EXHAUST / CAT QUESTION

[barcli]

Can anyone help with a couple of questions ?????
Found the rear boot carpet melting and nearly on fire as a result of the rear exhaust box falling apart inside and basically blocking the pipes - causing severe overheating to the box and subsequent melting of the fibreglass in the boot floor.
So late one night i remove the box cut open one end - find everything loose and falling apart inside - Ah hah I thinks, lets just empty all the c..p from inside the box weld the end back on and hey preston problem solved and nice and noicy . BIG PROBLEM Cerbie now seriously don on low-mid range power almost to the point of difficult to pull away in first gear !!!!

Question 1. has anyone else experienced this and does the fuel management system / settings all need adjusting becaus of the (now) lack of back pressure.

question 2. Does anybody know what the inside of the box should look like should I decide to rebuild it ?

Question 3 . Could I have a failed CAT - what are the symptoms?

All help much appreciated
John

[Mark Adams]

Hi John - if your silencer had collapsed and blocked the exhaust, then it would have caused some fairly major adaption by the MBE management system to cope!

In normal operation, the adaption is a powerful tool for the good. You may need to have your adaptive values reset by someone with the software (dealer usually) to restore normal operation...

[Barcli]

Mark, thanks for your help . Am i correct then in thinking that the MBE system would/ is ca pable of adjusting itself for the blocked exhaust but then would not re-adjust for the lack of back pressure when i refitted the rear box ?

[olly]

I would suggest disconnecting ECU for 30 seconds & re-plugging it back in. This just resets it back to the standard settings.... (ECU is located behind the false bottom in the passenger foot well)

[Julian64]

Barcli said:

Mark, thanks for your help . Am i correct then in thinking that the MBE system would/ is ca pable of adjusting itself for the blocked exhaust but then would not re-adjust for the lack of back pressure when i refitted the rear box ?

From what I remember of my messing the adaptive is running average with an unlimited memory. Each new adaptive is a staight average addition to that which is already there. So zero'ing the adapting allows it to start from scratch and change very fast to suit your car. After a while the weight of averages is pulling it down and it can only slowly and not fully adapt to changes, just like a rolling average with a high 'n'

[Barcli]

Olly ; Thanks am away from car until thurs so will try it then - is it accessable from inside or outside car ? - presumably under forward carpet by passengers feet or actually under the seat ?

Julian 64 : Think I know what you mean !!! just struggling a bit with the principle !!

[Barcli]

Olly - just one quick question - ignition only on - disconnect , wait 30 secs - reconnect OR engine running , disconnect , wait - reconnect ?

[Julian64]

I'm afraid that unplugging the car it unlikely to reset the adaptives. The adaptives are kept in whats called NVRAM, which is a form of flash eeprom.

I think if you disconnected for three or four years it might work

[olly]

Oh ok... ????

I presume the 4.2 & 4.5 ECU are the same ?

Couple of friends with 4.2's said this has help (in the short run) fix all sorts of problems ?

(ignition off as far as I know - disconneting just take the power away, so it forgets the existing map - although turns out this may not be the case !)

>> Edited by olly on Wednesday 15th June 16:18