De-sensitizing knock sensor!

[soldave]

Ok long story short doing some tuning on my Evo 1. With stock cams we were able to hit 1.5 bar with about 20 degrees of timing and only about 6-10 counts of knock running 100 octane fuel.

Ok here goes the tricky part. We switched my stock cams in favour of FP1x cams. Now the car reads a linear knock count progression up to 25-29 counts on the logging. It doesn't matter what boost we run or how much timing I pull out of the CAS it reads 25-29 counts consistently in a linear progression (even on stock boost it's just under 20 counts). We are also using the Apexi RSM logging back to back. Long story short I am positive the 25-29 counts are not real knock. Its engine noise.

My question is to you guys I have heard of using lots of teflon tape on the knock sensor and re-torquing to a lower spec, to desensitize the knock sensor. How much will this desensitize the knock sensor? As we basically need to reset the baseline to around 20-25 counts.

Any other tricks are anything that people know will desensitize the knock sensor and still retain it in the block? (no zip tying it to the firewall...that's a bit too dangerous at this point).

Thanks for any help in advance

 

[cbrfrenzie]

Make sure your lifters are not bottoming out in the head. The increased lift of the new cams could be causing the lifters to fully bottom out on themselves, causing very a large engine harmonic at or around the knock sensors frequency window. Also make sure the lifters were primed nicely.

The stock knock sensing circuitry is very good, as it filters engine noise very nicely (I've done a full frequency response on the circuit). It sounds like there is some other problem, and de-sensitizing the sensor would be a band aid.

There is a pin on the knock sensing "card" that is the "back ground" level that rises with RPM and feeds into the comparator circuit that latches the output. you could take the cover off of your ecu, and solder a temporary wire to that pin, and log its voltage to make sure it is in fact rising with RPM. IF this part of the circuit is failing then that will definitely cause your symptoms. My guess is that this is highly unlikely, since the system worked fine with your stock cams.

Just my 02

 

[soldave]

When you say "bottoming out on the head" are you talking about coil bind? If so then I have .030-.040" before coil bind so I should be OK there. And people use the FP2 cams all day long which have the same lift and no similar problems.

 

[bastard dsm]

make sure you installed the cams correctly,i have seen people install cams and have had the sames prob. ### they were off one tooth on the timing belt.

 

[cbrfrenzie]

When you say "bottoming out on the head" are you talking about coil bind? If so then I have .030-.040" before coil bind so I should be OK there. And people use the FP2 cams all day long which have the same lift and no similar problems.

I guess they don't really "bottom out on the head", they bottom on on themselves. Since they are hydraulic lifters, they compress on themselvs. If they are compressing all the way, they will make a nasty engine harmonic.

Since the problem didn't exist before the new cams, it makes me think valve train. Also, if the cams are a re-grind, and not brand new stock, then the base circle of the cams could be altered, meaning there is a small distance between the cam lobes and the rocker arms with the lobe 180 degrees off from the rocker arm. Each time the cam comes around and the lobe makes contact with the rocker arm, it could be making a "smack", instead of being in constant contact.

Do your lifters "tick" ?

More stuff to check

 

[bastard dsm]

these are fp cams and they dont have that prob.,the lift isnt that much bigger than stock but
the duration is longer.i dont think that is the prob. he is having, sounds like cam timing is off.
a dsm will run with the cam timing off a tooth and still not be noticeable unless you try to get in to boost.

 

[soldave]

But it's only noticeable at 6000rpm up, when the knock really kicks in. Before that there is hardly any knock. If the cam timing was off, wouldn't I be having problems further down the rev range? And would I still be making the large increase in power I've seen since installing the cams if the timing was wrong for them?

 

[mavisky]

Fp1's and Fp2's are fin on stock cam's, the X grinds require some sort of spring upgrade. Says so right on their site.

 

[bastard dsm]

But it's only noticeable at 6000rpm up, when the knock really kicks in. Before that there is hardly any knock. If the cam timing was off, wouldn't I be having problems further down the rev range? And would I still be making the large increase in power I've seen since installing the cams if the timing was wrong for them?

hmmm,well you said that you have always had knock to start with.you might have carbon build up on the pistons,try sea foam and see if that helps the knock prob.evo's have a very
agressive timing map and are gas here isnt 100octane like it is in japan.try mixing the gas with 1-2 gallons of e85 or octane boosters and see if that helps also,that can tell you alot.

