knock

[fast NY Six]

Can zero knock retard ever be achieved? I know everyone says zero is the goal but I have a stock pulley with all supporting mods, 3" downpipe, front and rear logs, stat, plugs, zzp tune and I still get upwards of 7 degrees. I just acquired hptuners so I want to attempt to tweak this myself, is there something I'm missing? Is 7 normal? Does anyone have an HP file they can upload that I can compare to?
thanks

 

[fast NY Six]

I installed a new fuel pump and Hotwire. I still get knock. It’s dropping down to low octane timing table also. I’ll get up to 3 degrees knock at 11 degrees timing. With 110 octane I get less knock but stays in high octane timing table. I guess this must be normal. Maybe a cam or rockers would help? I don’t actually hear any knock.

 

[TurboBuRick]

Absolutely possible...

What fuel management system? Assuming something other than stock if you are looking for a HP tuner file..

When collecting data, are you doing wot 3rd gear pulls with no shifts?

 

[kshef]

Put some octane in it and see if it goes away.

 

[fast NY Six]

Yes I’m using a stock gtp pcm with hp tuners. I haven’t done any wot 3rd gear pulls. I get knock in 2nd gear starting at around 3500 rpm. I even get some part throttle knock. Not near a shift. I read on the hp tuner site that the knock sensors are more sensitive on the l67 engines. The 110 octane helps. I’ve done all the supporting mods. I should be able to drop a pulley size.

 

[b4black]

I had an intercooler on my L67 and would see zero knock throughout the ¼ mile, so it can be done. You won't here the knock, which means the computer is doing it's job.

The IC was my first mod, so I don't have experience with a set up like yours. 7° does seem like a lot for the mods.


Have you compared the ZZP tune to a stock tune? Compare the timing and the WOT AFR settings. I'd write down everywhere they are different, upload the stock tune, then make changes one by one.

 

[fast NY Six]

Yes I’ve compared the files. I’ve messed with timing. I don’t have a wideband on it, but my o2 values were dropping on a wot pull. So I thought the new fuel pump would help. I’m in the low 900’s now steady. Nothing makes much of a difference. I removed the supercharger belt and there’s no knock. So it must be real. If anything I need a larger pulley. What was your timing at?

 

[b4black]

I ran up to 24° with the IC, E85 and a 2.9" pulley.

You could make the WOT AFR richer to squash some of the knocking. Richer will make a touch less power, but this will be more than made up for by less knock/timing retard.

You've done all the small (basic) mods. I had two of these cars and believe to really unlock the potential, you'll need to do something 'big'. Turbo, IC or E85 (or all three )

E85 is super easy with HPTuners. There is a small table for cylinder gain or skew. Bump them up from 1 to 1.3 for 30% more volume needed for E85. Then make sure you fuel pressure maintains at WOT and you good to go. Watch the injector duty cycle and when it starts going well above 80%, it's time for bigger injectors.

Used ICs are cheap and well worth it. Turbos are more work, but the biggest bang for your buck.

 

[fast NY Six]

Yea I’d like to go e85 but there’s very few stations in my area. Turbo is a big job, and it’s my daily. So I/c might be my only option.

 

[delcowizzid]

You tried closing the plug gaps a touch .even a noisy snout on the charger or noisy bearings in the unit can trigger the sensors and exhaust headers too close.they used to sell little beenies to go on the sensors to dull any harmonic vibrations effecting them

 

[fast NY Six]

I’ll try a tighter plug gap. There is a vibration or rattle between 4-5k that I though was maybe valve train. I rebuilt the snout but not the case. The case bearings are tricky. I haven’t figured out a way to clock the rotors after I pull the gears to get to the bearings.

 

[fast NY Six]

More fuel got rid of the knock. So at least I know it’s real knock.

 

[fast NY Six]

With the o2s at 940-950 I get almost zero knock. I'm around 13-14 degrees timing at 6k rpm. the pcm was adding timing for some reason, I didn't notice at first. When I added fuel, there's an afr timing adder table that was adding 6 degrees of timing when the richer afr was commanded. I'm running more timing than stock with no knock, I might try the 3.5 pulley.

 

[Jon Early]

Sorry if this is derailing, but I didn't realize that this sub-forum was still active. Maybe I should post my 3800 stuff in here!

Thanks for the info. I knew these engines had a lot of knock sensitivity, but I find it crazy how much will happen even with a stock pulley size. I guess every build and tune is different.

 

[dank GN]

As stated before put some race gas in her and see if she is still knocking if so then it’s something mechanical and not real detonation. Have u looked at a alky kit ? They are bad ass and allow you to run higher boost without retard

 

[fast NY Six]

I hope this stays active, I still have a few of these things and hammer on one everyday. Yes, please post everything 3800! The regalgs site appears to be inactive. I've tried to join but the website wont let me in. I had an l67 mounted in my 86 Regal, but had a hard time finding support, so I went with LS instead.
I've researched doing an alky kit but they say it's not normally done. I guess the alky eats the coating off rotors? I thought I had a good afr and spark table but then I get knock a little bit sometimes.

 

[b4black]

When I added fuel, there's an afr timing adder table that was adding 6 degrees of timing when the richer afr was commanded.

So that was your problem. The ZZP tune was bumping up timing too much for your set up. I'd put it back to the stock configuration, drop the pulley size and then add timing only if it doesn't knock. Check to see if the High Octane timing table is stock too.

When I added timing, I added some to the entire HO table (leaving the low octane table alone). I also used the AFR vs timing table to add an additional four degree only during Power Enrichment (PE) mode.

Timing should be fairly steady at WOT. Stock is ~16°

 

[b4black]

Thanks for the info. I knew these engines had a lot of knock sensitivity, but I find it crazy how much will happen even with a stock pulley size. I guess every build and tune is different.

Any engine is "knock sensitive" if it's running too much timing like this aftermarket tune was.

All modern engines run too much timing and let the knock sensor pull some back. That gives them the best fuel economy. (And fuel economy testing for the EPA is done using premium gasoline).

 

[fast NY Six]

Either the stock pulley was too small to begin with or 5+ degrees of knock was considered acceptable. Scary to think how many people dropped pulley sizes without a scanner, just because they followed a recipe from a vendor that said they should be able to.

 

[b4black]

5° would be no big deal. The ECM would see this, then start interpolating between the high and low octane tables to reduce the knock for the next time.