hey.. last nite something weird starting happening that continued today.

if i punch it or accelerate fast like on the highway.. about 3-4k it hestitates for a sec and then kicks in,,, seems to be when the turbo kicks in.,

well coincidently yesterday the temp has dropped drastically around here.. so i figured it was something with the cold...

it was doing it again today- and mind you it doesnt do it EVERY time, but alot.. and it was still very cold today... but its starting to bother me

im almost afraid its the clutch slipping???

could it be the start of the clutch slipping? but why does it only do it at 3-4 k - i can punch it at 1-2k and it dont feel like a slip at all, again, at around 3500-4000......

any ideas anyone??

thanks!

 

I think it would help if you listed your mods or told us if you are stock. If you have a boost controller, what boost levels are you running? It doesn't sound like fuel cut because that is much more apparant than a "hesitation", but I figured I'd ask your boost levels anyway since you mentioned the cold weather.

 

hey someone who cares! great!

ok here's what i got:

HKS SS BOV

HKS Racing Suction Kit

Autometer boost, airfuel, EGT gauges

thats it for mods folks.....

yea i really dont think its fuel cut....

 

hmmmm, could it be the stalling everyone talks about with the aftermarket VTA blow off valves??

 

Actually my car does the same.. Started doing it when the weather got colder. I was convinced it was fuel cut at first, but the stumbling feels like a misfire. It could be the car pulling timing, but to me it doesnt feel like it. Personally I'm convinced its something to do with ignition (plugs or coils) but so far I haven't isolated anything. Since you have the suction kit (open filter) It could be that its confusing the MAF sensor

When I hit fuel cut, it seems to hit HARD, but when this happens, it feels more like a stumble.. I can't say for sure its NOT fuel cut though.

I know exactly what he's talking about, Interestingly enough, it could be a lean condition because It seems to lean out at that range when you hit full boost on nearly full throttle at that RPM range.. The data logger I have isn't fast enough to capture any timing changes at that range when it happens though.

I know this doesn't answer your question entirely, but I am just elaborating on it.

 

Hmmm,

I've noticed similar stuff around tq peak. I tried to add a little more fuel with the SAFC (+2 or +3) and it seemed better/eliminated. If I tried to add more fuel at too high an rpm (closer to 5K), I would hit fuel cut easier it seemed.

It's been a ***** trying to tune the SAFCII, since it seems like it needs diff levels, or at least diff boost levels with the colder weather to avoid fuel cut or too much detonation.

Maybe I'll drive my car tonight and investigate. I also want to try my new Denso iridium plugs to see if it helps at all. I'm driving my wife's wrx since she's on vaca this week. Also, my all season tires/wheels should arrive today. Finally, I got a speeding/altered exhaust ticket Monday night, so I've been a little hesitant to drive it anymore...

Take care,

FB

 

I have the HKS RS intake and it's been DAMN cold around here, and I haven't had any of these issues.

If I'm on an on-ramp in say 4th @ 3000rpm, and go WOT, the rpms just start to slowly climb, then as I reach peak boost/torque she takes off like a rocket.

Mind you it's also been very very dry around here with the extreme cold (< 30F) and I run 93 octane all the time.

berkel, it absolutely does need to be changed according to the weather. Relative humidity, ambient temps, whether you're moving or not, pressure, these are all factors that affect how much air your engine is going to pump. It is not uncommon for these cars to hit fuel cuts when it gets very cold outside, as you are swallowing so much more air than if it were 85 and raining out.

 

well let me first say these posts are encouraging.. i was almost in despair that my clutch is going lol.. but maybe thats not the case after all...

as far as the unstable idle, yes i do suffer from that. but thats only at idle.. its never been a problem elsewhere.

a friend of mine took my car out and he was like.. dude you clutch is grabbing high, its not slipping yet, but you are gonna need a new clutch soon enough.(which is what put the clutch idea into my head) but funny enough the nite after that is when this started happening.. again the temp has drastically dropped in this timeframe.. so i have no idea what to attribute it to....

maybe this might help a little too: ill punch it say in 3rd gear on highway around 2800-3000. and as it hits right about 3500 it hestitates for a second, actually drops down to maybe 3000 then kicks back up and continues on.. but seemingly climbing more slowly than it used to accelerate.. does this sound like a fuel thing or clutch slip?? im at 15k now and ive done 6 runs at the track plus a few street clutch dumps.. so far no apparent damage.....

 

Sounds like you need new spark plugs.

 

new spark plugs? on a 8 month old evo?

 

It sounds like a misfire to me. First thing I do when I feel a misfire is change my plugs.

 

The HKS sucton kit cuases the car to run very lean in the mid range

Try getting a dyno shop to do a dyno pull logging your a/f ratios

I have a through the mail reflash for the hks suction kit which will really help the a/f tune

 

I just got back my through the mail tune from Al. I also have the hks rs kit. There is a ton more torque with this and the power finally feels linear from about 2700-3000 up. I also have a 3" turbo back with no cat and an MBC

 

They are probably not worn out, but they could be fouled. Especially if your running a VTA BOV, which is known to cause overly rich conditions during throttle lifts. In the cooler weather and with the stock boost control, your boost is probably spiking at it's highest point between 3-4K. Since this is most likely your highest boost point with the leanest fuel mixture, it would be the most difficult point for your plugs to fire. If your plugs are starting to foul this could be the most likely point for a miss-fire.
I have to agree with ShapeGSX, based on your description this is the first thing I would check. Pull your plugs and take a look, it's not that hard to do. Since it doesn't sound like it's missing too badly, they may not be horribly fouled, so be sure to inspect them carefully. Or just replace them and see if it makes a difference, you will need new plugs eventually, so even if it turns out to be somthing else the plugs won't go to waste.

 

I had a hesitation problem of my own. Come to find out, I was getting bad gas (didn't get a clean burn) and it trashed my spark plugs, not once but TWICE. I only had about 7,000 miles when the stock ones went out, 1000 miles later the new ones went out too. My experience is (if it's your plugs?) your hesitation will keep getting worse until the point where you can't punch it at all.

Now, I'm no electronic Wizard like some of these guys, but I would suggest starting by replacing the plugs first because it is very inexpensive (about 7 bucks) and it's a breeze to replace them. You can use either NGK BPR7ES/BPR8ES as a quick fill in. I eventually got the HKS plugs. Runs like a champ!

Good luck!