sudden change in car

[stonefish]

hi could someone please have a look at the attatched scan
s2 95 elan 58k miles
custom stainless exhaust
car has run fine for years, but now a loss in performance, seems to be vibration ans the exhaust note is definatly a lot deeper
ive looked at the scan and compared with others and the only thing i noticed was on this scan there was nothing shown on secondard throttle??? am i missing something,,
whats that??
thanks

[lotusgirlmarie]

The secondaries as they are refered to are a second set of intake runners cast into the inane plenum and have a set of butterfly valves. These valves open at higherengine speeds/loads to give more air and by extension more power. They're pneumatically operated by a vacuum vale which is controlled by the ECU and receives it's vacuum from one of the ports on the plenum. If it is indeed failing to open or is stuck open this will change performance.

Another option would be a "brick" breaking up in your Catalytic converter and turning sideways. This will also dramatically alter the sound and performance of your car by impeding the exhaust flow. I've had this unfortunate experience twice now by the cat impacting on a speed bump and breaking up. A year or so later.... Car stalled and died. Cleared it all out, got a new cat and all is right with the world.

[saska]

s2 95 elan 58k miles
custom stainless exhaust
car has run fine for years, but now a loss in performance, seems to be vibration ans the exhaust note is definatly a lot deeper
ive looked at the scan and compared with others and the only thing i noticed was on this scan there was nothing shown on secondard throttle???

The secondary throttle will only open above 4700 RPM which you never did during the run -- max during the run was ~4250 RPM.
The scan looks fine, there are 3 knock events but no retard was applied for any of them.
I concur with Marie, first thing to look at is blockage either in the pre-cat or exhaust or main cat (if it still has one).

[stonefish]

thanks for the advice guys and reading the scan...
same thoughts as me, as something in the exhaust may have collapsed.
ive taken the main cat out...and as you said could be the pre cat...have got a endascope so i will remove the oxygen sensor and have a look and let you know the outcome..if it has gone i will need a new one anyway to get through the mot..
thanks