Distributor Problem 4.9l
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Cadillac DeVille 1985 to 2005 including:
1985-1992 Fleetwood, 1993 Sixty Special, All FWD Forum Discussion, Distributor Problem 4.9l in Past Cadillac Vehicle Discussion; I need some advice. A couple of days ago I took my distributor out because it was making a grinding ...
  1. #1
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    Distributor Problem 4.9l

    I need some advice. A couple of days ago I took my distributor out because it was making a grinding noise, which I thought might be the gear going bad. I took care to mark its position. After removal I found a piece of plastic on the shaft and another one in the hole right next to the oil pump shaft (the gear was fine). I removed the first one, and fished the second one. After that I did some cleaning the the terminals and the button in the cap, and the contacts on the rotor. When I was done doing that I decided to scrub the around the pick up coil and the hall effect switch with some steel wool. Well, that wasn't so wise since little particles off the steel wool attached to the magnet on the hall effect sensor. I tried removing them with a flathead screw driver and the plastic piece holding the hall effect switch magnet snapped off. I had to then take out the sensor and glue it. While doing that without removing the shaft the solder on the little white board, where the chip for the hall effect is located, cracked and the board came loose. So, I had to re-solder it and glue the plastic pieces together.

    After I was done with that I reinstalled the distributor aligning it with my markings. My timing, though, was off and there was a lot of hesitation when accelerating in 1st and 2nd gear from a dead stop, and less power in general. The next day I bought a timing light, and timed the engine correctly. Now all of the power is back, but there is a small intermittent hesitation in 1st gear around the 1300 RPM range when accelerating slowly. If you use more rapid acceleration there is no hesitation. The engine performs well when at WOT as well.

    There are no DTCs. I checked the wiring harnesses and the resistance on the hall effect sensor, but was not sure what kind of numbers I need to see. I also poured in some Techron and did some highway driving - still the same.


    What would you guys suggest? Should I do some particular tests, or should I start throwing parts at it? The ECM uses the hall effect switch for camshaft positioning, correct? If the sensor is bad I'm assuming the engine should be hesitating throughout its power band, and not not just around the 1300 RPM mark.

    Should I just go ahead and replace the whole distributor, which anyway has that grinding noise (not a loud one, but that probably indicates the bearings are bad, since the gear was pretty good)? The hall effect switch is listed for $41 at Rock Auto. For the same money I can go to the Pick'n'Pull and get a distributor without the cap (with the cap and coil it's $11 more). The other option is I get a new distributor with the cap, rotor and coil for $88, and a $15 spark plug wire set all from Rock Auto, which will end up being a little less than $120 with the shipping.

    Let me know what you think.

    EDIT: I have cleaned the throttle body, EGR valve, and my engine grounds. The reason I put the Techron was that I thought since the engine was running so rough when it didn't have the correct timing, that probably the unburned fuel had gunked it up a bit.

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    cadillac_al is online now Cadillac Owners Connoisseur
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    Re: Distributor Problem 4.9l

    I wouldn't change the dist until I got a code for it. If it is bad you will get a code. I don't think the dist is the cause of your hesitation anyway. I would guess a lazy O2 sensor, or MAP sensor, or dirty injectors. You already ran the Techron so I would just run it until a code comes up.

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    mc_marto's Avatar
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    Re: Distributor Problem 4.9l

    Thanks for the advice cadillac_al. I cleaned the MAP and its vacuum line. That seems to have made the hesitation almost disappear, but time will show like you said. It's not a big problem, considering all the power is there, but I just can't figure what is causing it. Anyway, will see what happens after some time.

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    Re: Distributor Problem 4.9l

    I just thought of something. Is the distributor shaft supposed to move back and forth? What I mean is, if you have the cap off, should you be able to move the rotor, while attached to the shaft, back and forth. I thought that if I have bad bushings in the distributor, that would be causing the play (if it's not supposed to be there) and that might be the culprit of my hesitation. So, I hope someone like Ranger, Sub, Denis or Basscat are able to answer this question.

    If there's not supposed to be any (like I think) then that's telling me I need to replace the distributor for real, because of bad bushings - that might also be the cause of the small grinding noise I hear coming out of the distributor. I also remember there wasn't any gasket for the distributor, could that also be causing play in the shaft as well, or am I getting crazy?

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    No, the rotor should not move freely in any direction.

    Back and forth, not rotating, right?

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    Re: Distributor Problem 4.9l

    No, you can't rotate it by hand, but you can wiggle it back and forth about a quarter inch in each direction. The gear seemed fine when I pulled it out, but the problem is most likely in the bushings of the shaft.

    So, it's definitely calling for a replacement? Do you know if I can replace just the bushings, though, or should I just go ahead and order the $90 distributor they have at Rock Auto?

