Johh, permit me to give you change back for your 2 cents. Where is the slight correction? Everything Martin stated is correct. While what you state is true, it's only valid during warmup. It's hard to have WOT enrichment without CPR enrichment? That's exactly how it's done after warmup. Control pressure is maxed and stays at that value. On a stock D there is no vacuum supplied to the CPR (and no acceleration enrichment) after warm up. And as Martin states, the ignition advance is disconnected during warm up. These vacuum sources are swapped when the thermo valve changes state at appx 130F. Quoting from the manual does not impy an understanding of how the CPR operates. The CPR is pretty much dead weight after warmup, seving only as a static regulator to keep control pressure at it's maximum regulated valve. Listen to Martin and H. McElcraft, they seem to understand the details of how this stuff actually works. As for the delay valve, it's speced at 10 seconds but fwiw, I've never seen one take that long to bleed down. I've removed my CPR and use a digital controller that performs both warmup and acceleration enrichment by PWM. It also permits full manual mixture management, allowing tuning by EGT. This improves highway fuel mileage and allows tuning for either best power or best economy during steady state cruise conditions. (Anyone knowledgable about operating piston powered aircraft engines will be familar with these techniques.) It switches back to an auto mode when it senses load changes. The stock CPR does not allow mitxure control after warmup, leaving it to the FV for emissions and to the airflow sensor geometry for acelleration. The facts are that mixture tuning can be done by manipulating either control pressure or FV duty cycle. If you do it with CP you need to fix the FV duty cycle during that time or the Lambda will attempt to correct your "mistake". After all, the Lambda system does not provide true stoichiometric combustion...it's shifted slightly to the rich side of peak EGT. Full control via the FV is a better way, leaving a static control pressure to provide plunger damping and to set the range the FV will operate around. (Controlling both at first provides a wide lattitude for experimentation if you've seriously modified the engine in any way.) EGT monitoring (or by feedback loop) replaces the O2 sensor signal during this time but you'd better have a way to switch it back duirng load changes. For long highway drives over flat terrain you can't beat this system. You can even run slightly lean of peak as long as the induction air distribution is fairly decent, as it is in the stock D. An added benefit is that it keeps your pistons and valves very clean. ----original message---- From: John Hervey >>Martin, Slight correction. Our WUR are equipped with a dual spring set up. When the throttle valve is open further at full load, the pressure in the intake manifold increases....>snip< -----Original Message----- From: Martin Gutkowski<< >>The vacuum enrichment on the DeLorean's CPR is only active under warm-up conditions, at which time the distributor vacuum is disconnected. As the CPR vac is removed, it is placed on the distributor (so to speak). Martin<<