DragRaceResults.Com    Bracket Talk    Bracket Talk Forum  Hop To Forum Categories  Tech Talk - by Abruzzi    Erratic rpm graph
Page 1 2 
Go
New
Find
Notify
Tools
Reply
  
Erratic rpm graph
 Login/Join
 
DRR Pro
Picture of T/D6591
posted
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.


 
Posts: 1708 | Location: Portland,Oregon | Registered: January 18, 2009Reply With QuoteReport This Post
DRR / Crew
Picture of DragRaceResults
posted Hide Post
Where is the graph showing rough?
 
Posts: 1941 | Location: Gallatin, TN - U.S.A. | Registered: October 12, 2009Reply With QuoteReport This Post
DRR Pro
Picture of T/D6591
posted Hide Post
It 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.


 
Posts: 1708 | Location: Portland,Oregon | Registered: January 18, 2009Reply With QuoteReport This Post
DRR Trophy
posted Hide Post
check your spark plugs
 
Posts: 30 | Location: Nebraska | Registered: August 26, 2012Reply With QuoteReport This Post
DRR Pro
Picture of 27Keith
posted Hide Post
Is 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
 
Posts: 2084 | Location: out there | Registered: March 31, 2004Reply With QuoteReport This Post
DRR Pro
Picture of T/D6591
posted Hide Post
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.


 
Posts: 1708 | Location: Portland,Oregon | Registered: January 18, 2009Reply With QuoteReport This Post
DRR S/Pro
posted Hide Post
Are your tires feathered?

Just out of curiosity, why do you not have a 16v battery and have not gone away from running an alternator?


strangemagicperformance.com
oldsperformanceproducts.com




WD dealer for just about all your performance needs.
 
Posts: 1604 | Location: Suffern, NY | Registered: November 03, 2001Reply With QuoteReport This Post



DRR S/Pro
posted Hide Post
quote:
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.
 
Posts: 2054 | Location: Tewksbury, MA,USA | Registered: November 03, 2000Reply With QuoteReport This Post
DRR Pro
Picture of T/D6591
posted Hide Post
Strange(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.


 
Posts: 1708 | Location: Portland,Oregon | Registered: January 18, 2009Reply With QuoteReport This Post
DRR S/Pro
Picture of "The Bender"
posted Hide Post
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........
 
Posts: 3064 | Location: Yes | Registered: July 08, 2009Reply With QuoteReport This Post
DRR Sportsman
Picture of 329L
posted Hide Post
look 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
 
Posts: 663 | Location: Evansville, IN | Registered: February 24, 2010Reply With QuoteReport This Post
DRR / Crew
Picture of DragRaceResults
posted Hide Post
So that is Moes graph?
 
Posts: 1941 | Location: Gallatin, TN - U.S.A. | Registered: October 12, 2009Reply With QuoteReport This Post
DRR Sportsman
Picture of N2Ofrog
posted Hide Post
Possibly lean?
 
Posts: 929 | Location: Columbia Station, OH | Registered: January 05, 2001Reply With QuoteReport This Post
DRR S/Pro
Picture of "The Bender"
posted Hide Post
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........
 
Posts: 3064 | Location: Yes | Registered: July 08, 2009Reply With QuoteReport This Post



DRR S/Pro
Picture of Big Steve
posted Hide Post
If that is Moe's graph, I wish mine looked that smooth lol
 
Posts: 2243 | Location: Moving back to the door side | Registered: April 30, 2010Reply With QuoteReport This Post
DRR Sportsman
posted Hide Post
quote:
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 Here
 
Posts: 662 | Location: New Jersey | Registered: April 26, 2001Reply With QuoteReport This Post
DRR S/Pro
Picture of "The Bender"
posted Hide Post
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........
 
Posts: 3064 | Location: Yes | Registered: July 08, 2009Reply With QuoteReport This Post
DRR Sportsman
Picture of sr4440
posted Hide Post
I 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.
 
Posts: 1283 | Location: TEXAS | Registered: February 07, 2003Reply With QuoteReport This Post
DRR S/Pro
Picture of Big Steve
posted Hide Post
quote:
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...
 
Posts: 2243 | Location: Moving back to the door side | Registered: April 30, 2010Reply With QuoteReport This Post
DRR / Crew
Picture of DragRaceResults
posted Hide Post
are you pulling timing?
 
Posts: 1941 | Location: Gallatin, TN - U.S.A. | Registered: October 12, 2009Reply With QuoteReport This Post
  Powered by Social Strata Page 1 2  
 

DragRaceResults.Com    Bracket Talk    Bracket Talk Forum  Hop To Forum Categories  Tech Talk - by Abruzzi    Erratic rpm graph

© DragRaceResults.com 2023