A miss at idle, and other rpms with TST

cetaneaddict

cetaneaddict

Causing my own headaches
Joined
Aug 2, 2012
Messages
1,280
So I bought a used TST. It's an older one that did not have a controller. It was off of a 99 so I bought an 02 map plug for my truck. I wired it in using posi-taps(pump tap, 12v power supply). I start the truck it has a miss. I whack the pedal to bring the rpms up to 1200. The truck goes back to an idle but it's idling 100 rpms higher and missing. I play with the throttle and is misses and different rpms also. Fuel light is blinking on the box. I've checked connections 3 times. All looks good. Fuel pressure is good. What could be the issue ? I also have a smarty on it at level 5. It's a 6 speed so it has the HO pump. Any ideas. Looked at some threads from a google search. Nothing concrete. I turn the TST off no miss.
 
Don't think you can swap map sensors around. They read different to the ECM.
 
How old? I have a 99 box on the car, it has remote and works like a charm.
I would send it in and see what they can do for you.
If you have the 02 map harness t shouldn't bean isssue
 
tst has both map values and can be used on any year vp truck.

the pins like to spread on the 9 pin main connector. they are stupid sensitive with where they are grounded. it does sound like the issue may be the box itself.
 
I believe the serial number is S1963. I will look tomorrow.


I just grounded it to the one of the bolts on the intake horn. I could run a ground to the negative terminal on the battery.


The pins looked fine. Didn't see any weird looking ones or bent ones.
 
So since this box was built in 99 and doesn't have the phone jack in the back it only requires the .5 volt from the map sensor not 1.0 volt from the 01 and 02. So since its getting 1.0 volts it's trying to fuel at idle. TST told me that it will only work with 98-00 trucks. BUT he said try putting a resistor from the #9 pin wire and see if it works. He hasn't tried but he thinks it may work.
 
interesting. i'll keep that in mind for others. did you ask about upgrading the box or if they were able to? probably a complete board switch tho.
 
No the box it's not upgradeable. He said if I was looking for more power to sell it and get a newer model box/one that has the phone jack in the back.

I'm going to try the resistor this weekend. If it doesn't work I will just sell it.
 
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