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Thread: throttle body cleaning - messed up calibration?

  1. #1
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    throttle body cleaning - messed up calibration?

    I swapped out my CCV system this past winter and during that time I took the opportunity to clean out the ICV and throttle body. During that time I was foolish and pushed on the TB butterlies with in order to clean the TB further. Since then I've seen my mpg drop from 21-22 in the city to 18-19. This is likely foolish but would moving the butterflies screw up the calibration of the Throttle position sensor and cause poor gas mileage? Car still runs well, a little misfire on cold starts which was present even before i did the CCV, DISA is good, no vacuum leaks or codes with bmw scanner. Planning to do the VCG and vanos seals in the next couple weeks and inspect the plugs while i'm in there. car has new tires inflated to the proper psi, alignement was also done but no improvements. any thoughts to alleviate my concern would be appreciated!

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    In my opinion, I think that could be a likely reason for MPG drop.

    Maybe resetting adaptations through INPA will calibrate?

    Can anybody else confirm?

  3. #3
    geargrinder's Avatar
    geargrinder is offline Having No Trouble Here BMW CCA Member
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    The misfires indicate something is wrong. Seems highly likely that's related to the mileage issue. I severely doubt its because you poked at the throttle plate.

    You say "no vac leaks" and indeed maybe that's true... but... if I had a dime for everytime somebody insisted that for ages before finding... a vac leak.... well I'd be preziduntrichypants.

    What are your adaptations/trims? Assuming your O2's and MAF are OK the best way to know if you have some vac leaks as they'll be significant.
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    Quote Originally Posted by geargrinder View Post
    The misfires indicate something is wrong. Seems highly likely that's related to the mileage issue. I severely doubt its because you poked at the throttle plate.

    You say "no vac leaks" and indeed maybe that's true... but... if I had a dime for everytime somebody insisted that for ages before finding... a vac leak.... well I'd be preziduntrichypants.

    What are your adaptations/trims? Assuming your O2's and MAF are OK the best way to know if you have some vac leaks as they'll be significant.
    Apologies for the lateness. Had never checked trims before so i had to do some research before posting.

    I used a generic wifi elm obd scanner and dash command app on iOS. Ambient temp was 77 degrees and car at operating temp 96 C confirmed by app and mid secret menu. Fuel trims at idle of about 700-800 ranged from 0-4.1% with a mean somewhere between 1-2%. From what I've read this appears to be normal but please school me on this topic as I'm unfamiliar with it.

    Of note I also cleaned my KN filter yesterday with the recharge kit and cleaned the maf same time I did CCV. Lower intake boot was replaced at time of CCV and disa was replaced 1.5 years ago and held vacuum when CCV replaced one year ago.


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    I have this same problem after completing chain guides, intake gaskets, and ccv replacement. I did all this at once, but one additional thing I did was swap out my coils for a set I pulled from a parts car. They looked new, but I think it was because no one ever removed the beauty cover. Plugs are also about 20k old, but they are the recommended NGK EQUP 4 prongs that everyone swears by. The reason I swapped coils was the parts car coils had tighter boots that weren't splitting at the ends.

    I have my original coils on standy as well as a gently used set of the same spark plugs. My plan is to put the good boots on my original coils and see if my cold start misfires go away.

    I know there is some degree of necessity to a rough start when cold to get everything warmed up. It idles at about 900 rpm for a good 30 seconds to 1 minute, and I can feel the misfires while it does this because it shakes more than it used to. After a good minute it smooths out and the rpm drops back down to 500.

    So my point is just to try the standard check of your plugs and coil boots to make sure all is tight and moisture free. I can report back when I swap my stuffs out.

    ***Key thing I forgot to mention was I also cleaned my throttle body and finger blasted the butterfly, but I was gentle, and I don't think this is our issue. I have cleaned it before with no ill effects. As long as you don't fully open it and hold it open for extended periods I think its fine.
    Last edited by WBAD530i; 06-27-2017 at 11:37 AM.

