knock sensor

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On my '93 k2500 5.7 Suburban, what happens when I disconnect the knock sensor? Will the computer assume there is a knock condition and compensate, or will the computer assume there is no knock condition?
As part of troubleshooting slight irregularities in smoothness, I was thinking I could unplug this sensor to see exactly how much compensating the computer is doing. With the cost of gas and the amount my truck uses, I'm leery of filling up with premium (just put in 3/4 a tank of "cheap" gas today for $100).
Thanks, --Jeff
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You will get conficting "opinions" on the value of higher octane fuel but I have found that some modern higher compression engines can be very fond of it. I have a 89 4x4 burb that I bought new that has the same engine as your truck and I have driven it over 180K miles now and most of that on 93 octane fuel. It has gotten over 18 MPG at time on trip and is always 17 or better on highway even with A/C on. That engine really likes higher octane fuel and can really come alive with it. Try advancing the base line timing to 6 or 8 BTDC and using 93 in summer and 89 or better in winter (octane needs increase with tempature increases) Higher octane fuel resists preignition knock or detonation and allows timing to be set to where peak cylinder pressure are produced at a point in relation to crankshaft angle to extract maxium power from expanding gas. 87 is simply not enough to do this with 9 to 1 or better CR's without retarding or compromising ignition timing and hence the reason for the knock sensor in the first place to limit consumer complaints as they strive toburn the cheapest gas they can find while it is actually costing them more long term due to reduced efficency. There was a time when 93 was 20% or more than 87 and you would need a 20% increase in MPG for it to pay out but today, 89 is maybe 3% more and 93 about 6% more so if you get say 14 with 87, a increase to 14.5 would more than "pay" for 89 and 15 MPG would pay for 93. (if you are getting 11 MPG, 11.3 would do it for 89 and 11.6 for 93) Myself I would use 93 regardless because it runs so much better with it too but the best my burb ever got with 87 was 15 once and usually 13 to to 14 on road and was a slug on hot days. Now it gets in the 17 to 19 MPG range on road (19 plus at times with no A/C) and around 15 in urban driving and on one trip at 65 or less and no A/C it flirted with 20 MPG a few years ago. (it does better in city/urban driving with 93 than it did with 87 on highway). BTW, when they do EPA MPG tests, they have long used 93 octane fuel as it is in the regs for testing but they are not required by law to tell you that. (bit of smoke and mirrors) One more tip is quest for MPG, big agressive tires and lifts are gas eaters and cause engine to strain more with them and with lower octane fuel it can make matters even worse. If max MPG is you quest, you want no lift and smooth treaded stock type load range "C" tires running at or near max tire pressure to reduce rolling resistance as much as possible.
Now lets see if the Trolls weigh in on this. ----------------- TheSnoMan.com
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Mine is dead-nuts on zero right now, as it says in the manual. I had assumed the computer would fight you if you set it to anything else. I can try this at some point just to see what happens - easy enough to do.

My current tanks is a "baseline" and I'll get a MPG and performance read on it. I'll do a tank of mid-grade next and do the same to see what kind of numbers I get. Excellent point about temperature/octane - I'll keep that in mind.
However, I am still curious about how the computer responds (or doesn't) when you unplug the knock sensor. Anyone know?
Thanks, --Jeff
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Hey snoball, where is the knock sensor on the Dodge V-10????????????
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snipped-for-privacy@snoman.com says...

Where was that knock sensor on the V-10 again?
Snoball these links contain things that "YOU" wrote. If you do not like what YOU wrote then I suggest YOU stop posting. ___________________________________________________________ SBJ: 4T65E http://tinyurl.com/2lcjkv (Confuses a 4T65e with a 4L65e and won't admit it.) ___________________________________________________________ SBJ: Dumb brake question http://tinyurl.com/2ya3wo (Discribes the wrong brakes and won't admit it.) ___________________________________________________________ SBJ: Front wheel bearings-2000 Blazer?? http://tinyurl.com/2j44zv (Claims torque specs are wrong when they are not.) ___________________________________________________________ SBJ: Snoball Defense System v1.01 http://tinyurl.com/2okyfx (Snoball breaks these out when he knows he's wrong and doesn't want to admit it.) ___________________________________________________________
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Do you or azwiley1 know the answer to my question? It's on a '93 5.7 Chevy 4-bolt with TB injection. All stock.
I wasn't trying to stir the pot here - it is a genuine question that I'd like to get answered, if possible.
Thanks, --Jeff
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wrote:

