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CEL from hell/MAF data question (97 850) 850

posted by  Shaughnessy on  Mon Jan 4 12:14 CST 2021
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last visit: Fri Oct 3 23:53 CST 2014
[RELATED]

As I stated in another thread, I have had a p0171 CEL issue recently.

And because of that, I've replaced the plugs, re-routed the vacuum lines to their correct route, cleaned the distributor and rotor, re-connected a loose vacuum line, cleaned the MAF sensor like literally 5 times, and I'm still getting a CEL and (once again) code p0171.

I used the OBD scanner to check the data as the car is running, and my MAF reads about ~4.0 g/s when at idle.

Does anyone know what the normal rate is @ idle? I kind of have found results that suggest that's in the range, but also some that have said otherwise.

I purchased the current MAF in 2019, and maybe have 20K miles on the car.

I have one vacuum line that is original (it's part of the one that I had to re-route because I incorrectly routed originally). I don't know if that is an issue (I will eventually be replacing it, esp if it turns out that IS the issue. HA!)

Side note: the car runs better without the MAF plugged in too. The buildup to the turbo boost seems a little lagging, but nothing too bad.

thanks in advance
--
1985 245. 246K Gone..but not forgotten. Sold in 2013, found 2018! Still running on the road. Of course. 1993 Volvo 850 soon to be gone








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    posted by  someone claiming to be on  Wed Dec 31 18:00 CST 1969 [RELATED]

    Had something very similar on my '95 855T. Check the short hose from the IAC motor to the intake plenum. Two shops didn't find it even after "smoking" the plumbing. Mine had a large hole, rotted through by heat and oil. Cleaned the IAC motor, replaced the hose and problem solved. It's hard to reach as I recall. Great car but I sold it years ago with 225,000 miles and a bad transmission.

    Erwin
    Memphis
    745T
    945T
    855T
    V70 3.2
    C70



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    posted by  someone claiming to be on  Wed Dec 31 18:00 CST 1969 [RELATED]

    I did a smoke test, and it turns out my inner cooler hose was damaged beyond repair.

    Gotta replace that and see how much of a difference it makes (I think it will make a HUGE difference, as it was the only spot that had smoke coming out and it was a lot of smoke).
    --
    1985 245. 246K Gone..but not forgotten. Sold in 2013, found 2018! Still running on the road. Of course. 1993 Volvo 850 soon to be gone



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      posted by  someone claiming to be on  Wed Dec 31 18:00 CST 1969 [RELATED]

      What did you use for a smoke machine? If you made your own, how was it made?
      --
      Keeping it running is better than buying new



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        posted by  someone claiming to be on  Wed Dec 31 18:00 CST 1969 [RELATED]

        So I finally have driven the car enough miles (just about 600 or so ) to finally feel confident that the issue is at bay.

        The issue(s) I was having was related to the turbo hoses. I had a really bad hose at the inlet (it's early in the morning, so I'm drawing a blank on the name). I replaced all the hoses in the turbo, smoke tested it (I made a cheap smoke tester...blessing in disguise) and no smoke tests (outside of the weep hole in the inner cooler).


        No more CEL, and the car runs much faster now.

        Thanks to all who helped (mostly Klaus)
        --
        1985 245. 246K Gone..but not forgotten. Sold in 2013, found 2018! Still running on the road. Of course. 1993 Volvo 850 soon to be gone



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    posted by  someone claiming to be on  Wed Dec 31 18:00 CST 1969 [RELATED]


    Used the scanner to see what values you get w/ cold car, see what the scanner reads for air temp, air mass. At this point, the air temp reading must be close to ambient temp. Warm the car to open temp and see what the readings are.

    Usually if the car runs better w/ air mass meter unplug it usually indicates a bad meter.

    Look at the time freeze data and see at what point the P0171 is set.



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