Sorry for upside-down video. Tried flipping it then upload again to google drive but still upside-down? Click for video----->https://drive.google.com/open?id=1C2U79piZaYAI9N9y2JqGVKqAI0aQ2NLX 1977 US Turbo 930. Has run great since engine rebuild. This started out of nowhere after a few thousand miles. Putt, putt, putt, putt at idle and AFR goes slightly lean. Not lean enough to stall but it will stumble before clearing up when getting on throttle. Seems to rev and boost fine. Not driving it, don’t want to get stuck. When it started doing this was on my way home and I did get into boost. I did notice afr seemed to fluctuate/react faster to throttle modulation and may be going richer on boost? Wideband has data logger but haven’t used that feature yet. The video doesn’t show the sometimes quite lean condition 15-16.5 but mis sound can clearly be heard. At idle it does go away sometimes but only for a few seconds? System Pressure: 95 psi Volume Delivery Test: Passed Cold Control: 20psi Is this right? Hot Control: 35psi with wur vent vac hose plugged in(This is the reading with the engine running) (Car has run great this way the hole time?)(Only discovered this now after testing for misfire) Is this right? Hot Control: 51psi with wur vent hose unplugged(Plugged Vac hose)(This is the reading with engine off and fuel pumps running) New parts: Wires, Plugs, Cap/Rotor, WUR, Front Fuel Pump, Fuel Injectors, Fuel Filter, Porsche bov(Not vented to air) Old parts: Coil, Fuel Head, Rear Fuel pump, Fuel accumulator, all other devices that come on 930 Checked for vac leaks but nothing found. Used water spray mist. Continuing to check… Now I’m jonesing to drive! It’s like taking away drugs from an addict! Thank you all in advance.
Happy to report the mis-fire has been solved. It was the new beru wires. Replaced new set with the old set. It appears the new set quality is very poor. Noted a few differences. New Beru Wire Set: Boot that snaps on cap is not marked in any way and tears easily when trying to install or remove. It doesn’t snap into cap and is next to impossible to remove once pushed on. Most times the wire pulls out. Because it doesn’t snap into cap its difficult to know if it’s fully seated. The stem part of the plug boot seems to be my failure. Either the heat cycles or poor factory quality caused it to crack. #1 split clean in half when trying to pull it off plug. Didn’t measure them but they appear shorter in length than the old ones. Old set had more slack when installed. Old Beru Wire Set: Boot that snaps on cap is molded with the beru logo. Boot material is heavy/stronger rubber than new set. When pushing into cap they have a series of two snaps which I assume indicates fully seated. They can be removed easily without boot tearing or wire pulling out. Side note on new fuel injestors: I always planned on getting new injectors but put it off because it ran pretty good. Replaced them while trying to solve the mis-fire but they made no change. Once mis was fixed the best way to decsibe new injectors is wow! They have totally transformed the car. Rock solid AFR’s and smooth as silk. No run-on at shut down either. If your thinking about new injestors just do it!
