sudden loss power then backfire

[g20wel]

my car developed this problem today
say a boost 2nd to 7000 then shift to third it will boost but get to 6000 ish suddenly stop accelerating and back fire

the pfc says
max boost 0.76
max duty 81.5

its a 3" full system
stock twins
apexi filters
new sparks
arc smic

any ideas guys ?

[Jono FD3]

Possibly leads or a sensor packing up?? strainge it pulls in second, then spits the dumby out in 3rd though!!

[m1tch]

This happened with Profs car down the drag strip, its an FC but I think it was the fueling suddenly bogging and then clearing to cause a HUGE backfire and a cloud of brown smoke :rollin

[g20wel]

This happened with Profs car down the drag strip, its an FC but I think it was the fueling suddenly bogging and then clearing to cause a HUGE backfire and a cloud of brown smoke :rollin

what caused it do you know ?

[clive]

Some more info may help,

What is the engine doing now,

Does it start O/K cold and hot, do you still have power, does it tick over O/K

[g20wel]

starts hot or cold idles no problem works fine 90% of the time but as soon as your on wot and the revs climb over 5000 it will hickup but if you shift to next geat up and reapply throttle it works to limiter

[clive]

5000 revs would normally indicate boost cut and can be accompanied by a backfire as the engine effectively turns itself off to protect itself from detonation.

"If" this is whats happening then you will find that if you floor it it will not want to go above 5000 revs buy rev it slowly and it will rev through it.

If you you haven\'t done any further mods then it could be that you was near to boost cut but due to the cold air ATM thats making the charge much more dense then this could be making it boost cut ?

Hope this helps

[ianelvar]

You could also have a look at the fuel pump wiring and the speed control relay as it\'s load related. Check the voltage you\'re getting at the pump, the top of which is pretty easy to get to in the boot. You can bypass the speed control relay with a piece of wire and two crimps to check if that fixes the problem (the diagram on the top of the relay will tell you which terminals need to be shorted together). It\'s only there to cut the pump speed down at low load. There\'s a resistor in the pump circuit to drop some voltage before the pump, and the speed relay shorts it to bypass it and give the pump full votage. Just shout if you need any more detail.
Could also be the pump itself, the pressure regulator, or the vac line to it, but depends on your setup. HTH

[g20wel]

a local hero by the name of phil is sorting it out for me this week thanks for your help guys much appreciated