potentiometer testing on 89 TR

Have recently done an electrical check of entire car (following Steve's posts). Everything checks out perfectly except for the potentiometer tests on the F/Ds. Am I doing this the correct way? I was under the impression that when the bottom pin was touched to the top pin I should see 7 to 8 volts (fuel pump relays pulled, key on, wires jumped at starter solenoid) I am only getting .29 volts reading - the same on both F/D's. When touching the middle pin and topmost pin and slowly depressing the sensor plate the voltage smoothly goes from .39 to .8 volts ?? The tests for the actuators were good (tested at the wiring harness) one showed 20 ohms and the other 19.2. I am doing these tests while going after what appears to be a fuel distribution problem. I apologize for leaving a previous thread open concerning the rough running of this car but work and family kept me away.

 

Steve - your colors were correct and the red wire does have 12.7 volts - both F/D's have exactly the same reading. What the car is now doing - starts readily, idles nicely, revs freely but when you take it out for a drive it will surge 50% of the time under load with an occasional small backfire. I have spoken with David (who seems very knowledgeable) and he said to tackle fuel distribution as the probable cause. For a while the 7 - 12 bank was running cold and the CO hard to adjust, but now the exhaust temperature on both banks are within a few degrees of each other. Fuel pumps are both putting out well over a liter in 30 seconds at the return lines. Fresh fuel filters. Coils and spark test OK. The car (low mileage) still has the old metal injectors. They were pulled on the one side that was not running properly and tested. Four of them were hardly flowing - they were cleaned and when the spray patterns looked normal were placed back in the car - I have since ordered the newer brass injectors with Viton seals - if after installing these, the problem still exists, I am afraid I have to address the F/D's as David suggested. Since the car started to have a problem I now have read extensively on the Bosch CIS and KE Jetronic - but I am having difficulty in purchasing the WSM section D addition on KE Jetronic (pgs 68 - 101)

 

just returned home late from a busy work day - will do the new suggested tests in the morning - thanks - By the way, I just obtained a copy of the TR WSM extended D section

 

I have completed the above test and at this point am ready to drink some hemlock! The voltage on terminal 1 on both ECU connectors is only .4V - does not make a difference grounding to engine block. It appears on the wiring diagram (Fig3) that the red wires going to pin 1 of the ECU's originate from the C relay and go directly to pin 1 on the 1-6 bank and from there bridged over to pin 1 on the 7-12 bank. From there going thru a 2 way connector (where?) and continuing on to the water thermo switch and throttle micro switch. How is it possible that when the bridge is made at the starter solenoid and you hear the C relay working and there is 12V at the red wire on the water thermo switch that there can only be .4 volts at pin 1? On its way to the NC both red wires are connected together going in and out of the ECU. Also, the GR (yellow/red) wire going to the C relay terminal 30 is always hot even with the engine off and when the engine is running the red wires on terminal 30 will then show 12V - How, doing the above test, do you get 12V at pin 1 without the engine running? Somehow the red wire on the NC does show 12V without the engine running. I know i must be missing something here....

 

I just did the test again and the red wire at the thermo switch was at 12V but after a few seconds it dropped back to .3V - the same as pin 1 on the ECU connector - but when I tested pin 1 again it read .3V and then jumped to 12V for a short time and then read .3V again. The C relay smells funny. I am now getting the same .3V at terminal 87 on the relay as I am on pin 1 and the thermo switch. The relay was obviously working intermittently. This is a relatively new relay (part #92861512402) with the fuse inside the case - the fuse is not blown and the contacts are tight. This is a Porsche relay also. I actually bought it at a Porsche dealership. Bad relay? Or could something be causing this?

Steve,

1)when the bridge is made on the solenoid and you hear the protection relay open I should be getting 12V at terminal 87, correct?- which connects directly to pin 1 on the 1-6 ECU
2) Is there a way to test a new relay before placing it in the car?
Thanks for the assistance

 

Relay definitely bad -#30 12V, 87 very low V - will take ~ 1 week to get new relay and will follow up then