cold start problem - need help!

Hello - i am the proud new owner of a 1987 TR. I can share the purchase story another time, but it was not the smartest . This car, with 40K miles, just had complete engine out service, from a reliable mechanic who is a long distance away from me. The car did not get a lot of test/sorting before i took it home

When i try to start it, it just cranks but wont start the first few times. then it will finally start but runs very rough and then surges rpm up and down. If i give throttle during this time, it just stalls. After a minute or so, it smooths out and runs great

I turned the large brass bolts (idle speed screws) on the throttle bodies out half a turn and that helped a lot, so now it starts when cold, but still runs very rough and surges rpms for a minute or two. then it warms up and runs well, although now the idle is at 1500rpm+. which is probably because I turned those brass idle speed screws

I checked the fuse for the cold start injector, and it is OK. I swapped out another relay for the cold start injector relayt, and no difference. I pulled both of the cold start injectors and started the car with them loose, but neither one squirted any fuel at all. I checked voltage at the harness plug on the cold start injectors and I do not seem to be getting any voltage there at all, which suggests the car is not activating the cold start injectors

I tried to check resistance on the thermal time switch on the front of the engine, but i can not get my ohm meter to give any measurement there. interestingly, i also checked resistance on the temp sender on my 308 engine which is sitting on the floor in my basement, and got no reading there as well. not sure what is up with my ohm meter.
the plastic plug on the thermal time switch is cracked, and does not seat well, but not sure if that is relevant

Need some help on where to look next - I would rather not pull out the thermal switch if I dont have to.

justin (desparate and frustrated)

 

i tried to attach a video of the cold start but the file is too large for the forum to accept

 

would that explain why the cold start injectors are not working at all?
from what i have read and seen, i know a surging idle can be a balance problem, but once this car is warm, it seems very smooth. the experienced mechanic who did the work did a lot of tuning to it, but this problem was either missed or is new since transporting the car

 

This is a US version 87 testarossa.
When I checked the resistance at the thermal time switch, the G lead gives me appropriate reading of 40 to 60 ohms depending on the temperature. but I can’t get any resistance to read from the W terminal across ground. I also can’t measure any resistance between the two terminals themselves. I wonder if this switches defective? It’s kind of a pain to change.

if it’s not the cold start injector as the source of this problem, I am open to any other suggestions.

 

I am in New York, and the engine temperature is probably 50 to 60° in my garage before I get it running.
The engine is F113a.

 

F113A040 engine

 

According to my version of the TR manual, the cold start injector is always connected to ground on one end, and the positive signal is regulated by the cold start relay

Steve thank you for the suggestions. I will try to measure those values again tomorrow.
I hooked up a voltmeter to the fuse panel where the cold start relay is, terminal 30, which is supposed to be +12 V when they starter is cranking, but I did not get any volts. I will check that again tomorrow also

 

My copy of the book ends at page D60. Oops

anyway will check the protection relay as you suggest tomorrow.

 

as an aside, i found the missing pages of the TR workshop manual (D60 to 100). the wiring schematic for the cold start injectors, and the protection "safety" relay is ridiculously complex. Just saying ...

 

in order to check voltage at the red wire on the temp sending unit, can I remove the wire from the sender while the engine is running, or will that mess things up? i would rather not cut into the wire to measure voltage there. sorry for so many questions

 

here are my updates:
1. on the thermal time switch, the G terminal shows 60 ohms when cold/cool, across to ground. the W terminal shows infinite resistance compared to ground. there is also infinite resistance from G to W. this all suggests the thermal time switch is not working, so the cold start injector could not fire.
2. the cold starter injector relay on the fuse panel is getting power from battery when ignition on.
3. when I test the protection relay by measuring voltage from the red wire terminal on the temp sending unit on the front of the engine, i get 0.2 volts relative to ground. It is not nothing (0 volts). It is showing 0.2 volts. not enough to light up my test light, but enough to register a tiny bit of voltage with my digital voltmeter.

does that mean the protection circuit is bad?
to review, this car starts with difficulty, and runs poorly with rpm surging for the first minute or two, but as it warms up, it smooths out well. I have not driven on street at all yet. also, the idle is high (1500rpm) when warm, but that is because i backed out the idle brass bolts to get it to start and run in the first place

 

Inside the protection relay box, everything seems to look OK to my eyeballs. The 10 amp fuse is not blown. Any idea what to look for here?
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When I shake this unit that I’m sending a picture of, there is a rattle inside it. It’s not the fuse rattling around it something inside it. Is that wrong?
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Those voltage readings you are sending, is that with the key off, or the key on but engine, not running, or the engine running?

 

thanks for all the advice. i bench tested the relay and got no voltage output, so i am off to pelican parts to buy a new relay. it would be so exciting if this fixed the problem!
i guess at some point i should get a new thermal time switch. but that will need me to drain the coolant system, so i am less excited to do that now, but maybe...

 

looks likw pelican parts has it as a porsche abs sensor, cross referencing the bosch number. looks the same in the pic, for about $120. i guess that is good