Classic fast communicates with engine off but,,

[juxtoposed]

When the car starts it loses sync. I have tried all that I can think of like making sure the ignition and msd wires are not near the computer wires, checked the laptop cable, checked grounds. Got any ideas?

It is an IPU type in a 88 camaro.

Thanks

 

[HighPSI]

Sounds like your switched ignition power is losing power when you crank the car over.

 

[juxtoposed]

I don't think so, the car starts and runs fine. It just won't communicate with the engine running. It won't communicate if you try after the engine is running, or if you connect before the engine is running and then try to start it. It seems like electrical noise type of problem. I ohm'ed each of the three wires on the cable and twisted it all aroundand none of the three ever went open.

thanks

 

[Chuck Leeper]

Are you powering the LT off the cig liter, off the LT battery?
Have you tried to power it w/ wall plug power?

 

[juxtoposed]

Powering it off LT battery. The car owners laptop does the same thing, he was powering off 120v from the house. I brought my set up over to help troubleshoot. My LT works fine in all other cars I have tried it in..

Thanks

 

[GNDriven]

I am a little confused..
Is the LT the problem or the FAST Box?

Have you tried another LT?


Please add in more detail. Walk me through the steps.
I am an electronic engineer, maybe I can pickup on something if I had more detail.

 

[juxtoposed]

I was asked by a friend to tune his car once he gets it together. Cool no problem. He calls says it is running but keeps kicking me offline. I think laptop problem, Ill bring my own that works on many cars that I have tuned. His laptop was running off a extension cord powered off the house. Mine runs off a battery on the laptop that is good. Both laptops have the same problem, won't communicate when the car is running. It will connect with the car off with only a glitch now and then (maybe have to try twice every 5 or 10 times connecting) as soon as you start the car it goes offline. start the car with out the lap top connected and try to go online after it is already running wont work either. Turn that stinking thing off and turn the key back on (KOEO) it'll connect. Hope that is enough info.

Thanks

 

[GNDriven]

Does it loose sink as the car is turing over? or all sink lost events post running?

I a wondering is the FAST box itself reseting?

another thought, I would try a different serial cable? Is this the 3 pin on end and DB9 connector on the other? Is so, it maybe Pin 5 on the DB9 connect is loose. Can you ohm out the comms cable go from one pin on one side to the same pin on the other side? This maybe a null application so, pin 2 on one side may go to pin 3 on the other. You need to find out.

I believe the communication standard is RS232, if so take the DB9 connector coming from the FAST box to the PC and measure either pin 2 or pin3 with a volt meter. One should be -3 to -9 Vdc. This is the data send pin. Crank the car and watch the voltage on this pin start jumping around going positive and negative. If it reads 0.0Vdc then the FAST serial port has lost power internally.

Loosing power at the serial port could be caused by environmental factors or faulty electronics inside the box. See what you can find out.