I have a problem with my sti v5 type-r, on light throttle there is a slight bit of hesitation/missfire when this happens it records a fault on the ecu which is fault code 23 maf, I have replaced the maf sensor with a genuine new part, reset ecu and road tested, when I was on road test I notice the same fault so I checked the ecu and it had stored the same fault code even with the new maf could any other faults cause this to happen ie coil pack etc ?

Any ideas cheers mark.

 

Air leak between MAF and throttle body is another possibility

Check for: Lleaking blow off valve possibly if you've got an atmospheric one.
Cracked hoses

 

Can anything else cause problem ie uprated fuel pump Etc ?

 

A MAF code can be caused by:
1. Faulty MAF
2. Faulty MAF wiring
3. Possibly air leak (never seen this but a possibility to check).

Get a repair manual and follow the procedure in it to test the MAF and wiring.

 

Any more help or idea's ?

 

Are you doing a full reset procedure on the ECU??
If so, does it flash the all clear sequence??

If not then do one as per these instructions.

 

Keep doing a ecu reset but it keeps coming back ?

 

So it flashes the error code at the end of the reset procedure then??

Or

It shows the all clear code at the end of the reset procedure and then reappears a short time later??

 

Yes it shows all clear code after reset procedure and reappears later cheers, any idea's

 

As saiklon suggests really. Start by checking the associated wiring and connections. Perhaps with the use of a multi meter and some contact cleaner.

What air filter do you have fitted, OE box or IK cone?

Is there any movement in the inlet tract??

 

It's a oe airbox and filter and it has a new silicone intake pipe on, could a air leak under pressure near intercooler or throttle body cause this ?

 

Not in my experience. The check system works on voltage. If the ECU is seeing an incorrect voltage from the MAF then it will throw a CEL.

With you engine off, but ignition on, 0-0.3v (or 1.0v)
With engine at idle, 0.8-1.2v (or 1.0-1.7v) and increasing with load, you get the idea. (both readings as i do not know which ECU you have).

If these voltages are outside of the limits then the ECU will think, rightly or wrongly that the MAF unit is at fault. When in fact, it could be a fault with the plugs or loom.

IIRC your MAF sensor is the cartridge type, does it have the 2 contacts half way down, these could be worth a check as could the point where they contact inside the MAF sensor holder. (Not au fait with your MY's MAF).
Have you 'just' fitted the sensor, or have you actually removed the MAF tube/inlet tract and checked for water/oil contamination or obstruction??

 

I have fitted a new sensor but left the housing in-place could the lambda probe cause this fault as i had a simlar fault 5months ago and fitted a brand new non-gen
sensor now it seems to same, could I unplug lambda probe and see if it recorded mad fault again ?.

 

Sorry iPhone
I meant could I unplug lambda probe and see if it still records maf fault in memory again ???

 

It is logging a MAF 23 anyway isn't it??

You can unplug the Lambda of course, if it makes sense to you.

 

What Iam saying is maybe it's the lambda probe that's causing the airflow fault to show on ecu, so if I unplug the lambda sensor and then see if it still bring this code up on ecu?

 

The Lambda, if at fault will show it's own code, 32.
As i said earlier, you have a MAF fault, whether it be the sensor it's self or a plug/loom issue.
The MAF measures the volumetric air entering the system, if it, or it's connections are broken, obstructed or contaminated then it will misread which will cause your hesitation/rough running issues and possibly a CEL.

 

Ok cheers it just seems strange that it keeps flashing up on ecu because i replaced maf sensor, I will need to check wiring loom.

 

Any more idea's ?
Can any other component failure cause this ?