Plane mad Harry

Hi, I'm coming to the intelligent people on here as I need your help, my 2002 wrx has recently developed a slight hesitation at 4200rpm and at about 4800rpm, it seems to hesitate slightly and then breaks through and then it hesitates again before breaking through 4800rpm/5000rpm, I have noticed this just lately in 2nd and 3rd and 4th gear as I don't get it revving that high in 5th very often, lol. Could it be spark plugs or something else more major, its done 75k and has a nearly full Subaru service record. Are the NGK plugs the best ?.
Any help/advice much appreciated

Cambs_Stuart

iTrader: (3)

I had a similar issue when I got my 2005 blob wrx and cured it by cleaning the maf and boost solenoid.
I can't promise it'll sort out your issues but it's quick, easy, cheap and won't do any harm.

Plane mad Harry

What is the best way to clean these, should I use carb cleaner and spray it into the tubes on the solenoid and spray the Maf with it, also does the ecu need resetting after I've taken both these out and cleaned them.

Cambs_Stuart

iTrader: (3)

To clean the maf.
1. Unplug the cable.
2. Unscrew from intake.
3. Spray with cleaner. I used carb cleaner but I think electrical contact cleaner will also work. Make sure you do this well away from the car as some cleaners can be harmful to paintwork. Spray it until you can see clean wire going to the resistor.
4. Let it dry.
5. Re-assemble in reverse order.

To clean the boost solenoid.

1. Unbolt the boost solenoid from the car, and pull off the two tubes but leave the electrical connector plugged in. Make sure you take note of which tubes go where.
2. Spray cleaner down the tube from the air intake to boost solenoid, making sure you've got a rag to catch the solvent that runs out the end.
3. This is the tricky bit. Under the dash, near the ignition are two loose green electrical connectors. They can be tricky to find and reach. Plug them together so they click.
3. Now when you turn the ignition on (but don't start the car) the car starts in service mode. Lights will flash, fans will go on and off and the solenoid will click on and pulse, if you listen closely.
4. Hold the solenoid in a rag and spray cleaner down the holes. A suprising amount of brown gunk came out of mine.
5. Keep going until no gunk comes out. Alternate the holes.
6. Turn ignition off, disconnect green connectors under dash (these are fiddly) and re-assemble solenoid once the solvent cleaner is dry, making sure the tubes go the right way around.
7. Have a cup of tea then go for a drive.

There are plenty of how to guides on YouTube if you get stuck.
The ecu shouldn't need resetting after this.