I have a 88 iroc 5.0 tpi. I know the one sensor in the middle of the intake is the coolant temp. sensor. What is the one to the left (pass.) of that sensor. It has a connector like the fuel injectors.

 

A pink & I think a tan(?) wire on it ? 9th injector sensor/timer.

 

what is this for???

 

The 9th injector supplies extra fuel at cold startup so the car doesn't have to crank as long. If you want a real explination, 'd have to dig it u pfor you because I've don't remember exactly how it operates.
The 9th injector was done away with in (I think) 89 and extra fuel for cold start was programmed into the PROM instead.

 

I am not sure we are talking about the same sensor. This one is in the front of the intake just left of the coolant temp sensor.

 

The front of the intake manifold (TPI base that's bolted to the heads), there is a CTS (coolant temp sensor, 2 wires, black & yellow) for the ECM and
a Thermo-Time switch (2 wires, fuel injector harness plug, colors above) for TPI cars so equipped with the 9th injector.

If you inspect the drivers side of the TPI manifold base in between the front 2 & rear 2 runners, you should see a black looking cylinder deal with a bolt holding it there & a tube running to the back of the fuel rail, it is connects to the thermo-time switch.

If you don't have the 9th injector but, I'm fairly certain 88 still had one, or you're not talking about the base itself then disregard what I just said.

 

thank you.