causes for part throttle knock

[BADINBLACK6]

comes and goes every time I check to see if fuel pressure is matching boost it's fine lb for lb. My throttle body is dirty from sucking oil from a bad turbo( replaced turbo with ta49) could that cause it. The knock is about 50% of the time I hit 8-12 lbs of boost just enough throttle for scanmaster to record it, the other 50% of the time there is no knock a part throttle. Could my adj reg be going bad( it's pretty old andwas used when I got it)? No header cracks and no vac leaks that I can find.

 

[BlackBeauty]

My problem was that the previous owner put on an incorrect EGR valve. I was causing part throttle knock.

 

[Turbosix6]

Check the ESC module on the passenger fender.

 

[BADINBLACK6]

Turbosix How do I check it? And tonight the car threw a code 21 (TPS sensor) would that have anything to do with it?

 

[BADINBLACK6]

ttt

 

[salvageV6]

A top engine clean or alky. injection system should get rid of any oil residue. If it's been a while since the turbo has been leaking I doubt there is much oil left to cause knock.

Too much timing in the chip can do it.

Colder temps. can do it too.

 

[BADINBLACK6]

I check the esc module and the sensor has 5 prongs coming out of it but the but the connector that you plug into it only had four spot to connect to the fifth spot was just a hole. Is that correct?

 

[Quick6'n'-K.C.]

last thing i would check for is flat cam lobe-

a flat cam lobe can cause knock, but usually the knock happens more at 15psi-

how many miles on the fuel filter and injectors?

 

[Matt Weiser]

I'm coming in late on this thread but I'm having a problem with part-throttle knock too. Just swapped a 125k drivetrain from an '86 TR into my '83 Malibu wagon and I'm seeing quite a bit of knock (10-20*) at light throttle, like when the car is climbing a slight grade on the highway. Seems to go away if I get into the throttle a little more and get a couple # of boost. All the externals are new on the motor (injectors, plugs, wires, module, new valve springs and timing chain, headers, etc. etc.) and compression is good. However, I noticed quite a bit of carbon buildup on the valves and combustion chambers, and not sure if the original fp regulator is up to snuff. Could either/both of these be the problem?

Thx in advance...

 

[BADINBLACK6]

Matt, I wasn't seeing knock that bad I was only getting between 2-5 degrees knock at part throttle. Checkedout everything suggested and they seemed o.k.. Then a couple days ago I unhooked the vac. line going to the egr valve and stuck a golf tee in it and so far no more part throttle knock or tip in stumble. I guess I have a bad egr valve or solenoid. I don't know if that was it but it stopped for now. If that didn't work I was going to replace the adj. reg. mine is old and I noticed sometimes that my fuel pressure was late sometimes going up lb for lb with the boost, so I'm going to buy a new reg. anyway. Can you hear the knock or is the car falling on it's face it might be false knock. Try the top engine clean from what I hear carbon can cause knock.HTH

 

[Matt Weiser]

I haven't heard or felt any knock, but I see it on Scanmater and Tlink. I'm pretty sure it's not EGR related, as I just did a full diagnosis on that system and it seems to be working fine. Does false knock show up on Scanmaster and Tlink? How sensitive is the knock system to a downpipe that contacts the frame? Mine might be RUBBING a little but I don't know if it would actually bang around enough to cause false knock.

 

[BADINBLACK6]

If your down pipe is hitting it can definetly cause knock and it will show up on your scanmaster. Try putting some race gas in and see if you still get the knock, if you do still get knock it is probably false.

 

[turboaddict2]

You can check your motor mounts too if they are bad. Bad motor mounts cause fals knock too.

 

[Matt Weiser]

Was just wondering about using Top Engine Cleaner. Since all the gunk it loosens up will be going through the turbo, any problem with harming the turbo impeller with flying goo? What about clogging the catalytic converter? And should I change my oil afterward?