Bracket Talk
Erratic rpm graph
October 28, 2018, 12:39 PM
T/D6591Erratic rpm graph
Just throwing this out there. I noticed at my last race that my rpm graph on my racepak was not smooth like it normally is. The graph is rough with around a 75rpm swing. This is with a crank trigger and a Digital ignition. I swapped out the crank pickup but I haven’t raced the car yet. Just trying to get a handle on it before heading out to Vegas tomorrow.
October 28, 2018, 04:17 PM
DragRaceResultsWhere is the graph showing rough?
October 28, 2018, 04:31 PM
T/D6591It starts half way through first gear and again after the shift. If I knew how to post the picture I would. Funny as last time it did this two years ago in Chicago it ended up being some kind of feed back from the alternator. This time it looks similar but different. Hopefully the pick up clears it up. It doesn’t seem to effect the run as minor as it is.
October 28, 2018, 04:47 PM
joe Dirycheck your spark plugs
October 28, 2018, 08:08 PM
27KeithIs it choppy or wavy or up an down ? I had a carburetor issue that made my rpm graph goofy. What is fuel psi doing at this point in the run ?
4 X Track Champion ( 2 & 2 )
2 X Run off Winner
October 28, 2018, 08:19 PM
T/D6591I would call it choppy. Fuel pressure is being read off of my nitrous fuel regulator and it is steady at 5.7 just where I have it set at. The plugs,distributor cap and rotor have all been replaced. Plug wires were all ohm’s checked. Like I said it doesn’t seem to slow the car any it just is something I noticed that has shown up since my Sonoma race’s back in July.
October 28, 2018, 09:46 PM
Strange MagicAre your tires feathered?
Just out of curiosity, why do you not have a 16v battery and have not gone away from running an alternator?
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October 28, 2018, 11:14 PM
TOP38quote:
Originally posted by T/D6591:
I would call it choppy. Fuel pressure is being read off of my nitrous fuel regulator and it is steady at 5.7 just where I have it set at. The plugs,distributor cap and rotor have all been replaced. Plug wires were all ohm’s checked. Like I said it doesn’t seem to slow the car any it just is something I noticed that has shown up since my Sonoma race’s back in July.
Spikes up are interference and down is loss of signal.
I have also seen a bad battery cause graph issue too. Not sure what caused it but the battery got weak so I replaced it and the spikes were gone.
October 29, 2018, 12:02 AM
T/D6591Strange(Andy) the tires are not feathered and the pinion graph doesn’t show any signs that match the rpm graph to make me think it is the tires. But I won’t rule that out. As far as the 16 volt battery goes I have been running those for the last 6 or 7 years if not longer. I also run an alternator because of the electrical load I have from the ignition,fan,water pump,fuel pump and 4 solenoids for the nitrous. My car usually runs a steady 17.2 volts throughout the run. Top38 good point on the battery. This battery is barely a year old and I run the heavy battery because it has move reserve than the lightweight battery that came with the car. Like I had mentioned before I had something similar but more pronounced that ended up being the feed back from the alternator. I do have a spare alternator from HOP that I may swap out in Vegas also. Thanks for all the ideas.
October 29, 2018, 06:58 AM
"The Bender"Here ya go Moe
272" Spitzer
540 Chevy
The Blower Shop XR1
FTI XPM Series Converter
FTI Level 6 Powerglide
3.69@199
.916 60'
2017 Bradenton Heads Up Madness
Open Outlaw Champ
2018 PDRA T/D #5
2019 PDRA T/D #2
2020 Retired From T/D Competition....
2020 Bradenton NMCA Hemi Shootout Winner
2021 getting back into bracket racing with a Gen3 Hemi powered 87 Cutlass.
October 29, 2018, 07:19 AM
329Llook for loose wire connections on the tach circuit(s). Mine is usually where the tach wire hooks to the K&R mother board when it happens.
Jeremiah Hall
October 29, 2018, 08:31 AM
DragRaceResultsSo that is Moes graph?
October 29, 2018, 08:34 AM
N2OfrogPossibly lean?
October 29, 2018, 08:51 AM
"The Bender"quote:
Originally posted by DragRaceResults:
So that is Moes graph?
Yes.
272" Spitzer
540 Chevy
The Blower Shop XR1
FTI XPM Series Converter
FTI Level 6 Powerglide
3.69@199
.916 60'
2017 Bradenton Heads Up Madness
Open Outlaw Champ
2018 PDRA T/D #5
2019 PDRA T/D #2
2020 Retired From T/D Competition....
2020 Bradenton NMCA Hemi Shootout Winner
2021 getting back into bracket racing with a Gen3 Hemi powered 87 Cutlass.
October 29, 2018, 08:52 AM
Big SteveIf that is Moe's graph, I wish mine looked that smooth lol
October 29, 2018, 09:00 AM
Greg Kelleyquote:
Originally posted by T/D6591:
Just throwing this out there. I noticed at my last race that my rpm graph on my racepak was not smooth like it normally is. The graph is rough with around a 75rpm swing. This is with a crank trigger and a Digital ignition. I swapped out the crank pickup but I haven’t raced the car yet. Just trying to get a handle on it before heading out to Vegas tomorrow.
which ignition box Moe?
also can you e-mail me the actual log file?
email procedure #21
HereOctober 29, 2018, 09:08 AM
"The Bender"quote:
Originally posted by Big Steve:
If that is Moe's graph, I wish mine looked that smooth lol
I hear ya!
272" Spitzer
540 Chevy
The Blower Shop XR1
FTI XPM Series Converter
FTI Level 6 Powerglide
3.69@199
.916 60'
2017 Bradenton Heads Up Madness
Open Outlaw Champ
2018 PDRA T/D #5
2019 PDRA T/D #2
2020 Retired From T/D Competition....
2020 Bradenton NMCA Hemi Shootout Winner
2021 getting back into bracket racing with a Gen3 Hemi powered 87 Cutlass.
October 29, 2018, 09:52 AM
sr4440I didn't see where you said it lost some ET, because if it did, then i would look at ignition. if it didn't slow down i would look at the recorder side.
Does the Digital ignition show the input signal like the grid?
Joe
Without data, you’re just another guy with an opinion.
October 29, 2018, 10:00 AM
Big Stevequote:
Originally posted by "The Bender":
quote:
Originally posted by Big Steve:
If that is Moe's graph, I wish mine looked that smooth lol
I hear ya!
Must be a blower thing...
October 29, 2018, 11:00 AM
DragRaceResultsare you pulling timing?