knock wont go away

[imdrax]

The problem im having with this car is no matter what we do we cannot get rid of knock at pretty much any boost level over 10psi. The car now has:

750cc injectors, Eprom Ecu with chip for compensation for the 750's, walbro 255lph, aeromotive afpr, b16g, 2g maf, fmic, &supportings.

Trying to tune this setup at 13 psi we are getting anywhere from 20 counts of knock with afc at +10 to 5-7 counts with .91 o2 and only 50% duty cycle over 4000 rpms with the afc at +30%!!!!!!!! I just dont understand how we can be at such a low duty cycle but be leaning out with the afc at 30+???
That is even with the new ecu compensating for the injectors. This has been the same problem since day one and nothing has fixed it. I will list EVERYTHING we've tried below:

replaced fuel filter, tested afpr for 1:1 rising rate(passed), rewired walbro, changed wires, plugs, sent afc neo to be reflashed to updated program version, boost leak tested, no fuel leaks, car runs fine, idles fine, fp set to 43psi with vac disconnected(tried 37,45 nothing matters), cylinder 1,2,3 spark plugs are white and cyl 4 is not white, and more i cant think of.

Before the new injectors we were running 560's with stock ecu and all the mods the same. we were +30% on the afc running around 90% duty cycle and still getting knock at 13psi. We have not been able to turn up the boost over 13psi because i have never gotten even one solid pull with no knock. We are completely stumped. Ive dealt with 6 of these cars previously and never had i had so much trouble.

If anyone can help me think of anything else that may be causing this please let me know. The only thing next i can think of trying is to pull the pump and ceck the wiring there, and test the coil pack. Otherwise i am out of ideas.

 

[talondave]

Do you have a wideband? Kinda sounds like rich knock if you have the fuel +30 on the afc with 750cc injectors. Also check to see if anything is loose or vibrating around the knock sensor.

 

[the_mork]

It sounds like phantom knock if you can get it to be repeatable and consistently high then that is probably your problem.

Do you have revised lifters? One thing that I've just learned about that is very popular with the evo crowd is a device called a det can. It is a very simple audio monitoring device that amplifies engine noise into the cabin so that you can listen for knock without relying on the knock sensor. Do a search or the instructions are on the second to last or so page of the evo8 ecu thread. If you can verify that there is no real knock then you have some work to do. On an evo you would adjust the knock multiplier for the range you are in but I have no idea if the chip burners have devised a way to do this yet.

 

[imdrax]

Im 99% sure its not rich knock. By adding fuel i can reduce the knock but by the time i get knock to go away i am at 30+% on the afc. I did a base pull on the new ecu with the compensation and left the afc at 0 and pulled nearly 25 counts. I was able to tune down to 5 counts by adding 25% which leads me to believe its not rich/phantom knock. Although the knock sensor is quite possibly the only part left on the car that i have not tested/replaced.

Also the lifters do make quite a bit of noise but if im able to tune out some knock by adding all this fuel again i dont see how it would cause knock.

Does anyone else have any more thoughts given the circumstances?

 

[PIMking]

I'm also having knock issues around 2500 and 3k under light loads. I have came to the conclusion that my pos knock sensor that came on the car is probably bad so I got a new one on the way.

I know I run lean on the upper RPM ranges so I just have to add fuel. Wideband helps alot I have to wire it right to the ecu so I can log it.

 

[dylnwit]

imdrax-
Have you checked the knock sensor in some way? (looked at it, felt around it to see if it's 'gooey', used a known working one from another car?). If you haven't checked the sensor, then I'd recommend doing so, especially if it's the original. Do you have a wideband to use? The stock 02 sensor is probably better than nothing, but it doesn't have the resolution you need.

 

[PieEyedPiper]

I don't see how you could possibly have any kind of tune with SAFC settings of +30% at 4k and up.
I'd start from scratch. But what do I know, I don't even own an SAFC.

 

[the_mork]

I think that you aren't tuning the knock out at all. I think you are moving to a different section of the load/fuel maps that doesn't provide knock/phantom knock. It isn't about more fuel quenching it it is that you are walking around a minefield. Make a det can or fill it up with 110, start your tune over and see what you get.

 

[turboglenn]

I have to agree with pieeyedpiper, at +30% you should be hitting fuel cut something serious if the AFM was working correctly and everything was wired right., no to mention that at 0% it should be rich as h3ll, but then again I've never liked the NEO, and haven't seen too much come from them even after hacing them flashed.

 

[imdrax]

Knock Sensor is Firm and im sure thats not the issue. mork im not sure i understand what your saying? We have tried running race gas before on the 550's and it did little to help knock, and we still maxed out the injectors at less than 15psi. It just doesnt make sense to me. If you read above right when i put in the new chip with the 750's we made a pull with the afc zeroed out and had 109 counts of knock by 3k rpms and 20 counts by 4k rpms. I cant understand how with the chip compensating for the injectors the car can still run that lean at only 13psi.

 

[toofast82]

Do you have a stock timing map on the chip?
Was the chip coded to correct compensation to run the 2gmas?
It is intended to run 10psi and not much more. Try turning your base timing down a degree or two to see if it helps to get rid of knock. If it does then you're in the right direction.
Get a wideband!
Knock sensor reads in the 40s as max

 

[jrohner]

The stock 1G timing map is quite aggressive, and running an afc makes it even more so. Turn your base timing down. With way too much timing, you wont get rid of knock no matter how much fuel you run; plus there is also such thing as rich knock.

