8973 Question

Hi,
Just hooked a 8973 up a few meetings ago & it ran good.

Last meeting I was on the Tranz brake with a air throttle control set @ 4000rpm. With No change from the last 2 meetings
But It was on the limiter @ 2800 rpm.
Question
Dose the 8973 have a built in Launch rev control ?
A how do I change it ?
& why would it change by itself?

Thanks

 

it does have a 2 step in it but never seen one change without you doing it. have you checked the air throttle and your tune up? maybe the air got bad and its real fat .... we leave at wot and let the 2step set the rpm and it never changes that way

 

8973

Thanks Gt & Mike,

Wired as your instructions. Blue wire extended
Took car to line & I could hear the 2 step on
Check my data & car on the stands only rev to 2800rpm

I have check in the data editor Rev Launch was set at 4000rpm.
I'll need to send it back to the pc & re-send to msd.

So I can take that air throttle off & just use the 2 step in the 8973
Set the rev launch 4000rpm. Hold foot flat & it should only rev to 4000rpm when tranz brake is activated.

Dave

 

Ok,
Need more help please.

Every time I hook my laptop to the car & open the MSD program
It starts transfer MSD to PC ,
Is that what it normal dose?
Another question
When I send a Transfer to the MSD & verify
It will come up with 3 boxes
User Data All Data Cancel
Which one do I click on User or All data ?

Thanks

 

8973

Mike,
Thanks again for you reply
It was confusing to me it was like it was going hey wire.
Thanks for the tip to hook lap top to car when running
Next race in 2 weeks

 

Mike,
Race on weekend Put 7 laps on car.
Put new map into 8973 Leaving the startline at 4200rpm,
Even hook up laptop & checked it out. Was all good.
Made 5 laps Rpm Startline 4200rpm.
Then for the last 2 laps Rpm changed by it self back to 3200rpm.
I did not change anything, & I did not even hook the laptop to the car.
Any Idear why this is ?
Thanks

 

8973

Mike,
I am going to re start the car on sunday with the laptop hooked up & try the Tranz brake.
then I will send whats in 8973 & have a look.
I will let you know

Dave

 

8973

Mike,
Ok hook car up & it sent the MSD map back.
Monitors tells me.
gear 5
pressure 2.00
step 1 on
time ret 6.1
every thing else 0 or off

Start the car.
Try the tranz brake only rev to 3200 rpm with no shift light coming on as it was when it is working correctly.
Tacho tell me retard 6 deg as what I have set.

looked in Data editor.
Rev burn Rpm 7000
Rev Max 8000
Rev Launch 4200
Launch retard Deg 5.0 Ramp 1.00
Step 1Rpm 1200
Step 2 800
Step 3 800
Launch Light
Rpm Hi 4200
Rpm Lo 4000
Rpm Time Sw
Rpm on 2000
Rpm off 6000
Time Sw
on Delay 1.0
o Time 2.0
Where to I go from here?

Thanks
Dave

 

8973

Not sure what is going on but my first step in troubleshooting any MSD software controlled device is to make a new file and load it into the box. I had a corrupt file do a bunch of strange stuff regarding rev limiting recently.

I was told its a good idea to make a new file about every 25 runs. I had been tweaking the same files for years.

 

8973

Thanks Mike & OverKill

I did map a new file it only lasted 4 runs before it changed corrupted itself.
Step retard/ yes Mike to adjust timing.
Rpm/Time switch, Not quite sure No fuel by pass. I should switch that OFF ?
Yes still made the runs when it drops the rpm, All good just a bit slower.

The only things I use the 8973 is to pull timing to control shake & blowing the tyres off
& launch control.

Regards

Dave

 

outside the box

Just a thought, you said it worked well for the first couple of meets then started acting irregular. I have had a torque converter go bad on me and limit RPM way low on one pass then work fine on the next. Just saying it may not be the 8973 but a bad converter, assuming you run one. If you have a clutch then disregard this line of thinking.

Scott

 

Scott thank for your input.
It did work well for the first meet.
next meet it was off,But I just left it as I did want to change any thing.
Third meet re map it worked well for 4 laps then it changed.
the problem is only when on the tranz brake that the rpm changes
& yes it is a converter car
What when wrong?

 

converter

It cracked the inner sprag race that is splined to the pump and did not let the engine come up on RPM when on the brake. I don't recall the actual numbers but it was a 5500 stall and it would only go to say 32-3500. It was intermittent and drove me crazy I was chasing the fuel and barrel valve for two events until we figured out it was the converter.
Not to say that is your problem but if you have a spare try it.