tii starting FAQ

If you tii is hard starting, here are some checks you can do.
Start with the basics.
1. Check timing, line up the ball at 2,400 RPM (25 degrees BTDC)
2. Check your point’s gap (0.016”) if you have ‘em
3. Check your dwell (59-65 degrees)
4. Check your plugs (use Bosch silbers, W7DC/W8DC gap at 0.024 – 0.028”)
5. Check valve clearance, refer to this FAQ article for details
6. Check compression, refer to this FAQarticle for details (below 130 can indicate a worn engine and hard starting will be a fact of life)
7. Buy a reference manual and read it. Get Mike Mccartney’s book, “BMW ’02 Restoration Guide” or the Haynes Manual (the Chilton manual I have does not cover any tii specific issues).

Once the basics are checked and verified, then proceed to the next possible steps. The tii injection system and start up is relatively simply. A bi-metallic switch in the thermotime sensor sends a signal based upon coolant temperature to the timer box. The time box then sends a signal for the cold start valve (CSV) to inject gas directly in to the throttle body. Check each unit. A failure or fault in any or more of them will contribute to hard starts.
8. Check the thermotime switch. Located next to the sender for the coolant temp on the coolant neck.


8.1. Check for continuity between the switch and the timer box. Both the brown & black and the black & white wires lead back to the timer box. As a general rule, if any wire is frayed or suspect, replace it with the appropriate 14G wire. Buy a crimping tool and terminal spades, making sure they are sized for 14G wire. Use the same colors or make notes in your owner’s manual or other documentation as your memory is not what you think. This is good time to throw that 150’ foot role of yellow 16G wire in the trash.
8.2. With a cold engine (coolant temp below 88degress) and 12v test lamp, connect the “W’ terminal on the thermotime (the terminal for the brown & black wire) and know good 12v source. The lamp should light. You can also use a multi-meter and should register at least 13 volts. The light will go out after a short while.
8.3. Replace the switch if it fails the above test

9. Check the timer box located by the firewall




9.1. Make sure you battery is fully charged.
9.2. Assuming continuity is good between the thermotime and the time box, check continuity to the CSV. The red & white wire leads to the CSV.
9.3. Disconnect the lead from the coil to prevent the motor from starting
9.4. You will need an assistant to crank the engine while you test the timer box.
9.5. Connect a test lamp to the “SV” terminal on the timer box and a good ground.
9.6. Have your assistant crank the motor. The test light should light up immediately. If does not stop cranking and recheck all connections and try again. Depending on the temperature, the lamp should remain on between 1 and 15 seconds.
Temp (Fahrenheit) Duration (seconds)
4 degrees 9 – 15 seconds
32 degrees 4- 10 seconds
95 degrees 1 second
9.7. Replace the timer box if it fails the above test

10. Check the cold start valve (CSV). Located on the throttle body.



10.1. Check continuity between the CSV and the timer box (see 8.2 above) Also check the ground connection for the CSV (the brown wire is the factory ground color),
10.2. Check to see if the valve is working. The CSV always injects gas at startup.
Note: this test involves the CSV spraying gas. Make sure you conduct this test in a well-ventilated area with a cold engine. Wear eye protection and gloves.
10.2.1. Remove the CSV from the throttle body housing. Aim the CSV into a plastic bottle or similar container that will be used to catch the gas sprayed from the CSV.
10.2.2. Turn on the ignition (you must hear the fuel pump running) and connect a fused12v source to the “SV” terminal on the time box. The CSV should click, gas will be sprayed and the valve is working. Dispose of any fuel properly.
Note: if you are running a Petronix, there is a risk of “cooking” the Petronix unit when switching to “Fahrt”. Make all your connections first and use an assistant to minimize the test.
10.2.3. Remove the lead and gas will stop. If the valve continues to drip it will cause a rich condition during warm start ups. Turn off the ignition when the test is complete.
10.2.4. Replace if it fails the above tests.

11. If your CSV works but either the thermotime or time box is defective, you can rig up a manual bypass to activate the CSV. In this case you can use a push button and a fused 12v source to complete the circuit for the CSV (replacing the red &white wire from the time box).
_________________
Colin K.
Malaga '72 tii