R32 surging at start up...need some opinions!

[sniffy]

im sorry for this being soo long for what i hope is a simple problem with a simple solution, but i feel it will help to know the details that i know!

i have a mate who has a 4dr r32...it has only just been purchased a few weeks ago so we dont know the recent history. what i do know is that it was an auto and is now manual and apart from that it apears to be "stock". since the purchase it has had a 3" exhaust fitted, BOV, and air filter put on. when putting the air filter on we noticed the intake pipe to the turbo was loose(because we knocked it off!) after fastening it back on, it went for a drive...the next day when started, it surged on idle reving 2000rpm down to 1000rpm (roughly i didnt check exactly) and it will do that till you go for a drive then it will just idle high...around 2000rpm. although it never did idle lower than 1000rpm before hand - maybe this is an auto to manual conversion problem with the ecu? maybe the ecu needs to be "fixed" to suit a manual gear box?

i first thought to reset the ecu...i used to do this on my old r33 by disconecting the battery, hold my foot on the brake for 10 seconds then conecting it again. so we did that...nothing happened and it still runs the same...is this how u reset an ecu on a r32?

im thinking it has to be intake related as that is all we "tampered" with, or ecu...maybe a sensor problem...i havnt done a diagnostic test yet - 2 reasons...1. i havnt looked that up yet on how to do it, from what i remember reading is its a lot more complicated than the r33, and 2. i have no idea where the ecu is...but i havnt looked for that either!

anyway, enough of my dribble...if you can help, or have an idea on what might be causing it to surge, please comment...(and dont tell me the AFM is stuffed!)

[MegaGTS4]

The things that contol idle is AFM, timing, AAC valve and ECU, The AAC valve might need cleaning:

Its located at the back of the plenum chamber (inlet manifold) there is a maroon electrical plug (brittle) and a hose which need to be removed first then there is four ten millimeter bolts that also need to be removed before the whole assembly can be (careful if you want to use the orignal gasket again) removed from the car.

then there is two screws that hold the solenoid on, once this is removed the remaining assembly can be cleaned by useing carby cleaner (I used kero and a compressor to dry and clear any blockages) also make sure that the spring moves(smooth) and the valve works.

Reassemble in reverse order with a bit of sensor safe silicon with the original gasket(or you could make another one it depends on weather the gasket comes off in one piece)

Spark plugs, have them gaped to 0.8mm this helps (platinum/iridium plugs also are a good choice for turbocharged engines)

If that doesn't work then the AFM might need cleaning or replacing, timing might need adjusting, The ECU is located in the passenger side wheel kick panel, There is a screw on the ECU that affects idle it is to be adjusted in conjunction with the screw on the AAC valve,Sounds like the AAC valve needs a clean as this basically controls the idle, although in the workshop manual it states that the idle speed, ignition timing,CO and HC density (airflow-meter) are inter-related. Any adjustment to one effects the others and requires an additional inspection.

To adjust idle speed From a workshop manual:

The screw that is located on the AAC valve is to control idle speed, But first you need to remove the ECCS control unit(computer) from the passenger side kick panel and there is a screw there that controls idle aswell, now if you can read japanese the writing near the screw says "CAUTION Adjust within indicated range. Do not turn with excessive force" Low idle is at the bottom with high idle at the top and just a little bit past the high idle mark there is self diagnosis. This screw needs to be turned to the low idle mark and the engine warmed then remove the electrical plug from the AAC valve and start engine, Idle should be at 900 rpm, if not turn screw on AAC valve assembly to adjust engine speed to 900 rpm.

Turn screw to the left (counter clock wise) to increase engine idle.

Turn screw to the right (clock wise) to decrease engine idle.

Once the target 900 rpm is achieved plug AAC electrical plug back in and observe if there is any change in Rpm if there is this needs to be adjusted at the ECCS control unit with a maximum of 250 rpm adjustment, another Caution if you turn the screw on the ECCS control unit near the self diagnosis spot it sets the engine speed at the lowest setting Rpm minus 50 rpm.

Edit: It could also be related to your BOV, as these have a tendancy to make the idle unstable too.

MEGA

[sniffy]

thanks mega, i'l look into these things and hopefully i can come back with some positive feedback!