 

[soldave]

Fp1's and Fp2's are fin on stock cam's, the X grinds require some sort of spring upgrade. Says so right on their site.

Spoke to FP a number of times about this (including this evening) and they said the spring upgrade would not be necessary in my situation.

hmmm,well you said that you have always had knock to start with.you might have carbon build up on the pistons,try sea foam and see if that helps the knock prob.evo's have a very
agressive timing map and are gas here isnt 100octane like it is in japan.try mixing the gas with 1-2 gallons of e85 or octane boosters and see if that helps also,that can tell you alot.

But before the cams went in we were tuning up to 1.5 bar of boost with, at the most, a couple of counts of knock.

 

[soldave]

OK - maybe this will help you guys a little or give you some more info to go on. Got 3 logs for you here. The first one is pre-cams installation and is when I was boosting about 22psi/1.5 bar. Second log is with new cams in and running about 18psi/1.25 bar. Third log is post-cams and running stock boost on the car (11psi/0.79 bar).

Pre-cams
Post-cams, 18psi
Post-cams, stock boost

 

[soldave]

A couple more logs for you to analyse here. First of all, this morning I put the stock chip back into my Evo to compare with the newer chip I had in and see if it helped with the knock problems I was having. I think the timing is better with the stock chip to be honest, and the only problems with it are the lack of launch control and the speed limiter is back on. And I was making just about the same amount of power with the stock chip. See the first link below for details of this run. We were still getting the knock though, and now we are pretty sure that the knock is real. We confirmed this by taking the car to redline in 4th gear but staying off boost. At the most we had 1 or 2 knock counts. On boost we were getting 30+ counts again.

We then adjusted the cam angle sensor to 2.5 degrees, and then proceeded to remove the knock sensor and teflon tape it. The knock sensor could probably do with being replaced with a new one, but without having one to hand, we put this back in and loosely torqued it. It did its job partly, reducing knock counts to around 20. This was also shown in our power figures, and we ended up doing one run and hitting 323HP according to our Apexi RSM - an increase of 19HP from the start of the day.

So getting better but still plenty of knock that needs to be removed somehow.

Here are the logs:
First run of the day on stock chip
Final run of the day after teflon taping knock sensor and playing with cam angle sensor

 

[soldave]

I should probably add a P.S. to this. Although the timing readings are in the logs, we have been manipulating the cam angle sensor which logger did not compensate for. For example, for yesterday's runs the logger had a base timing of 5 degrees set, but the cam angle sensor was set at 2.5 degrees.

 

[JeffGST]

Instead of manipulating the CAS to 2.5 BTDC, you should retard timing at 5500 and ESPECIALLY 6000 RPM. The stock ECU peaks and targets over 22 degrees of timing at 6000 RPM. This is the spike that you need to get rid off. Read my timing page and study the 1G timing curve graph toward the bottom of the page.

http://www.jeffgst.com/id20.html

The 5500 and 6000 RPM areas are what you need to concentrate on. When DSM's begin to knock, they wont stop knocking until you let off the throttle. BUT, if you can stop the knock from even starting, then the whole log is usually knock free to redline.

What EM are you using?

EDIT : Did you pull your plugs and notice any metal flaking on it yet?

 

[soldave]

I'm gonna be very dumb here, but EM? Engine management? This is where another problem comes in at the moment. I am using the stock ECU with a stone-age 5-knob SAFC for tuning AFRs. But I do have an Ostrich on order at the moment and when I get that I'll be installing Tunerpro on a laptop and (providing I can find a definition file for the early Evos), I'll be able to actually change timing without playing with the CAS.

Haven't pulled the plugs as the ones that are in are brand new (as in less than 100km on them)

 

[64_Frankenstein]

I guess they don't really "bottom out on the head", they bottom on on themselves. Since they are hydraulic lifters, they compress on themselvs. If they are compressing all the way, they will make a nasty engine harmonic.

Since the problem didn't exist before the new cams, it makes me think valve train. Also, if the cams are a re-grind, and not brand new stock, then the base circle of the cams could be altered, meaning there is a small distance between the cam lobes and the rocker arms with the lobe 180 degrees off from the rocker arm. Each time the cam comes around and the lobe makes contact with the rocker arm, it could be making a "smack", instead of being in constant contact.

Do your lifters "tick" ?

More stuff to check

I think this could the problem Im having. My cylinder head has tons of nose. It wasn't like this before I upgrade the valve springs and the cams. Also it shows 20+ counts of knock during lightly acceleration according to my datalogger. Thought that it was a bad knock sensor but that wasn't the problem. I hope the cylinder head is the problem.

