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Chrysler 300M



  • sdmike2sdmike2 Posts: 2,909
    For anyone who has done any significant mods to their M, like dual exhaust, better flowing intake, bosch plugs, etc., I highly recommend doing the battery disconnect thing. My computer used to tell me that I had about 280 miles left on a tank when I filled up. After the re-set it now says about 340. My guess is that I've been getting better mpg since my mods and the computer needed to forget the old information in order to better predict under my current set-up. Also, I think I'm getting a little better mileage, at least according to the computer. On the highway at 70mph the computer tells me I'm getting around 24-27mpg..more than before. Not sure if my engine is more efficient after the re-set, or if the computer now knows that my car has been getting better mpg since my mods. Either way it's better.

    Finally, the car exhibits noticably higher acceleration performance. Technicall speaking, it runs like a raped ape when I tromp on the gas. It's all good! :)
  • i second that. i ALWAYS do when i do a performance mod. its SOP.
  • ruskiruski Posts: 1,566
    If I get get a new 300M in a couple of months, I want the upgraded stereo with 320 watts and 11 speakers, and the PHG package. Just like my 99 300M.

    The problem is that here in South Florida there are very few PHG-equipped 300Ms on the dealers' lots. And as far as I can see when they order PHG, they only order the "first" stereo upgrade. It seems that the order the better stereo upgrade only for the 300Ms with the luxury package, but they figure the old farts who want luxury aren't going to want PHG.

    I guess I could order a new 300M but then I probably couldn't expect to get any good deals. And I am not as rich here in FL as I used to be in NYC.
  • Go into your local dealer and build yourself an M you may be quite surprised how much you will save by factory ordering your car. Remember the dealer does not have to pay for having a factory ordered car in their lot. I saved a bundle and got all the options I wanted. You are in the drivers seat NOT the dealer.
  • 300michael300michael Posts: 1,815
    Thanks Otto for posting my picture. If you do not have the bored out TB you will notice less of a change, but it still will help. There are three restriction of 2.5 inches, the interior of the Plenum, the 90 degree bend and the throttle body it self. Some of us bored out out throttle bodys to 2.75 inches so opening up the restrictions help noticeably. The 3" tube helps because it allows the same amount of air to travel slower around the restrictions (bends in the line).

    Phases, the worst thing is that you could grind all the way through the bend. There is two restrictions one at the top (one and two O clock and the one Otto is talking about at seven O clock) that can be removed.
  • no, i dont have the tb bored, but i sure would like to, but im bettin it takes more than a dremel tool right? if i can do it safely with a dremel, i will..

    i only took out the bottom left restriction, tomorrow ill work on the top right, but there doesnt look like much to work with.

    also, my plenum doesnt look restricted at all. doesnt have the rivets in it like the pics that were posted. any other advice would be appreciated, i love more power. MWAAAAHHAHAHHAHA!!
  • on the TB, the two cords, wires, whatever ( i assume the gas and the cruise control), how the heck i get the TB off with those things on there???
  • scotianscotian Posts: 1,064
    2000 Service Manual, p. 14-36:

    1. Disconnect - battery cable.
    2. Remove wiper arms.
    3. Remove cowl screen.
    4. Remove cowl plenum.
    5. Disconnect air plenum from throttle body.
    6. Remove throttle cable bracket.
    7. Disconnect electrical connectors.
    8. Disconnect top vacuum hose.
    9. Remove throttle body support bracket from the bottom of the throttle body.
    10. Remove 3 throttle body bolts.
    11. Hold throttle lever in wide open position. Remove throttle cable and speed control cables from throttle arm.
    12. Clean mating surfaces.

    There are no illustrations.
  • scotianscotian Posts: 1,064
    Where can I purchase the TB part that was bored to 70 mm and how much was it? Also, is there a separate plate that is involved with all of this?
  • scotianscotian Posts: 1,064
    He's so sick of me talking about my car that he said if he won the lottery, he'd buy a whole fleet of 300Ms and crash two a day in front of my apartment -- just because he could.
  • For those wanting to hollow out the plenum, I have a suggested approach that worked for me.

    Remove the plenum from the car. Both ends are slightly flanged. You can start at either end and go around the circumference with pliers breaking off the flanged part of the inner sleeve only. After that, you can insert a small screwdriver between the inner and outer sleeves. Applying pressure with the screwdriver allows you to grab small pieces of the inner sleeve with pliers and break them off. You start to gain a feel for how much pressure can be applied without breaking the outer sleeve. Patience is a factor, because the thing comes out in literally hundreds of pieces.
    If you get sick of it, you can slap it back in the car and forget the whole thing. Eventually you work your way inside the box and need vicegrips or channel lock pliers to reach in there. Then you start all over at the other end. Bottom line: tedious, but do-able.

