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msd digital 7531

16K views 90 replies 14 participants last post by  bracketchev1221 
#1 ·
anyone running the msd digital 7531 what a pain n the ***
 
#3 · (Edited)
msd

i gonna quiz u here, here gos i had a msd 7aL2 in my vega the motor trans and converter where all new, i made 19 passes on this motor trannie an converter ran to much bottle an burnt 4 pistons on the 19 pass the last pass was 5.35 n eight mile, so i pulled motor an trannie an built 67 nova i had the car wired by the same person that wired the vega he called an said lets go with the 7530t i said im no tv repair man, against my better judgement i said ok go ahead with th digital box,he wired the car an installed the 7530t along the same motor and trannie an converter,got the car back an when i transbraked it the converter would only stall at 4000 it would stall at 4800 with the 7AL2 in the vega, the rev launch was set at 5000rpm so msd blamed it on my converter my converter guy blamed it on the box so i had the converter cut open it checked out ok, so i sent the box back to msd they said it checked out ok but they said they would send me another 7530t just for customer satifaction, i told msd send me the 7531 now the 7531 stalls at 3000rpm when i trans brake it an rev launch was set at 5000rpm i moved the rev launch up to 12000rpm an saved it to msd it still stalls at 3000 rpm
 
#5 · (Edited)
msd



im going to delete my post at drive tran an performance an keep my post here, i saw your post there i understand that setting the rev launch at 5000 will not make my converter stall at 5000 when it will only go at 4800, with the 7530tit will only stall at 4000 even though i have the rev launch set at 5000 why is that ??? and with the 7531 it only stalls at 3000 with rev launch set at 5000 and rev launch set again later at 12000 it still only stalls at 3000 why is that ????
 
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#8 ·
msd



ill find out if i have any other issues this weekend, i havent gotten over this hump yet went to the track only 2 times this year dident go back because it woulent let the converter come up to the 4800 stall at 4000 it wouldent even spin the tires when i let off the transbrake button with the 7530t box, all my wiring is correct scott walter who was tony christen crew cheif wired this car
 
#6 ·
The ignition box has nothing to do with where a converter stalls. If you are saying it's on the rev limiter, that's something totally different. Do you have the very last item in the programming tree set to Arm LaunRevLim ? Can you E-mail me your MSD xxx.IGN file you are using? I'd be happy to take a look at it. documike@comcast.net
 
#7 ·
msd



ill have to see if i can email that, i understand the rev limiter is different then the rev launch the rev limiter is set at 7800 and the rev launch is set at 5000, i dont no about the very last item in the programming being set to arm lauch rev lim, but i do no that the rev launch is set at 5000 joe ponda at msd went over all this with me over the phone while i had the laptop connected to the box
 
#10 ·
You should be able to E-mail the file as an attachment. The light blue wire should be going to your Line Lock and the dark blue wire to your transbrake. When the transbrake gets released, it triggers the box to begin the programmed sequence. If the box is not being reset or some other programming or sequencing issue, it can appear like it's not functioning correctly but in reality it's doing exactly what is being asked of it. I'm wondering if maybe it's not getting the 12v signal to activate the RevLaunch function. Send your file if possible, there may be something programmed incorrectly. Here's an extract from the 7531 Help File that describes how the RevLaunch functions.

RevLaunch provides a multi-function. This function is activated when
the dark blue wire is switched to +12 volts to enable the RevLaunch revlimit
RPM value, the Launch Retard timing value, the Gear 1 Retard Curve, Launch
RevLimit Curve, resets the Shift Light sequence to the first RPM value,
Gear1, enable the Launch light and to arm the Launch History record. Also the
RevLaunch wire disables the Slew Rate Revlimiter. The launch retard is adjustable
from 0 to 15 degrees and is summed with Step1, Step2, Step3 and the Gear 1
Retard Curve retard values if they are also enabled by these wire inputs and
above the programmed speed value.


The Launch Revlimit limits the engine RPM to the RevLaunch RPM value
programmed until which time the dark blue wire is opened (removed from
+12 volts). When the RevLaunch wire is active and the Burnout Revlimiter wire
is deactivated, the 7531 is armed to record the Launch history record.
The record begins when the launch wire is active and the engine RPM
increases until the launch revlimiter is active, if AcqArm is set to
ArmLaunRevLim; at this time the record begins recording the prelaunch
and once the launch wire is removed from +12 volts and the vehicle is
launched and begins recording the data of the race event.
 
#13 ·
msd



msd wonts to blame it on my converter the converter guy blames it on the box i blame it on the box also if u read my second post here u will see that, i think msd has a makes a good product they just have a problem admiting when someing wrong, i have heard of some people who have had problems with there stuff that when they send it n to msd msd says theres nothing wrong with it and when they get it back it works, my issuie is going to be related to msd, the converter was working fine when i pulled it from the other car now it doesent. it stalls dead nut on 3000rpm now with the 7531 box with rev launch set at 5000rpm:confused:
 
#15 ·
If MSD says nothing is wrong with the box and your converter guys says nothing is wrong with the converter and "you" think it is the box seems to me that you have no other choice than to pull the box out and replace it with another one. If it is to complex for you to figure it out then send it to me and I will send you my Digital 6 plus box which has been on my car for less than 2 weeks. Not trying to seem like a butt here but you don't even want to take anyones advise here. You already have your mind made up it is the box and nothing else. So guess you will have to change it and hope you don't waste another $800 on a box that may or may not be the problem.
 
