big technicial problems with vr4

[fiendish_boy]

i own a 99 ec5 2.5L twin turbo galant vr4. i upgraded the intercooler, got the battery put in the boot and built a cold air box where the battery used to sit. after this the car starting coughing farting and missing as soon as it has warmed up when its cold it boosts purfect. i was told that getting the exaust with a wastegate would fix this.... so i did that as well but it still does it. i've replaced the idle stepper, engine temp sensor and tried new coil packs. nothing has worked!!!! could the factory ecu need upgrading or even remapping? any suggests would be great

[bradc]

I would suggest the cold air box is messing up the signal to the maf and that you won't be able to fix it unless you go with the original intake setup.

Have you taken it to mitsi motors? They have diagnostic machines that will tell you what the actual errors are in the ECU.

[KiwiTT]

If you can bring the car to our meet. Some of our guys and gals can offer you some other suggestions too!

[EDD]

Definately your air box. I bought a 5 series BM while my VR-4 is in the garage getting fixed again! The Bm has had a K+N fitted by the lad who had it before me and that causes it to cough and splutter. This only happens at low revs though. Mainly under harder acceleration from stand still. Standard air box is the way forward with a K+N panel filter maybe. I fitted a super chip which seemed to prevent most of the spluttering but it isn't perfect.

[valmes]

Term "coughing" could describe too many situations...

My car was "coughing" up top and just didn't pull right... came out - EMU wasn't receiving RPM signal for some reason, so no corrections were made since EMU was always on a 0 RPM cell. As soon as I solved the problem - coughing went away and car is happily re-gained about 50HP and is pulling strong up to the rev limiter. /Nuuu

Bad plugs (or wrong ones), fuel cut related, too much fuel (flooding), too much air(knock), bad coil, dying fuel pump, faulty fuel pressure regulator, bad sensor somewhere that is causing the engine to go into safe mode and stay on a rich side, faulty MAF... those are few simple ones.

MutII is your friend at this stage, unless you are absolutely sure what's causing the problem.