knock at low boost

[6instantaneous6]

Hey guys, here is the story.....

Had boost set up at 8 lb and showed incredible kr at 11 and jump to 16 kr at about 70-80mph. Figured this was false knock but still turned boost down to 3 lbs just to see what happens. Well, at 3lbs of boost I got 11 degrees or a little higher...let of throttle and then comes down gradually.

Checked out the knock sensor and it was excessively tight...so adjusted to finger tight. After, kr came down started at 4.5 then up to 5.5 @ 70-80 mph and scanmaster read- 839 on 02's.

Here are scanmaster numbers at idle
AF 06
lb 43
lnt 127
bl 106
ats 97
iac 00

 

[BlackBandit]

Clean the threads on the knock sensor and then torque it with a torque wrench. I think the proper spec is 14 ft-lb's. What are your o2 readings during all of this? Do you have a pressure gauge on the rail? If so does it hold pressure when you turn off the car? Have you pulled your plugs and looked at them? If not you should.

 

[6instantaneous6]

Clean the threads on the knock sensor and then torque it with a torque wrench. I think the proper spec is 14 ft-lb's. What are your o2 readings during all of this? Do you have a pressure gauge on the rail? If so does it hold pressure when you turn off the car? Have you pulled your plugs and looked at them? If not you should.

I did clean the threads on the knock sensor, don't have a torque wrench that is goes that low in ft lbs.
O2 readings were 839.
I do not have a fuel pressure gauge.
Plugs look like they are burning normally (fairly new as well). I could take pics of the plugs if need be.

 

[BlackBandit]

Sorry, I missed the o2 number when I read your first post. It looks like you need to adjust your iac. I'm assuming you're tps numbers are correct. Pics of the plugs would be good. If you can't get them then look to see if there is any variation in the color between them. What kind of fuel pressure regulator do you have? It would be a good idea to check your fuel pressure with the line off and also while under boost. If you can't check the actual pressure right now then at least check to make sure you are getting a vacuum signal to the regulator.

 

[6instantaneous6]

Sorry, I missed the o2 number when I read your first post. It looks like you need to adjust your iac. I'm assuming you're tps numbers are correct. Pics of the plugs would be good. If you can't get them then look to see if there is any variation in the color between them. What kind of fuel pressure regulator do you have? It would be a good idea to check your fuel pressure with the line off and also while under boost. If you can't check the actual pressure right now then at least check to make sure you are getting a vacuum signal to the regulator.

To be continued on taking pics...can do that monday. I have stock fuel press. regulator.sorry for not posting list of mods...here they are..

TA-49, MAF translator, pypes exhaust, turbo savor, stock chip, stock injectors

 

[87granny]

Well if you have a stock chip with a TA 49 thats not gonna work good for you for starters you need to add fuel through the chip about 10 to 12 % more because the 49 pushes more air than the stock turbo ask me how i know i suggest getting in touch with Eric a Turbo Tweak and getting a chip burnt for your combo to start with also your gonna need an adjustable fpr cause he says to adjust fuel pressure to 43 psi line off also your iac is too low. Also don't hammer on it anymore unless you wanna be in the i blew a head gasket club

 

[6instantaneous6]

Well if you have a stock chip with a TA 49 thats not gonna work good for you for starters you need to add fuel through the chip about 10 to 12 % more because the 49 pushes more air than the stock turbo ask me how i know i suggest getting in touch with Eric a Turbo Tweak and getting a chip burnt for your combo to start with also your gonna need an adjustable fpr cause he says to adjust fuel pressure to 43 psi line off also your iac is too low. Also don't hammer on it anymore unless you wanna be in the i blew a head gasket club

Understood.

 

[6instantaneous6]

Update 7/12/09

Ok...here's whats been done since start of topic:

walbro340 and hotwire, afpr, 42lb injectors, TT chip.

Well it seems I am STILL getting knock...at about 65-70 mph i'm getting kr of 3.5 then to 5.2 and 6 AT 4 LBS OF BOOST.

o2 readings are about 820.

