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2.5L idles rough when put in a chip

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  • #16
    I'd recommend sticking with the stock chip for your application for now. The term "2.5 L" covers a wide range of cars. In your case, you have a bigger motor, higher compression, and a fairly stock style head with stock cams. I would guess that you are making around 175 HP to the rear wheels and that a stock chip and AFM can easily support that. The stock timing maps are very conservative and will match your 11:1 compression without issue. You could potentially use a std 2.3 L performance chip as long as you are not in Cali and can get access to 93 octane gas but that should be safely tested on a dyno. Optimally, you may want to install a bigger cam at a later date which will match the 11:1 compression much better than the stock one. We see 2.5L engines that make anywhere between 165-250HP to the wheels. These are all 2.5's! The chip will need to match the timing, cams, and ultimately the estimated power. In your case, the stock 2.3 is most likely the best chip you will find. Do not waste your money in the other parts until you make the mods for more power.

    2.5 L track car (284/276, 11.25:1, Stage III head, Alpha-N, DTM CF manifold, Sport EVO header, etc) and a 2.6 L street car (276/264, 11:1, Sub-box in the trunk).

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    • #17
      Originally posted by dynospot View Post
      I'd recommend sticking with the stock chip for your application for now. The term "2.5 L" covers a wide range of cars. In your case, you have a bigger motor, higher compression, and a fairly stock style head with stock cams. I would guess that you are making around 175 HP to the rear wheels and that a stock chip and AFM can easily support that. The stock timing maps are very conservative and will match your 11:1 compression without issue. You could potentially use a std 2.3 L performance chip as long as you are not in Cali and can get access to 93 octane gas but that should be safely tested on a dyno. Optimally, you may want to install a bigger cam at a later date which will match the 11:1 compression much better than the stock one. We see 2.5L engines that make anywhere between 165-250HP to the wheels. These are all 2.5's! The chip will need to match the timing, cams, and ultimately the estimated power. In your case, the stock 2.3 is most likely the best chip you will find. Do not waste your money in the other parts until you make the mods for more power.
      actually this is what i'm thinking. im building the car in stages. for this moment, cams is not on my budget and will be added later along with other goodies. the stock 2.3L chip is doing very well for my set up at the moment. i might just stick with it for a while until the motor is broken in at least.

      it's a good way of looking at it and actually the first time i hear it. thanks
      1988 E30 M3 Alpinewhite II 2.5L (sold)
      1997 E39 528i Platinum Gray

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      • #18
        [quote=M3 Adjuster;236771]baxter E30 speaks the truth....

        Dlance .. Tell VAC to keep their chip... and if you get their injectors, cross reference and confirm what injectors you got and what their flow rate is. If you are running a 2.5 off of an AFM, don't jack around and get injectors with the sport evo part # on them.... The one's VAC supplies likely are not one and the same.


        I will get another chip, and I will be getting evo injectors. I guess I should run 2.5L AFM?? Does anyone have a good place in eastern Pa to get dyno work done. Not Vac.
        -Darren

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        • #19
          You only need the upgraded AFM if you have the right software. The upgraded AFM doesn't allow in more air.

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          • #20
            can someone provide me with the EVO3 / 535i AFM part number?
            1988 E30 M3 Alpinewhite II 2.5L (sold)
            1997 E39 528i Platinum Gray

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            • #21
              www.realoem.com will yeld the proper list of options and part #.

              You can do some cross referencing and search by part number to check what cars have the same part.

              Lee


              [email protected]

              1969 2002 racecar
              1989 M3 racecar
              e39 Touring

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              • #22
                Helvetica and DLlance.
                Be sure of what you have. Do not just mix and match afm, injectors and chips.
                I run my 2.5 with the tms chip, much more conservative than the vac chip. I use it with green injectors and e3 afm. However, it is designed to work with them. As I recall, the vac chip was for stock afm...but I could be wrong. I do know it made big power, but detonated badly so I pulled it.
                Suggest you talk to Luis Marques on the board, he designed the IIGO chips and knows this info in and out.

                As you have a bit of a mismatch of components Helvetica, I would suggest you may want to get a wideband o2 to make sure you are not running too rich or lean.
                Good luck guys!
                John
                88M3 henna


                73T100C
                97 540\6-Gone
                2008 MINI Clubman S

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                • #23
                  Thanks Jedm3,
                  I have stock AFM and injectors so I will contact Marques to see what he says. I will just upgrade later as my car has been sitting for a year now and I'm ready to fire her up!!!!
                  Thanks,
                  -Darren

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                  • #24
                    Follow up

                    Hi all,

                    I just wanna follow up this old thread since I'm the new owner of helvetica's car. Not long after, I installed evo injectors, afm, 284/276 cam and still the car got very rough idle on low RPMs with the VAC chip. Switched back to stock chip and it was fine although there was slight knocking below 3000 RPM. Turner sent me the J-chip but it was obsolete as the car wouldn't start.Finally, I ordered Iigomotiv chip and solved all the issues. Car started normally and no more rough idle. So my conclusion is maybe there is some defects on mass produced chips like VAC and J-chip and it really does worth it to go custom chip. Thanks to Luis for the prompt response. Track day is coming and can't wait to test the car

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                    • #25
                      I think sometimes it is not made clear enough in these forums how complex it can be to build an engine with major mods (2.5, cams, compression, better breathing, etc) and then to tune the EMS to get the most out of the mods. Often it sounds like one just bolts the parts on and goes, and it is almost never actually that simple....

                      After I finished my 2.5, I ran the TMS chip at first, the one designed for the build I had. I went with the complete "package", EVO injectors, AFM, etc. Car ran like crap....major pinging....etc.

                      Then I got an IIGO chip that matched my application. This was better, but I was still left with a HUGE lean spot around 4500-5500 RPM. Apparently the port job on my head flowed better in that region than most, and this was enough to thow the chip completely off. Jefrem (RIP) then made me a custom chip based on repeated WBO2 printouts I sent him, and repeated corrections (I think it took 4 tries). Then the car ran pretty well.

                      The problem, is that any additional slight changes or mods would pretty much throw everything off. That is the frustration of "chip" tuning, and what eventually led me to go with standalone EMS.

                      I think the basic problem, is that even with similar builds there are always enough variables to make "standard" chips a rough compromise at best. You either have to accept the compromise, or budget more money for WBO2, a custom chip or a new EMS system.

                      That is the ugly reality, IMHO.

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