So for the past few weeks the Z has been backfiring heavily when coming down the rev range in any gear - without being pushed at all (just shifting down a gear and leaving it come down on it own).

Recently i had the O2 sensors changed by Jimmer and some fresh turbos and it is more or less since then.

 

I have bought a brand new MAF from Z1 and just changed the spark plugs all-round.

 

Im also idling around 950 rpm, and can hear some break-up in the exhaust tone every few moments.

 

Any suggestions on what to check next?

 

91TT Btw.

An ignition problem? Unburned fuel. Are you getting scorch marks on one side or the other?

I cant see any blatant marks, i am assuming it is ignition as there is a fuel smell

 

I have checked for ECU Codes but nothing to report - i should also add it is a JWT ECU, although it wasnt having the issue previously.

Do you have a Conzult?

I had backfires from a dying Ptu.

Unfortunately no conzult best i could do was ECU Codes

 

I will test the PTU thanks Ali

I am attempting to test my PTU following the continuity test but the diagrams aren’t matching..

 

Can I just take abcdefg as 123456E?

yes its just a reference for pin position.

Thanks for confirming, not getting any continuity through it. Perhaps it’s dead..