So i'm having some issues with my evo 8, I tried searching and did not come up with much. car is mostly stock with exception of a borla manifold, turbo back exhaust, intake, wally 255, and perrin fuel rail. yesterday this issue started when I did a short pull, at around 4500 rpm, and it wanted to stall. From there it was running very rough, basically couldn't keep it running. I pulled to the side of the road and realized the uicp and silicone tubing had totally disconnected from eachother. So I fixed it, went home, and double triple checked every single connection. So today driving to work I started experiencing another issue. The idle is smooth, however it fluctuates, from 1300 all the way to 2300ish rpm. I gave it a little gas on the way home from work and between 4500 5000 rpm the car just cut out. Not like a misfire, more like the uicp came disconnected. So I get home, checked all connections on intake piping, everything was secured. I have no cels and am having quite the time trying to diagnose this problem. Any input would be appreciated

 

I would start with a boost leak test. After that I'd head toward the spark plugs. This may not be your fix, but this is generally where people start.

 

Never ran into something like this, don't have a clue. But first thing that comes to mind is resetting the ecu, if you havn't tried that yet.




Another thought, is that your idle air control valve got clogged up while the intake piping was off/loose and while unfiltered crap flew into your intake manifold(might of been loose for a long time before flying off?), (I'm assuming that's where it disconnected since you said upper hose).
You can just clean it off with intake cleaner spray.




Other than those 2 things I'm really not sure what else to check. Goodluck.

 

thanks guys, performed a boost leak test about 2 months ago. I tracked down a few and got them fixed. I was hoping to do it again soon since im getting a tune in two weeks, ill try the intake cleaner spray, this problem is driving me nuts.

 

just to update the thread, the problem was resolved. I checked the idle air control valve and it looked fine, but tried the intake cleaner regardless. Than I reset the ecu and the problem did go away. thanks to all who responded, will update thread if problem returns. Thanks

 

glad you found the problem!

 

Have you replaced or upgraded the IAC? If it's still the stock one, it will fail eventually.

 

I have not, I just bought the car 6 months ago and I highly doubt the previous owner did either. I plan on doing it when I do a throttle body soon

 

Updating this thread...unfortunately. Hoping to solve this problem soon, as well as help anyone else who may be experiencing it. This morning when getting on to the free way. Something strange happened. At about 4500 rpm in 4th, the car seemed to lose all power, hit a brick wall. No sputtering, no cutting out, boost didn't drop a bit, the car just bogged as if the ebrake was engaged. I've been searching all day from issues like fuel cut (convinced this is not the issue) to spark plugs, fuel relay issues, fuel pump issues (supposedly is new) andeverything in between. I plan on doing a compression test this weekend, along with a boost leak test and also will be finishing up installing the wideband. So at some point I will be checking spark plugs. I really wish the car would throw a code so I could get some type definitive direction here. I've double triple checked all comections and looked for anything obvious, not a bit of smoking, just this annoying issue and a slightly rough idle sometimes. I will update as I continue to track this issue down. In the mean time, feel free to chime in and a big thanks to those who already have!

 

Can also try checking your fuel regulator

 

I will look into that, one thing I did fail to mention is the car runs rough on start up. if its been sitting for at least 12 hours, it will die right away. If I start it back up it will run rough for about 10 seconds and than be completely fine, I feel as though these two issues could be related

 

Try checking all your electrical grounding points around the engine/transmission/chassis, maybe even add a wire or two if they look old. Might be as simple as a loose connection.

 

i actually installed the wideband this weekend, i didn't get a chance to poke around under the hood, i only had about half of sunday. I will get into it more when it stops raining.
I do have an update though. As mentioned i installed my wideband. afrs are eratic, idling between 15:1 and 16. under a good amount of load its rich at 10. After letting off the throttle, it goes very lean, it goes to between 16 and 17:1, or sometimes past the point the uego can read (two lines, no numbers), but returns to normal after a couple of seconds. i have a forge recirculated diverter valve, not dumping atmospheric. i also did some datalogging on Saturday, i did notice that under load past 3.5 k rpms or so there is some counts of knock (under 10 i believe). None at idle, none during normal driving. the car is getting tuned on Saturday, i would really like to get these issues resolved before than. another not so pleasant update, the car did receive some good hail damage today while parked at work.....guess its time for a new paint job to:/ t

 

also checked the regulator, nothing seemed out of the ordinary, vacuumed hose was fine, everything looked good

 

one more note to add, the bogging problem was not happening when i was datalogging, the problem seems to be intermittent, its been back at it since yesterday though