Hello I recently purhcased a bone stock 2003 Evo with 10k miles. At wide open throttle or 3/4 throttle the car studders violenty from 3500 up to redline. When this happens I do not get a SES light. I have researched the issue and found out there is a common misfire problem. I also saw that there is a ECU flash upgrade that can be done to fix this problem. I was wondering if anybody has successfully cured the problem. I currently own a 96 3000GT VR-4 and a 1995 Eclipse GSX and they both have no problems. I just sold my NSX to purhcase an Evo to save $$$$ on repairs and mods. I hope this Evo doesn't turn out to have the reliability of a Lotus.


After spending all day at the dealer nobody can repair this problem. The dealer re-flash on the ECU did nothing. If anybody can give me any leads or advice I would greatly appreciate this.

Any help would be greatly appreciated.

Thank you in advance,
-Mike

 

Could be the plugs not gapped properly, that would be the easiest explanation.

Could be a terrible boost leak

Could be the service techs raped your car before you bought it and broke something, 10K of abuse.

It could be over boosting, and then missing and detonating. The 1st thing iwoudl do is buy a boost gauge and see what the PSI is, then Get an MBC to control it.

Honestly i would just ask for my money back and get a new 05 GSR, demand sticker or a discount for the trouble.

 

It wouldn't hurt to check the plugs but is almost certainly a boost leak. Build yourself a boost leak tester like this: http://vfaq.com/mods/ICtester.html and pressurize the intake.

 

Like what everyone else said, check the plugs, tighten the clamps up on your intercooler piping, and then check your vacuum lines.

The previous owner could have had a boost controller installed and didn't put it back to stock correctly. Check your vacuum lines coming from your stock boost solenoid under your air box. There should be a restrictor pill between the solenoid and the Y connection. Just squeeze the line with your fingers to check. There should also be another pill in the line between the turbo housing nipple and the Y connection.

 

Also check that the plastic fasteners are in the scoop that goes up to the airbox. It sounds silly, but if the scoop is not attached properly, it lifts as the airbox pulls in air at rpm, causing it to be partially blocked and the car to stumble severely.

Hope you get your problem rectified soon!

 

i have a feeling you need to check your plugs.

i had the same problem. under part throttle above 4k rpm it would be fine but anything over half throttle making boost it would stumble like hell. I later found out that the plugs were gapped too wide causing the spark to blow out.

 

definitly check the plugs, i had an white 03 gsr act like that before and the ceramic on the plug in the block had separated and was covering up the tip, during idle it was fine but throw a lil boost to it and it ran like crap, i would just go ahead and replace the plugs with a one step colder plug from ngk. and invest in a good boost gauge, every turbo car should have one.

 

Thank you all for the help. I am going to try everything and I will let you know how I make out. I really hope it's as simple as bad spark plug gap or over boosting. The lemon law does not apply for me seeing I am not the original owner. I can only sue mitsu for a breach of warrantly resulting in a partial settlement if I were to win. If none of this works I am going to try the cinder block on the gas peddle off a cliff trick.....

Thanks again,
-Mike

 

hey I don't know if you have resolved this problem or not, but I had the exact same thing happen to my evo twice. I had 2 fuel pumps go bad when I was bone stock. The car would accelerate fine unless I got into boost then would start for fuel and make a sputtering type noise and studders like a biatch. I would almost put money on this being the problem. The dealership kept guessing at my problem and ended up costing them more money than if they would have just fixed it right the first time...got new coil back, bov, and fuel pump out of it though..hahaha.

 

that happened to me when i got a lil water on top of cyl 3 when washing the bay .. had the intake covered.. but the magnecor plug wires dont seat as low as the stock ones and got some h2o in there.. just take a towel if its there and dry it out.. check your maf sensor wires .. if you cant find it.. then it aint there..