Help needed please with misfire on bank one.

[Acousticplayer]

Hello all. Help seriously needed here. 1998/1999 2.8 Roadster. Car misfiring on all three cylinders of bank one. Got the codes.
PO170 Fuel trim bank control limit
PO301
PO302
P0303
Obviously something common to bank one.
Where do I start looking please?

 

[Stevo7682]

First things are check all the air intake pipes , breather hoses for splitting that could be your fuel trim code.

Take out coil and plugs cyl 1, 2 ,3 checking for black tracking marks on plug ceramic indicator coil short.
Check plug condition.
If all ok take out 4 ,5 ,6 swap coils and plugs around so 123 into 456 and 456 into 123 reset fault code start still missing see where fault codes now lie will give you idea of what to be doing next.
Stephen.

 

[Acousticplayer]

Hi Steven thanks for coming back on this..I'll swap around tomorrow but I thought it unlikely that all the plugs and/or coils on one bank would fail all together.but could be wrong. My first thought was something that was relevant to just the one bank and that is why I have asked about the oxygen sensors in a previous post. I realise of course it could be a host of other things. I'll swap the plugs and coils and come back. Thanks again.

 

[Acousticplayer]

Hi again to Stephen. So I swapped the plugs and coils over putting 1,2 and 3 into 4,5and 6, and deleted all the codes. Took it for a short spin and scanned again. Cylinders 1 2 and 3 still threw up the same misfire codes so it looks like the plugs and coils are ok. I didn't get the fuel trim code up again but I only drove it about a mile so perhaps didn't get hot although the temp guage showed it was up to temperature. I didn't notice any perished rubber or from where there might be an air leak but I think I'll buy a cheap smoke device and check it out. Apart from that any suggestions moving forward?