knock sensor code 1226 need advice!

[marklanderson]

Hi all, a few weeks ago I was looking for a cheap car. I ended up buying a 1995 318i M42 with 181k for $1,300 bucks locally on eBay.

Love driving this car and have been reading this forum non-stop ever since for all of your great ideas - thank you!

However this morning as I was leaving for work I put her into drive and she sputtered for about 2 seconds then died. Now it turns over like usual but won't fire. Almost like it ran out of gas (but there's plenty).

The odb1 pedal trick now gives me an error code of 1226, which is listed as "knock sensor #2" but it's a little strange since I've heard no knocking and most people here with this problem mention rough idling and loss of power, which I haven't experienced.

No problems starting at all before until it died today, but I did notice last week that the temp gauge would rise to just over half way when idling, then drop to normal when driving.

Since replacing the knock sensors is a pain and it's cold outside, I'm wondering if I should do that first or try other things. I've seen lots of threads about this error, and many people recommend replacing o2 sensors, fuel pump, disconnect battery and reconnect, checking that the coolant system is full and air-free, etc.

Within the past year the previous owner replaced the air filter, spark plugs, fuel filter, battery, front brake rotors, calipers and brake pads, front struts, front lower control arms, front bushings, and a new alternator.

Any other ideas before I jump into knock sensor removal/replacement? Thanks for any input! - Mark

[flyfishvt]

Cover the basics. You need spark, air and fuel. See which one is missing before you dive any deeper into this. It could be a bad fuel pump, fuel pump relay, dme, faulty spark plug coil, wires or a hundred other things. Obviously the knock sensor code is a good clue and a place to start once you figure out which one of the three things the car isn't getting.

[marklanderson]

Thanks for the fast reply! I'm searching for the best ways to check spark and fuel delivery (wish there were DYI's for this because I'm not much of a mechanic!)

When I used to check for spark on my old motorcycle I'd pop out a spark plug, reattach the plug wire, hold the end of the plug against the engine and turn it over, so I'm assuming it's the same for a car. For checking the fuel delivery it looks like I need to listen for the fuel pump kicking on somewhere behind the rear seat, then I'm guessing pull a fuel line somewhere and see if anything comes out when I crank it..

Off to do more searches - if you happen to know of any threads that might help please pass them along. Thanks!

[flyfishvt]

One test you can do is to take the cover off the air filter and spray starter fluid into the intake while someone cranks the car. If it fires up then you have spark and no fuel. You can also pull one of the plugs after trying to start it and look at the electrode. If its all wet with fuel then you know you're getting fuel but no spark. You may even find the plugs are fouled and a good cleaning is all they need.

[marklanderson]

That makes perfect sense and is a very helpful reply - I'll give it a shot. Thanks!

[marklanderson]

Well, I'm pretty sure my fuel pump is dead, as I don't hear or feel it kicking on when I turn the key on, but there's power when i test the white leads going to the pump. However, my fuel pump only has one hose going into it, but the Bentley manual says there should be a return hose as well. Should I be worried? Or is the second hose only on newer models?

http://d.imagehost.org/0358/fuelpumphose1210a.jpg

And what's the best way to get these rediculous hose clamps off? Are the crimped on or something? Just tear em apart?

Got the hose clamps off by prying up on the edge behind the little teeth... that loop on the clamp was throwing me off!

Also figured out that the missing return line is actually attached at the driver side sender unit, so there's only one hose to the pass side fuel pump assembly on the 95 318i.

Replaced the fuel pump with a junkyard pull ($45) and it fired right up. Did the gas pedal trick to start the codes and it gives me 1444 all good, so the knock sensor code has dissapeared after replacing the pump. Hope it stays that way! Thanks for your help - Mark