30 Counts of knock, Not sure why.

[punkrocker00406]

I have a new motor (less then 4000 miles). Compression is good. Timing is good every where. I have a Big 16g turbo running 10psi. I don't think I have a boost leak because it holds 10psi very steady. I logged a 2nd and 3rd gear pull and the results are not good. In 2nd gear the logger says:
RPM 6093
INJD 55.4% (I don't see how thats possible with stock injectors and a big 16g running 10psi)
KNCK 6
O2-R 0.00V (?)
TIMA 19deg
FTRL 83.5%
FTRM 114%
MAFS 1116Hz

Then in 3rd gear:
RPM 5593
INJD 55.4%
KNCK 31
O2-R 0.00V
TIMA 6deg
FTRL 83.5%
FTRM 114%

If any other info about my car is needed please ask. Any insight would be greatly appreciated!!!! Thanks!

 

[punkrocker00406]

Bump. Anyone? Please!

 

[pboglio]

Do you have knock at part throttle or when your at full throttle. It could be a vacuum/boost leak, holding 10 psi even with a large leak is still possible.
If I run aggressive timing at 3000 rpms the car knocks all the way thru the rpm band, only takes +1* more than usual and it goes knock crazy.

Check coolant temps.
Check intake temps.
Run Lucas octane booster or NOS octane booster and see if knock goes away.
Do boost leak check using homemade intake pressure tester.
Run a heat range colder spark plug.
Flush & clean I.C. with solvent.
Run combustion chamber cleaner thru intake manifold to remove cylinder deposits.
Swap out to a known good knock sensor.
Log "front" 02 voltage.

 

[punkrocker00406]

I have a home made boost leak tester. I'll have to do that one of these days soon. I only get knock at high RPMS WOT. Ill have to check the coolant temp. I don't have an intake temp sensor. I.C. was just cleaned less then a month ago. And O2-f a constant 2.08V on my logger. What is confusing me though is the injector duty. How is it only 55% with a big 16g and stock injectors?

 

[pboglio]

55% is lean, I've run anywhere from 65% to 70% at .92 Volts on 450cc injectors and a T25 pulling about 20 lb/min airflow. A Big 16g should pull that kind of airflow at 10 psi and 55% seems way too lean for that. Also, if you have a unwired fuel pump that isn't helping either. I don't know what 2.08 volts would represent, is that a wideband or something?

What exact type of fuel system do you have (fuel pump, engine management, etc.)?

 

[punkrocker00406]

Walbro 255lph pump, not rewired yet I'll do that this weekend, new replacement fuel filter, stock fuel rail, stock injectors, generic AFPR set to like 5psi over stock. Thats the stock o2 sensor by the way, and I have a SAFCII but it's untuned right now. All it acts as right now is a read out for volts and all that. Know what i mean?

 

[PIMking]

Do you have knock at part throttle or when your at full throttle. It could be a vacuum/boost leak, holding 10 psi even with a large leak is still possible.
If I run aggressive timing at 3000 rpms the car knocks all the way thru the rpm band, only takes +1* more than usual and it goes knock crazy.

Check coolant temps.
Check intake temps.
Run Lucas octane booster or NOS octane booster and see if knock goes away.
Do boost leak check using homemade intake pressure tester.
Run a heat range colder spark plug.
Flush & clean I.C. with solvent.
Run combustion chamber cleaner thru intake manifold to remove cylinder deposits.
Swap out to a known good knock sensor.
Log "front" 02 voltage.

On 1g's we only have a front o2

 

[pboglio]

Edit: Yep, 0.00 volts is not good. This happened to me 1 month ago, my speed density pressure transducer reported 12 psi to the ECU when I was at 28 psi, car leaned out to 0.00 volts, car lost 100 h.p. and injector duty cycles were about 30% lower than they should have been. The car didn't knock one bit because I was running 2 bottles of octane booster and a 30% mix of 118 octane xylene. On pump gas I would have melted the motor to the ground.

Time to start looking thru the fuel system starting with fuel pressure at WOT which should be I believe 35-38 psi + boost pressure, etc.

Do this, buy 2 bottles Lucas octane booster at Autozone, dump that into 1/2 tank. I use this stuff when I run 23-25 psi on a hot day on pump gas.

This will kill whatever "real" knock there is, guaranteed. That means clogged injectors, low fuel pressure, over-advanced timing, low duty cycles will all be taken out of the equation depending on the severity. If it still knocks its most likely false knock thru some mechanical source or a bad knock sensor, otherwise it's fuel/timing related.

 

[punkrocker00406]

I just had a vague memory of doing the hacks on the MAFS. And i remember digging the silicone off of that screw on the MAFS that lets air through un-metered. And for some reason I think i opened it the whole way. And if thats the case, that would cause me to run lean. I'm gonna check it tomorrow. I'll let you know what I find.

