Atap Log for my '03 Z...Take a look
10-17-2003, 03:53 PM
#1
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Atap Log for my '03 Z...Take a look Hey All,
Finally got the zo6 out to run a few autotap logs this afternoon, and I had some questions. Its an '03 Z with 1,700 Miles COMPLETELY stock.
Here is some information:
-Logs done in 3rd gear from 2000-6600 RPM
-Intake air temperature pretty constant at 68 degrees (63 degrees outside this afternoon)
-Coolant temperatures constant at 189 degrees
-Timing starts around 22 degrees and linearly rises to around 29 degrees until ~ 3800 RPM
-Timing drops to 22-23 degrees from 3900-6600 and stays constant
-O2 readings hover between .880 and .910 for the entire run (.9-.910 up top in the RPM range)
-2 runs are free of Knock Retard and two runs show 1-2 degrees of KR at 3900 RPM both times.
It looks like the computer pulls about 2 degrees of timing when KR takes place, but timing curves for the 2 runs without KR and the 2 runs with KR are not significantly different (with or without KR the computer pulls about 6 degrees of timing around 3800 RPM). The computer pulling timing in the midrange is pretty consistent with what I see with my Trans-Am. In my T/A I see 25-31 degrees of timing (increasing linearly from 2000-3500) then the computer pulls the time back to 22 degrees @ 3500 RPM and begins to climb linearly again to 6300 where it peaks at 30 degrees. Mike at Rapid Motorsports told me that the LSx engines tend to detonate between 3500-4000 and GM tuned the cars this way to prevent detonation, any insight on this?
My question is about the KR. The two pulls with KR were on *Slight* uphill grades while the two without were on *Slight* downgrades. I thought it could possibly be a bump in the road causing the KR but there is no indication of any Kiccup in the RPM curve that would be consistent with the tires slipping after a bump (RPM Cure is linear in this section). The KR occured at 3900 RPM on both of the KR runs. I was also thinking maybe this is from the motor not being broken in? Intake and coolant temps look good so I dont think Pinging is the culprit. Could the noisy valvetrain be the culprit? There was no audible sign of pinging.
Good news is that when I am running through the gears (1-2-3- and a couple of seconds in 4th) there is no sign of KR. On the 1-2, 2-3, and 3-4 shifts the RPM curve was well above 3900 and all of the graphs looked great (O2s looked good, timing looks decent, No KR, ...).
I will post more after-mod information after I add a Halltech TRAP, and then again after a ported TB to show changes in Air Intake Temperature, and the Air to fuel Ratio.
Please throw out some guesses on the KR, and let me know what you think about it. Anyone else have some logs on stock '02 or '03 Zs to compare?
Sorry so Long
TIA,
-Nick
Finally got the zo6 out to run a few autotap logs this afternoon, and I had some questions. Its an '03 Z with 1,700 Miles COMPLETELY stock.
Here is some information:
-Logs done in 3rd gear from 2000-6600 RPM
-Intake air temperature pretty constant at 68 degrees (63 degrees outside this afternoon)
-Coolant temperatures constant at 189 degrees
-Timing starts around 22 degrees and linearly rises to around 29 degrees until ~ 3800 RPM
-Timing drops to 22-23 degrees from 3900-6600 and stays constant
-O2 readings hover between .880 and .910 for the entire run (.9-.910 up top in the RPM range)
-2 runs are free of Knock Retard and two runs show 1-2 degrees of KR at 3900 RPM both times.
It looks like the computer pulls about 2 degrees of timing when KR takes place, but timing curves for the 2 runs without KR and the 2 runs with KR are not significantly different (with or without KR the computer pulls about 6 degrees of timing around 3800 RPM). The computer pulling timing in the midrange is pretty consistent with what I see with my Trans-Am. In my T/A I see 25-31 degrees of timing (increasing linearly from 2000-3500) then the computer pulls the time back to 22 degrees @ 3500 RPM and begins to climb linearly again to 6300 where it peaks at 30 degrees. Mike at Rapid Motorsports told me that the LSx engines tend to detonate between 3500-4000 and GM tuned the cars this way to prevent detonation, any insight on this?
