Car Missing Under Light Throttle And On Idle.

[R33-RB26DETT]

Hi,

I need to pass emissions testing therefore I have brought my car back to completely stock.

The history is that I took my car in to the mechanic to fix the below and bring my car back to stock:

-Install stock airbox

-Install stock exhaust

-Install stock cat.

-Replace 1 faulty 02 Sensor

-Replace 6 leaking injectors

Now that all of this has been completed my car is idling like crap, and is missing when driving under very light throttle the car hesitates/chokes from about 2,000 RPM up until 3,500 RPM.

Although if I drive with heavy throttle the car drives and revs normally.

My mechanic advised me to replace my spark plugs as they are most likely fouled as since they needed to start/stop the car heaps of times whilst repairing it.. So I replaced them with (0.8 Gapped plugs) as recommended by him.

I did this, but the problem remains exactly the same.

What could the issue be? Maybe I need to run the recommended stock gap of 1.1?

[TAKUSHI]

mmm sounds like its doing what my car does

but does your prob go away once the engines warm?

[R33-RB26DETT]

Nope, stays there even after it is warm.

[geraus]

Have you tried resseting your ecu? Are you also using stock coil packs? also try cleaning your AAC valve.

[MR R33 GTS-T]

Are you using the stock bov? i had similar issue put stock bov back on and it was fine

[joeleo87]

are u using stk turbos? or aftermarket?

aftermarket turbos with stk ecu can cause problems

[murrayis]

Tried changing the spark plugs?

[R33-RB26DETT]

Are you using the stock bov? i had similar issue put stock bov back on and it was fine

Yep, Stock BOV.

[R33-RB26DETT]

are u using stk turbos? or aftermarket?

aftermarket turbos with stk ecu can cause problems

Stock ECU, Stock Turbos - everything stock now to pass EPA.

[R33-RB26DETT]

Tried changing the spark plugs?

Yes, I have changed the spark plugs as I suspected that maybe the previous ones had fouled.

I pulled them out and they were very black becuase my car was running very rich prior to fixing my 02 Sensor.

New sparkplugs have gone in with (0.8) Gap and the problem is identical.

Perhaps i should only have them gapped to (1.1) even though my mechanic says not too?

[R33-RB26DETT]

Have you tried resseting your ecu? Are you also using stock coil packs? also try cleaning your AAC valve.

It may be my ACC Valve needs cleaning, I just found a thread on SAU about this, and I will give it a go.

Other than that I have no idea what it could be.

[R.3.2.G.T.R]

checked afm - plugs/dry solder joint.. maybe not related.. there's a thread on that as well

[R33-RB26DETT]

Taking it in to the mechanic tommorow to diagnose the issue.

Will let you know what it was.

[peter_fc]

May have a vacuum leak?

Is it missing in one particular cylinder or just idling rough?

[Wacky Dee]

try regapping plugs to 0.9 or 1.0 .. My car was constantly misfiring on idle/low load when new plugs the mechanic put in were gapped at 0.7

[R33-RB26DETT]

They just put it on the dyno and found out its the other 02 sensor.