a 4-gas yet it's planned for the morning.
My first thoughts are that the valve timing is late, either skipped a tooth or opened up keyway on the crank or similar, or possibly late ignition timing but I'm not sure how that could happen on this engine.
Am I missing something obvious?
Shaun