Misfire when NOT on boost

[REDEVO951]

Ok past few day my 03 viii will stall out at lights. I fixed that by noticing the vacuum line on the DV was cut open so I fixed that now she runs real rough until I'm boosting and she will hit full boost about 28 and runs fine from what I can feel. When I'm cruising and its about to go in to boost from vacuum it will misfire. The check engine light is on and later this afternoon I will check the code on it. I will also do a boost leak test. Where else should I check? Thanks a lot guys!

My mods are 272 cams
evo 9 turbo
1300 injectors
tuning tech intercooler piping
mini battery
and running E85
and more.

[Alfred@TTech]

The Original 2003 and 2004 Evo's are notorious for having a random multiple misfire problem. What you describe is exactly how most other people experience this too. Typically it is caused by severe wear on the transmissions undersized input shaft. This was remedied by a redesigned larger input shaft in 2005. There are some tricks that can be done to make the ecu less sensitive to these vibrations but it just depends on how bad it really is.

Please send me a pm and we will look into this for you....see if it cant be solved. You will also want to do a thorough check under the hood to be sure all hoses and connections are solid. I look forward to hearing from you


Alfred

[tschad]

i would check your spark plug gaps and/or buy new spark plugs. i've seen a lot of motors including mine that popped due to misfires. A 60 dollar cost could save you a 6000 dollar cost.

[Supra2JZGTE]

Tricky since the issue doesn't occur when in vacuum. If it happened when boosting, I would agree to check the plugs for fouling and gap.

[Mike W]

Check your EGR hoses too. Every EVO 8/9 should have them zip tied by now.

Mike W

[REDEVO951]

turns out it was a combo of a cut DV vacuum line and my number one fuel injector electronic connector came off. the evo is not a DD so that's why i have not worked on it since that day. thanks for the help guys. i hate when you search a problem and they never say what was the cause and fix for the problem.they just leave you hanging.

[Black Evo Beauty]

Thanks for updating :)