Got the car back today.... BUT (Update)

...I am knocking like a bi**h!!!

First off I can notice a BIG difference with the 3.4 and supporting mods. But we could not figure out why it is knocking so much. I'm getting like 2-4* sometimes 5* of knock as soon as I hit 65% trottle.

We think it could either be fuel or exhaust related. He asked what kind of fuel I run and I said the highest octance. So he told me to try a different brand and we also put some fuel injector cleaner in there. So we'll see how that goes later on it the week. Also thinking fuel injectors. Other thing he was talking about was exhaust. He was think at some point I should end up going 3" the whole way back cause it gets kinda restrictive toward the cat.

Another thing he metioned was something concerning the dampener and chain, I believe, but don't hold that to me.

So we are really puzzled, so any suggestions will more and likely be looked into. Thanks guys!

Mod list?

The pulley is too small.

What supporting mods?

2-4 sounds like normal with minimal supporting mods.

Here you are guys:

2000* Ceramic Coated Pacesetter Headers/3" Cat'd Downpipe, ZZP 3.4 MPS, Gatorback Belts, GMPP Sway Bars and Trailing Arms P/U Endlinks, K&N CAI, Optima Battery (Red-Top), Autolite 104's, PRJ 10.4mm Race Wires (Red), Drilled 180* T-Stat, ZZP 3-gauge Pillar Pod, Aeroforce Scan Gauge (Red/Black), Glowshift Oil Pressure and Boost Gauges, ZZP S/C Coupler, Drilled/Slotted Zinc Coated R1 Concept Rotors, Hawk Ceramic Pads, ZZP High FLow Fuel Filter, Aluminum LIM Gaskets, VVME 8000K HID's

no pcm upgrade or tune?

Yes Tuned by PRJ Performance, sorry

So.... Headers, intake, T-Stat, and tune.

Looks like you have one of the lucky cars that needs more. Or get a bigger pulley.

YES!!! I'm so excited to spend more money... SIKE!

Yeah, I guess that's the price you get for modding right...

Someone was telling me to look into a wideband. So what else to you think I should add to the list to get rid of some KR. I've also heard fuel pump and/or injectors and a cat-back to replace the stock piping.

Did you flip your sway bar? It could be false knock.

Some people have had to stratigically place dynomat in the engine compartment and it solved some of the strange KR.

Actually someone else mentioned that on another board. Said it could be rubbing on the headers.

Sway bar on the downpipe can cause false KR. Take off the S/C belt and go WOT. Do you still get knock?


A wideband is absolutely needed. It is a shot in the dark without one. You don't need injectors yet, I would guess your fuel filter before your fuel pump.

Only way exhaust could be the problem would be if you had a clogged cat. How agressively did PRJ tune? You may just need to decrease timing for the smaller pulley.

you got the Aeroforce, let us know some things.

LTFT's are important when you go WOT as well.

If your LTFT's when going WOT (or over like 50% throttle) are NEGATIVE, then that is not very good, neither is being positive but atleast you won't blow the motor from leaning out.

Your PCM has a base value in it for fuel trims when it goes WOT. This base value then adds or subtracts your LTFT from it when you go WOT. So if you're LTFT is negative when you start accelerating and then you go WOT it will take away X amount (X = LTFT) from that base value in your PCM. That could be causing your knock as well, it could be either too rich or too lean. A wideband would be able to tell you exactly but since you don't have one we'll have to work with your LTFT's.

When at WOT or whenever you are seeing knock what are your:

LTFT's
MAF freq
Ignition Advance (timing)
KR
Injector Pusle width

actually, you want your LTFTs to be slightly negative, never positive. If they are positive, you are running lean, PCM has to add fuel to correct the condition.

yes, you are right, but I said when going WOT. When going WOT, it's a completely different story. Some sensors are ignored and other values are put in place.

When cruising around, you can be a little lean and not really worry, their isn't much load on the motor.

If the LTFT's are positive it means that it is adding more fuel to the mixture (yes, you are right, it's running a bit lean) BUT it's doing so to make it stoich. So when it is stoich it is neither rich nor lean.

So, when going WOT if it is negative (taking away fuel from the mixture) it's taking away fuel from the base value which is a best guess stoich mixture, which in turn may very well lean it out. Like I mentioned before, going WOT is a completely different story than just crusing and you'll never know if you are rich or lean at WOT without a wideband.

Ah, good point, my mistake. :-)

Hey, thanks man! I will look into all that as soon as I can. Right now the weather is pretty nasty, don't wanna take a chance.

Zalfrin, i'm not exactly sure how aggressively he tuned it. I'm pretty sure he told me it was running on the rich side.

Yeah, I think i'm going to definately look into getting a wideband. That's kinda my mistake, I guess I shoulda listened to some of you guys and forked over for the wideband. Rookie mistake.

