Weird rough idle

[BUSTIVA]

I'm having a weird idle problem everytime I pull up to a stop. When I sit at the light the car idles fine for a few seconds, then the rpms drop and the car sounds like it has a vaccum leak. If i barely give it throttle it keeps the roughness, but if I rev it up it seems a bit laggy but clears out and idles fine, then repeats itself all over again...any ideas?

Video of idle problem

http://www.youtube.com/watch?v=wzE1tCJTZVM&list=UU6fJNMc7owmW_FroFLtF4jw&index=1&feature=plcp

[jjk1224]

Are you monitoring your A/F ratio? Sounds like it might be running too rich/lean. Take a good whiff of the exhaust while the idle is erratic. My explorer does this when its cold because it does not properly go in and out of closed loop, you can noticeably smell the unburnt fuel at stoplights early in the morning.

[BUSTIVA]

No monitering at the moment. I hasn't always done this with the turbo setup, and all vaccum hoses are properly placed, IAC is tapped pre-turbo, only thing not connected is the crankcase vent that used to go back into the intake.

[BUSTIVA]

My super precise technically advanced A/F meter (aka my nose) is reading rich during the rough idle.

[Movin]

check compression..check EGR...check boot - hose from Throttle body to air flow meter..do not use cheap plugs..

[BUSTIVA]

I thought the EFI models didn't have an EGR valve, do you mean PCV? No air leaks from afm to tb. Car has brand new NGK V Power plugs. Guess a compression test wouldn't hurt...No excessive crankcase pressure, and no oil consumption or burning/smoking. Car runs great until I stop and let it idle for more than 20 seconds. Then the rough idle begins...

[Movin]

Did you turbo a B3 ?

[BUSTIVA]

Yes sir...

[Movin]

Nice... And you are right, no EGR on the B3, Gotta love that simplicity!

Turbos on a B3 can be a little rough on the fuel pressure regulators if yours
is stock or like stock, if so unplug the vacuum line and check for fuel seeping
through into the intake.

[BUSTIVA]

I have checked absolutely every possible senerio (AFM, IAC, PCV, Compression, O2 sensor, MAP sensor, Vacuum Leaks, Idle Screws) except for a bad FPR...gonna check that in just a little bit.

[jjk1224]

After you look at your FPR, check your coolant temp sensor for resistance. Im not sure if coolant temp is monitored by the ecu or not on our cars. If it is and if the sensor is out of spec it could easily force your system to stay in open loop. If your ecu thinks the engine is cold, it will dump extra fuel to compensate for the temperature.

[FestYboy]

not to doubt, but HOW did you test your o2 specifficaly?

[gauge_half_inch]

Just a thought what bov are you using? Is it vented or recerculated?

[FestYboy]

bahh i forgot its a B3+t

[gauge_half_inch]

When I set mine up I used a stock DSM, after a short time it kept surging at low hot idle. It wasn't sealing well enough with low vaccum. Try putting your hand over the opening if its vented.