Knock sensor differences/problems

[WhatsADSM]

Okay, I have been battling this problem for sometime now...

Since my new motor build my car has been acting funny with knock sums. Basically I get P-Knock like noones business but it is especially true in the lower gears.

For example when I let out the clutch in first gear and give it gas away from a light, my logger shows generally 35-42 counts. Then I shift to second and once I let the clutch out a give it gas I get the same thing.

However lets say I go to first and let out the clutch as explained above and I read on the logger 40 counts. Then I take my foot off the gas and put it back on.. The knock count completely goes away and my timing comes back.

Also important to note that if I go WOT, but starting without engaging the clutch I wont get any, or at least very little knock, running through all of the gears including the higher ones.

So the whole thing just doesnt make sense, there is no real reason I should be knocking in 1st as opposed to WOT in 3rd?!

All pertinent info about my setup:
2k mile old Built 6-bolt at about 8.3-8.4:1
Big16g currently at 16 psi.
New knock sensor (put in with the new motor)
3g lifters (no lifter tick here)
Walbro255, ChargedAir AFPR at 43 base, 550s, SAFC
2g MAS

My ideas:
-Knock sensor torque.. I couldnt find the spec anywhere in the manual.. What is the torque spec on this thing supposed to be. I have tryed snug and finger tight so far... maybe I should be using MORE torque?!

-Did the eagle dealer mess up and give me a 2g sensor? Are there any external differences between the 1g and 2g knock sensor?

Thanks in advance for the responses guys.

 

[Newlogics]

Originally posted by WhatsADSM
Okay, I have been battling this problem for sometime now...

Since my new motor build my car has been acting funny with knock sums. Basically I get P-Knock like noones business but it is especially true in the lower gears.

For example when I let out the clutch in first gear and give it gas away from a light, my logger shows generally 35-42 counts. Then I shift to second and once I let the clutch out a give it gas I get the same thing.

However lets say I go to first and let out the clutch as explained above and I read on the logger 40 counts. Then I take my foot off the gas and put it back on.. The knock count completely goes away and my timing comes back.

Also important to note that if I go WOT, but starting without engaging the clutch I wont get any, or at least very little knock, running through all of the gears including the higher ones.

So the whole thing just doesnt make sense, there is no real reason I should be knocking in 1st as opposed to WOT in 3rd?!

All pertinent info about my setup:
2k mile old Built 6-bolt at about 8.3-8.4:1
Big16g currently at 16 psi.
New knock sensor (put in with the new motor)
3g lifters (no lifter tick here)
Walbro255, ChargedAir AFPR at 43 base, 550s, SAFC
2g MAS

My ideas:
-Knock sensor torque.. I couldnt find the spec anywhere in the manual.. What is the torque spec on this thing supposed to be. I have tryed snug and finger tight so far... maybe I should be using MORE torque?!

-Did the eagle dealer mess up and give me a 2g sensor? Are there any external differences between the 1g and 2g knock sensor?

Thanks in advance for the responses guys.

What you have my friend, is a classical case of phantom knock, which is most induced by one of these things:

(1) Balance shafts out of ballance. (Your knock pattern will have sharp incline and then gradual decline, provided throttle is more or less constant.)

(2) Excessive Carbon build-up on your pistons. That causes piston to actually slap the head with that carbon crown. (Your knock will rise in low gears, or even when revved in neutral. It will usually stay up untill throttle is let off, and when its applied again, knock usually doesn't re-occur.

Being as luck as I am, I had both. 1st one isn't very persistent and doesn't bother me that often, but the second one had me pretty bad. At times, my timing was being pulled to negatives because of that. Car actually feels slowing down when on throttle during extreme knock cases.

Mine seemed to do that more closer to the oil change and with thinner oil. What mostly cured it, is pouring some 'sea-foam' combustion chaimber cleaner into my PCV valve hose (into the manifold) while the car is running.

I have also read people recommending pouring some of the cleaner right into your cylinders and letting it stand overnight. Then syphoning it out (important!) and doing an oil change, as some of the cleaner will leak down though the rings.

As I said, I mostly got rid of it. I still get it once in a while, both not even close to often enough to bother me. (and not 43 count anymore)

 

[pneumo]

It's possible you are getting real knock. Many cars have low rpm knock issues because the timing map is so aggressive at low throttle settings. The best way to check if the knock is real is to pull the plugs, grap a flashlight, and look at the piston tops. If there is no knock the pistons will be a smooth carbon black color, if there are spots of bare aluminum showing that means you are getting real knock. I've had some luck tuning it out by going much richer on the high throttle settings at 1k and 2k rpm. Good Luck.

