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Posted by: 2-OH! May 7 2007, 04:39 PM

I have already sent this to Brad Anders, but I decided I would like your opinion as well...

Going thru hell with 1973 - 1.7 D-Jet running awful from 0 to 180 degrees (oil temp)...Bucks, snorts, spits, unstable RPM, all before 180...Runs OK (not great but OK), after 180...

Newly rebuilt MPS (Bleyseng), switched ECU's with known good unit, no help...

Newly purchased from Pelican, Head Temp Sensor shows 3.16 OHMS...Old HTS shows 3.65 OHMS...

Currently re-sealing all intake runners, plenum, TB, etc. looking for vacuum leaks...While I had the Thermo-Time sensor off the block, I checked it with an OHM meter both hot and garage temp (approx. 75 degrees) and got no reading at all...Indicating to me that the unit is open...

As I read the wirnig diagram, all the Thermo-Time switch does is complete the ground for the Cold Start valve and therefore would not effect starts in 70 degree weather...

Is that your intrepretation of the Thermo Switch...If so, I can eliminate that as a possible source of my trouble...

Thanks,

2-OH!

Posted by: swl May 7 2007, 09:14 PM

QUOTE(2-OH! @ May 7 2007, 02:39 PM)

Posted by: jim_hoyland May 7 2007, 09:17 PM

Posted by: MrKona May 7 2007, 10:20 PM

Here's the description for the L-jet system, page 13. (Would assume it applies for all systems).

http://www.everybus.com/~greg_potts/Bosch_L-Jetronic_FI_Manual/

Controls the cold start valve.

Posted by: Jeff Bowlsby May 8 2007, 12:03 AM

"all the Thermo-Time switch does is complete the ground for the Cold Start valve and therefore would not effect starts in 70 degree weather..."

Yep, Uh-huh, javol...

Rich or lean when cold? Have you verified the AFR with a reliable exhaust gas analyzer? Geoff does excellent MPS work, but even a subtle adjustment to the MPS can make a big difference.

Posted by: Bartlett 914 May 8 2007, 07:55 AM

Make sure you have the correct ECU and CHT. Ones from a 74 will not work correctly. You also need a ballast resistor in series with the CHT. I am not sure of the correct resistance for the CHT for a 73 when cold. I know the resistance in in K ohms (3K, 2.5K something like that). You can always place a pot in place of the CHT. I would use a 5K pot with a 270 ohm resistors in series. Use this to find out if the problem is with the CHT or if it is some other problem like the MPS.

Posted by: 2-OH! May 8 2007, 12:36 PM

Don't know about the Rich/Lean situation because I have not checked it with an analyser...Don't know anyone who has one...But I think that is the problem, Rich/Lean...

I must disconnect the inlet temp sensor to get it to run at all...

I agree with the resistor in line with the CHT...But I was under the impression that the Resistor situation was only applicable to the 2.0 motor...I think I have a line on a pot setup and I would like to slave it in to gauge the change in performance...

Finished the re-sealing of all vacuum areas last nite and it drives pretty good after 180 degrees...This morning it was better, but still spittin' and sputterin' until I got to work because the 20 minute drive warmed it up...

2-OH!

Posted by: Jeff Bowlsby May 8 2007, 03:27 PM

Unplugging TS1 richens the mixture, so if it runs better that way, sounds like you may be running lean. Could be berry-berry-bad...check your plugs for a lean condition.

Posted by: 2-OH! May 8 2007, 05:16 PM

Thanks Jeff,

Currently, the ECU is set at one click past the midpoint...I may try to turn it up for the morning start tomorrow and see what happens...

New rings are still not broken in yet so we have sooty plug at this point...Hard to read Lean or Rich...

2-OH!