ok heres my problem,
i just moved down to north carolina from philly, and before i moved i changed out the plugs with bpr7 ngk's. for the week before i moved the car ran fine. i drove the car down here to nc, (which was 500miles) and about 350miles into my trip the car started to sputter under boost (above 15lbs). so i decided to take it easy and get it home. next day i changed the fuel pump with the walbro 255hp i had sitting here for it, and checked the plugs, they looked fine i checked the gap and it was at .025 where i put it. now it the problem seems to be getting worse.

current problem: when i first start the car it runs fine for about 5 minutes. it seems like once it gets hot it runs like ****. every gear it goes lean on my narrow band at 12-13 psi and its starts sputtering and feels like fuel cut. then there are certain times that it wont feel as bad but the car wont go anywhere (it feels like it has a big boost leak) i already did a boost leak test on the car and it was fine. the car has all the same mods before i left philly and all the symptoms occured during and after my drive down here.

my mods are as follow.
injen intake with upper intercooler pipe
10.5 hotside
helix o2 housing
tbe no cat
walbro fuel pump
mbc set at 20 psi
act 2900

the car has not been flashed yet, and i already did a compression test and leakdown and everything is fine. im at a loss i know i need to flash it but i have cams and a different fmic for it but i dont want to put them on until this problem is fixxed.

thanks in advance
devin

 

ttt

 

Well, first of all, it's very unwise to be running all those mods with no tune, especially the intake.

Secondly, what exact plugs do you have? NGK BPR7ES, BR7ES, or something else? Have you tried putting in a fresh set just to check instead of relying on your ability to diagnose their condition by eye?

Thirdly, have you done a pressure test to check for boost leaks? A large boost leak would wreak havoc on performance, but I would still expect the sputtering to be related to ignition.

 

yes i did a boost leak test and everything was fine. i also put in a new set of bpr7es and i still have the problem once the car has been running at operating temp for about 5-10 minutes.

 

Take the intake off if you can

 

check a couple of things.... first off, don't trust a narrow band a/f gauge. i would inspect all of your clamps holding on the UICP, as well as the intake and the LICP. the clamps can hold tight under static pressure but if the engine shifts, it might reveal a hose not on all the way, or a clamp improperly tightened down.

next, when was the last time you filled up with gas? i suspect on a 500 mile trip you may have filled up somewhere along the trip, and if you have already done a thourough boost leak check, that would leave the fuel system suspect. sure you didn't fill up with E85, or 87oct? E85 will leave you running really really lean and the 87 will cause knock on boost, the ECU will try to correct as much as possible.

 

It's good that you've done both of those steps, because they are the 2 most obvious troubleshooting steps, imo - good on you. I do have to make sure, though, that when you say you did a pressure test, you actually pressurized the entire system with up to 25psi and found 0 leaks. That's what you're saying? Things get lost in translation on the Net, so I want to be sure.

If the other set of plugs behaves the same way, then I'd try to find another local Evo who will let you install their stock plug wires just to see if yours have gone bad...

 

i already checked all the hose clamps and everything is really tight (the uicp has t-bolts on it. as for gas the last time i put gas in the car was right outside of nc in virginia at this sunoco that looked like a hell hole, but i did put 92 in it. i still have a 1/2 tank so ill try to get rid of it (is there a drain on the gas tank like on a talon). and fill up with some new gas and see if the problem is gone.

at first i just thought it was my forge rs bov but i took it off and put on the stock one and im still having the problem.

thanks devin

 

yeah i actually pressurized it at the intake pipe and it held 28psi the only spot it bled off is through the throttle body a little bit (i think the pressure was opening it up).

 

were you having the problem before you filled up? if so i wouldn't worry about draining the tank. if you did start having the problem after you filled up, then the gas is definately suspect.

 

Sounds like you have an incredibly tight system if you had no leaks up to 28psi. Try the coil packs and plug wires next if you can get ahold of a local Evo owner...

I can't think of much else that would cause all the sputtering - you've hit most of the bases that I would have suggested.

 

I had that same problem when I was experimenting with spark plugs.

My stocker were getting worn out so I tried BPR8, BPR7, BR7's.
BPR7/8's were fine but as soon as I put the BR7's.
It started missfiring at 14psi. Swapped it back to BPR7's and it was back to normal.

I was thinking maybe a cracked porcelain in the plugs but could not find any. Maybe I just had a bad set or my car just ran better with the BPR.

I'd get another set or just try other plugs.
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