Help!!

Eric Merryfield · 04-04-2011, 04:09 PM

Quote:

Originally Posted by Ed Wright

Joe, I have a Fluke DVOM, and a Fluke 98A digital lab 'scope. Both will record, the 'scope has a faster capture rate than the meter. May have to make some passes with one of them connected. It's usually off close to 1/10th of a second. Don't know the sample rate for the FAST data logger. Need to check that.
I did replace those power wires to the FAST ECU and MSD box and the ignition switch Saturday. May have fixed it. Need to test again this week. I'm wearing it out chasing this down. Eight passes Friday, and accomplished nothing. I do know what it isn't. <G>
Thanks, Ed

Just thinking here Ed, have you tried a pass or two foot braking it? If it did the same thing then you could isolate from there, if not......How about all the non-tracked/under tracked stuff, injector harness perfect, fuel pump 100% ? I feel for you that is hell to try to figure out.

Good luck

Eric

Ed Wright · 04-04-2011, 09:13 PM

Quote:

Originally Posted by Eric Merryfield

Just thinking here Ed, have you tried a pass or two foot braking it? If it did the same thing then you could isolate from there, if not......How about all the non-tracked/under tracked stuff, injector harness perfect, fuel pump 100% ? I feel for you that is hell to try to figure out.
I put a new ECU harness on it late last year. This started first race this year.

Good luck

Eric

No Eric, I maybe should. I replaced the trans brake solenoid and microswitch. I think I'll record the waveform from the trans brake to see hig big of a voltage spike I may have.
Foot braking would isolate that circuit. Good idea.
Thanks, Ed

Adger Smith · 04-05-2011, 03:05 AM

Ed,
Could the 3 step be faulty and sending a charge back to the T-brake?

Alan Roehrich · 04-05-2011, 08:01 AM

Ed, is this thing a speed density set up, or does it have a MAF sensor?

What are you using for a distributor?

I want to go back over some of this, and see what you've replaced, or bypassed.

MSD box?
Coil?
Batteries?
Crank trigger pick up?
Coil wire?
ECU?
Transbrake switch?
Master switch
Ignition switch?
Transbrake solenoid?
Starter solenoid?
Battery cables?

Anything else?

Have you tried looking over all of the wiring, and using wire ties or "strain relief" to keep the wires from moving anywhere?

Have you tried tapping sharply on your electrical devices? I'm sure you're familiar with the old "tap test" that we all used to use checking things like the MAF years ago.

Also, what was changed, or what happened, immediately prior to this problem rearing its ugly little head?

buzzinhalfdozen · 04-05-2011, 08:05 AM

Adger has a good thought, are you using a two or three step and if so at what RPM are the "pills"? Is one of them the same as the RPM engines dropping back to? Though I've never tried it I'd suspect even a small amount of voltage say 8-9 volts at the rev. limiter may be enough to activate it, where it would reqire full voltage to activate the trans brake. Joe

Ed Wright · 04-05-2011, 10:53 AM

I use the 7AL2Plus boxes. Heard too many stories about the 7AL3 stuff. I use the rotory 2 step RPM selector, but did plug a regular chip in it's place Friday. thought I had it one pass, then it did it again. It is speed density. I have tapped on everything, flexed and tugged on wires. Only thing I have not yet tested, but it's next, is the master battery cut-off. I have banged on it, and jerked on the battery cables trying to make it cut off, mis-fire, something. Right now both battery cables are on the same post. Guess I'll find out this weekend. Wanted to rent the track, but they are working on it this week. Water problem near the finish line. Been so dry here, I can't imagine where it's coming from.

buzzinhalfdozen · 04-05-2011, 11:13 AM

Any issues with fuel pressure? Though I'm sure you've looked it's not fluctuating is it? Joe

Michael Compton · 04-05-2011, 01:13 PM

Very valid point about the fuel issues. At the Topeka National a couple years ago, my car would fall on its face after letting go of the tranny brake. Changed carbs, spacers, richened, leaned, etc and nothing worked. Then we looked at the fuel pump pressure from the pump to the regulator and it was way down from the original setting. Changed it and increased the fuel pressure from the regulator to the carb and it all went away. Turns out (according to Barry Grant) the regulator and pump were taking a nose dive. Ended up getting them repaired and sold all of them for Magnafuel. Best switch I have made so far.

