My Engine Tune up :) (kinda long)

[skid542]

The the other day was the 1 year anniversary of the union between my Legacy and I and I finally had a chance to do some work to her now that I'm out of school for the summer. I did several things over the course of a few days, grounding mod, reset the ecu, spark plugs and an oil change.

First thing I did was reset the ECU. This was accomplished by disconnecting my battery thursday evening around 6 and friday around noon I got it hooked back up and took her out for a spin. The first thing I noticed is that the hesitation and the small power bands at low RPM (less than 3k) were gone. The throttle response was good and crisp again and she climbed right up the RPM range quicker than before. I should also note that before hooking the batter back up I cleaned up the battery poles and the connectors.

Second thing I did was the grounding mod. First off I pulled off all the stock grounds, sanded them (all surfaces of course) and put them back. Next I ran a wire (10 gauge jumper cables that I cannabalized) from the negative battery terminal over to the passenger side of the car and grounded it pretty much like the stock on the driver's side. Next I ran another wire (again the 10 gauge) from the negative terminal to the engine block. I found a small bracket that holds a hose in place and screws directly against the block behind where the AC sits. This gives me a ground pretty close to the coil pack and the knock sensor. Thirdly I ran a wire (cannabalized extension cord) from the negative terminal, around to the back of the firewall and then down and connected to the outside of the O2 sensor. This all didn't take too long and when I took my baby out for a spin I couldn't feel any difference in acceleration but the idle was down about 150 RPM (now sits about 550).

Thirdly I put in new spark plugs. Replaced the old ones with the recommend NGKs. I didn't really have to gap them much but I set them all to 0.040" and then in the engine they went. The old ones looked decent but they were definately worn and no longer properly gapped. Well so now that I had new plugs, back to the road to test them out. The engine sounds better and seems to accelerate better but the acceleration difference is negligable and we all know how accurate the ole' butt dyno is.

I mentioned in the begining of my post that I changed the oil. I keep my oil changed every 3k and have been using synthetic for a while and recently had more and more problems with leaking oil so I switched back to a dino, Valvoline Max Life 10W-40 to be more exact. After the next 3k I might switch to GTX Max Life.

All in all I can definately say I am glad I took the time to tune it up some and give the ole' engine a little TLC. The grounding mod seemed to have negligable effects but I am glad that the idle is lower and I feel better knowing everything is grounded out properly. The spark plugs were worth doing (hell only cost 7 bucks for all 4), not a lot of performance gain felt but I can tell the engine is running better so I'm happy. Reseting the ECU made the biggest difference of all and is probably something that I may consider doing on a semi regular basis (every few months?). The oil switch I think will help with the leaks. I took her out today and pushed it hard (still keeping the RPMs<4500) and she went great. The top speed has definately dropped since I've had her but I've also put 16k mi on her and I know the turbo wheels dropped the top end a little too but given a little room she'll hit 100 which is fast enough (until I get my legacy out of school and fix it up etc.). My 0-60 has definately improved though, straight up took a Neon yesterday, God I love my Subi.

Sorry for the long post but I figured I'd share my experiences and my excitement.

Lee

[TheShocker]

I think it's funny you mentioned that you "took a Neon". I hope you were being sarcastic.

[skid542]

I was being serious, it wasn't one of the new ones that have has that ridiculous straight line speeds and acceleration.

[vrg3]

Did you reset the ECU again after the ignition tuneup and the grounding mod?

Also, when you say RPMs dropped to about 550, do you know that the mark on the tach that looks like it should mean "500 RPM" actually means about "700 RPM?" Normal idle speed should put the needle right around that mark.

[skid542]

I haven't reset the ECU yet again, I wanted to drive a few days to get a feel for it before I reset so I'd have a good idea of how it drove before the second reset.

Also, yes I am aware that mark is for 700, my needle now sits below it after the engine is good and warmed up.

Lee

[j0nny]

So would you recommend resetting the ECU on a semi-regular basis a good bit of "self-maintenance"?

[vrg3]

I don't think I'd recommend resetting the ECU as maintenance. I do think it's a good idea to reset it after you make modifications, though.