PDA

View Full Version : what to do?



voorhees
11-26-2005, 12:35 AM
so i went for my yearly dealer ship check-up--w/ CEL on knowing it was the knock sensor... dealership says I need new Cat, so I want Stromung high-flow Cat w/ Borla headers.....good choice? better ideas? feedback will be greatly appreciated. Thanks all.

BAC5.2
11-26-2005, 01:38 AM
Did they give you a reason for why you need a new cat? They could be trying to steal some moneys from you.

Wiscon_Mark
11-26-2005, 02:55 PM
the Stromung Hi-flow and Borla headers is supposed to be a good combination. I have a Stromung Hi-Flow (no Borla :() and I like it, it beefed up the sound a little, not much for performance changes, but I think it would make a bigger difference with headers and a cat-back.

Huffer
11-28-2005, 11:53 AM
CEL = knock sensor

no reason to get new cat
IS reason to relocate knock sensor!

Wiscon_Mark
11-28-2005, 12:01 PM
maybe they think you need a new cat because you have a bad o2 sensor?

Huffer
11-28-2005, 12:03 PM
who has a bad O2 sensor?

Wiscon_Mark
11-28-2005, 12:04 PM
voorhees

Huffer
11-28-2005, 12:08 PM
so i went for my yearly dealer ship check-up--w/ CEL on knowing it was the knock sensor... dealership says I need new Cat, so I want Stromung high-flow Cat w/ Borla headers.....good choice? better ideas? feedback will be greatly appreciated. Thanks all.

Mark - where in the post does it say "bad O2"?

Wiscon_Mark
11-28-2005, 12:24 PM
You're misunderstanding me. there may have been a code for the o2 sensor pulled that voorhees didn't know about that the dealership saw, and though the needed a new cat. sounds kinda unecessary to me, unless the cat piping is rusting through.

Huffer
11-28-2005, 12:50 PM
True - but voorhees didn't say the dealer pulled the codes. You're assuming they did. Some dealer's don't bother.

voorhees
11-28-2005, 03:20 PM
i had 2 codes-----gas cap and knock sensor. Service tech says i have backup in my cat, bad flow! so I have purchased the Stomung Hi-Flow cat and the Borla headers...I went in to spend 375 and spent 1061....timing belt, AC belt, random gaskets. new front pads...I was raped!

Huffer
11-28-2005, 03:33 PM
Did you need new timing & AC belts? They only need to be replaced every 30,000 miles (basically every 2 years). Or maybe it's every 60,000 miles.

BAC5.2
11-28-2005, 05:10 PM
Timing is 60k. AC and PS/ALT belts can be had for under $20 each at any NAPA or other parts stores, and replaced in 5 minutes each at the most.

Timing belt is worth having someone who knows what they are doing, do it. It's easy, but intimidating.

Don't relocate the knock sensor. Then it won't be doing what it is intended to do.

What year is your car? 1st Gen Legacys had a knock sensor TSB, because some of them (with a gray connector), cracked and would read falsely. I had this problem, and replaced it for $10 bucks for a used (revised design and low mileage) knock sensor.

voorhees
11-28-2005, 06:39 PM
car still had original timing belt---the AC belt was done, it squeeled all the time....what does knock sensor do by the way?

BAC5.2
11-28-2005, 09:03 PM
Knock sensors listen. They are essentially microphones, and when they "hear" a knock, they send that information to the ECU. The ECU, subsequently, retards timing enough to stop knocking. Usually it returns to normal after a little while (and knock is no longer heard). The car will not permanantly go into limp-mode if you throw a knock sensor code. Some ECU's DO seem to stand "at the ready" and quickly pull timing (even if not 100% necessary), if a knock sensor code is in the cache.

What year/trim Legacy do you have?

voorhees
11-28-2005, 11:22 PM
99 L 2.2 4EAT Green 30th Ann Edition---they fixed the heat shield rattle but the CEL is still on

BAC5.2
11-29-2005, 12:51 AM
What was the CEL code for?

Are you SURE it was knock sensor? A rattling heat shield wouldn't cause a Knock Sensor CEL. I've had a loose shield for thousands of miles, without any issue or CEL.

The Knock Sensor CEL is intermitant. It will go off on it's own a short period of time after the last knock. The computer will store a code, but stored codes are not represented by a CEL. There is no visual confirmation of stored CEL's.

Huffer
11-29-2005, 11:04 AM
regarding relocating the knock sensor - there are instances of Imprezas which have had problems with hesitation under load, due to an overly sensitive knock sensor. the workaround is relocating it slightly to reduce pickup of normal vibrations.

It's not a far leap of logic to think that the problem affects the Legacy.

The CEL might still be on because the dealer didn't clear the codes.
I would either go back and ask them to do so, or just disconnect the battery for a half hour.