Hi:

I just got a Power FC for my Legacy RS (is the Power FC MY93-MY96 for Impreza). Since there aren't mappers in my country, I'll take this task for my self, so I need some help...

My Legacy have a lot of hydraulic lifter noise, and a LOT of Knock reading. I made a run with 15 psi and I hit 62 in the knock scale... Well I thougt this was because of the base map is for 100 octanes, so by using de Ign/Inj function I set +9° of ignition retard (Is this exagerated?), and again, the knock reached 60 again.

I realized some facts by using the peak hold function:

- While normal driving I hit 40 (with no boost!!), but usually by watching the scale I realized the knock readings were about 25 to 35

- There are peaks of knock with Throttle lift offs

The question is, How much the hydraulic noise affects the Knock reading? It seem my readings are not normal...

Thanks in advance

 

Hi Freddy,

I think i have a bit of trouble with hydraulic noise too (Impreza tho). On cold start up the knock level can easily go into the 30s for a few seconds (while you can hear the engine tapping). I generally get into the teens (12-16) while cruising on the motorway, maybe 4-5 while doing 30mph. It will idle at 1 (when hot) with the ocassional blip up to 4-5.

I do think tho that into the 60s is not just noise. What does the graph look like when in monitor mode (knock only). Does the level gradually increase to 60 with rpm or are there spikes? You said you used the ign/inj setting to +9 retard, so i presume you set this to -9 in the controller? If it actually said +9 then you've added 9 degrees .

Tony.

 

Thanks Tony!

Well I did this... first I set +9 in the controller, I thoug "Damn, the car moves very well!!" after that I realize my mistake... At least it was a very cold night and the engine didn't explode...

After that I set the Ign in -9 and I begun to watch the monitor:

- In a stop light I kept 4000 RPM sustained for 2 or 3 seconds, the Knock reach 34-35, no boost, no speed...

- In WOT, I didn't see any knock spike, but a gradually increase.

- Also I noted a knock increase in the lift offs.

I think the most of this "knock" is because of the hydraulic lifter sound, but I didn't think this could be so high.

 

Does sound like a lot of 'background' noise if you can get 35ish while sat at the lights, also if there are no spikes it sounds promising with regards det.

It could also be an earth fault letting in unwanted noise. Do you have any additional earths from the battery? With the car getting a little old these may help. I need to check mine too as i believe a lot of my noise comes from the electrical system.... i can see the knock level rise slightly when the cooling fan (or other high load items) come on.

Tony.

 

You could try some different oils to improve flow to the hydraulic followers. I went from a 15/50 to a 10/40 in my legacy and the noise improved.

Paul