Bypass Knock sensor 89 chevy 350


gr_mich_mush
05-19-2009, 06:04 PM
In my '89 Chevy K1500 the 350 engine has a lifter tick that comes and goes about every ten minutes(starts soft gets louder and louder then stops). The knock sensor picks this up and does it's job, retards timing. So I have attempted to hang a knock sensor out in the breeze to avoid the timing being retarded for no reason. Now the truck is setting a knock sensor code. I soldered a wire to a brass fitting then attached that to ground. Then threaded the knock sensor into the fitting. Then zip tied the mess to a section of wiring harness. I saw somewhere that it expects to hear knock at full throttle and if it does not it will set a code. Is this true on my truck? Any suggestions on how to bypass it without setting a code?? Does the ECM do anything when the code is set? Or does it just set it and ignore the Knock Sensor?

J-Ri
05-19-2009, 07:48 PM
A knock sensor shouldn't pick up ticking from a lifter, I have seen engines that were rattling from the worn valvetrain and they didn't show any knock. If it's coming and going, I wouldn't think it would be the lifter anyway. Usually they'll tick until they get good oil pressure or get warmed up, then they'll stop. There's a first time for everything, but I really don't think lifters are causing this. Having a knock sensor attached to wires isn't a very good idea either, it will move around and may show knock when there isn't any, which will only hurt performance a bit. On the other hand, if you actually get some knock, you want a sensor in the block to tell the PCM that. Can't say on what the PCM does when the code is set, I would assume that it would limit the timing advance "just to be safe", but if you can live with the drop in performance it shouldn't hurt anything mechanically. You may want to try some SeaFoam in the engine oil, but only use about half of what they say to use and leave it in for about half the time. It's not good stuff to have in there, but I did use it in my truck (same engine as yours) before I knew what it really was, and it caused no problems. A lot of people claim it cleans the lifters out and reduces ticking, as much "black stuff" as it got out of my engine, I don't doubt that... just put it in the engine while it's hot, run it for 5-10 minutes at idle. Let it sit for maybe 15 min, just to let it penetrate anything buildup in the engine, and drain the oil. The reason it's bad is that it reduces the lurbrication to the bearings, if the engine's off you're getting cleaning without any wear on them. Add 4 qts of oil, run it for a few minutes, drain that oil out, change the filter, and add 5 qts of oil. Keep the oil clean and you shouldn't have problems with buildup in the future.

gr_mich_mush
05-19-2009, 08:44 PM
I did take great care to keep the sensor from coming in contact with anything. It is hung on a large bundle of wires and wire loom. As for the Sea foam...I already ran that for 1500 mile in my engine. Did not seem to help. The engine already appears to be very clean. It's a young engine. Just outta warranty. :runaround:It is a Marshall engine, http://www.marshallengines.com/ . We plugged the scan tool in and as the tick cycled through we could watch the knock sensor react to it. As far as it not being a lifter tick...it may not be. Audibly, it sure sounds like one. Symptoms wise, you are right it does not fit the typical lifter tick scenario.

wafrederick
05-19-2009, 10:23 PM
Do not remove the knock sensor,further engine damage will occur and that is part of the timing.Marshall engines are junk and I know one Carquest parts store that stopped selling them.Northwestern Auto Supply in Muskegon,Mi stopped selling them,my father put one in their delivery vans and would not warranty it after there was a problem with it.Any reman engines from auto parts stores are junk,the warranties suck also and use the cheapest parts.

gr_mich_mush
05-20-2009, 05:17 PM
Ok I hear ya...but are reman engines from auto parts stores any good?

Do not remove the knock sensor,further engine damage will occur and that is part of the timing.Marshall engines are junk and I know one Carquest parts store that stopped selling them.Northwestern Auto Supply in Muskegon,Mi stopped selling them,my father put one in their delivery vans and would not warranty it after there was a problem with it.Any reman engines from auto parts stores are junk,the warranties suck also and use the cheapest parts.

J-Ri
05-20-2009, 06:01 PM
As was said in the post you quoted...

Any reman engines from auto parts stores are junk,the warranties suck also and use the cheapest parts.

They aren't the cheapest engines because they're the best engines.

wafrederick
05-20-2009, 07:09 PM
Recon is one to stay away and I seen one chicken *&^% repair they did.Replaced one a second time and the third time pulled the driver's side on a Vortec 350.Recon put a sleeve down one of the headbolt holes sticking out a 1/16" an inch of the head gasket surface and it was a cause of a blown head gasket.I have seen proof auto parts store reman engines use cheap parts.A Jasper rep I know brought in a set of King bearings which the reman engines from auto parts stores use,made in Israel.Jasper only uses the highest quality parts using Clevite bearings.Plus the pistons used in a reman engine from the auto parts stores are made in China and that includes all the parts.Most of the warranty work on an auto parts store reman has to be done at one of their places and it is a hassle.Jasper is another story,take the vehicle to any Jasper dealer and Jasper pays the labor on the spot after it is called in from the Jasper dealer

herkyhawki
06-02-2009, 12:46 PM
http://www.enginebuildermag.com/article/2421/general_motors__chevy_19131l.aspx

Rebuilder’s survival tip: The main wiring harness runs along the right valve cover. It has a "dip" in it that is supposed to go under the heater hose. If the installer turns the harness upside down so the "dip" goes over the heater hose, the harness is close to the plug wires and it will induce a small current into the harness when the engine is run hard.

This small voltage in the circuit for the knock sensor is all it takes for the computer to "think" that there’s erratic spark or detonation present, even though there really isn’t a problem, so it sets a "Code 43" after a road test. The computer always checks the spark control circuit at start-up and sets a Code 43 if there’s a problem in the electronic spark control circuit, but it should never set a Code 43 after it’s been running down the road. If it does, then you’ve got the "Mysterious Code 43" that is probably caused by the high voltage plug wires inducing a current into the harness. We have fixed several of these pickups with this problem by rerouting the harness under the heater hose.

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