problem 1999 Legacy triptroinc

[Danihellfire]

Seem to have a problem. Car is driving fine on 1st turbo... but is shuddering as the secondary is coming online. No check lights, can't hear any det, no smoke, idles fine. Drive normal down low, boosting 11psi on 1st and 14psi on 2nd with hose 10 mod. Tank is full of mobile 98 which I've always run. She is coming due for a service and was going to do the plugs as I'm running coppers. Was thinking they might be fouled? Thoughts/suggestions?

[Rosssub]

Can you describe the shuddering a bit more?

[Danihellfire]

its like a shuddering/jolting/cutting the hole car hiccups when the 2nd is coming on but its fully boosting ok.. Ive put factory BOV back that didnt help at all..ive looked for boost leaks or loose clamps all looks good..

Edited April 20, 2016 by Danihellfire

[Percy]

Mine did that when the knock sensor was poked, but not quite poked enough to trigger a CEL.

[Danihellfire]

Cool i'll get one and give that a try!! is it hard to changed??

[Percy]

 Danihellfire said:

Cool i'll get one and give that a try!! is it hard to changed??

Its not that had to change, just a pain in the arse.

Its right at the back of the block under the intercooler etc, which entails removing a whole lot of stuff just to get in there.

[Rosssub]

Check your plugs over. Also test the diaphragm inside your BOV and secondary relief valve, by connecting a length of vac hose to the diaphragm nipple then suck on the hose and block it with your tongue. Both the BOV and secondary relief valve should hold vac permanently, if not the diaphragm is split.

Put the car into test mode and make sure the ECV and IACV actuator rods are both moving in and out.

If you do change the knock sensor, these pics are all with the TMIC removed. Take note of the knock sensors rotation to the block, the new one needs to go on the same angle.

Original knock sensor:

12mm bolt undone and original knock sensor removed:

New replacement knock sensor through Strongs/Subaru Speed:

To fit the new sensor I find it easiest to fit the bolt before lowering the sensor onto the block:

Again fitted in the same rotation as the original, then tightened to 24 N·m (2.4 kgf-m, 17.4 ft-lb):