post and then spend hours calling names. Kinda like children. Wonder if they ever thought of answering the questions? But anyway, I believe on that engine your knock sensor is on the starter side of the block. It is located near the center of the engine. You can take it out and put a couple rounds of teflon tape on the threads then reinstall it but not torque it to specs, leave it a few lbs loose. I'm not looking at a book right now but I believe it is supposed to tq to something like 17lbs. Try it about 10. This will sort of muffle its ears, if you get audible spark knock reach in a tighten it a little more. You will find a sweet spot somewhere. You will get most of your knock under heavy load at throttle positions above about 70% when your ecm goes into power enrichment mode. You might also want to listen carefully when you are cruising under light throttle at highway speeds and accelerate lightly, sometimes this will cause you to go a little lean for a second or two. During this instance it is usually a very light spark knock and not going to hurt anything. Your base timing will move all 3 timing tables in your ecm. Go to http://www.moates.net/ and do a little reading in the forums there. Do a little reading on highway mode. Just a short description but at light throttle and sustained highway speeds under light load your ecm would go into open loop. During thisopen loop the ecm would not monitor the knock sensor or oxygen sensor, it would lean out to about 17/1 and advance timing. As soon as your vehicle exceeded the value for throttle position or engine load it would kick back to closed loop. There are also some time variables. But this is disabled, yep it didn't follow the EPA guidelines so GM could not enable it.Even the big guys like Hot Chip won't mess with it. I picked up over 3mpg using it on long trips. But you gotta do it yourself with a chip burner.
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wrote:

That's excellent information - thanks for taking the time. I'll check out the site as well. I'm not concerned too much about mileage because I'm sure if I focus on a well running engine, the MPG will be acceptable (it's a 3/4 ton 4x4 truck - I don't have high expectations). I haven't messed with a chip burner since back in my cash-register days, but that makes sense (the EPA blocking the adjustment by the OEM and after market folks). OEM is fine with me - I'm just looking to fine-tune the engine to get it running it's best and learn how things work along the way. I'd love to have diagnostic equipment to check the burn and monitor the engine/computer, but that's out of reach for me. So I'm just trying to make do with what I have.
I think I'll just try unplugging the sensor and see what happens. If it's knocking under "normal" situations, I'd like to know that it's knocking so I can see what can be done to correct it - different plugs, different gas, additives, etc. I don't want to get extreme by any means.
Thanks again, --Jeff
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Not need to ship burn here. The nice thing about TBI engine is that you can rest base line timing. The stock setting of TDC is done mostly for knock/low octane fuel tolerance because the ECM does not care at all because there is no crank or cam positon sensor on it. The kconk control on that system is limited to about 20 degress of retardation unlike Vortec engines that can electronically control timing over a range of more than 40 BTDC to more than 40 ATDC. Advancing baseline times does boost performance and MPG but it will rule out 87 octane pretty much. (BTW with that engines CR ratio you can not regulalry burn 87 octane with a retard spark, active spark control or both or it will self destruct over time. BTW, I have monitoring equipment that record spark data in OBD2 cars and you can record timing under load and normal operation and when it is being retarded. Also I have advanced the timing on many TBI SB's pver the years and they all responed well to it, LD and HD and owners were happy with results and had no problems with giving up on 87.

No sure what you think you are gaining here. It only retards spark when it hears a knock and not otherwise and is disabled and engine knock you are not gaining anything and "oing" BTW is very hard on valves over time and one of the leading causes of burnt valves. Pinging or knocking even at low levels cause valves to vibrate in seat and leak a bit and over a period of time to start to flame cut then finailly burn. Some smart alec Troll who knows nothing other than cause trouble will likely tell you otherwise. ----------------- TheSnoMan.com
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wrote:

There's an old saying Snowman.. "I'd like to buy you for what you're worth and sell you for what you think you're worth". Come to your own conclusions on that one.
Denny
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wrote:

Yes it is quote true about you in that you do not understand the subject so you discredit it. Ignition timing and poper fuel is VERY inportant to best posible engine performance. Up until 1972, engine had very agressive timing curve but with the advent of emission control in a major way in 73 they chopped compression and retarding overall timing a lot and this was the main reason for the big lose of performance that year and beyond. While it was true that they stared "net" HP ratings too the big power loss was for reasons above. TBI engine respond quite favorably to advanced timing and better fuel, VERY favorably. ----------------- TheSnoMan.com
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You've posted so many contradictions on so many subjects it's obvious that you don't understand -any- subject.

What is 'poper" fuel and why is it inportant? (maybe you meant 'pooper?' because, frankly, I've cut farts that had better technical expertise than this mush)

Right... before 1972, no one went to a speed shop and bought distributor advance curve kits (i.e., lighter advance springs), and the market for distributor machines was non existent.

Exactly WHAT does TBI have to do with your above mentioned "big lose" of performance due to "chopped compression?"
More miscellaneous ramblings from

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On Thu, 15 Nov 2007 14:47:56 GMT, aarcuda69062

No I have not but in your limited understanding of thing you come to that conculsion to make yourself feel more secure.

A troll answer, attack a typo when they cannot begin to understand the message otherwise. Damn you must REALLY be insecure!!!

Troll, how does this relate??? We went from stock engine to modified ones. I guess this is a vain attempt to try to make yourself look good huh. So sad! BTW, troll I used everytype of distributor made in 60's on and you could not even begin to tell me anything about them. You are a legend in your own mind.

Such a dumb arse. I was explaining the effects of timing on engine operation but again you are always looking for a way to make yourself feel less insecure

Yes this is very true. He is so insecure he tries to attack anyone that calls him out. Unlike him I am not here for notches on my gun grips. Sad part is if he would stop acting like a child he might just really learn something but then that may be beyond his maturity and abilty to do. ----------------- TheSnoMan.com
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Pay attention bozo, there's a fair number of people who agree with me that your advice is shit.

