Someone on a thread said 308 starting issues was like the prostate. Gets us all at some point. This is an 84 QV with Lambda. Have a starting issue, probably been going on for a year, but It's so intermittent I ignore it but as of late seems a bit worse, so I thought I'd provide a few details and see if anyone has some ideas to check. Sometimes cranks over in one second, other times you have to turn it over for a few seconds and apply gas pedal. Mostly on first start of the day, but can happen during the day. Does not matter the air temp. For example, it happened today, and it was 70 degrees air temp at first start. Usually on cold engine first start but will occur with a hot engine, just not as often or rarely. Checked the AAV - moves as it should. Cold its more open, warmer it closes and has 12v Cold start injector - did not remove but does get 12v WUR - Only checked for 12v - yes But I kinda think it's not a cold start issue as it can happen when engine is warm. Here could be a key to someone that understand the CIS. If you unplug that frequency valve (1984 QV with lambda) while it's running it will almost kill the motor or actually kill it. From what I read it should run rough but not die, makes me think it's having to work to compensate for something? Also on the first start while sitting pondering what it could be, it smells like its running rich, maybe? Last question - Would a bad crank sensor cause a start issue but run ok? BTW - After it starts it behaves as expected. A couple years ago I replaced the fuel pump and accumulator. Thanks!!!
Bad crank sensor could affect starting, but would also typically affect the running condition as well, so not likely the cause of what you describe. Bad/dirty O2 sensor? Dist caps + rotors recent? As usual these things require some ruling out more basic causes before delving into the complex bits.
Unknown on o2 sensor, caps and rotors were done with cam seals and cam belts recently. Would an o2 sensor jam up starting but run normal? I also wonder about the lambda frequency valve clue? Threads I read on it say unplugging it, or it is not working causes the engine to run rough. When I unplug mine, it runs really bad and dies. Jim
Basics - Air, fuel, spark. Its easy to go chasing parts on an issue like this. I have a carb car and moving to EFI so never had the bosch issues. BUT...basics. Start with your electrical connections and always good to check and clean the grounds, they are the ire of so many issues once perceived to be something else. It seemed you checked your battery is at 12v. Check your plug wires and power to everything in the system. Even remove the spark plugs and inspect them - they tell a story. Check the connection from the alternator to the starter. Sometimes on these old cars, the starter terminals crumble and create bad connections. At very least, clean them. Fuel Filter? How old is yours? - good to check and make sure its clear... Have you checked to see gas is getting to the manifold in all passages. At least check the air filter and make sure there's nothing blocking in the system. Only with all that gone through, would I start chasing sensors and other parts.
This is both good news and bad news. The good news is that it indicates a lot of goodness for the whole system, but the bad news is since you have this problem both cold and warm = it's an intermittent Gremlin = the hardest thing to find . I'd have to initially go with "no" on this as, if it was the problem, dwiddling the acc. pedal doesn't change what the crank sensors are doing. This can depend on where the manual mixture screw is set. When you unplug the FV (or lose +12V power from the Protection Relay), the system goes very lean. If the mixture screw is set to the lean side of the spec, going even more lean can cause the engine to immediately stall. If the mixture screw is set to the rich side of things, the engine can maybe stumble along with going more lean with a dead FV. This can be misleading if you mean you cranked it a bit and it hasn't started. If so lean that the cylinders aren't firing, fuel can still be being passed into the exhaust system. IMO, the first easiest thing to do would be just try a different ...101 relay in the "Relay for Start Injector" position. During cold starts, the engine cranking RPM will be a little slower (because the engine oil is cold) = safety switch probably closed = puts the +12V thru one set of contacts inside that ...101 relay to close the fuel pump relay and run the fuel pump. Opening the throttle can allow more air into the engine = might open the safety switch = puts the +12V thru a different set of contacts inside that ...101 relay. You could also just try unplugging the safety switch (for a test) and see if the cold start behavior is any different. You would be super-lucky if this is the problem, but it's so easy to do no downside to doing this first. Beyond that, I'd be doing (more difficult) things like: 1. Monitoring the WUR control pressure (cold and warm) to see if it different for problem vs no problem. 2. Monitoring the voltage output of the Protection Relay (or at the FV) to see if it different for problem vs no problem. Good hunting!
OK - So FV unplug killing, it is actually normal is the mixture is in the proper range. Rich smell is with it running after cold start. Not so much later, so that's probably a non issue. I did the old unplug the fuel pump safety switch so it runs upon key turn. No change. The time I unplugged it, it actually did the 3 or 4 seconds and gas pedal to start, to no effect there. Would that WUR come into play on a warm start that has an issue? I see a cold start but warm also??? Also will the cold start injector fire on a warm restart? I never did check to see if it actually "spewed" out fuel. Thanks for the help! jim
One more thought for my day. The battery is 3 years old, test ok. But I just bought a new one and dropped it in. I did measure 12.6 at the battery and 12.4 at the digiplex just to check things. Seems a .2 drop could be ok. Digi looked clean and good ground. But would an "ok" battery combined with an original starter possibly be the cause. Starter needs more current at old age and on starting it can on occasion drop the voltage too low for the Digi and other 12v starting items and cause this???? Going to start every am with new battery and see what happens, or I am smoking too much crack? jim
If there's some sort of (intermittent) blockage in the WUR (or the control pressure return path to the tank) during a warm restart = control pressure very high = fuel delivery very lean = hard to start. I didn't state it directly but just measuring the cold and warm WUR control pressures to see if they are quasi-reasonable wouldn't be an unreasonable thing to do IMO. I don't think so (if the thermo-time switch is working correctly), but not 100% sure about that. On the US 308i-2V, there was a separate thermoswitch to ensure that the cold start injector did not squirt on warm restarts, but they eliminated that on the US QVs.
