New O2 sensor, and a strange burning smell

[NckT]

Yes, it will draw in air right and cause a high idle if there was an air leak in there.

You could try adding 2 bolts/ wine corks/ bungs etc in the houses where the idle motor goes, and if there is still a high idle then the problem is not the idle motor or the ecu

[rjd2]

ok-i removed the idle motor. i can confirm it moves freely.

where to next?(can i assume we are moving downstream of the ECU?)

[NckT]

......You could try adding 2 bolts/ wine corks/ bungs etc in the houses where the idle motor goes, and if there is still a high idle then the problem is not the idle motor or the ecu

[rjd2]

ok, think i may have found the culprit, or at least made some progress: i took voltage measurements at the ECU. it's working properly. i choked off the idle motor hoses. same deal. checked all electrical harnesses. replaced o-ring at rear of mixture unit. all with no change.

when i pull the rubber pin at the fuel distributor, the idle drops down to "normal". after speaking to Steven at Delorean, I now think that my mixture may be off, with the car resulting in a high idle. i've tried several times to get a good dwell reading, and have never been very successful; any tips on how to get the mixture bang on? thanks for the help!

[NckT]

A simple method to get it to an approximate setting (assuming that the CPR/WUR is working within spec, vacuum hoses on correct and the vacuum system operating correctly) disconnect the oxygen sensor electrical connection so that the frequency valve operates at fixed dwell, on a warm normal operating temperature, use a 3mm Allen key turn screw right until the engine dies, then turn screw left until the engine dies, then turn it back to the middle of those 2 points, and insert the bung where the tamper proof plug was.

Obviously, count the number of turns you've done so you can go back to your start point if need be

[rjd2]

well, i think i'm back at what i now remember to be my starting place in all of this; the reason i did the thermister job in the first place:

the car won't hold an idle once it warms up. it will also often not start once it is warmed up, upon stall out; i can crank all i want, it wont start. i have to wait til it cools down to start it again.

i can tune the mixture so that the car will idle close to 850-ish(more like 1000 often times) at start up. as soon as it warms up, the idle will drop slowy, and then stall out. i think it's possible that the car was at one point tuned rich to compensate for a vacuum leak. when i overhauled the intake seals/thermister/O2 sensor/WUR, it's possible i solved the vacuum leak, and was left with a rich running car; i no longer get the 2000-2500 idle upon cold start.

any ideas as to what could cause that behavior? i have a new warm up regulator, 02 sensor, thermister, stainless steel fuel lines, o-rings, intake seals, distributor in place. i have verified the vacuum advance, idle motor, ECU, are all working properly. kinda stumped. could this just be a matter of getting the mixture set right? this is one thing that i'll admit i'm not a pro at. thanks!!!

[rjd2]

Think I have made progress! As of my last shakedown session, I was able to get the car to hold an idle under 1000RPM. This may sound silly, but it appears that the rubber plug at the mixture unit has hardened or dried out; if I force it down with an alan wrench, it would stay well below 2000RPM. While I'm not doing an entirely scientific mixture adjustment(basically going lean til it stalls out, then going clockwise till it holds an idle), it seems to work for now. Thanks for all your help, you guys!!