 

[WhatsADSM]

I will agree that it is possible that I am getting real knock... As far as the 2 things you suggested tho Newlogics, I honestly dont think that is what is going on with mine.

Remember this motor is about 2500 miles old and I PERSONALLY did the motor build. The pistons are brand spanking new ross's so I dont think the carbon build up is the problem. And of course the balance shafts have been in my basement for some time now, so it can't be those out of phase. I think I will try to richen her up in the low throttles.

Ill keep you all updated..

 

[doug]

As far as the torque spec on the knock sensor, the short answer is "not much". I don't remember the exact number, but it's small-- on a 2G I think it's around 9-11 ft/lbs. I would imagine the 6-bolt number would be similar.

[Edit] I just looked it up, and for a 2G it's 14-18 ft/lbs, so it's probably the same for a 1G.

 

[bodymandave]

Hey
Now i have alot of phantom knock too, but im thinking having the balance shafts removed has something to do with this and im thinking about installing a washer between the sensor and block. does anyone else agree with this approach to getting rid of phantom knock?
Dave

 

[Newlogics]

Originally posted by bodymandave
Hey
Now i have alot of phantom knock too, but im thinking having the balance shafts removed has something to do with this and im thinking about installing a washer between the sensor and block. does anyone else agree with this approach to getting rid of phantom knock?
Dave

You should log it a look at the knock pattern.
I have a washer 'mod' now, and Although it does mute some of the knock, it didn't really solve anything untill I cleaned chaimbers with some MCCC.

 

[WhatsADSM]

Thanks for the response guys... I think part of it may be the torque on the sensor....

I went home and looked on the DSM manual and I swear, the spec is NOWHERE... I looked through all of the 1g Manuals.

At first, when building the motor, I basically put a wrench on it and made the sensor "snug." I was having the problem so I then went what people have called "finger tight" and if anything, I would say it got worse. So I would venture to guess that tightening it may actually help. I have a tranny AND (good old DSMs) clutch change coming up here so I'll have a more straight shot at it then...

 

[WhatsADSM]

Ok well I changed out the transmission and tightened up the knock sensor a little. I will say that it seemed to help the partial throttle conditions alot... However I am still having knock problems, because I figured I would put my new injectors in (the pte 50 trim should be in next week):

Here is what I found the car ALWAYS gives me 43 knock counts unless I richen it up to the point where the car is literally back firing under WOT.. and then I get 0 knock counts... What gives?

I am really starting to think I have a 2g knock sensor here, because I remember reading that they are more sensative than the 1g. And honestly I can't see a reason my setup would be knocking... New motor, EASILY enough fuel, new injectors, new lifters...

Does anyone know what how the 2g and 1g knock sensor's compare? I.e. what each looks like?

Thanks again.

 

[johnnytsi]

Have you identified you knock problems yet?

I have been battling these exact same symptoms in my car for about 3 months now, I basically have untunable knock, no matter how much gas I add or remove from the fuel trims, the knock is still there, I even tried race gas, no change. While I had a tank of race gas, I unscrewed my knock sensor from the block and made an easy run or two to check the ecu. the result was 0 knock, so my problem was definately an engine noise. All of the basics were checked, i used a pressure tester to test for boost/vacuume leaks, compression test is good, Other things I have tried: 1.) new 3g lifters. 2.) new mitsu knock sensor 3.) new timing belt idler bearings and water pump (there was a small whirring noise from the front of the block.) my car has had the balance shafts removed long ago. I also had personally rebuilt my enging about 10,000 miles ago so was dead set convinced that it couldn't be mechanical problems.

Well, I finally gave up last week and pulled my engine out and tore it down. To my horror, the lower end was totally trashed. All of the mains and one of the rod bearing were totally wiped??? The engine had plenty of oil pressure and didn't make any audible rod knocking sounds. At this point my best guess is that something nasty wasn't cleaned out of the block. Not sure how, as after the machine shop was done cleaning, I personally opened all oil passages and ran a set of cleaning brushes through the block and head with LOTS of soap and water. Maybe the oil cooler??

Even though there was no indication that my lower end was bad, the knock sensor was hearing the bad rod bearing. Sooo, I guess my point is that if you can't find an obvious reason for your knock, there is a possibility that the knock could be lower end problems.

John-

 

[WhatsADSM]

Well for a quick update.. I went to the track and noticed that basically when I am using race gas the car is a totally different animal. I get all my timing back, I can lean it out a bit so it doesnt have to be so pig rich, and I can turn up the boost a bit.