#18 ·
msd


no im not being a butt head here what advice have i not taken i pulled the converter had it cut open an had 3 converter shop inspect it everyone said it ok i did this 3 months ago took the car back to where i had it wired all wiring is ok. its real simple for me to understand its not the converter the converter was working when i pulled it from the vega and droped it n the nova now it doesent work thats send a red flag to a msd issue the box n the vega was a 7AL2 THE CONVERTER WORKED WITH THAT BOX NOW WITH THE 7530T AN 7531 IT DOESENT WORK.
 
#24 ·
msd



read my 2nd post yes i have the same motor tranny converter this was all new when installed n vaga made 19 passes burnt 4 pistons had all new same pistons installed and put this motor trans an converter n nova went from 7AL2 box to 7530t an to 7531 dident have stall issues until i switched to digital boxes
 
#32 ·
i sent it back to them they said nothing was wrong with it an msd said they would send me another 7530t just for customer satifaction why would they offer to do that if nothing was wrong with the box
That's pretty typical of them; they never admit a problem with their products, but when you get it back it's either been rebuilt or replaced with a different part--my friends box came back with diodes and other things attached OUTSIDE the box, but they didn't see anything wrong! Told him it should be fine.
 
#37 · (Edited)
msd



well u an hook the laptop up to the box an set what rpm u wont it to shift at,u can set the rev limit so the motor doesent over rev on the other end an u can set a 5000 stall converter to stall at any rpm up to 5000 all this is programmed to the box. did u receive the pm i sent u today?
 
#38 ·
The box is not changing the converter stall, it's simply turning on the engine rev limiter at whatever RPM you set the RevLaunch at. I just wanted to ensure we are on the same page and using the correct terms. I have not received your .ign file yet. I had also asked about your crank trigger cable...if it's shielded or not. You are using a crank trigger correct? One thing I've seen is if the crank trigger wires are reverse polarity connected it will do some strange stuff as far as timing etc. The engine will run fine but when the retards or limiters are supposed to kick in, it goes wacky. That's something to check.
 
#42 ·
I had a few problems with my 7530t box. The first thing was the down track rev limiter time out. Something else I found out was not to leave the data cord with the usb converter hooked up. It did all kinds of strange things. something else I found out is I also use a 7al-2 in some of the classes I run in. The older box advanced my timing about 7deg more then the 7530t that was strange. But I also had a problem were my car would only stall to 4000 on a 6500 stall converter. It was the diod in the converter was blasted. I hope this will help
 
#52 · (Edited)
msd



BINGO!!!!!!!!!!!!!!!! i talked to another head yeasterday at msd (edger) i told him the converter would only stall at 3000 i told him the rev launch was set at freaken 12000rpms right then he said set the spool rev, i click on spool rev it was at 3000, he said that as low as it would go, when i saw that 3000 setting i new something was fixin to happen, i set it at 5000 an BINGO its stalls at 4800 everytime now just like it did n the vega, i was calling msd yeasterday to have them send me a 7AL2 box like i had n the vega and was going to hook it up just to prove a point that ITS NOT MY FREAKIN CONVERTER. i went over the settings on the 7531box 2 different times with joe at msd he never ever told me to go to spool rev setting, he said with the rev launch set at 5000 it should work, when it diddent he kept blaming it on my converter, so what do u do when your not a tv repair man, an msd personal tech support keeps blaming it on your car, when i would call to talk to someone else at msd tech support i would tell them i have been dealing with joe they would just say he would be the best one to deal with. so it was the luck of the draw if edger hadent answered the phone i would have still been screwed, i wood have had to wait for (SEATTLE MIKE THE TV REPAIR MAN) to post (JUST FOR GRINS) hey mike your the MAN for sure for sure, thanks for hagin with me on this one. if it warms up tomorrow i going to tset an tune at the track.:woot::woot::woot:
 
#53 · (Edited)
I got to thinking about what could do this and saw that if the RevBurn and RevLaunch wires were both active it enables the RevSpool function which defaults to 3,000 RPM. I was looking at my own programming tree and noticed the 3,000 RPM default...that's when the light came on.

I thought it had to be something simple that was being overlooked. My RevSpool is set to 3,000 and my RevLaunch is 4,000, so make sure your wiring doesn't have both the RevBurn and RevLaunch active (+12v) at the same time or it will use RevSpool vs RevLaunch unless you are using a turbo setup where you want to spool it up.

If I would of seen your graph from the 7531 I would of seen the RevSpool as active right away which would of indicated what the problem was.
 
#54 ·
So if the MSd was limiting the RPM the whole time then is should have been pretty easy to hear the ignition killing cylinders, it would sound different than a motor running full spark and trying to stall against a tight converter...

FWIW running 1400# bottle pressure when the tune calls for around 950# would probably melt the pistons pretty quick depending on the size of the hit. You are shoving about 30% more nitrous in the engine and not introducing more fuel to compensate... Yeah its gonna be lean:yes:
 
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