need help with boost problem
 

86 951, API stage II chips, Lindsey dual port waste gate, manual boost controller ( cycling valve delete) Lindsey billet diverter valve.

Ok so out of the clear blue with no prior problems: at or about 15psi the car starts "breaking down< running like crap<almost like someone was inside the engine compartment and pulled off a few spark plug wires". On the way up to 15psi the car pulls fine with no issues then at 15-ish it starts bucking/skipping ect. I've checked all the vacum lines ect nothing obvious. I decided to toss the stock chip back in and oddly enough it does the same exact thing except at the lower factory boost level of 11-12. WTF Any ideas ??? Could the waste gate be a problem ? Hmmmm stumped.

I forget to mention that the boost does not drop off so to speak but the boost gauge needle seems to osillate rapidly in concert with this nutty engine note.

fuel delivery problems. spark problems. fuel quality problems. bad wastegate. bad blowoff valve. bad DME/KLR.

i'd try a known good set of computers, first.

check your spark plug wires for any cracks and look at the distrubitor cap rotor. I had a very similar problem and the rotor had cracked.

Risking sounding like a broken record but... did you check the intercooler pipe couplers? May seem tight, but at 15psi, they could pop on and off and you'd never know they were loose. Happened to me, same symtoms.

oh, that's a good one. i've seen this happen, too.

you mentioned it happens at different psi's, can you verify if it happens at the same rpm?

if yes, it may be the distributor/rotor/coil.

thanks for the input men just summoning the motivation to start yanking on hose clamps, wires, bla, ect. TPS switch checked out fine.

Also check the large rubber pipe that connects the compressor to the boost tube upstream of the intercooler. I've see a cracked one cause an engine to run like yours.

Your plugs are fouled.

Confidently,

Rick