Ok well i havent seemed to get any help when this was posted in a strictly turbo thread so maybe i'll get some help in troubleshooting....

So about a week and a half ago i was driving down on the service road of the highway after about a 10 minute drive when my SES light randomly went on and my idle jumped up to anywhere between 1200 and 1500. I disconnected my battery terminal and reset the ecu, the SES light is gone and hasnt come back, but the idle problem has not gone away. If the car is cold and i start it up it idles normally, 1100 or so then down to 700-750, but after a drive of about 5-10 minutes the idle goes back up to 1200-1500 and will not come down. I've checked all Vac lines and there are no leaks, the PCV valve is fine and there is no leaks in the vac line from the IM to the PCV. The care runs normally, boosts fine, and i have no other problems other than this idle issue. Occasionally the idle will reset itself back down to 750 after sitting at idle for a few minutes but if i rev the car a few times the idle will go right back up there, and turning the a/c on or off makes no change. Every so often i will get slight idle surge too (surging between 1200 and 1500 rpms rhthymically) but that only lasts for 3 or 4 cycles then evens out. Any body have any suggestions of what to check? Oh yeah, there is no boost leaks, no leaks in the intake piping, no vac leaks, and my coolant levels are full....

 

bump?

 

head to an autozone and have them pull the last code from the ECU, probly give you a good idea of what's going on.

 

get the codes....MAF or idle speed sensor

 

Yeah perfect timing. The idle has seemed to even out, but the SES light went back on, so i'm gonna get the code pulled thursday or friday...

 

Got the codes pulled today. 2 codes for the warmup cat (which is to be expected since it was replaced when the turbo was put on). 3rd code is P0507 which is "engine RPM is higher than expected for the current Engine Operating conditions" which seems to tell me nothing.

Anyone have any idea?

 

Bump? anyone

 

check/clean your EGR system, change PCV valve, clean MAF, injector cleaner, oil change, and check your spark plugs....we'll go from there.

 

Well the problem still hasn't gone away. I've done the following....


1) Took the PCV valve off and blew it through with cleaner and compressed air. Nothing
2) replaced the vac hose from the PCV to the IM. Nothing
3) Took the maf out of the car, completely clean, no foreign matter or gunk on the inside. Nothing
4) checked and topped off the coolant. Nothing
5) Checked all vacuum lines for leaks. Found none. Nothing
6) sprayed the sh*t out of the throttle plate and the passage for the Idle Air Control Valve with carb cleaner. Nothing
7) SPark plugs are clean and look good. No major whiteness indicating any lean conditions, no major black soot indicating rich condition. Seem to be perfect, look like they are brand new out of the box. Nothing
8) tightened all intercooler hoses and even switched my system around putting the maf on the pressurized side just before the TB and Venting the BOV to atmosphere like a few people here on the board...Nothing
9) Pulled the plugs off of the ICV under the throttle body and the plug off the TPS sensor (i think) on the side of the TB closest to the firewall while the idle was high, did nothing...

I'm out of ideas. Anyone got anything else? How do i check the EGR system? As far as i can tell there is no leaks or tears in the Vac line to the EGR valve....

I'm 1 step shy of bringing it into my guy and just being like "here, you fix now"

 

your EGR valve might be sticking open. it's on the lower driver's side of the intake mani. make sure its not all gunked up.

 

from the outside appearance it looks good. How do i check the inside?? All i see is just a vaccuum line going to it

 

Anyone? How do you check if an EGR valve is working properly

 

you'd probably be getting a code other than what you've been getting if you were having problems with the EGR valve. i don't think the EGR valve is the problem.

you can pull it off and spray it down with some carb cleaner if you'd like--it COULD be clogged up. a new one will run you about $140... so be nice to it.

 

remove the valve and then clean it out. I believe it's a one way vavle so you should be able to blow into it and have the air come out only one side. I doubt this is it because there's a specific code for FUBAR'd EGR. Ask me how I know

How's your throttle return spring? give the throttle a few manual openings with the car off and see if it sticks at all.
Maybe you're getting some vacuum into the cruise control solenoid and it's holding the throttle open when the engine bay gets hot.

My code reader says P0507 is "idle control system RPM higher than expected for condition"
did you mess with the idle control screw early on in your tuning?

Can you reproduce the effect if the car just sits for 20 minutes or so? (OR- is this only happening while driving? Could it be a heat related issue?)

don't take the car to a mechanic because you probably won't be able to reprodce the effect while they're with you

 

Well i pulled the vac line off the EGR and it did nothing so its def not the EGR valve.

This seems to happen once the car is warmed up and post driven. If i let the car sit for 20 minutes and idle fully warmed it will not do it, it isnt until i take the car for a drive and then come to a stop, and even then sometimes it wont immediately go to high idle. For instance before, i got off the train, warmed the car up in the parking lot, drove the car home which is about a 3 or 4 mile trip on back roads, during which time i had boosted the car a few times. Pulled into the driveway and the idle was normal, it wasnt until i revved the car a few times that the idle came up. I've noticed that if the idle is high, sometimes if i rev the car up to say 4k, then let it come down, the idle will go back down and either A) sit there for a minute and then go up, or B) sit there and not come up.

THe only other issue i'm having besides this is since i've relocated the MAF to the pressurized side i'm having a little narrowband lean condition on 10-25 percent throttle once the turbo starts spooling and blowing air. The narrowband reads full lean, my plugs dont look like they've been run very lean, and theres a slight loss in power when the narrowband dips to lean, almost like the timing being pulled for a split second, but the minute i push the pedal down a little further and throw the car into open loop it goes to full rich and the power comes back. I know many other people have the maf on the pressurized side with no problems. SO that stumped me. I have a wideband on the way so we'll see what the actual numbers are. ALso i have an adjustable BOV on the way to tighten it down a little more at idle and partial throttle since the evo stock BOV doesnt seat fully until around 30 or 40 percent throttle.

But back to the idle issue. I think my next step might be pulling off the Idle control valve and seeing if its gunked up. Then resetting the ecu again once i have the tightened BOV in. Correct me if i'm wrong. THe TPS sensor is on the back side of the Throttle body and the ICV is on the bottom....?

Any other advice is greatly appreciated. I know with honda guys the issue is usually the Fast idle control or the Idle control valve. WIth DSM guys its the idle set screw leaking air. I know its not my set screw because this started happening before i tried adjusting it to compensate (to which point i put it right back where it was after i adjusted it) and putting my finger over the screw to cover any air leaking out doesnt make a difference...

Any other suggestions with this high idle?