CidE

iTrader: (1)

So this has been going on for a while, and no one seems to be able to track down the issue so I'm turning to the rest of the Evo community to see if anyone else has experienced something like this.

Basically the car (03 Evo VIII) under load at around 10-11 PSI starts getting what I can only describe as fuel cut. It starts mis-firing, stuttering, and sounding like it wants to explode. Car is stock, no codes being thrown. I've replaced coils, map sensor, fuel pump, plugs, and thats about it.

Anyone have any idea what this might be? I'll try to answer any questions I can to help come up with some ideas here it's pretty much driven me to the point where I would just rather light the car on fire.

MOREPSiTEHBETT4

AL from dynoflash had a video where he had a crapload of problems, he replaced almost everything electrical on a vehicle until at last he replaced the frigging battery; and the problem in fueling was fixed(he replaced coilpacks, spark plugs, etc. to no avail)

CidE

iTrader: (1)

Unfortunately the battery has been replaced with no results, I wish it was that easy. Anyone else have some ideas?

Falcon350z

iTrader: (6)

Oil on your spark plugs will absolutely do this. When I had my head built, some oil leaked down into the cylinders and coated up the new plugs. It would drive fine without boost, but as soon as I hit 5-10 psi, it would start bucking and misfiring. I replaced the plugs, and it ran great across the board.

If this doesn't work, you might also want to check your head. The reason I had my head built was because it somehow lost a rocker arm for one of the exhaust valves, and it would misfire (but this was more load related than boost related). I'd say this is a pretty unlikely possibility... but maybe look there last?

Definitely try replacing your plugs. Make sure your wires and coils are good also.

I'll note that if you DO find oil on your plugs, and you don't know where it came from, you might want to check into it.

Good luck.

heavens turbo

is that snorkel thing attached and locked down? the one before the stock airbox? without any codes, it's most likely mechanical. check your turbo by removing the intake plumbing and see if the shaft moves. chek to make sure all intercooler plumbing is attached and good. you gave a pretty good description, but without some more info, you gotta start with the basics. good luck. if you had a scantool, you could check the ect., and voltage and sensor parameters. you may have to bite the bullet and take it to a shop.

04WWRS

iTrader: (18)

when's the last time you cleaned the maf?

CidE

iTrader: (1)

Air box is attached properly, and I've checked the turbo to make sure it's spinning freely. I don't have any reason to suspect intercooler pluming as I've never messed with it but I suppose I can look at it for ****s and giggles. The maf has been cleaned.

OneEyedJack

iTrader: (6)

I've had more than one car do this with a bad MAF

Ryan.Kauz

iTrader: (11)

are you then able to go over 10-11psi after the stutter issue?

If not then WGA or boost controller hoses are loose/cracked?

smokedmustang

iTrader: (7)

Did you do the boost leak check, and make sure all hoses are connected, even the ones on the throttle body by the firewall? I mean the actuall boost leak test??

Grounds all good?

Are the holes in your valve cover stripped (Where the coils attach??)

Did you have this car from new?? If not, it maybe stock now, but was it when you bought it?

I had a stock hose fray and cause a hole, right where it bends around the battery. is that good?

Any other problems but this one?? How many miles has it been doing this. Is it staying the same? Or getting worse? Is it weather dependent? ie worse when it rains, gets cold, etc???

Find a friend with an evo with no problems, and swap MAF's, and see if that fixes the problem.

Is your airbox snorkel secured properly?? ie is the plastic "Screw" in place on the front of the intake snorkel, and properly secured to the radiator support?? If not, at about that psi, you are sucking that part of the snorkel up, and its cutting off the air getting in the box, causing the MAF to say WTF?!?!? lol

Fast_Freddie

iTrader: (50)

Do a boost leak test and report back...

CidE

iTrader: (1)

Wouldn't it throw a code for a bad maf or not necessarily?

I've checked the hoses and I didn't see anything obviously wrong with them.

I can't say I've done an "Actual boost leak check" as I'm not sure what that entails. Holes on the coils are good. I've owned the car since new. I had a after market intake and downpipe on it at one point. I've since reverted back to the stock ones. It's done it with both aftermarket and factory intakes so i don't think it's a issue of air getting cut off. I haven't done a close inspection of the intercooler hoses for holes or fraying. This gives me some things to look at though. I don't have any super close friends with evos for swapping out parts, but I do have some friends of friends who might let me.

CidE

iTrader: (1)

Ok I looked up how to build a leak tester, I'll do it this weekend and see what I find.

smokedmustang

iTrader: (7)

I would say, once you do the boostleak check, you will find your problem! Visual boost leak checks cost me more money they I want to mention. More here:

https://www.evolutionm.net/forums/ev...s-go-read.html

Your MAF is saying WTF because the air volume in the box doesn't match what should be in there at "xyz" boost.

Another remote possibility: If you put the new Intake and downpipe on, it had a different "Air volume" in the system, so you should have re-set the ECU so it could auto learn the new parts/volume. Disconnect battery, start the car (DON'T touch gas pedal) and let it idle for 10 minutes. presto, auto-learned. lol. You needed to do the same thing when you put the stock pipes back on.

Sometimes when you put aftermarket intake on the car, they are coated in oil from the factory, and that oil can mess up the tungsten wire in the MAF if some were to get in there. if you cleaned it with MAF ONLY cleaner, you ok. I wouldn't use brake cleaner on that wire either.

I say, you suffered from what I did, and you have a leak that will stick out like a sore thumb when you do it the right way....GOD I wish I had!!

EvolutionTime

iTrader: (1)

Same thing happened to me while getting tuned!!! Sounded super scary and like it was gonna explode!!! Turned out to be the honeycomb inside the MAF had dislodged itself. Took about an hour to figure that out too!!! Symptoms were exactly the same as yours. Check and let us know. Good luck