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    JTL1043 is offline Cadillac Owners Member
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    Re: Distributor Problem 4.9l

    Did you do the reset process ?? If I remember wright turn on switch don,t start let ecm come on{ off warm three time after 07 }
    turn off switch after third reset hit auto on control enter turn off switch then start should idle up and then come to normal.

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    Re: Distributor Problem 4.9l

    I am not aware of such a procedure.

    Anyway, two updates: I used the procedure in the FSM to check the hall effect switch and it turned out it didn't detect when the blade was passing through it. So, I went to the pick'n'pull the next day and I got a sensor in a pretty good condition. I installed it and the engine runs better, but there is still a mild hick up. I also ended up replacing the vacuum hoses for the metal line running to the transmission modulator - the tranny had started slamming the gears and it made an occasional scary grinding noise - repaired the vacuum lines and that stopped.

    I just poured some more Techron and filled up at Shell (the first time I poured it the wrong way - tank was full not empy). I'm also about to change my oil and filter - the OLM says 0 now, and will see if the hick up clears out completely.

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    stoveguyy is offline Cadillac Owners Connoisseur
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    So your distributor still has a lot of side play from worn bushings? You mentioned replacing Dist but it sounds like you only changed Dist sensor?

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    Re: Distributor Problem 4.9l

    The play I originally said it had was a little exaggerated. It is actually just a couple of mm in each direction, and I think that's normal. When I was pulling the hall effect sensor from the car at pick'n'pull, there was the exact same movement of the shaft, so I consider it being normal.

    I drove it on the highway after the oil change today, and after that while being in normal stop'n'go traffic I did notice the hiccup just 2 times and it was much milder, so it's probably going away.

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    Re: Distributor Problem 4.9l

    I wonder, though, if my hall effect was bad why didn't I get an error code. I've been reading the FSM some more, and the description of the hall effect is a camshaft position sensor, which helps the PCM to precisely calculate fuel delivery. It says if there is a crankshaft positioning signal (which comes from the pickup coil) but the camshaft signal is lost the PCM will set a code. Well, I never got one.

    I wonder if there is another sensor malfunctioning that chimes in when in closed loop, because that's the only time the car would experience the occasional hiccup. Maybe an IAT? My o2 sensor is good - I replaced it last summer, because my original had gotten lazy. Well, this one is Bosch Premium and it is pretty active - it changes outputs in less than a second, and it even lets the car enter closed loop earlier - half way before the engine reaches normal operating temperature. Could that be it? Maybe I should try to put my old Delco back on and see if I experience the same symptoms?

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    Re: Distributor Problem 4.9l

    Here are a couple of updates:

    I replaced the cap, rotor and wires,and adjusted my TPS. Spark plug wire #4 was burnt from the exhaust manifold, so I was sure that was the problem, but unfortunately it is still the same. The TPS was showing 0.2 degrees on warm idle, while it's supposed to be within 1.6 - 4.6 degrees.

    I guess it could be the ICM or coil. I have done resistance checks of both and they seemed fine, but I'd like to know if there are other ways to test them. I'm leaning more toward the ICM since when I had the faulty Hall Effect I did not get any code through the computer.

    Or, is there a possibility that I reinstalled the distributor in a notch off? Maybe there is a fairly small amount of ignition advance around 1300-1400 RPMs and that's why it is missing, but at higher revs the advance is bigger and that's why it doesn't miss anymore?? Could it be that?

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    Re: Distributor Problem 4.9l

    Here is an update:

    I just fixed my issue tonight. It was something really stupid that I never looked into until tonight.

    I'm guessing someone had the distributor removed at some point. When they reinstalled it they did not rotate the base enough so the cap seats good. I'm sure I didn't screw it up because I had marked everything prior to the distributor removal, and aligned everything when I installed it. There is a small notch on the cap so it can go one way only on the distributor. I guess they did not notice that on time and later on just shaved the notch a bit, so it could slide over and look flush with the distributor base. When I replaced my cap I didn't notice the notch and just had it positioned the way the old one was. Well, that wasn't letting the cap be flush first of all, and second - the cap got cracked from me trying to tighten that bolt as much as the others.

    I discovered the notch on the cap tonight, and looked for it on the distributor base. There it was but it was 180* from where it was supposed to be, so the cap can mesh with it good. Well, I loosened the bolt, rotated the base, glued the crack in the new cap, installed it, and re-adjusted the timing. Took the car for an hour drive and there wasn't a single hesitation. Just a smooth acceleration all the way through. I'm so happy that I finally found the problem. I just wish I would've found it much earlier, and not have spent weeks of trying to fix it and researching similar issues online.

    I appreciate all of your help. Thank you all!
    cadillac_al and bigm57ict like this.

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