Okay, I've searched this site as much as anyone can, without knowing specifically what my problem is related to. I've just typed in certain key words that I thought would be helpful, but with no luck. I'm taking my car into the dealer as soon as I can, but I'd just like to throw out a general question to everyone, to see if they have experienced this. Here goes:

About two weeks ago the weather got really cold, this is my second winter with the Evo, so I know it drives differently, but never like this. At first it would just jump rpms a little and rev differently. This would only happen in 5th gear at about 80 mph, on interstate of course. No big problem. Then the check engine light came on. Was not able to go to dealer right away, so I unhooked the battery to see if the light would reset itself in the cold weather. When I turned it back on, everything was fine, then the light came back on about 100 miles down the interstate. Decided to leave it alone this time, until the dealer could check it out. But this time, the light turned itself off and by the time the dealer checked it, the ecu had no record of the check engine light, only like two days after it was on. My good luck that the dealer didn't charge me for reading the ecu. Since then, my car has been acting completely different. When it's cold, it barely wants to go, and then when the turbo spools, everything seems sounds fine, except that the extra power isn't being delivered. I have to shift up quickly and keep it under boost, or it will just rev up, with the rpms increasing and the car barely crawling. Once I'm in a gear, or going good, it's fine. But I can't speed up without the turbo spooling and the car just creeping along. Once enough boost has built up, it does seem to go to the engine and the car will take off, the bypass valve even sounds a little. So I know some air is getting through. (I've checked all air hoses, intake/intercooler, that I could get to) I'm at a loss as to what it could be, but it feels like my car is half the car it used to be. I'm eventually taking it to the dealer this week and leaving it, but it's been hard since it's my only car. They don't seem like they have heard anything like it when I describe it, so I'm asking anyone here if they have. Anything will help. My only mods are HKS Suction Intake and HKS Hi power exhaust. No flashes or anything else. I just want my much loved Evo back.

Thanks in advance,
Grant First post, sorry if it's long.

 

Put your stock intake on and see if it goes away.

 

You might need a flash for the intake. Do you let your car warm up before driving?

 

I've had the intake on there for over a year and it was on last winter, didn't have any problems. Thanks though guys.

 

Check your plugs first. Your clutch could also be gone.

 

check ur plugs see if they are fouled up. also check to make sure ur IC hoses are tight.

thirdly since it got cold i started havein clutch issues my self and im lookn into gettn an act street disk

does it seem like ur rpms kick up higher and ur car just doesnt go faster?

or do ur rpm and mph stay in line while the car just doesnt pull like it use to?

if it doesnt pull like it use to check into the IC pipes and pluggs.

 

Like, 2000 rpms until turbo kicks in, it's fine. Then if I push the pedal, rpms go up by about 1000, but the car just kind of stays the same speed. Rpms keep climbing until enough pressure builds up and then the speed finally shoots up.

 

Try a different gas station.

This re-formulated winter gas crap is probably the cause.

The dealer should've checked for Pending or History codes. It should still be recorded in the Ecu's memory.

Good luck !

 

This seems very similar to a problem that I had. I fixed mine by putting the stock intake back in. It is definitely worth a try. My guess is that since your intake (I had a typhoon for over a year and through one winter it was fine) still uses the stock MAF, with the now really cold and more dense air, the MAF is giving a weird signal to the engine and it is not matching the A/F ratio correctly--note this can cause the SES/CEL to goone because of the weird reading the o2 sensor gets. I had weird power delivery problems as well. Sounded great, and I could hear the DV discharging air back into the intake, but the power delivery was weird. I did not have my exhaust on during the first winter, but I had my K&N and forge recirculating. I did notice that I had way higher MPG with the K&N then I do now, so I'm guessing that it was running lean then. Then with the exhaust on, fine for months, but when the cold came I had weird stalling issues, generally in traffic with slipping the clutch and such, it would stall. That was more my concern. But lots of what you said sounds VERY familiar. Sorry if this is long, PM me if you have any other questions.

 

An old topic here again...


Yesterday I also drove on the Highway, it was about 0°C, I had to drive behind lorries for quite a while. When they finally went to the right, I floored it in 4th to redline and then a bit in 5th. I felt a bit of an unsmooth power-delivery and then the engines check light went on.
As I also was in a hurry, I just disconnected the battery and the light disapeard. I thought, if it is a substantial mistake, it will come again. After some 300km of driving "normaly" and coming back to the area where I live, I tested out the car many times. It behaved just normal.

My idea is that driving slowly for a long time at higher revs makes the car run rich. When I floor it for the first time then, the exaust gases are probably very rich, which might overflow the cat and therefor generates the "mistake", which is actually none.

I will have an eye on this.

The solution would surly be a generated second lambdasond (like for example the ECUplus does it). This would avoid the problem.