That's not a typo, that's a habit from someone with no discipline, sloppy work habits and not enough intelligence to realize how shitty his posts look and make HIM look.

Pointing out how full of shit you are.

We did? Installing a set of advance springs constitutes a "modified engine?"

Key point here is 'you guess.'
You guess a lot, and then you post it as gospel.

Sure you did. Another wild claim just like the one you made a few days ago that you bought your first car before I was born. You have yet to reply to my challenge to that claim, care to do so now?
Oh, and since when does using anything, distributor or otherwise mean that someone (you) actually understands anything about them?

No shit I couldn't. You're unteachable.

Nope, just an auto mechanic who happens to have real credentials, not the vague veiled pseudonyms that you've been trotting out any chance you get.

Sorry to tell you but, you weren't explaining anything, that is/was just a random bunch of mumbo-jumbo strung together to add filler to an otherwise useless mass of mumbo-jumbo.

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On Thu, 15 Nov 2007 20:39:32 -0600, aarcuda69062

Yes fellow trolls and children like yourself. Not a group to be pround of

You mean like how childish your posts make you look don't you?

No pointing out that you do not know anything about this and have hijacked thread to feed your insecurity needs

I know you have limited though abilties but were in OP's comment did he ask about changing weights or springs in a old style distributor????? I seemed to have missed that.

No you are the one guessing here

No, but you think you are the master here.

Perhaps you can look in your cut and past but I do not reacll car but I do recall 4x4 and very likley before you even new what one was. As far as you age, it would be very said to think a 60 year old man would act the child that you do so I assume you are yonger.

Classic, because you do not understand it, I must not either huh. Your limited knowledge must really bother you a lot.

By you I am that is for certain.

Yes I know your type, the kind that makes work and looks for problems not there because it is a income source and not interested in really fixing anything properly. You likely feed your client BS andwhile empting their wallet while hoping if you change enough parts you will accomplish to things. First most importantly line your pocket and second maybe fix problem for a while.

Yes mumbo jumbo is all you speak. You have got to be one scary mech. heaven help your victims

TheSnoMan.com
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And you think that your incoherent ramblings are something to be proud of?

No, I mean exactly what I stated. Comprehension never was one of your strong points.

Like bringing up 35 year old technology doesn't feed YOUR insecurity.

You also seemed to miss the fact that his truck wasn't built in 1972.

I can only guess each time you wander to some irrelevant data point from 3 decades ago.

Yeah, I do. As mentioned previously, that's what it says on numerous certifications. What does yours say, 'we plow snow and mow lawns?'

Dodging the question again. Again, is it too hard for you bragger?

You assume that in hopes that it will lend some credibility to your poorly thought, ill advised half-assed backyard Bubba, shade tree butcher fixes.

I don't NEED that criteria to know that you don't understand it, I (and anyone else) can read your stupid canned sermons and know how limited your knowledge is.

By anyone.

WOW, that's quite a list of accusations. Sorry numbnuts, the old "he's a mechanic so he must be a crook" bullshit doesn't work.
Then again, I've known quite a few snow plowers that fit those descriptions quite well also. Tearing up trees, knocking over mail boxes, piling snow in handicap parking spaces, plowing other peoples driveways shut. Yeah, real noble profession you got there Betty. It's what, one notch up from washing dishes isn't it?

Another infantile dodge. Answer the question; what does TBI have to do with anything you mentioned in that paragraph? IOWs, cite some timing data comparisons between TBI engines and carbureted engines. (I'll gladly prove you wrong if and when you do)

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snipped-for-privacy@snoman.com says...

___________________________________________________________ SBJ: 4T65E http://tinyurl.com/2lcjkv (Confuses a 4T65e with a 4L65e and won't admit it.) ___________________________________________________________ SBJ: Dumb brake question http://tinyurl.com/2ya3wo (Discribes the wrong brakes and won't admit it.) ___________________________________________________________ SBJ: Front wheel bearings-2000 Blazer?? http://tinyurl.com/2j44zv (Claims torque specs are wrong when they are not.) ___________________________________________________________ SBJ: Snoball Defense System v1.01 http://tinyurl.com/2okyfx (Snoball breaks these out when he knows he's wrong and doesn't want to admit it.) ___________________________________________________________ Snoman these are things YOU wrote. Don't like what YOU wrote? Then YOU should stop posting.
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On Thu, 15 Nov 2007 10:03:31 -0500, Heatwave
Again no post complete without some dribble from Master Troll Heatwave ----------------- TheSnoMan.com
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The subject was YOU! Everybody with a ounce of sense understand's that YOU are a friggin' Idiot
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Se that is you problem you only have maybe a ounce of sense so anything beyond that level in complexity (which is basically everything) seem like nonsense. The problem is it is not and it is only your very limited metaql abilty that sees it as such. Anone with above troll intellect can see it far different than you do. You are simply to dense to see what you are and what you are really doing here is belittling yourself far more than me. ----------------- TheSnoMan.com
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