What might cause a big backfire under full throttle??

[AE86fan]

My Turbo 4age has a massive backfire under full throttle. I recently had it tuned and in 8 hrs of tuning the Link didnt do it once, now I cant get full throttle without a huge bang and sudden loss of power.

If I give it moderate throttle it gets on boost no problems and pulls hard, Im pretty sure its getting to max boost of 14psi, so dont think its a fuelling issue and had no probs at all with fuelling on the dyno at 130 rwkw.

I dont think its an electrical fault as its not dropping a cylinder... more like dieing completley for a second.

Could this be an issue with the TPS signal??

[strx7]

What model Link is it? The only way you can be getting a massive backfire under boost is either

a) there is a major timing retard for whatever reason,
b) there is far too much fuel all of a sudden,
c) there is no ignition at all suddenly...

Sounds like its hitting some form of ignition cut rev/boost limiter

[AE86fan]

Link is a LEMV5e.

I would think it is option c as:

There is no fuelly smoke at all when it backfires
The rev limiter is the only sort of ignition cut and thats set at 7500 rpm, to my knowledge there is no knock sensor retard or boost limit.

The reason I ask if it could be TPS signal is that a couple of times during tuning there was no TPS signal which I think could be a faulty conection in the TPS plug (the TPS is brand new)??

[AE86fan]

Just phoned Link and they said that my version Link has a boost cut which may have been set too close to the target boost level, which kind of makes sense as I might be getting a bit of a boost spike under sudden throttle.

Thanks for your help strx7, ive got a serial link coming and will have a play and see if it sorts it.

[QikStarlie]

will be boost cut as they say rase the limit 10- 20kpa