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    don't know how many times I have had the TB off of my car to clean it. I always hold it open with one hand and clean the butterfly with the other. 350,000 miles now on the car , and never have had a problem working the TB . Now you might not like it, but the Air Filter your running, is great for some vehicles . Ran one in my 66 --R Code Galaxie for years. That filter is nothing but trouble in our cars, the Maf's don't like getting oil on them. There might be your trouble, you recharged the filter when doing your other work. I would try cleaning the Maf a few times and see how it runs, without contaminates on it

  7. #7
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    Quote Originally Posted by WBAD530i View Post
    I have this same problem after completing chain guides, intake gaskets, and ccv replacement. I did all this at once, but one additional thing I did was swap out my coils for a set I pulled from a parts car. They looked new, but I think it was because no one ever removed the beauty cover. Plugs are also about 20k old, but they are the recommended NGK EQUP 4 prongs that everyone swears by. The reason I swapped coils was the parts car coils had tighter boots that weren't splitting at the ends.

    I have my original coils on standy as well as a gently used set of the same spark plugs. My plan is to put the good boots on my original coils and see if my cold start misfires go away.

    I know there is some degree of necessity to a rough start when cold to get everything warmed up. It idles at about 900 rpm for a good 30 seconds to 1 minute, and I can feel the misfires while it does this because it shakes more than it used to. After a good minute it smooths out and the rpm drops back down to 500.

    So my point is just to try the standard check of your plugs and coil boots to make sure all is tight and moisture free. I can report back when I swap my stuffs out.
    You make a good point. I have pulled the coils and though they are original they LOOK ok, but I know that really doesn't mean much. Plugs were changed by PO approximately 45k ago to ngk's. Plug wells have just a hint of oil in some of the cylinders and i plan to do the vanos seals and VCG at the same time in the next couple weeks. I've considered buying new coils as a set of 6 Bosch oem coils is only 140 bucks but I'd rather find a cause than just throw parts at the thing


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    Quote Originally Posted by Poolman View Post
    don't know how many times I have had the TB off of my car to clean it. I always hold it open with one hand and clean the butterfly with the other. 350,000 miles now on the car , and never have had a problem working the TB . Now you might not like it, but the Air Filter your running, is great for some vehicles . Ran one in my 66 --R Code Galaxie for years. That filter is nothing but trouble in our cars, the Maf's don't like getting oil on them. There might be your trouble, you recharged the filter when doing your other work. I would try cleaning the Maf a few times and see how it runs, without contaminates on it
    I actually swapped in the filter brand new when I did the CCV about a year ago, first recharge was last night since I was doing some maintenance on my wife's car I figured I may as well do mine. I'll clean the maf again and see if that helps. The car pulls well, just a slight misfire on cold start that doesn't throw any codes and smooths out after 30-60 seconds. Good to know that yes not the TB though as I've done it to other cars in the past but just wanted to make sure


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    And no one has a clue what a 66..R Code Ford Galaxie was. LOL

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    Quote Originally Posted by Poolman View Post
    And no one has a clue what a 66..R Code Ford Galaxie was. LOL
    Without looking I'd guess it was the 427 engine?
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  11. #11
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    I wouldn't be too optimistic for purely MAF contimination on the 540 - these don't get dirty problems nearly as much as the old school bosch hot wire ones. Mine acted up with tons of stuff on it but not until it was a pile of wet frothy oil-water emulsion foam nastiness.

    Not to say not to give it a try cuz why not, but these are not the same as the old ones that indeed didn't like the oil coming off K&N filters. (also watch out for overoiling gauze filters... easy to get sucked into doing... I let mine sit for a long time before running, then the excess oil will tend to drip out... )

    - - - Updated - - -

    Ooops right 530 - well same difference - M54 has same modern type integrated hot film MAF.
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  12. #12
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    Quote Originally Posted by geargrinder View Post
    I wouldn't be too optimistic for purely MAF contimination on the 540 - these don't get dirty problems nearly as much as the old school bosch hot wire ones. Mine acted up with tons of stuff on it but not until it was a pile of wet frothy oil-water emulsion foam nastiness.

    Not to say not to give it a try cuz why not, but these are not the same as the old ones that indeed didn't like the oil coming off K&N filters. (also watch out for overoiling gauze filters... easy to get sucked into doing... I let mine sit for a long time before running, then the excess oil will tend to drip out... )

    - - - Updated - - -

    Ooops right 530 - well same difference - M54 has same modern type integrated hot film MAF.
    I don't assume that's my problem either, I let the filter sit for 24h after oiling but will try cleaning the maf anyways.

    Any insight as to the fuel trims?


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