Sudden drop of load during pull...
Sep 26, 2008, 09:42 PM
#1
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Sudden drop of load during pull...
i am going to give the whole story in order to figure out what happened...
Last weekend i went to the track, hopefully to get the 11 second timeslip on pump...
Did three passes...
car weights 3300 lbs with me, pumpgas, 23psi (just passing 1.6bar on my Gizzmo ebc) spike dropping to 22psi at the revlimiter, very conservative timing 12-13 degrees up top, 93 octane Shell, Dunlop M3 snow tires...
first pass when i arrived at the track... I only managed to have my friend get out and get his camera, wear my helmet and jacket and run after a 70 mile trip...
almost bogged, very slow gear changes managed a very bad 12.5@115...
Second run i launch with a bad 1.9 60ft, and lose 4th gear, managing a 12.15@117. Actually the car picked up knock while changing in 4th but right after started cleaning up fast and by the end of the run had 0 knock as always... 1/8 was 92mph....
Third run i do a better 1.82 60ft which was bad again and i even back pedaled to lessen the spin, 92mph to the 1/8 mile, always full lift shifts, but as soon as i put 4th gear the car drops on its face like i blew a pipe or something and continued accelerating slower.... managed a 12.03@114 only...
check the log, 0 knock every where... full load was touching 300 and sitting at around 260s on average before each gear change, but as soon as i put 4th in the car falls to around 220 load and keeping it throughout the rest of the pass with a pretty high timing of around 17 degrees which is more than what i have on my timing map... even then the car didn't knock but clearly lost a lot of power thus giving my such low trap speed...
the first 3 gears felt even better than the second 117 mph pass (with knock thus low timing because of the missed gear) thus i estimate that the car would go even better, trap wise...
Has this even happened to anyone else? all of a sudden having the car fall on its face and have an VERY steady load of around 220?
Just to note when we left the track on the highway the car was pulling with no problems whatsoever....
vids
12.15@117
http://www.youtube.com/watch?v=7mKv41URxSg
12.03@114
http://www.youtube.com/watch?v=AGFmW...eature=related
Last weekend i went to the track, hopefully to get the 11 second timeslip on pump...
Did three passes...
car weights 3300 lbs with me, pumpgas, 23psi (just passing 1.6bar on my Gizzmo ebc) spike dropping to 22psi at the revlimiter, very conservative timing 12-13 degrees up top, 93 octane Shell, Dunlop M3 snow tires...
first pass when i arrived at the track... I only managed to have my friend get out and get his camera, wear my helmet and jacket and run after a 70 mile trip...
almost bogged, very slow gear changes managed a very bad 12.5@115...
Second run i launch with a bad 1.9 60ft, and lose 4th gear, managing a 12.15@117. Actually the car picked up knock while changing in 4th but right after started cleaning up fast and by the end of the run had 0 knock as always... 1/8 was 92mph....
Third run i do a better 1.82 60ft which was bad again and i even back pedaled to lessen the spin, 92mph to the 1/8 mile, always full lift shifts, but as soon as i put 4th gear the car drops on its face like i blew a pipe or something and continued accelerating slower.... managed a 12.03@114 only...
check the log, 0 knock every where... full load was touching 300 and sitting at around 260s on average before each gear change, but as soon as i put 4th in the car falls to around 220 load and keeping it throughout the rest of the pass with a pretty high timing of around 17 degrees which is more than what i have on my timing map... even then the car didn't knock but clearly lost a lot of power thus giving my such low trap speed...
the first 3 gears felt even better than the second 117 mph pass (with knock thus low timing because of the missed gear) thus i estimate that the car would go even better, trap wise...
Has this even happened to anyone else? all of a sudden having the car fall on its face and have an VERY steady load of around 220?
Just to note when we left the track on the highway the car was pulling with no problems whatsoever....
vids
12.15@117
http://www.youtube.com/watch?v=7mKv41URxSg
12.03@114
http://www.youtube.com/watch?v=AGFmW...eature=related
Sep 27, 2008, 06:33 AM
#3
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i am sypathetic towards your problem but am unable to offer any help. i'm simply chiming in to ask that you edit the thread title. i laughed when i read it.
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Sep 27, 2008, 07:32 PM
#9
117 is pretty hit traps for a 3300lb loaded car and 23psi, ESPECIALLY if you aren't cammed. 117mph is certainly fast enough to get well into the 11's too 
I agree that the 300 load is high for 23-22psi (should be more like 250-260 peak load). If you dropped to 220 load and the timing went up to 17* without knock, you really were at a load of 220. So the question is why did the volume of air reduce? Possibly a wastegate malfunction or the Gizzmo EBC? Thats where I'd put my money. Was it past midnight during that pull and you got your gizzmo wet?(Gremlins reference...sorry)
Curious what your stationary rev limit settings and tire pressure was if you don't mind.
