ive owned about 3 n/a fcs so i though it was time to go turbo. i recently picked up a 87 t2. it hesitates after 3800 rpm, when the secondaries kick in. it has a replaced stock cpu, maf, injectors, vac lines, harness, fuel cut defender, cai, and h/e. the only thing i can think of is a faulty tps but it idles at 800rpm. i thought it was the vac line to the pressure sensor but for some reason the pressure sensor vac line is connected by the tb. all emissions removed including all of the solenoid valves, acv, and bac. for some reason there is no o2 sensor plug on the harness. i also changed the fuel filter. it has a fd fuel pump also. any ideas? what computer components do i need to boost it to atleast 250hp? much appreciation!

 

Check the FAQ for information on the common 3800 RPM hesitation. Typical solutions are grounding related.

If you're still using stock injectors and a stock ECU, ditch the FCD. Those things are engine killers, and your stock primary injectors will not flow enough to handle boost spikes over ~9 psi before the transition. Browse through the 2nd gen tech, single turbo and engine management sections for upgrade info. There are many, many options from chipped ECU (Rtek) to full standalones. The secondary injectors should be upgraded, and your injector staging point should be lowered if you're trying to push the stock turbo to its limit (~250 whp). Timing and fuel adjustments will also be very beneficial.

 

It's definitely typically related to grounding. With the staged injection system, increased current is required when the secondaries come online. There's an excellent write up on diagnosing the 3800 RPM hesitation at Ted Koseki's FC website here

http://fc3spro.com/TECH/FAQ/3800.html