"Chairman Kaga" (mike-mckinnon)
01/25/2016 at 10:39 • Filed to: None
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"Chairman Kaga" (mike-mckinnon)
01/25/2016 at 10:39 • Filed to: None | 2
| 4 |
Well dammit. A couple of weekends ago I finally got my ‘82 Alfa GTV6 slapped back together. Took her out for a quick spin a week ago Sunday just to make sure everything still worked. Aside from the clutch plates being locked together (back end on jack stands, start in first gear, alternate brake and gas, it’ll come free) she was amazing. Full drift in 1st gear at 20 MPH, singing the loveliest song.
I got into fine tuning the Bosch L-Jet ignition this past Saturday since the engine had a full complement of new vacuum hoses, fittings, a few bits here and there. Got to the O2 sensor, last issue on my list, and it was reading high. The single-wire sensore should output about .45 volts, fully heated. I was getting .7 to .8 after idling for 15 minutes with 60 seconds of 50% throttle. The ECU should have been out of the startup fuel map by then, and I’m pretty sure it was because the reading is static when the O2 sensore is in closed loop but begins fluctuating somewhat wildly once the output signal starts feeding the mixture.
So I started by testing the coolant temperature sensor, which could prevent the car from reaching full operating temprature. Good reading. I’d also just cleaned the probe when I rebuilt the thermostat. Next was fully opening the idle bypass valve in the AFM module, letting in unmetered air, and loosening the AFM flap spring to factory setting (it’s common to tighten it, thus enriching the mixture to get faster throttle response). Got output voltage down to .65-.7. Still too high.
So, possible culprits? All of my plugs are sooty but the #1 plug was also wet. A stuck injector would explain it. I pulled the plenum, fuel rail and injectors. A couple of the injector o-rings, which are only a couple of years old, were cracked. Also possible problems. I’m taking the injectors to a local shop for flow testing tomorrow, with new injector seals on their way, as well as a new Bosch O2 sensor and coolant temp sensor. Why not.
I wonder if converting to a 3-wire (self heating) O2 sensor might help stabilize things though? Alfa switched to a 3-wire design in .85, I think. It would just need 12v and a ground, both of which are right there on the firewall. Otherwise stoich is stoich, right?
Also checking wiring, much of which is new.
If you ever wanted an Alfa, this is what it’s like. You get 15 minutes of driving for every 15 hours of work. I think an SR71 is more efficient in that regard!
RallyDarkstrike - Fan of 2-cyl FIATs, Eastern Bloc & Kei cars
> Chairman Kaga
01/25/2016 at 11:41 |
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Yes, but 15 glorious minutes of driving, right? :P
Good luck fixing your issues! The world needs more classic Alfas back on the road, you’re doing North America a great service. *salutes*
RallyWrench
> Chairman Kaga
01/25/2016 at 14:06 |
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Did you also check the cold start injector? They hang up more often than the mains do. How is the fuel pressure? If the regulator (or vacuum feed to it) is bad it’ll bump the pressure by 5psi or more.
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Chairman Kaga
> RallyWrench
01/25/2016 at 14:41 |
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I thought the same thing so I disconnected the CSI after the car had warmed up, shut it off, started it back up, and the O2 was still too high. Although maybe if it’s just stuck open it doesn’t matter if it’s plugged in or not? Although I’d probably notice if it was jammed open while unplugged during a truly cold start, correct? I’lll try that.
The regulator is pretty new. The inlet for my cheap Harbor Freight fuel pressure is too small for my fuel hoses and I don’t have an adapter, so my tests were done without a complete seal, just clamped as tight as possible (and balanced over a jar to collect the spillage), but I was still reading 33-35 PSI, with 36 being spec. I chalk up the discrpancy to the equipment. The regulator also maintains high pressure after the car is shut off, so I more or less know it’s not leaking. The pump is new as well.
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RallyWrench
> Chairman Kaga
01/25/2016 at 17:07 |
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Sounds like pressure is ok, then. Gauges are often inaccurate, but you won’t know unless you try another. And you’re correct, if the CSI is stuck, it doesn’t matter if it’s plugged in or not because it’s constantly fed pressure.