 

[imdrax]

The chip is factoring in both the 750's and the 2g maf. I understand that the knock sensor maxes at 43, my old 90 tsi used to max with a bad sensor. I definately know its not rich knock, seeing as how at 0% correction on the afc it knocks like crazy. I will try dropping the base timing but at 5k rpms we are only seeing a max timing advance of 17 degrees so its unlikely we are too advanced. One issue im trying to figure out is this afc neo, even after having it reflashed it just seems like its not making the right corrections and is the cause of all the problems but theres no way for me to tell unless i go and buy an afc II. I cannot find a single wiring diagram or install guide online for the 1g because the install is different from afc I & II, the wire colors are different on the NEO. Also in order for the NEO to read right we have to set it for "2 cyl" or else if we set it on "4 cyl" our rpm reading is cut in half. Not sure the other versions of afc require this, i cant remember.

 

[the_mork]

If race gas didn't get rid of it then your car is probably not actually knocking.

 

[DJ23GSX]

Agreed if race gas didn't help I don't think its a fuel issue but
I had similar issues with knock. Couldn't tune it out no matter how much fuel I added or took out on the safc. Turned out to be 2 things. The first thing I found was my fp guage was inaccurate. It was reading 8psi higher. I thought I was running 42psi bfp but with the new liquid filled gauge it was really only 34psi. That was actually the second fp gauge that went bad on me in a year or so. I upped the bfp up to a true 38psi and it helped for about a week until my real issue surfaced. Turned out my rewired walbro wasn't pumping out the fuel I needed in the higher rpm's even though it passed the 1:1 rising rate test. I put in a brand new walbro and now I'm running 23psi with 0 knock.

Good luck man I know the frustration.

 

[JayRolla]

WBo2. You need to get one and stop guessing before you kill this motor. Also Im guessing you have a 3" exhaust. You sure your not getting boost creep. Make sure you look at that boost guage at redline and see what boost you are sitting at.

ALSO POST A LOG, ITS WORTH MORE THAN ANY WORDS YOU CAN SAY

 

[imdrax]

How were you able to diagnose the walbro? Ive been wondering about it because its one of the few parts i didnt install on the car myself so i cant verify its functionality. I will be getting a new fp gauge soon also because the one i have im not even sure what brand it is and its made in taiwan. the exhaust is full 3" and no creep. boost is solid where we set it at everytime. I am using mmcd and have no way to upload my logs the best i can do is post a single snapshot or timeframe.

 

[imdrax]

and wbo2 is in the works. im still trying to figure out an inexpensive way to actually log the wbo2 so that i cant look back on it with rpm. as far as i know the aem uego does not do that.

 

[talondave]

Your going to blow your motor if you dont put a wideband in it!

 

[imdrax]

You dont need to be so dramatic. I have successfully tuned more than a few of these cars with as little as a data logger and AFC. I understand a wbo2 or egt is needed here but i can still get a fair look at the engine performance by just reading my knock count and o2v.

 

[toofast82]

and wbo2 is in the works. im still trying to figure out an inexpensive way to actually log the wbo2 so that i cant look back on it with rpm. as far as i know the aem uego does not do that.

For innovate lc-1, you can splice into the egr-t input at pin15 of the ecu. I run my car in "open loop" all the time, so I run mine spliced into the signal wire of oxygen sensor as well and it reads the actual number on mmcd instead of having to convert the decimal figure for the egr-t.
I'm not familiar with how the AEM unit works

 

[DJ23GSX]

How were you able to diagnose the walbro? Ive been wondering about it because its one of the few parts i didnt install on the car myself so i cant verify its functionality.\.

I didn't really diagnose it. I tried just about everything else fuel related with no luck. I was hesitant on dropping $90 on a new walbro not knowing if it would help but I actually found a brand new one (255lph high pressure) for $55 shipped so I jumped on it. The walbro I replaced I put in about 5 years ago and only had 15k miles on it. I guess the only hint I had was every once in a while it would make a weird screech kinda noise and the whine was kinda loud. The new walbro is a lot quieter.

 

[imdrax]

I didn't really diagnose it. I tried just about everything else fuel related with no luck. I was hesitant on dropping $90 on a new walbro not knowing if it would help but I actually found a brand new one (255lph high pressure) for $55 shipped so I jumped on it. The walbro I replaced I put in about 5 years ago and only had 15k miles on it. I guess the only hint I had was every once in a while it would make a weird screech kinda noise and the whine was kinda loud. The new walbro is a lot quieter.

I did notice this one is fairly loud. I think my only option is to just replace it. I will get back to the thread after i drop in the pump and log my afr. Thanks for the help.

I have read about the egr-t splice but i havent found one solid answer from anyone if this works on a california car or not?

 

[RipperXX]

Anyone know the limits of a un-rewired Walbro 190lph I was told that it would only flow around 121lph but isn't that about the same as the OEM pump?



The reason I ask, is I am encountering knock over 4,000rpm at WOT, and with my mods that shit should not be happening. Link shows the car running lean, and seeing as the fuel map starts pulling fuel back out around that point it kind of makes since, but the WB shows about 10.6:1 A/F ratio. However the WB's wiring harness is damaged and I think could be throwing the reading off...



Make since to anyone else? Sorry for the slight off topic post... just also trying to figure out if I should try to toss in a old 255lph HP pump I got off a 2g.

 

[the_mork]

There should be plenty of information in this thread.

http://www.dsmtuners.com/forums/tuning-engine-management/244522-injectors-fuel-pumps.html