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Idle, warm starting and mileage problems

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    Idle, warm starting and mileage problems

    Folks, I'm a bit stumped.
    Background: my 1990 325iS has about 117kmi on it and as of now is 101% stock (minus some cosmetic interior stuff). Last summer, due to scoring in the camshaft journals, the head was replaced. Since then, every single rubber hose/gasket in the engine bay has been replaced, the injectors + manifold were cleaned, the air meter was recalibrated, etc. I will not go into the details of how much money was spent (I can't do most of the stuff myself, having very limited time) but suffice it to say that I have literally run out of options on what to replace.
    The mechanic helping me in the endeavour is held in very high regard in the local CCA chapter and is generally considered the 'go to' person for E30s.
    After all this work, the engine still has three problems:
    1) with the AC disconnected, it idles around 600-650 rpm, therefore it's rough at idle. The ICV has not been replaced because mr. mechanic maintains that this is correct idling behaviour. I maintain that it is not. Ideas?
    2) The car has developed a lovely warm-start issue, wherein to start it when warm you have to have the gas pedal slightly pressed, otherwise you have to crank it for literally 40-45 seconds. This results in a significant unburned gas smell, something a car with a cat should never have.
    3) Gas mileage is positively horrid: I get 18-19 MPG on a regular basis, managing to get to 23-24 when I do highway only, below 80mph. The result of a recent trip up to NYC where 80 mph was somewhat exceeded compares unfavourably with the 996 turbo in europe - at twice the speed.
    CO levels were measured and they were sort of OK - not as good as I expected them, CO2 was a little low and CO was not at 0, plus Lambda was not at 1.00.
    I am starting to suspect 1) the air-fuel meter 2) the ICV 3) one or more injectors. Any help will be appreciated.

    #2
    You said you recalibrated your air meter (AFM)... this could be your problem for it may be wrong.
    Next i would suggest replacing your ICV because once it is new you dont have to worry about that and this should fix your rough idle.

    1986 325es (69k) Garage Queen Buy It Now 10k;1986 325es (track rat) 2.7i How-To & 1.1/1.3Motronic UpGrade
    1991 318is (daily driver) 1991 318is M42 Maintenance How-To;1989 325i (parts car)

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      #3
      Thanks for your reply, first of all.
      As to the AFM, we played with it multiple times to get to behave. The current setting works significantly better than the previous ones, but I'd say the car is still running rich.
      We'll check it again, perhaps I can persuade the gentleman to swap it for a new one, to see if that is toast.
      ICV will get replaced as soon as I can persuade him - he's trying desperately to save me money, but at this point the inconvenience is far outweighing the cost, not to mention that it feels utterly absurd to get 19MPG out of this thing. And costly.
      There are two more things that have been mentioned by some people but I am noncommittal about: coolant temperature sensor and throttle switch. These 'should' have been checked but at this point I'm starting to doubt everything. What do you think?

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        #4
        I checked http://www.r3vlimited.com/board/showthread.php?t=101152 , since the problem seems to be similar. I'll add what's mentioned there to my checklist.

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          #5
          i hope you tried to clean that ICV instead of shelling out for a new one
          Also the hard start while warm sounds like an injector issue , were those replaced or refurbished when you did the head work ?
          :pimp:

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            #6
            Unfortunately right now the car is being actively used, so the ICV is still as it was. I concur that it should be cleaned, especially after seeing the price of a new one.
            As to the injectors, I concur that that seems to be an issue; the whole system was cleaned (toghether with the manifold) by the professional cleaning people when the head was changed. This was done without my consent, but I was only told after the fact. The (very) curious thing is that the injector problem is recent: it developed now, after the car sat for about two months. I wonder?

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