knock sensor

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

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

Hey snoball, where is the knock sensor on the Dodge V-10????????????

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

(Confuses a 4T65e with a 4L65e and won't admit it.)___________________________________________________________SBJ: Dumb brake question (Discribes the wrong brakes and won't admit it.)___________________________________________________________SBJ: Front wheel bearings-2000 Blazer?? (Claims torque specs are wrong when they are not.)___________________________________________________________SBJ: Snoball Defense System v1.01 (Snoball breaks these out when he knows he's wrong and doesn't want to admit it.)___________________________________________________________

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

Way back in the "Acetone in gas tank" thread I pointed out just these same numbers for the difference in cost given the current prices, then politely asked if the MPG increase would be greater than the 6-7 percent cost increase. You never responded. Now reading your numbers, I make it that you are getting a 35% to 46% increase in MPG, which more than offsets the added cost. Why didn't you reply with these numbers for your specific vehicle and engine?

However, I think a blanket statement like "using higher octane gas in a vehicle improves cost per mile" is not accurate, but in at least yours it is true.

Also, will it pass a smog check with advanced tim>

"JeffH" wrote in message news: snipped-for-privacy@v65g2000hsc.googlegroups.com...

You are posting in the wrong group. Here everyone waits for a answer to a 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

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.

It is completely impossible that simply switching to 93 Octane fuel will result in a 35-45% increase in fuel mileage, with all other things being equal. There's just no way. I don't like to get involved in the pro and anti Snoman debate, but this is a ridiculous statement. The reality is that the vehicle must have been driven in a more agressive manner with harder acceleration and the throttle open more to maintain the same level of percieved performance attatined with the higher octane fuel. Otherwise, the statement is basically saying that 93 Octane fuel has 35-45% more energy content that 87 Octane.

Jeff, both Heatwave and I know that you have a valid problem and we are not making light of that. However, please be aware that the individual that posted the disertation of an answer should have all info he posts in repy taken with a grain of salt. You will likely get and anwser to your question soon from some of the much more qualified folks in here.

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

Although I use moates products there are links to a hell of alot of other mfgs and info. Links on moates.net with instructions to build data loggers that can read and display real time info to your computer. You can build one for less than $30.00 or cheaper if you have a old code scanner around. You can drive down the road logging what your ECM is actually doing or have someone else drive while you watch it all on your laptop. Other people have every right to dispute my postings or take them with a grain of salt but I am sure there are alot of people involved with ECM programing on Moats that will make even the GM experts on here look like foolish children when it comes to specifically engine management. In fact there is information on this site that was posted and then later used by GM. I don't know if GM programmers had the info 1st and had not used it yet or if maybe their developers keep an eye on sites such as this one too.

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

The ECM will see the open circuit and set a fault code. The ECM may also switch to a modified spark schedule based on it knowing that it has lost Electronic Spark Control.

If the knock sensor isn't detecting any knock or anything that mimics knock, there will be no compensating. ESC adjustment by and large can't be felt while driving.

To David and Robin, funny thing how you want to bag on this group and the supposed lack of support/information/answers that are provided. The OP posted the question at 5:54 am (according to the time stamp) and less then 12 hours later, some one is answering the question. You may not like what it said or how fast answers are provided, they are answered when people read them and actually have the ability to reply. It would serve you well to understand that those folks, such as aarcuda and others, who can and will answer the posts do not have to ability to do so all day every day because of work and having a life outside of here, and that you should afford them the time to see the questions, BEFORE you start with the rants about how bad this group is or how childish we are.

Also for the record, do your home work on Snoman, he is a fake and a fraud and will be called on it EVERY time he posts something. If you are foolish enough to follow his dangerous recommendations and it results in something bad happening, you will not be able to say that you were not warned. We owe it to the unknowing posters to ensure they are informed of such dangerous information, just as much as they deserve an answer to a question.

Have a great day! :)

There's not a whole lot of improvement to be made on a conventional factory engine because the OEM has done their best to provide a maximally useful product.

If you want significant improvements you need to get into doing the race car stuff with special camshafts and other performance enhancement products. There are folks around doing that for a living. They'll throw your engine stats into a computer and show you various performance curves for special camshafts that can be machined to make the engine into more of what you're looking for.

30 or 40 years ago snoball would have been here touting a special 100mpg carburetor and ashless dispersant oil.

His claimed performance improvement is a sham. "If it sounds too good to be true, it is."

Though I kno we are talking about Chevy trucks in here, I would like to share a little experience I had concerning use of different octanes, but on my dual carbed motorcycle. Though some might not find it relevant, I would be that it does go to prove a little something.

Long and short of it is this, my bike is recommended at 87/89 octane, however, since I have owned it I have (until recently) run nothing but

92/93, figuring I was "making things better."

Then I had been informed that I was actually costing myself money and some power, of course I did not believe it. SOOO on a full tank of

92/93 I had it dyno'd wasn't the greatest numbers but what do you expect from a little 600.?

Ran it dry, filled up with 87/89 for two tanks, after the second, I took it back to the same place, dyno'd it again, and low and behold, the hp jumped up. Now, I do not have the numbers handy, but when talking about a little motorcycle weighing 500# a little more hp makes a HUGE difference.

The moral here is that running a higher octane DOES NOT mean you are going to gain anything other then a lighter wallet.

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