 

[punkrocker00406]

Ok, I was wrong. I actually screwed that screw in the maf all the way in. Which should cause it to run more rich. Also, i never removed the lower honeycomb like most people do. So its not that I'm getting too much airflow. Its gotta be in the fuel delivery, or maybe the o2 sensor is going bad. I'm gonna try to come up with the cash to get a uego.

 

[punkrocker00406]

I tried turning up the fuel pressure. Did another log. Only got 25 counts of knock this time. 52.3% INJD. 12DEG TIMA. Coolant temp 104.3C... One thing thats confusing me now. Why is o2-f steady at 2.03V. Shouldn't only be getting a read out for o2-f cause its a 1g. The o2-r is all over the place while I'm logging, any where from 0.00V-0.87V. Any thought on that?

 

[pboglio]

Your injector duty cycle is too low. Stock ECU should be flooding the motor with fuel, its not. Something is wrong with the ECU's idea of how much airflow is coming into the motor.
Bad MAF or maybe airbypassing around the MAF in the compressor intake pipe somewhere.

Fuel pressure increase will help, but you need WAY more fuel to bring it back in line. I'd expect around 70-75% injector duty cycle on 450cc injectors. 02 voltages should be between .85-1.00 volts at WOT.

Coolant temps are 219*F which is high enough to cause the motor to knock even more.

 

[punkrocker00406]

Is that too hot? Because thats a brand new motor. And my gauge reads dead center in the op. range. Once it heats up it never moves from that temp. Coolant mixture is good. New thermostat. Fan works the way it should.

 

[DSMopar]

Your injector duty cycle is too low. Stock ECU should be flooding the motor with fuel, its not. Something is wrong with the ECU's idea of how much airflow is coming into the motor.
Bad MAF or maybe airbypassing around the MAF in the compressor intake pipe somewhere.

Fuel pressure increase will help, but you need WAY more fuel to bring it back in line. I'd expect around 70-75% injector duty cycle on 450cc injectors. 02 voltages should be between .85-1.00 volts at WOT.

Coolant temps are 219*F which is high enough to cause the motor to knock even more.

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You've screwed with your MAF that'd be my first suspect, find an unmolested stock one to try first...

 

[punkrocker00406]

Ok. Thanks! Just out of curiosity, which sensor is for the low coolant light inside the car? The reason I'm asking is I went for a short ride today. Let the car warm up as usual. And when I would boost on flat ground or an incline, my low coolant light would come on. But, I check the coolant and oil every time I drive it. And it was full. Thanks!

 

[DSMopar]

It's for the overflow bottle not the 'system' persay... Check the level in your overflow first, the sensor is at the bottom, it's probably fine though.

 

[punkrocker00406]

Oh! Ok. Do you know off hand what the stock MAF maxes out at in terms of HZ?

 

[punkrocker00406]

No one ever did answer my one question. Is my coolant temp. of 104C too hot? Because its a new motor with a new thermostat. Good coolant mixture. But my coolant temp. sensor did come out of a junk yard. Is it going bad maybe?

 

[pboglio]

Yes, 104*C is too hot. Typically should be no more than 95*C (203*F) while cruising. Idle can see as high as 102*C (216*F) before the fan thermostat kicks the fan on.
I believe a stock 1g MAF is done at 2100 hz.

 

[punkrocker00406]

Ok, well the coolant is mixed properly and is full, the gauge never goes higher then dead center in the op. range, my fan works properly, new engine, new thermostat. So should I assume the coolant temp. sensor is going bad? Or what? Thanks!

 

[punkrocker00406]

Bump

 

[Turbo Talon DL]

You have a datalogger so just check for trouble codes. It will tell you if the coolant temp sensor is bad. Another way of checking it is to figure out what the OAT is and then compare that to what the coolant temp and air temp sensors are telling your logger. I think the resistance of the coolant temp sensor rises as it heats up so you could drain the coolant and then pull the sensor and check it out with a meter. You need to check for boost leaks and the O2-r should cycle back and forth. High .89s to mid .95s is a good O2 voltage. Ultimately you want no knock but that is about normal for O2 readings.

I havent seen stock airflow over 1599 HZ in my car. I run an Evo 3 at a lowly 14 psi. My IDCs are usually maxed at the low-mid 90% range on 450s.

 

[punkrocker00406]

Well i just got all this knock crap straigtened out. Just thought I would share what I found for future reference. When I Installed my SAFC I was told that as long as I didn't go in and change settings it would be neutral, meaning not making any correction. Well thats not true . I started doing research on how to tune with the SAFC, I go in and find that its currently set at -28% from 1000rpms up. Thats way lean obviously. So I used my data logger and started adjusting the fuel up. started out at 0% across the board. And progressed from there and got my High Fuel Trim to 99.2% running 14psi of boost. Injector duty cycles are much better now, maxing out at 89%. For the most part i get 0 knock and every so often ill get 3 or 4 counts here and there. And one time i boosted it from roughly 2200rpms up and got 9counts. I did want to put this question out there. Because as far as i know its pretty common. But why is it if you build boost from way down in the rpms like that you are more likely to get knock as compared to building boost from 3200 and up?