In any case I think sometime next week we are going to tear it apart and replace the head with a totally polished one hoping to eliminate any hot spots, because there is no real reason I should be knocking on 8.4:1

Murray.

 

[LightningGSX]

When you guys speak of knock count or knock sum, is this counts of knock over a certain time period?average?

 

[loreak]

when i ran at the track and did a log i had the hugest spike of knock in 1st gear it was like all the way to the top of the graph, then it went away completely in 2nd and 3rd, i was like wtf, and it occasionally does it on part throttle, im gonna try MCCC

 

[1LE]

As an aside... The usage of Mobil1 motor oil seems to cause phantom knock for some people.

 

[GSX JOE]

well this is an old thread i found while searching, any updates w/ anyone? Im getting a lot of the same symptoms as most people in this thread. Im getting 43 counts of knock while at part throttle which is about 20-25% throttle on the afc. As soon as i left off though the count will drop to 0. My car does have pretty low compression also if that matters.

 

[GSX JOE]

O and I am using mobil 1 oil right now too, but im not sure on how that would cause phantom knock?

 

[Newlogics]

Well, I pinpointed my part-throttle knock to my tranny.
It's making some sort of nois/vibrations to trip knock sensor.

The reason I know it, is because I'm on a new fullly built engine and still get some phantom knock at part throttle.

I do know that there were other contributers to te knock situation, since it has been worse before the engine swap. Cleaning conbustion chambers with MCCC did reduce phantom knock quite a bit on my old engine.

 

[Groomz]

I'll add my knock story to the saga.

My 95 2G has lifter tick out the wazzoo. I am running 15W-50 Mobile 1 which may contribute, as well as the stock lifters. Its fun to drive because as you reduce the throttle the timing comes back and the car accelerates faster. Less throttle and more speed.

I plan to switch oil brands and lifters to solve the problem. As for WhatsADSM, I would check for any loose parts that could cause vibrations. Maybe you've already done that, but I found a bolt loose that was vibrating like crazy when driving. I tightened it up and things got a little better. Good luck figuring it out.

 

[Fattie92]

Im pretty interested in the Mobil 1 casueing knock... I run there 15-40w in my motor (stock internal 92 6 bolt)..I dont get much knock while crusin, just when i go more then 50% throttle. It will go to 43, and stay there till i let off ... my knock sensor (stock), is all goowie. som i ordered a new one hoping that will fix it.

But if Mobil 1 can cause it, then what oil should I switch to?

 

[Newlogics]

Originally posted by Fattie92
Im pretty interested in the Mobil 1 casueing knock... I run there 15-40w in my motor (stock internal 92 6 bolt)..I dont get much knock while crusin, just when i go more then 50% throttle. It will go to 43, and stay there till i let off ... my knock sensor (stock), is all goowie. som i ordered a new one hoping that will fix it.

But if Mobil 1 can cause it, then what oil should I switch to?

Although it's a neverending saga, when it comes to which oil is better, I can say that I had positive experience with Penzoil 10W-30 synthetic. For some odd reason, redline increased my knock on the old engine by a lot. I haven't tried redline on the new one.

 

[doug]

Interesting-- I just bought some Red Line for the first time and am going to put it in this evening. I'll look forward to seeing if there's any change in my knock count (or lifter tick problem). I am getting a little knock starting right at 5000 RPMs, on the few pulls I've done with DSMLink.

 

[Newlogics]

Originally posted by doug
Interesting-- I just bought some Red Line for the first time and am going to put it in this evening. I'll look forward to seeing if there's any change in my knock count (or lifter tick problem). I am getting a little knock starting right at 5000 RPMs, on the few pulls I've done with DSMLink.

Dude, you don't have to live with that lifter tick!

A set of new revised lifters is $7.50X16, and it's relatively easy to put them in. You don't even need to take cams out.

 

[ITSME4G63]

I've heard that removing the knock sensor does wonders for your car, no?

 

[GSX JOE]

Is that a gaurantee to stop lifter tick? I would assume thats a mitsu part? And how likely is lifter tick to cause knock at wot?

 

[Newlogics]

Originally posted by GSX JOE
Is that a gaurantee to stop lifter tick? I would assume thats a mitsu part? And how likely is lifter tick to cause knock at wot?

I've replaced mine about a year ago, and never heard a tick since. The revised lifters have top oiling hole that is about 5 times bigger, so it doesn't get clogged easily.