 

[Black_Bullet]

Soldave,

Did you ever get meth, ostrich and. or Tunerpro going?
I was wondering your results. You should replace your knock sensor with a new one for sure.

Im positive your knock issues will be manageable when you can properly tune your timing maps
like I mentioned awhile back over on dsmtalk.

I also found that cams increase cylinder pressure/ make the car more detonation prone at the same psi. At least it did with my car, Initially I had to retune it some because precams I had 0 counts of knock on a 3rd gear pull before installing, and then after I put the cams in I was consistently getting 7-10counts on the same exact psi. But

I found what the car likes and I can get decent timing advance now ( up to 19-20degs) with 24-25psi falling to 20 by redline on my e316g- pump gas. Ive found that its not so much the overall peak timing deg ( within reason)
but more so the shape, aggressiveness of the curve and the increase rate of your timing adv which is most crucial.

 

[soldave]

Was gonna wait until I got the meth fitted to post a big reply, but yes I got the Ostrich installed and after playing around with it had quite a bit of success.

Started the day with 334BHP (reported on the Apexi RSM) and a reported 27 counts of knock. With taking out timing and manipulating the fuelling a little, an hour or so later we had hit 362BHP and 5 counts of knock at the most. Think that coule be classed as a minor victory! I know the RSM is probably a little out on its absolute power estimations, but it's a great way of checking if the things we do increase or decrease relative power.

Meth kit is here bt still waiting to go in. My tuner guy is busy with his own stuff at the moment and I'm happy with how quick my car is... for now! If anyone is considering it, I can highly recommend the Ostrich.

 

[haioku-rocket]

Was gonna wait until I got the meth fitted to post a big reply, but yes I got the Ostrich installed and after playing around with it had quite a bit of success.

Started the day with 334BHP (reported on the Apexi RSM) and a reported 27 counts of knock. With taking out timing and manipulating the fuelling a little, an hour or so later we had hit 362BHP and 5 counts of knock at the most. Think that coule be classed as a minor victory! I know the RSM is probably a little out on its absolute power estimations, but it's a great way of checking if the things we do increase or decrease relative power.

Meth kit is here bt still waiting to go in. My tuner guy is busy with his own stuff at the moment and I'm happy with how quick my car is... for now! If anyone is considering it, I can highly recommend the Ostrich.

We will hook it up next weekend dave and retune the car. I didn't forget about you.

 

[soldave]

Haha. Hey man, how's it going?

There's no rush at all on the meth - get your car car up and running first. Mine needed a break anyhow.

 

[Black_Bullet]

Was gonna wait until I got the meth fitted to post a big reply, but yes I got the Ostrich installed and after playing around with it had quite a bit of success.

Started the day with 334BHP (reported on the Apexi RSM) and a reported 27 counts of knock. With taking out timing and manipulating the fuelling a little, an hour or so later we had hit 362BHP and 5 counts of knock at the most. Think that coule be classed as a minor victory! I know the RSM is probably a little out on its absolute power estimations, but it's a great way of checking if the things we do increase or decrease relative power.

Meth kit is here bt still waiting to go in. My tuner guy is busy with his own stuff at the moment and I'm happy with how quick my car is... for now! If anyone is considering it, I can highly recommend the Ostrich.

Great to hear. So a rough guess you probably got about 320 to the wheels or something with only 5 counts ! See thats what im talking about. That also comfirms your previous knock was real. Good thing its fixed now, your motor will be much happier. Im going to have to jump on a ostrich soon also soon as I get a laptop for xmas.
Ive been tuning with evilscribe, I probably wont switch over to Tunerpro but sounds like your having good success.

Just keep us updated with your results on meth.

 

[soldave]

I may have meant to say WHP for my HP figures instead of BHP. The RSM gives figures in PS, but am assuming the way it works it will find a WHP for you. It is a little on the high side I think but pretty swift either way.

Once I get meth on I will report back and may post my maps to show you how it has all changed.

 

[Black_Bullet]

I may have meant to say WHP for my HP figures instead of BHP. The RSM gives figures in PS, but am assuming the way it works it will find a WHP for you. It is a little on the high side I think but pretty swift either way.

Once I get meth on I will report back and may post my maps to show you how it has all changed.

Yea like i said, 320 wheel hp
Yea just post those maps. That 100 octane must be nice to get at local gas stations.