Why is my car knocking so bad?

[Mike_Levy]

I really don't understand whats going on. 93 CAI it was getting 6.5° of ST KR in the mid range and top end. Tried adjusting the fuel and spark to no avail. So now I installed the 91 CAI tune. A little better, but still getting 4.5° KR. I don't get it. Nothing I do eliminates it. I'm using Mobil 93 octane gas, and have tried 2 others brands of 93, so thats not the problem. I have no idea what is. I think I'm going to try logging a stock tune, just to see what comes up.

I'm gonna upload the log in a little while. I need to clean up the OSV so I can fit it on Scan Depot.

[mikel]

SRT8?
Oil in the intake....

[Quick]

Do you have a wideband? I think you may find that stock the a/f (WOT) is pig rich. Like even in the low 11's. With not much timing. Before I had a wideband I logged knock on the stock setup. Spike to 4.5 or even 5 right around shifts or when lugging the engine. Drops off quickly and zero the rest of the time. I've been meaning to check stock a/f and timing myself. Maybe today

[SRT8Tech]

I logged my stock tune and got 1.5 - 2.5 ST KNK retard on my SRT8. I was in your same boat for a while but got the KNK down in the 93 CAI tune by going +4.5, +6.0, +5.0 on the fuel and went down -1* of timing accross the board. I now have the KNK to 0. Spikes to 2.5 at times but they go away in several hundred RPMs. I did notice a CRAP LOAD of oil in my intake and thats why I ordered my catch can. I havent put it on yet but I bet it makes a big differance. I hope I can go back to the out of the box settings on the 93CAI tune. I was getting 6.5-7.0 ST KNK out of the box tune before I tweeked it a little.

[Mike_Levy]

Yep, 07 SRT8. No oil in the intake, removed it and cleaned it out when I installed the catch can.

No wideband yet, but on the narrowband the AFR is 14.41 when theres no knock, and dips into the 12's when there is.

I'm also noticing that the throttle position is going over 120%, but the blade isn't going further then the mid 70's.


Here's todays scan. I added more parameters, so keeping it below 1MB was difficult and made me have to remove low speeds and coastdowns. http://www.scandepot.net/viewscan.php?pk=4897

[Chrispy]

Mike,

I'd record just the following:
ST and LT knock
Timing cyl 1
RPM

Put the car in autostick (2nd gear) at 2000rpm and go WOT through all of second and into third gear. Then stop the log. You dont need to record all that extra shite

It'll make things nice and clean and you'll get a better sampling rate and it'll be easier to analyze the logs

[Quick]

I threw on the stock tune yesterday took a couple of logs. It was interesting. I didn't really wait for any adaptives. reset parameters, modified stock tune for fans and raised shift point, drove 15 min to the freeway and did a few bursts at different rpms. Surprising that the a/f in the low rpm range seemed to be around 12.8 to 13.0! In the mid rpm range around 12.5 and in the high rpm range around 12.0... (hope I didn't reverse those numbers for the 3 ranges). That wasn't what someone else had said. They said it was in the low 11's and didn't say anything about differences in different rpm ranges. Timing seemed to be fairly advanced. I guessing around 18*. I'm just guessing because there was a lot of knock retard. We're talking about 4.5 to 5 and even one spike to 6. This was on every WOT burst. Unfortunately there was a lot of traffic so I didn't get to do a 1/4 mile run or even go through a couple of gears. It was basically going between 60 to 80, lock it in a gear to get the appropriate rpm and floor it for 3 to 5 seconds. I did get a WOT 2-3 shift in there.

Also interesting. I definitely hit the rev limiter big time on the shift. This was the stock tune with fans and raised shift points. I've never done that with the CAI 91 Oct tune... or before when stock.

So I went all the way and reverted to the Original Backup and repeated.
Pretty much the same with everything. Even the shifts? although I didn't hit the rev limiter as hard. Maybe a residual effect from the adaptives that would go away after a while.

Slapped my tweaked CAI 91 Oct tune back on and went to bowling . Basically I was just curious where abouts (roughly) the stock a/f was.

[Chrispy]

Thanks for posting, unless you are measuring with a wideband I wouldn't reference the stock PCM readings. Did you raise the rev limit when you raised the shiftpoints? They both need to go up in the stock tune.

I'm thinking there is a fair bit of correction going on after several drives in various load/throttle conditions. I'm going to drive mine for a couple of days and log again. I found out that 91 shell gas up here in Canada is not oxygenated so I'm running a tank of that and will test on the 91 Perf tune. I've added 3% fuel to all ranges to account for the HF cats and will see how it works in the coming days.

Cheers
Chris

[Mike_Levy]

Just out of curiousity, I ran and logged 93 CAI this afternoon w/ +1.5% fuel. What a disaster. 8° of ST KR, 2° LT KR, A/F numbers going into the 11's. I think adding fuel is just causing more issues. Tomorrow I'm gonna cut it back and see what happens.

[mikel]

That makes it sound like not so great gas, if running high 11s for A/F caused more KR....like more bad fuel will cause more KR...

[Mike_Levy]

Its Mobil 93. I'll put in something else when I fill up this weekend. Maybe BP, or use another Exxon-Mobil station, or try adding Toulene (yes, I know what I'm doing. I used to make my own gas blends when I had my 2000 GTP).

[SRT8Tech]

When I took away fuel my ST KNK went to over 9*!!!! I wouldnt take too much away. BY the way, I just put my B/Tcatch can on. Im going to see if it makes a differance with the KNK in a couple days. Im going to pull the intake off tomorrow at work and celan it out. Under warranty of course.

[Mike_Levy]

I just tried leaning it out. KR went to 5.5° on both ST and LT. AFR was way down to 10.4! Am I going the wrong way? I leaned it out and the AFR went down? Should be going the other way.

[rodneyiii]

... or try adding Toulene (yes, I know what I'm doing.).

Do you mean Toluene?

[Mike_Levy]

It can be spelled either way, doing a Google search showed both.