    One end has a tab anchoring the inner sleeve to the bottom of the box. I drilled it out from the bottom and later patched it with a black plastic rivet and cement. Also, the factory clamp on the TB side of the box is non-reusable, so you end up replacing it.
  • For anyone thinking about Throttle Body Modifications,

    Here's the deal on the TB. Your stock TB has a 68mm plate, but narrows to 62mm at the end where the intake hose connects.

    If you want 68mm you can dremel the intake sides of the TB to match the opening around the butterfly plate. Grind and polish, etc. You might also grind the manifold side to remove the ridge there too. Finally grind the throttle stop a little to get the plate to open a full 90 degs.


    You could disassemble and have it bored to 68mm, grind the throttle stop, put it back together and go.


    You could disassembly and have it bored to 70mm. This requires this 70mm replacement plate from Holley, part no 26-130. The shop that did mine also shaved down the rod that holds the plate on one side and cut off the other side. The also tried to use low profile bolts to hold on the plate. This is what they do to their custom Holley 4 barrel carbs, so we both agreed it should help. Also, finally grind the throttle stop for full 90 deg opening.

    Now you've seen my pics on my TB after it was bored with this new Holley plate installed. It looks mighty thin in the walls, but it is strong. I am however careful not to tighten the intake hose clamp too hard though. :)

    Lastly someone suggested biasing the throttle position sensor to make the car think the accelerator is pressed down a little more than it acutally is. Supposedly will dump additional fuel. To do this it was suggested to drill the TPS mounting holes into slots so it can be rotated and locked down. I might try this, since I have another sensor anyways.

    Oh, one last thing, these plates and the butterfly opening are not completely round. Actually it is slightly oval. I think so that a little air can leak around for idle purposes. BTW, if you don't play with the idle screw, it will idle fine when you put your TB back together. It requires a special torx screwdriver anyways, one with a hole in the center.

    Sorry so long.


  • 1. Electrical storms.

    2. Heading in to 5* to have my second rear window motor replaced. Only 2 months/10K miles left on my warranty.

    On the bright side, window motors have been my only complaint with this car.

    Maybe dealer will have more info on the not-so-special Special. Not!
  • Thanks for good info on TB options. That is going to be my winter 300M project.
  • With all this talk about boring out the TB, does anyone have any performance data before/after? How much difference is there. Thanks
  • You folks who are looking to replace your OEM Goodyears or another brand tire with a stock size tire, and are sick of the road noise your tires make or the harsh ride, steering shakes or shimmies, you gotta get a set of Bridgestone Turanza ER33 H rated tires.

    After one week (about 300 miles) of driving on mine, I couldn't be happier. With these tires, road noise is virtually nil and this is a very firm yet smooth riding and stable tire. I'm expecting my gas milage to increase a mile or two per gallon as well since rolling resistance and steering effort also feels lower.

    and no I don't work for or sell Bridgestones, just want to pass on my experiences with them so far.


    The Consummate 300M Pages

  • Ok, Tried the Slotted Throttle Position Sensor thing with my extra TPS sensor from my original Thottle Body. I used a drill bit to drill out the metal sleeves. They drilled some, then just pushed out of the plastic.

    Ok for the Results:

    Don't bother doing this. It only seems to make the idle faster and the car harder to stop. The tranny is confused too as to when to shift. 4th is hard to get in autostick since the car doesn't let you upshift into 4th if the accelerator is pressed too far. I can't say it was any faster, since I was so focused on the drivability changes in effect.

    So I put the old sensor back on and all is fine again.
  • Hey did you have Badyears before changing to the Bridgestones?

    I'm very pleased with the Michelins and was planning on getting the Pilots a lot of people are upgrading to.