Might be worth looking into. I believe we set the fuel pump to regulator at 28 pounds. Was at 15 when we were having problems.

04-05-2011, 03:05 AM	#3
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	Re: Help!! Ed, Could the 3 step be faulty and sending a charge back to the T-brake? __________________ Adger Smith (Former SS)

04-05-2011, 08:01 AM	#4
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,113 Likes: 1,571 Liked 1,825 Times in 414 Posts	Re: Help!! Ed, is this thing a speed density set up, or does it have a MAF sensor? What are you using for a distributor? I want to go back over some of this, and see what you've replaced, or bypassed. MSD box? Coil? Batteries? Crank trigger pick up? Coil wire? ECU? Transbrake switch? Master switch Ignition switch? Transbrake solenoid? Starter solenoid? Battery cables? Anything else? Have you tried looking over all of the wiring, and using wire ties or "strain relief" to keep the wires from moving anywhere? Have you tried tapping sharply on your electrical devices? I'm sure you're familiar with the old "tap test" that we all used to use checking things like the MAF years ago. Also, what was changed, or what happened, immediately prior to this problem rearing its ugly little head? __________________ Alan Roehrich 212A G/S

04-05-2011, 08:05 AM	#5
buzzinhalfdozen Senior Member Join Date: Sep 2006 Location: Bellevue Ohio Posts: 984 Likes: 0 Liked 11 Times in 8 Posts	Re: Help!! Adger has a good thought, are you using a two or three step and if so at what RPM are the "pills"? Is one of them the same as the RPM engines dropping back to? Though I've never tried it I'd suspect even a small amount of voltage say 8-9 volts at the rev. limiter may be enough to activate it, where it would reqire full voltage to activate the trans brake. Joe __________________ Joe Buchanan SS/BX 3117

04-05-2011, 10:53 AM	#6
Ed Wright Veteran Member Join Date: Mar 2005 Location: Sand Springs, OK Posts: 8,132 Likes: 896 Liked 390 Times in 170 Posts	Re: Help!! I use the 7AL2Plus boxes. Heard too many stories about the 7AL3 stuff. I use the rotory 2 step RPM selector, but did plug a regular chip in it's place Friday. thought I had it one pass, then it did it again. It is speed density. I have tapped on everything, flexed and tugged on wires. Only thing I have not yet tested, but it's next, is the master battery cut-off. I have banged on it, and jerked on the battery cables trying to make it cut off, mis-fire, something. Right now both battery cables are on the same post. Guess I'll find out this weekend. Wanted to rent the track, but they are working on it this week. Water problem near the finish line. Been so dry here, I can't imagine where it's coming from. __________________ Ed Wright 4156 SS/JA

04-05-2011, 11:13 AM	#7
buzzinhalfdozen Senior Member Join Date: Sep 2006 Location: Bellevue Ohio Posts: 984 Likes: 0 Liked 11 Times in 8 Posts	Re: Help!! Any issues with fuel pressure? Though I'm sure you've looked it's not fluctuating is it? Joe __________________ Joe Buchanan SS/BX 3117

04-05-2011, 01:13 PM	#8
Michael Compton Member Join Date: Dec 2003 Location: Neosho, MO Posts: 215 Likes: 0 Liked 59 Times in 13 Posts	Re: Help!! Very valid point about the fuel issues. At the Topeka National a couple years ago, my car would fall on its face after letting go of the tranny brake. Changed carbs, spacers, richened, leaned, etc and nothing worked. Then we looked at the fuel pump pressure from the pump to the regulator and it was way down from the original setting. Changed it and increased the fuel pressure from the regulator to the carb and it all went away. Turns out (according to Barry Grant) the regulator and pump were taking a nose dive. Ended up getting them repaired and sold all of them for Magnafuel. Best switch I have made so far. Might be worth looking into. I believe we set the fuel pump to regulator at 28 pounds. Was at 15 when we were having problems.