My question is about the KR. The two pulls with KR were on *Slight* uphill grades while the two without were on *Slight* downgrades. I thought it could possibly be a bump in the road causing the KR but there is no indication of any Kiccup in the RPM curve that would be consistent with the tires slipping after a bump (RPM Cure is linear in this section). The KR occured at 3900 RPM on both of the KR runs. I was also thinking maybe this is from the motor not being broken in? Intake and coolant temps look good so I dont think Pinging is the culprit. Could the noisy valvetrain be the culprit? There was no audible sign of pinging.
Good news is that when I am running through the gears (1-2-3- and a couple of seconds in 4th) there is no sign of KR. On the 1-2, 2-3, and 3-4 shifts the RPM curve was well above 3900 and all of the graphs looked great (O2s looked good, timing looks decent, No KR, ...).
I will post more after-mod information after I add a Halltech TRAP, and then again after a ported TB to show changes in Air Intake Temperature, and the Air to fuel Ratio.
Please throw out some guesses on the KR, and let me know what you think about it. Anyone else have some logs on stock '02 or '03 Zs to compare?
Sorry so Long
TIA,
-Nick
10-17-2003, 11:48 PM
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Re: Atap Log for my '03 Z...Take a look If the car is under a load then you might see a better chance of seeing detonation “like going up a hill”.
Also look at your logs on the run’s with KR and see if the IAT sensor was reading lower, the IAT affects timing “lower temp’s means more timing” but i'm sure you already knew that
Also look at your logs on the run’s with KR and see if the IAT sensor was reading lower, the IAT affects timing “lower temp’s means more timing” but i'm sure you already knew that
10-18-2003, 06:45 AM
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Thread Starter
Re: Atap Log for my '03 Z...Take a look
If the car is under a load then you might see a better chance of seeing detonation “like going up a hill”.
Also look at your logs on the run’s with KR and see if the IAT sensor was reading lower, the IAT affects timing “lower temp’s means more timing” but i'm sure you already knew that
Also look at your logs on the run’s with KR and see if the IAT sensor was reading lower, the IAT affects timing “lower temp’s means more timing” but i'm sure you already knew that
.the IAT was pretty consistent at 68deg, so I am pretty sure that the car was on its more aggressive timing tables. The o2s were reading around .900 at the time of KR. I Know there is more load going up hill, and the upgrade might have been enough to casue a significantly higher load. The car sits alot (gets driven about twice a week) so I am thinking it could be gas also, but it has only gotten AAmco "white" 93 since day one. I am not that concerned because it only did it on the slight uphill pulls and the most I saw was 1.8 degrees or so, I am just wondering if it was from fuel, IAT, lack of breakin....
10-18-2003, 10:37 AM
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Re: Atap Log for my '03 Z...Take a look I have tried almost every type of gas around, but I think we have a local AAmco station but I have not tried their gas. My point is on my 98 every type of gas I have tried does not affect knock “it still knocks”. My next step is to find out if my knock is real because I don’t hear it either, I will be adding some Xylene to my gas, I hope to get around 96+ octane by doing this. I don’t know if you want to go and poor a few gallons of paint thinner in your z-06. I will also be trying to change over to the ls6 PCV system and new knock sensors.
With the low amount of miles you have on the car I could see a little extra noise from break-in, but the knock sensors only pickup a siren frequency? I guess they could pick-up other noises too. But they only pull timing when they pick up noise in that frequency range
I’m not sure why the stock tune has a huge drop in timing but I’m sure it relates to detonation. The 98’s seem to have a more aggressive timing table then other years and I think that is some of the problem. Also the fact that they have the early design PCV system. I see around 3.9 deg at 3500 to 4000 rpm but my timing is 20 or 21 deg in that range with knock. Then it slowly fades away as a reach redline then i have full timing.
With the low amount of miles you have on the car I could see a little extra noise from break-in, but the knock sensors only pickup a siren frequency? I guess they could pick-up other noises too. But they only pull timing when they pick up noise in that frequency range
I’m not sure why the stock tune has a huge drop in timing but I’m sure it relates to detonation. The 98’s seem to have a more aggressive timing table then other years and I think that is some of the problem. Also the fact that they have the early design PCV system. I see around 3.9 deg at 3500 to 4000 rpm but my timing is 20 or 21 deg in that range with knock. Then it slowly fades away as a reach redline then i have full timing.