BTW! Is it ok if I leave the 3.4 on there as long as I don't get of the thottle/create knock. If I just drive normal the KR=0. So is it fine to leave it on there.

Thanks a ton guys!

yes, just don't get into PE much (>35%-ish throttle) and you will be fine.

It will be fine. Just don't go crazy. If you go WOT enough you will be shopping for a shortblock.

Take the belt off and see if you get knock

3-4 is not quite the worry. You'd be surprised at the number of stock GTPs that are running 3-4. Get this quite a few of GMs new V8s in the trucks are even getting 3-4 degrees of KR.

Stupid question, was is PE?

PE = power enrichment mode.

Once you hit a certain % of the throttle and under load you'll enter PE mode.

Herc, you do have to remember that a knocking 3.4 is a lot more dangerous than a knocking 3.8. Its the FI that makes it dangerous, the more the pressure, the higher the risk.

[QUOTE]Originally posted by HercMan:
3-4 is not quite the worry. You'd be surprised at the number of stock GTPs that are running 3-4. Get this quite a few of GMs new V8s in the trucks are even getting 3-4 degrees of KR. [/QUOTE

3.8 pulley making 6psi with 4* of knock is not the same as 3.4 pulling making 9psi with 4* of knock.

Apples to Oranges with the trucks. No forced induction.

Ok guys, I emailed Paul about some of the stuff you guys had questions about and this is what he said...

Sway bar is already flipped and has plenty of clearance. 99.99 % chance you won't have knock with the SC belt off... for two reasons... if it is false, then the engine isn't torquing as much with it off so it won't happen. If it is real, then it isn't gonna happen cause it never has happened while not in boost. Wideband will only help for tuning at WOT. You have two problem KR areas, part throttle just as it gets into boost, and WOT... the part throttle KR needs to be determined what is causing it first. I have a wideband that I can used for tuning, but need to have a O2 sensor bun welded in before the cat for the wideband sensor to go into. I would try switching to Shell or BP gas... Or, pick up 5 gallons of 100 octane unleaded race gas and put it in the tank once you are down below 1/4 tank. If the car is still there, it is something false causing it.

You don't want any knock. However, I ran around hard for a year with plugs, wires, intake, ubend on a 3.4. I scanned finally during a mod day and had 6* kr. My engine running fine, just slow at the track!!
Now the tuning world of gp's is soo rich, any kr seems like a disaster. But you can run it till as long as you keep I on the kr.
And your last post, are you saying you have false kr, I am confused?

^^^That second paragraph is what he sent to me...

Paul thinks that my KR is false, but we don't know exactly what is causing the false KR.

I have 2 points when I see KR, when I first get into boost and of course at WOT. What he said about taking the S/C belt was, If I take the belt off he is saying I will not see knock because taking the belt off, I will have less torque and nothing will show up AND nothing is going to show up because I have never seen KR without being in boost.

You should still get the engine rocking pretty good flooring it without the supercharger belt, its worth a try.

I agree with Zalfin. An NA engine is going to more with or without a blower on top

I had part throttle kr.
Dave added fuel to a specific table where it gives more fuel as soon as the pedal goes down.
I can't remember the table, but it allows for more fuel as you start to give it throttle.
Helped me out with the kr.

Looks like you are in my category gtp, nice mods but slow and kr.
So Paul tuned it, so we know you got a decent tuner there. I suggest a wideband, that'll help with WOT tuning. What about maybe trying AL103s?
What about your gatorback belt? age? Belt slip?
I know I was experiencing this due to old gatorback belt being worn and my 85k mile tensioner assembly not doing its job.

That would be the Acceleration Enrichment (AE) table, 20gtp02. It richens your mixture when you first get on the pedal, then gradually leans out.

I have had the belts for maybe 2 months.... not experiencing any belt slip that I know of.

Put some BP gas in today and it seemed to reduce the KR at the beginning of getting boost, but when I tried going towards WOT I saw KR and backed off.

Maybe needs cam or rockers.

Got some good news, I think. Well I put in a fresh tank of BP gas and also added in some Octane Booster and got some decent results.

Today when I got off work I tried it out. The first run I was just messin' with a guy after work and I gave it some gas (Probably around 70% throttle) and didn't even see one blip of knock. The next run I got up to about 8psi of boost and still didn't see any knock and this was around 80-90% throttle at about 80MPH. When I went to put my foot down just a lil bit more, when I saw 9-11psi of boost, that's when I started seeing 1-2* of knock and backed her off.

All I did was put in a full tank of gas and the Octane Booster.

...Now what are you guys thinking??? haha

Well yes, higher octane is going to ward off detonation so that is why you are getting less KR. That does however rule out false KR as a possibility.

So basically, you're back to square 1 :p

...Ah poohy lol

I have been looking at getting some rockers. I'm starting to think I might have a collapsed resonator or bad muffler.

So PRJ personally tuned this car? I think he did an awful job

Hey Taz, Did you ever solve this KR issue?