TR Cold-Starting Problem...ONGOING...

For Steve...who has been helping me...Thank You! This is a contunuation of my earlier thread "TR cold-start...ongoing....update 5-14-05" . I don't know how to link to it...so if someone else does please feel free to do so. I'm starting a new thread with the title not dated to eliminate any confusion you may have....I know I do.

 

PLEASE SEE LAST POSTINGS IN THE ABOVE MENTIONED PREVIOUS THREAD. Otherwise this may not make sense. Sorry for making things so complicated.

Well.....I once again removed a cold-start injector....and wrapped it with paper towels. I then cranked over the motor....it fired for an instant then died. I checked the paper towels and they had a spot of fuel about the size of a half-dollar. This indicates that they are indeed working. But at full strength I don't know.

I also performed another test: With everything plugged in, I measured the voltage between the Orange wire in the "J Connector" and ground during cranking. The meter showed voltage climbing to around 10 volts or so and then dropping....this event taking place in about 2 or 3 seconds. Steve mentioned that the voltage should be about 12 volts and then drop to a low voltage, mine "seemed" to drop to zero.

Another test: Voltage from Red/Green wire in the "J Connector" to ground. It should be low for the first couple of seconds during cranking and then go up to 12 volts. Mine showed no activity what-so-ever.

I've done all I can for now without losing my sanity. Any help is greatly appreciated. Thank You.

 

Just a thought.

Have you considered that the Warm Up Regulator (if yours is a K-Jetronic) could be faulty?

 

Jeff -- By "low" I meant "zero to a few tenths of a volt" so that part of your test is A-OK. Also, in these kinds of tests 10V is about 12V (high) so that's good too.

The small incandesant bulb is a more reliable "meter" for measuring at the "j" orange wire (the response of a DMM is sometimes slowish/weirdish). How about the "blip" test -- do you detect that same line going +12V if you blip the throttle when cold running? That is the money wire which fires the cold-start injectors.

"Low" here also meant "near zero" so measuring "no activity" was correct for the start of the sequence. I messed this up a little because if the engine actually starts and you release the key (i.e., stop starter motor cranking) before the thermo-time switch opens you'd get what you got (it just stays low/zero). To do this test, you'd need to remove the fuel pump relays R & T so the engine doesn't start -- if after 10~15 secs of starter motor cranking on a cold start, the voltage on the red/green wire doesn't go to +12V this means that the thermo-time switch has not opened (but since you got the 2~3 secs of +12V at the orange "j" wire at initial start that's a very good sign that relay U and the thermo-time switch are working OK and there's nothing to fix there).

If you pass the "blip" test when cold-running, you've got to look elsewhere for your poor cold-running issue.

 

Are your cold start valves working?
Are your throttle plates adjusted correctly?
Are your air bypass valves colsed to far?
When the car is warm and running, can you shut the airbypass valves and the car maintaine an idle speed of 900RPM?
Are both banks of the engine balanced correctly by use of vacuum gauges or mercury colum?
How is your cold rest pressure?
Do the airflow meter plates have approx 1/4 inch free play up and down with the key on engine off when cold?
Are the fuel distributor pintels moving freely?
Is your Co adjustemnt correct? Too tight, too much fuel, too loose not enough...
How is the coolant temperature sender..is it functioning?
Is your TPS set up correctly..is it sitting in its idle position?
How is the wiring with the large round connector on the right hand side of the engine compartment just behined the ECUs which plugs to the relay box which also houses the pressure sensors?

Just a few things to check...Maybe you have already..HTH