xSandbagger

I’m a newbie to EFI tuning.. I did some logging on a 2000 C5 m6, only mod is the cable tie CAI and noticed that I am getting KR in first gear starting from about 1700 rpm and continuing all the way to the rev limit, but strangely no KR in second gear with more timing. I am also curious about a drop to 14* at 2200 and another to 11* at 2600 but only in first gear. I am running 93 octane, OAT is 89*, engine stock for cable tie CAI.

Is this normal or am I likely getting a false knock?

I will post the logs tomorrow.

code4

iTrader: (30)

When I was tuning my heads/cam set up I was getting KR in first from a standing WOT run. Running lean was the cause. I found that each gear was a little richer. I don't know if this is because of load on the engine or what. I found that I had to tune it to around 12.7 in 4th to get 13.0 in first on the street. I am not an expert tuner but this is what worked for me.

xSandbagger

Thanks Code4. I am waiting to get the printouts from a recent dyno (unfortunately didn't have EFIlive to log with on the run) run but the dyno AFR monitor in the tailpipe indicated it was running quite rich. From memory it indicated that AFR started in the mid 11.X and went to low 11.X at higher rpm.

Also any ideas/explanation for the two significant drops in timing in first gear (see image below)?

RedWS6 00

Just an idea, but before you pull away in first is the engine getting hotter? when you get to the 2nd/3rd gear runs the temprature has dropped?

IAT wasn't logged. Also I guess your fuel is getting hotter in the rails.
Extra heat causing detonation, therefore causing knock.

brad8266

iTrader: (23)

If you are that rich and getting real knock with a near stock engine you might first want to run some seafoam through the engine to clean off the piston tops first and then scan again.

It could also be false knock. If you can get some race gas put a bit in and see if it goes away. If the knock stays its probably false and desentizing the sensor might be what you want to do.

RedWS6 00

Talking of possible false knock, isn't there some newer knock sensors you an fit which dont react to false knock as much? I read this somewhere but cant remember where. Something along the lines of 98-99 are sensitive later years are less. Or perhaps its the location....

xSandbagger

Thanks for the responses. I am going to try running on some race fuel first to determine validity of the knock. I got the printouts from the dyno run and will post later but AFR dropped to 11.42.

Rob

iTrader: (6)

Might be false. Check the motor mounts and trans mount.

My Turbo TA would false knock in first gear because the engine torqued over so much, the down pipe hit the frame.

Just a thought.

Doc

iTrader: (9)

Um am I missing something or do I not see a wideband in this picture?

Slowhawk

iTrader: (12)

The KR is probly false from drivetrain noise,vibration.

xSandbagger

Rob,

Thanks for the suggestions will check.

Doc,

You're right, but I have an LM-1 on order so that will be fixed soon.

Doc

iTrader: (9)

The lightswitch will come on with the LM-1. If you need any assistance with it PM me.

brad8266

iTrader: (23)

You missed it, he said AFR was read on a dyno pull.

Doc

iTrader: (9)

That he doesn't have access to, and is at some shop not doing him any good. Furthermore having to read a printout and transcribe the events into the tuning tool is not necessary and time consuming, with EFI Live. With EFI Live you can highlight a recorded parameter (in this case the wideband O2)and have the corresponding affected cells in the VE, PE,...etc tables be highlighted for you in the Tuning Tool. I am merely pointing out that without the wideband input the OP is missing out on one of the coolest features of EFI Live.

The OP got my drift and said so.

brad8266

iTrader: (23)

I agree with ya, it is of course best to have everything recorded with software so you can make good use of the data, especially with all the neat stuff EFI does.

xSandbagger

Here is the latest:
I with the car indicating 50 miles to empty I added 5 gals of 104 unleaded fuel and drove about 30 miles then ran the 1/8th while logging. The first 2 passes I had KR then on a hard burnout I heard a load thump and haven't had any KR since.

I am still not getting maximum timing in first gear but atleast i'm not getting KR. However I am still getting a significant drop in timing between 1600 and 2000 rpm while transitioning to wot which I can't seem to find any reason for. The recorded timing is significantly lower than what the low octane table calls for. I noticed that even with the 104 in most cases I wasn't getting to the timing indicated in the high octane table, is this normal?

Btw, I received the wideband o2 late on Friday so will have that installed and logging in a few days.