I have a 1987 TII and the car starts up fine (will die if i dont let it warm up not sure why for that though?) but when it gets to operating temperature, it will just turn over and over but will never kick or start to kick over. I was told its a hot start sensor that sits in the back of the block that has gone bad and i should just ground it and it will fix the problem. Any pics of this sensor and any idea how to go about fixing it? Any input is appreciated. Thanks.

 

Miles on the car?
Dieing on warm up sounds like the thermowax/BAC/Dashpot was removed by a previous owner (?)

Do a compression check. Hotstart issues are a telltale sign of bad compression.

 

hey mine does the same thing havent found an answer yet but i havent tried that sensor yet and it sounds like it might work i would like to know where it is too

 

Following a fresh rebuild, mine did the same thing. Turned out in my case, the wiring inside the temperature sensor connector had pulled itself out of the plastic part. So the connector looked connected, I thought it was plugged in, but the wires weren't making contact. It ran as though it was unplugged, meaning it defaulted to a baseline temperature. So it was fine for cold starting, but hot starting was made difficult because it would instantly flood.

 

so where is the sensor we are looking for cause i wanna check mine now to see if its working properly

 

So does anyone know were the sensor is? A picture or something would be the best. How do you run a compression test? What is a thermowax and a Dashpot?

 

Right behind the thermostat housing. It's a little hard to get to. What you really want to do is check voltage at the ECU. I can't stress checking voltages enough!

Refer to the FSM

Look on page 4B-32, and see that the water thermo sensor is on pin 2I, and that it should have 0.4 - 1.8 volts. If it's almost 0.0, or almost 5.0, then you'll know that there's either a short, or open, and it will default to failsafe and screw you on hot startups. Check it at the ecu, under the passenger's side floorboard by pulling up the carpet under the dash, then unbolting the big metal plate you see there. Then you'll see a big mess of wires. This is where you want to be.

On page 4A-33, you'll see the connector view. This tells you exactly where the pin is. It's the medium-sized one. The wire color is green/white, so voltage there using any ground as a reference. Let's see what you're getting before you go any further with this.

 

The amount of fuel used during Starting, is determined by the items described in the graph/jpg attached below.

The afm is not used during Start.

The afm IS used during Start if the Start/Cranking signal (pin 3B) isn't seen by the ECU.

The amount of fuel delivered during start using the AFM is much less than that delivered by the internal Start Map inside the ECU.

Less fuel during Hot starts results in a easier start and no flooding.

A RTEK2.1 has an adjustable Start map for the ECU. Or let's say you can adjust the internal Start fuel map of the ECU. A jpg out of the Digital Tuning instructions explains it.

A fully hot engine results in a voltage of 0.40 to 0.5 vdc, depending on the thermostat used.

Several other things can cause a hot start/no hot start problem. Like low compression, bad timing, blah, blah.

 

I agree. However, why is it that the hot start assist blocks off vacuum to the fpr when starting, and for 90 sec after the hot start. That raises fuel pressure.

Por que?

 

I've no idea. Seems dumb as a rock to do so. Perhaps its to get a lot of fuel to pass thru the fuel rail to cool it off? Too keep the fuel in the rail for percolating? Nah, nothing makes any sense on doing that.

I have documented the results of using the afm for starting vs the fuel map in the ECU before on this forum. There's considerably less open time of the injectors using the afm vs the ECU map. First seen on a digital meter (Fluke 88) and later on a Palm using a RTEK. Depinning 3B resulted in 100% successful starts with a hot engine. Downside was difficult starts when the engine was cold.

 

ok i found it is the screw in bolt thing coz i looked a the wire gave them a little tug and they fell off just holding on by couple of wires. so i took it out and found that it had been repaired before covered in silicon. i took it all off and the wire that come out of the unit just fell out so now i gotta get a new one hopefully it fixes it

 

Yeah, it should be a 2-wire sensor. One is a 5v supply, and one is reference voltage. I know on some turboII models there is also a temp switch, but it's a single wire.

If that one that just fell apart is the 2-wire one, then looks like you found your problem.

 

yeah she was the two wire on the back of the thermostat housing so im getting a new one and hopefully my car will run a mile bucks again

 

ok went to the shop they didnt have any in stock had to order it. when we were looking in the book they had pictures and the coolant temp sensor that was meant for my t2 was completely different ie one wire and mine one i took off the car looked excactly like the one the book said was for na. I ordered the na one as it was the same as what i had but wil it make any difference they both should read the same temp

 

Same thing.