I'm shooting for 11's this month too on the stock 8 turbo, FMIC and piping...hoping the alky kit makes up for a bigger FMIC and your evoIX turbo,lol.
I agree that the 300 load is high for 23-22psi (should be more like 250-260 peak load). If you dropped to 220 load and the timing went up to 17* without knock, you really were at a load of 220. So the question is why did the volume of air reduce? Possibly a wastegate malfunction or the Gizzmo EBC? Thats where I'd put my money. Was it past midnight during that pull and you got your gizzmo wet?(Gremlins reference...sorry)Curious what your stationary rev limit settings and tire pressure was if you don't mind.
I'm shooting for 11's this month too on the stock 8 turbo, FMIC and piping...hoping the alky kit makes up for a bigger FMIC and your evoIX turbo,lol.
Last edited by Jack_of_Trades; Sep 27, 2008 at 07:49 PM.
Sep 27, 2008, 10:23 PM
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i am cammed, cossie M2s... still i haven't transferred my logs my the laptop to my mac to post, i will try and do it tomorrow... load was spiking at 300 in some of the gear changes but it was settling to the 260s for the most part...
i am not sure if it was a malfunction of my ebc since it worked just fine after... what confuses me is the fact that the car didn't knock at all during that pass....
The 117 trap i did it with a lost gear change in 4th and because of the miss the car picked up knock and pulled timing... The car should run closer to 120 mph at that boost pressure, maybe over 120 mph with a boost closer to 25 psi...
i really want your opinion especially on the 3rd run because have never seen such response from the ecu ever before neither i have read it in any of the forums... all of a sudden i saw a spike at around 300 load value, then dropped a little bit and then a VERY steady 220 load value....
My 2-step is set at 5900 rpm and i am using 12 degrees timing at the 2-step load cells...
Tire pressure was 1st pass 33 hot, 2nd pass 27 psi hot and 3rd pass 25 psi hot... if i had another run i would go down to 22 psi just to see if the car would hook up better...
Jack_of_Trades..... i am not on the stock turbo.... i have a tubular BR3065 kit which is a large GT30
The car eventually will go into the 11s easily as soon as i drive it properly... Always full lift shifts... And no point to try racegas yet since i want to see what i can do with the car as i drive it every day....
i am not sure if it was a malfunction of my ebc since it worked just fine after... what confuses me is the fact that the car didn't knock at all during that pass....
The 117 trap i did it with a lost gear change in 4th and because of the miss the car picked up knock and pulled timing... The car should run closer to 120 mph at that boost pressure, maybe over 120 mph with a boost closer to 25 psi...
i really want your opinion especially on the 3rd run because have never seen such response from the ecu ever before neither i have read it in any of the forums... all of a sudden i saw a spike at around 300 load value, then dropped a little bit and then a VERY steady 220 load value....
My 2-step is set at 5900 rpm and i am using 12 degrees timing at the 2-step load cells...
Tire pressure was 1st pass 33 hot, 2nd pass 27 psi hot and 3rd pass 25 psi hot... if i had another run i would go down to 22 psi just to see if the car would hook up better...
Jack_of_Trades..... i am not on the stock turbo.... i have a tubular BR3065 kit which is a large GT30
The car eventually will go into the 11s easily as soon as i drive it properly... Always full lift shifts... And no point to try racegas yet since i want to see what i can do with the car as i drive it every day....
Sep 27, 2008, 10:36 PM
#11
Well then, 300 load after a shift is REALLY not normal. Unless of course you normally see 300 load between 5-5.5k rpm during a 3rd gear pull. The super high tire pressures explain the high 60' times and high trap speeds. I think a JDM map sensor would be of GREAT use to your logs. That EBC is probably what needs tweeking.
Sep 28, 2008, 03:26 PM
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i doubt that it was clutch slippage....
i will post two graphical representations of the two passes.... the 12.15@117 with the missed gearchange in a way.... and the 12.03@114 with the sudden load drop....
The 12.15 pass
The 12.03 pass with the 'problem'
also i includes some values to give you an idea... cannot figure out anything else that might created this...
i will post two graphical representations of the two passes.... the 12.15@117 with the missed gearchange in a way.... and the 12.03@114 with the sudden load drop....
The 12.15 pass
The 12.03 pass with the 'problem'
also i includes some values to give you an idea... cannot figure out anything else that might created this...
Sep 29, 2008, 07:10 AM
#15
Those screenshots just showed what you explained in the 1st post. Load dropped in 4th. As Jack stated, what is your airflow doing?
Perhaps load is dropping because IDC dropped due to a sudden decrease in airflow. Airflow can drop due to DV, boost leak, or MAF pipe leak. But there would be no way of telling without logs of AFR, IDC, IPW, and airflow.
Perhaps load is dropping because IDC dropped due to a sudden decrease in airflow. Airflow can drop due to DV, boost leak, or MAF pipe leak. But there would be no way of telling without logs of AFR, IDC, IPW, and airflow.