Knock knock..

Hey guys,

I just recently installed a 3.3" pulley on the riv and damn shes starting to pullll . But alas, during WOT in the upper 4000RPM + range Im starting to get some knock up til 3*. Before the pulley, With all my current supporting mods I never had any resulting knock til i installed the new pulley. Does anyone have any recommendations as to a way I can get rid of the knock and enjoy the newly installed pulley? I ordered an AFC 1.1 and I'm contemplating ordering the rear ported exhaust manifold... any thoughts? thanks!

id forget the PEM and sell the front plog and get some SSAC headers and a tune with a 3.3 pulley

That is a thought, though I already welded in my down pipe and cat to the resonator, and a lot of the headers I've seen incorporate their own DP and not bolt up to my cat. I'm currently on a tight budget so thats why the PEM seemed rather obtainable. Any other thoughts? Would sending in my PCM to Intense or ZZP be an option for a updated tune? Or would the AFC 1.1 be able to tune out some of the knock?
Thanks!

Yeah I couldn't run my 3.4 KR free until I put 1.9 rockers on. I could never run my 3.2 pulley KR free. I can now - I have a cam and Gen V blower, so I can run the 3.2 pulley no problem, but before the cam and Gen V I couldn't do it. I tried a ton of things, adding fuel all over and the only thing that works is pulling away timing, to the point where the car was slower.

Headers might help you get over the edge, but I can't say as I could never get it to work.

Good luck!

Someone once told me that KR can detonate pistons.. I don't buy it

When i looked at the Dashboard and saw the title( knock, knock) and the name of the last person to post (98rivieara98)........
I thought, I wonder what Travis has to say.?????
Knock, knock...............BANG.

Timothy, the AFC is a good idea for an inexpensive tune, but the AFC 1.1 isn't enough - you need an AFC 2.0 or higher. Then you can use the Aeroforce to scan and add some fuel where needed.

Note: you can add fuel to kill the knock, but if you add too much you won't make any more power, even if you can drop to a smaller SC pulley. The extra boost will build low end torque, but not much HP. I think 3.4" is plenty small for your current mod list. To get the most of what a 3.3" has to offer, I'd suggest headers.

Nothing wrong with tuning the 3.4" and enjoying a safe, good running car.

Rickw wrote:

When i looked at the Dashboard and saw the title( knock, knock) and the name of the last person to post (98rivieara98)........
I thought, I wonder what Travis has to say.?????
Knock, knock...............BANG.

Hey guys, thanks for the feedback.

Aaron, unfortunately, the only AFC I could find was the 1.1 Where could I find a 2.0 or higher?

My current set up has been working wonders. The only thing is, I had gotten side swiped last year and my riv was totaled. ( but I rebuilt her ) Sooo in the meantime i was hoping to get a lil more power out since I only have 65000 miles lol

Would going back to the 3.4" and getting an updated tune from zzp or somewhere be a better option?
Or pushing onward with the 3.3" and is the AFC 1.1 any help to me? I was also considering having my M90 ported ( Ive heard that can make it nearly as efficient as a gen V? )


Thanks !

I would say you could make more power and keep your engine safer on the 3.4. The only way to drop lower than a 3.4 without headers is an IC IMO. You could try to run a cam but the exhaust would still be a severe bottleneck. I've heard on a scale of 1-10 with 10 being the Gen V, a well ported Gen III would rate a 7, so it would be a good improvement, but if youre gonna take the time to port it ya might as well just go Gen V Its pretty hard for Intense or ZZP to tune the PCM if they cant make any real time runs on it, so you'll end up getting one of their cookie cutter tunes which may or may not suit your mods and car. Investing in a tuner is a great mod that would help you in your quest for smaller pulleys. Plus there are many people on this site who are willing to help out with your tune!

Thanks a lot guys for all your input! I caved and ordered the AFC 1.2. This was my first shot at tuning. I adjusted it to 102% and my LRFTs actually leveled out from +7.8 to 0.0 and i killed about 3 degrees of knock ( 6*+ to 3 *) And really felt some of the power comeback from the lack of knock.Then i adjusted it again to 104% and my LRFTs are steady around -5.0 but lowered my knock from 3* to about 2*

Aaron, taking into consideration what you had to say , should i just stop here and not add anymore?

