Hi everyone i have a 2001 mustang gt 5 speed that i recently installed MHS stage 3 heads, MHS 2.5 N/A cams, CAI, throttle body, Plenum, Injecters, and 255 Walboro fuel pump. Also have other basic mods such as coil packs, long tube headers, catless h pipe, and custom catback. The car ran on the stock tune but sputtered at high rpm's and would not idle after the install. I recently took the vehicle to a local tuner to get the car dyno tuned. After the dyno tune the car ran like a champ. I did not drive the car for over 5 weeks and then when i did the car threw a whole list of about 10 dtc codes and was running terrible. I set the car back to stock with my sct tuner and reset the computer on the car. I then loaded the tuners tune back on the car and it ran good again. Now no matter what i do the car is tempermental. The car will run perfectly fine sometimes when i start it and other times the rpm's hang a little high at idle and the car will sputter to about 1800 rpms. It will usually continue to do this throughout the day and sometimes downloading from tuners tune to stock tune and then back to tuners tune will fix the problems but other times not. There might be no way to answer this question because of it could be so many things but have got some great info off this site and thought i would ask. Is it the bigger cams making it sputter until that rpm range and idle different everytime? Is there a possibility it is a bad tune that i should take back to the shop. I have not taken it back because its 80 miles away and very expensive to get work done there. Could it maybe be a fuel pump or injector problem? i just dont see it that way because after it gets passed those rpms it runs great. Thank you for any help in advance
stuttering at low rpm after head/cam/tune install
- Thread starter mikemora01
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Cobra123089
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I have dealt with some of the issues you mentioned, I have MHS 4.5 cams. For the hanging idle here is what i did:
I followed this procedure
http://www.lasotaracing.com/tech idle.html
with the bigger cams the t/b blade needs to be opened a bit more for it to idle with out too much help from the Idle Air Control (IAC)
I also did the IAC restriction mod, I made a new gasket for it and I believe i ended up with a 1/4" hold for my desired results, you will have to play with it.
As far as the stutter goes, I would say the aftermarket coils are hurting you. They have mixed reviews to begin with and I personally have seen how bad they can be right out of the box. New OEM coils are can be expensive, but they are the best IMO.
Here is what i ended up with, FWIW I did all of this after my dyno tune because i was not happy with what i had.
I followed this procedure
http://www.lasotaracing.com/tech idle.html
with the bigger cams the t/b blade needs to be opened a bit more for it to idle with out too much help from the Idle Air Control (IAC)
I also did the IAC restriction mod, I made a new gasket for it and I believe i ended up with a 1/4" hold for my desired results, you will have to play with it.
As far as the stutter goes, I would say the aftermarket coils are hurting you. They have mixed reviews to begin with and I personally have seen how bad they can be right out of the box. New OEM coils are can be expensive, but they are the best IMO.
Here is what i ended up with, FWIW I did all of this after my dyno tune because i was not happy with what i had.
I have been struggling with the hanging rpms for months and drives me absolutely crazy and am not happy with what i have like you mentioned. as soon as i get the chance i will be trying the IAC mod and setting the throttle body blade. I would have never thought it to be coils but have heard other tuners in the area also not liking after market coils so i will definitely put the stock coils back on and would be extremely happy if its that easy. Thanks again for info the car has been on my last nerve.
