boost problem at full trottle
 

Hi,

The car is a 88 944 turbo S, since the installation of the 3 inch cat bypass, big exhaust and after-market chip; the power of the car cut in fourth gear when i am at full trottle for few second.
The boost climb at 15 PSI and after a few second the car cut ignition ( i think ).

The feelling when the car cut is same if i put the brake hard, after this happen one time if i boost up to 1.2 bar the car cut always.

At first, i think it was a overboost problem so i replace the cycling valve by a manual boost control but i have to adjust the MBC at 12 PSI max if i want to eliminate the trouble.

I have check the tube of the KLR and all is OK.

The TPS and the AFM are OK.

I also unscrew the knock senser for looking if it detect false situation and it's not this.

The same thing happen with the stock chips and the big exhaust or the after market chip whit the stock exhaust.

I suppose the trouble was cause by a bad DME or KLR but what happen exactly ?

The KLR detect a false overboost condition ?
The DME detect something ?

Something else the check ?

I don't have any idea, help will be very appreciate !

What chipset are you using ? (Vendor)

EDIT: I LIED!

2 things came to mind re-reading what you have said.

1. If ignition is pulled back - knock is being detected and timing is being pulled.

2. If fuel is cut off - you have overboost protection kicking in.

I ae1969,

I use cintex chip ( sold by Fabspeed ), i try 2 differents set and the problem is the same.
I have the same problem with the stock chip and the big exhaust.

About the ignition, I have unscrew the knock senser to be sure the system don't detect false knocking and modify the timing until it have no ajustement and suddenly cut.

I'm not sure if the timing is cut off or the fuel by it's so fast than i suppose it's the ignition and not the fuel.
The car still running well after the cut off .

Thank you !

I bet its the overboost protection kicking in, But I dont have a 951 so dont take my word for it