And Matt i definitely agree, I won't go the ZZP route, but i might look into the tuner since i know this won't be the last GM I own lol

That's the main problem with AFC 1.x - you can't tune idle, cruise, and WOT independently. So you might see 0 LTFT sitting idle, but something else at 65 mph, and WOT is up in the air. When you say you have -5 LTFT, is that at idle, cruise, or WOT?

Yea I'm definitely starting to notice this flaw. With the setting at 104%,and a bit more driving, it would idle at -7.0, cruise around -5.0 and WOT around +3.0 with 1* knock. I then set it down to 102% drove for about 40 mins and it would cruise around 0.0, idle around -3.0 and WOT +6.0 with a peak of 3* knock.

To get a better idea of how this works, the PCM reads the MAF, which then interprets the frequency, and commands the fuel injectors accordingly, and then the LRFTs self correct the fuel injectors by reading the O2 sensor?

Please correct me if I'm wrong, I just want to get the rite flow chart in my head lol

Also, I know the ideal is to stay at 0.0, but is it a better situation to be in if the engine is operating in the +7.0 range and no AFC, or in the -7.0 range with the AFC?

are these just blimps of 3* or are these consistent?

ericde wrote:

are these just blimps of 3* or are these consistent?

dude, this thread died Nov. 26th 2009

I didn't want to be the one to break the news, but I noticed that also, and I've not seen landyaht97 (the last one to post) on here since.

The riv was all warmed up and it was 50-60* out and i had no knock from 0-60mph, but from 60-75mph it spiked up to an average of 5.3KR an in less than 1 second it goes down to 2.8-3.5KR. how bad is this and what can i do to fix or reduce the knock? i use 93oct and put in drigas with injector cleaner in every week or biweekly.i plan on upgrading fwi to be colder.

robertwolf86 wrote:

The riv was all warmed up and it was 50-60* out and i had no knock from 0-60mph, but from 60-75mph it spiked up to an average of 5.3KR an in less than 1 second it goes down to 2.8-3.5KR. how bad is this and what can i do to fix or reduce the knock? i use 93oct and put in drigas with injector cleaner in every week or biweekly.i plan on upgrading fwi to be colder.

I would lay off the dry gas (NY state gas already has a lot of alcohol) and find someone with or purchase a PowrTUner and adjust your fuel trims/maps.

Albertj

Rob, I have two suggestions/observations based on your issue:

1) around here (MA), they use a winterized blend of fuel until mid April. It is weak stuff and all our performance cars are more prone to KR here until the summer gas comes back.

2) I couldn't run a 3.4 pulley KR free until I put in 1.9 rockers. You don't really have enough airflow for a 3.4 based on the mods in your sig. Try a 3.5 pulley until you are ready to open the valves more. A cam would work even better

deekster_caddy wrote:

Rob, I have two suggestions/observations based on your issue:

1) around here (MA), they use a winterized blend of fuel until mid April. It is weak stuff and all our performance cars are more prone to KR here until the summer gas comes back.

2) I couldn't run a 3.4 pulley KR free until I put in 1.9 rockers. You don't really have enough airflow for a 3.4 based on the mods in your sig. Try a 3.5 pulley until you are ready to open the valves more. A cam would work even better

Agreed, headers would also do the trick.

what would be the lest amount of money for the results

it is almost out of the question to put a 3.5 inch s/c pulley on b/c i have no way to get it on b/c no one has a pulley press around hear.

How did you get the 3.4" press on pulley done.?

robertwolf86 wrote:

what would be the lest amount of money for the results

I would say cheap headers (SSAC). You could run a cam or rockers, but that extra airflow would still be restricted by the stock manifolds.

robertwolf86 wrote:

it is almost out of the question to put a 3.5 inch s/c pulley on b/c i have no way to get it on b/c no one has a pulley press around hear.

You could buy a used snout with an MPS installed

SSAC'c and 1.9 modified rockers are a good first step.