    Why go Bridgestone (aka Firestone :( ) instead of Michelin?
  • Good to hear all went OK with the intake mod. Now if you really want to feel some grunt you will have to make one of those custom 3 inch intakes and totally get rid of the factory setup. Get the bigger TB also . The guy on the Intrepid site claims about 20 h.p with intake and TB
  • Yes, my 99 300M had the Badyears... I don't care to remember how many times I complained to my dealer about them as they rotated, rebalanced them, etc. for over two years (36K miles) and they just kept being poor tires...
    When I started looking for replacements, I made the mistake of letting the local Evans Tire store convince me to try Falken ZE-502 performance tires in 235/45-17 size. I posted about my experiences with the Falkens. Thankfully they had a 30 daysatisfaction guaranty period, so I gave them the benefit of the doubt and drove the Falkens for 3 weeks and took them back for a free rebalance, then one week later after doing some tire research I told them I wanted Bridgestone Turanzas instead of the Falkens. To which they did the swap out, no arguments. The Bridgestones came with a 30 satifaction guaranty too, but I won't be taking them back.
    I considered Michelins and several other brands as well, but based on my research, my short list said to try the Bridgestones first and I couldn't be happier with them.
    I'm certainly not knocking Michelins or any other brands (except Goodyear :P) and others have had good things to say about their Michelins but I'm so pleased with the Bridgestone Turanzas, I'm gladly done with tire hassle for the next 40,000 miles.
    I did discover one thing through all this which is that tire performance is a very subjective thing and each individual driver has to decide for themselves what tire works best for the kind of driving style and ride/performance combination they're looking for. That's one thing that makes it hard to say that any particular tire is best. But if you looking for similar tire performance results that I was looking for which was a smooth, quiet and stable ride with very good handling characteristics, the Bridgestone Turanza ER33 is one very good choice.
  • I solved that problem....Just not buying another 300M :)
    Tell me about the salarys coming from NYC too :(
  • Well, I'm done with any more performance mods to my M. I'm happy with what I have, & if I need more, I'll take my 96 Impala out of storage :)

    I might do the signal mirrors, but that's not a performance mod.
  • Well, I had my M in for my oil change today, & I was walking around it just checking things out, & I noticed that the little inside piece of the Monza yellow tips I have had on my M for almost 2 years, broke off. It's now ratteling inside the tip. The others are fine. So now I need to buy new tips again, to fix it. Makes no sense to get only 1 tip to replace the broken one, because it wouldn't match the wear on the other one. Has anyone else had this happen to the dual Monza yellow tips? I don't know if I want to buy the same ones again. What other options are there for tip, & maybe part numbers for them too.
  • scotianscotian Posts: 1,064
    What are the approximate prices for a new TB and a Holley 70mm plate?
  • 300michael300michael Posts: 1,815
    Speed mods results.
    Stock 300M with Goodyear LS tires. 0-60 time_7.8
    Dual Exhaust___________________7.4
    K&N st. replace air filter___________7.3
    Bored outh TB with 3" tube________7.2
    Bridgestone S-03 pole posit._______7.0
    Hood Scoop forced air____________6.9

    Times are rounded up to the nearest tenth. Times can change for example if you put the K&N filter first it will cut down you time about .2 instead of the .1 after installing the exhaust, but then you will only get about .3 out of it from adding the exhaust. Also air tempiture, altiude, and other air and road conditions will effece your times.
  • scotianscotian Posts: 1,064
    Haven't actually done anything yet. But I plan to order a plenum, even if it's an older one that I have to hack apart. Once I install it and the cone filter, it should be as effective as a replacement 3" tube. Someone here said they noticed no improvement when they switched to a tube, but did when they switched to a cone filter and again with TB mods.

    I like keeping my engine compartment mods hidden from view. Having something that looks completely different from factory in there would only confuse the monkeys.
  • Otto-about that claimed 20 horsepower gain. Can you direct me to that post? Is it on Edmunds or where? Thanks again for your constant support for this group.
  • Just finished reading an article , that states your President Bush saying "That the United States has no more important relationship in the world than the one we have with Mexico" WOW I thought we Canadians had the most important relationship with the U.S .
  • 300michael300michael Posts: 1,815
    Why not do as I did. Keep the Plemum in tact and just get a 3" pipe and a 45 degree bend and use them. If you have problems just stick them back in. It would only take a minute or two.
  • Here is what was posted on the site

    Now the nuts and bolts of all this Horspower gains!
    >The trepid weights ~3555 lbs so I searched for a HP
    >calculator that would give numbers to match the stock
    >setup. I found one that if you put in the numbers
    >(3555 lbs and 89mph trap speed) gave exactly 242HP!
    >So stock is 242 HP
    >To get 1 mph improvement in the quarter takes about 8
    >hp.(varies from car to car based on weight)
    >My HP is 265 HP which fits with the # Im getting.
    >TB alone gives little improvment (it needs air)
    >good for 4 or 5 hp
    >Air intake with TB gives about 20HP
    >I did not do a run with just an intake and a stock TB
    >but people that have just got the intake have noted a
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