I can feel a big difference in power though the car just doesn't want to go anymore while still giving out kr @ 4 lbs of boost. (TT chip is set for 15-17lbs, 93 oct)

fuel pressure is set at 43lb line off (don't know what it is at WOT...Gauge is mounted on rail)

Here are readings from scanmaster at idle....
Af-04
L8-30
Int-128
Bl-132
Ats-93
iac-14
cc-223

Someone please point me in the right direction. This car hasn't ran right for about 1 1/2 years.....which is why I havn't driven it.

PS.....I put 10 gal of 93 octane and 2 gal of 100 oct that I had left over.

 

[TurboDave]

First off, what kind of wastegate are you running that you can get the boost that low? External gate?

In reading your posts, you're implying that the KR is happening while going down the highway, and NOT at WOT... Is this true??

If so, you have false knock and need to track down what is hitting what to make the noise.

 

[6instantaneous6]

First off, what kind of wastegate are you running that you can get the boost that low? External gate?

In reading your posts, you're implying that the KR is happening while going down the highway, and NOT at WOT... Is this true??

If so, you have false knock and need to track down what is hitting what to make the noise.

I'm running stock adj. actuator. So there is no way I can get that low of boost with this actuator?....maybe the nylon hose to the gauge has kink in it? I'll double check my lines and run another gauge and hose to make sure.

My kr is going down a highway and comes before I can even get a recording on the scanmaster.

As far as false knock goes-I've checked dp to a arm clearance, exhaust to firewall clearance, and the knock sensor. What else causes false knock....if that is my case?

 

[V8Assassin]

Be very careful, I thought I had false knock one time, turns out it wasn't false and I blew the bottom end of the motor apart.

 

[6instantaneous6]

Be very careful, I thought I had false knock one time, turns out it wasn't false and I blew the bottom end of the motor apart.

Thanks for advise....I don't get on it, as soon as I see kr go to 5 or higher- I let go.

 

[BlackBandit]

How are you measuring boost? If you're using the stock boost gauge then I'm gonig to tell you it's most likely wrong. 5 degrees of knock is too much. A better strategy would be if you see knock, lift.

 

[darkred87T]

I have the same problem. As soon as I get ANY boost, my Caspers guage climbs into the red then goes green if I stay in it. It does this even at part throttle with hardly any acceleration. I have an EGT and WB02 that I watch now instead of my knock guage.

I'm pretty sure my problem is flase knock as my AF is mid 10's and egts are 1330s with knock gage in the red at WOT. Iv'e made several passes in the high 11's, low 12's with no problems.

 

[6instantaneous6]

How are you measuring boost? If you're using the stock boost gauge then I'm gonig to tell you it's most likely wrong. 5 degrees of knock is too much. A better strategy would be if you see knock, lift.

Have aftermarket boost gauge (autometer carbon fiber series to be exact)

 

[6instantaneous6]

I have the same problem. As soon as I get ANY boost, my Caspers guage climbs into the red then goes green if I stay in it. It does this even at part throttle with hardly any acceleration. I have an EGT and WB02 that I watch now instead of my knock guage.

I'm pretty sure my problem is flase knock as my AF is mid 10's and egts are 1330s with knock gage in the red at WOT. Iv'e made several passes in the high 11's, low 12's with no problems.

Well, hopefully we can get this thing figured out!!! I'm anxiously awaiting what my T can do at its full potential.

 

[V8Assassin]

Did you check the heat shield on the pas side? and what kind of motor mounts are you running?

 

[6instantaneous6]

Did you check the heat shield on the pas side? and what kind of motor mounts are you running?

The heat shield on the headers? What am i checking for?
I'm running stock motor mounts.

 

[GNRick]

This might seem strange, but check for vacuum leaks. I was getting a lot of knock and turned out the cap on the turbo inlet (where the pipe attached to the valve cover when your car was new) had fallen off.

 

[6instantaneous6]

This might seem strange, but check for vacuum leaks. I was getting a lot of knock and turned out the cap on the turbo inlet (where the pipe attached to the valve cover when your car was new) had fallen off.

Ok, just to make sure...its the hole on the inlet bell? If so, yes it is capped.