Intermittent choke heater?

[Greg]

This question is mostly for Dan because he was having the same problems, but if anyone else has a good response then please help!


OK, so my high idle problem is once again intermittent. Sometimes when I start the car it will idle high (betw 2000 - 3000) for 5 min or even 3 or 4 min, but sometimes it will take 1/2 hour for the thing to drop to 900rpm.

Dan -- after you played around with the choke heater, did your intermittent problem get fixed? Was there a bad connection in there that you had to solder or something?

Could something else be causing this intermittent problem?

I rinsed down all my linkage w/carb cleaner a few weeks ago, and everything was running fine then. I don't THINK my problem is sticky linkage, but I really don't know for sure.


This is driving me crazy because it goes away for a few weeks after I rinse away some stuff and take stuff apart and put it together again, but then it comes back!!!

You guys down south or in Hawaii are spoiled because you don't have to deal with this freezing weather shit. I'm gonna be out on the street on my lunch break messing with this stuff while it's snowing in Chicago!

[DanG86LX]

Just insert ur multimeter (10A input) in series with choke heater wire. Pull the wires through firewall (he,he i don't have A/C so i use that hole for wires and vacuum lines) so u can check the reading while starting ur car or driving.. Should get readings like 0.5A -> 1A -> 0.5A for the first 5mts or so...
No, i couldn't repair the choke heater without destroying it. Mine start working again after removing it from the car, for a while it was showing infinite, then some huge resistance and then normal like 25ohms!
So far so good, sometimes is coming off too soon!

[Greg]

Dan,

Do you know what regulates the power that it gets? What switches the current from .5A to 1A and then .5A?

I think my problem is intermittent choke heater AND erratic or sticky throttle controller. I'm going to try to lube the TC arm and maybe change it's vacuum source to a constant vacuum from somewhere else. I'm thinking that I will rig it to the Choke opener where line 26 goes since my choke opener is disabled & I have my cable instead. 26 goes to cranking leak solenoid, which I don't need since I'm not using the choke opener. And I'll leave 18 connected betw choke opener and FIU.

I'm also going to cut the tabs on the lever that the choke-opener operates so I can pull open the choke more with my cable. I'm hoping that even if the CH is intermittent, I can pull it open a little more until engine heat pulls off the bimetal spring fully.

I like your idea of pulling the wires through the firewall to test. It certainly beats taking it apart every time it starts misbehaving (which is like every couple weeks for me). And I'm sure it's getting damn cold in Alberta now too.

I'll rig my stuff through the firewall somewhere too. I have AC, but maybe I can run it through somewhere else.

thanks,

-Greg in Chicago

[DanG86LX]

What switches the current from .5A to 1A and then .5A?
The choke gets 12V but it's a smart ass. A resistor of about 24..26ohms take .5A when car is started up to about 2mts. All this time is heating up till an internal thermo-switch connects a thermistor (which is basically another heating resistor) in parallel with 1st resistor, therefore the current jumps to 1A. Now the heat increases faster but.. what a thermistor does is it increases its resistance with the temperature -> current start decreasing slowly from 1A ..0.5A within ~5mts and it stays to .5A till the car is turned off.

TC ? depends how is rigged. My is quite simple like a M/T (also mine is A/T):
Manifold vacuum =[6]= (green-blue) dashpot check valve =[6]= TC diaphragm.
Well ur car might be different with that frequency solenoid C which means it controls idle speed too function of A/T load..
Which one u got ?

[Greg]

I have M/T. I think I may have been looking at an A/T because I thought I had the freq sol C. I was considering my vacuum re-routing because I thought maybe freq sol c was being flaky.

I probably just have a stick TC arm or maybe a tiny leak in the TC diaphram or something, but I don't feel like taking the diaphram apart in the cold weather.

Isn't a whole lot of other vacuum junk routed w/the same manifold vacuum source as the TC and its check valve? I was thinking that maybe some of this other stuff was malfunctioning sometimes and leaking vacuum away from the TC. (like the EGR system uses this vacuum source too, no?)

I get an idle surge when I hit the clutch sometimes (especially when cold), and sometimes it jumps to 2500 or 3000. Normally my high fast idle stays at like 2000-2200. But the surges are only occasional, and then seem to go away for a little while when I take everything apart, clean the Throttle linkage w/carb cleaner and then spray a little WD40 on it. I'm not sure if it's a problem of the actually throttle linkage sticking, the TC arm sticking, or an occasional sticking vacuum device (maybe a sticky check valve or something???) It is hard to diagnose because the problems are not constant. But when they do occur, I can have a terrible idle surge to like 2500 for the first 25 min of operation.

I was thinking about trying the re-routing just to see if it changes anything.

So the thermistor that's routed in parallel with the heater is actually integrated into the body of the CH itself, right? I took the cover off the CH the other day, and saw that it was all closed-up and insulated w/ that same insulation stuff that's on ignition coils. So I guess I'm not gonna mess with the CH itself.

Anyway, I'll let you know if I discover anything helpful while messing with this stuff.

Do you ever get the idle surge from stepping on the clutch (TC malfunction???)

[DanG86LX]

I wish i had a clutch...not autoclutch anyway.

Problems with TC and dashpot check valve has been reported by DuchBoy guess..
TC doesn't do much while driving, just follows throttle valve (TV), and keeps TV from closing too quickly while decelerating. U have a point here, i would say disable TC system and see.. How? Either tie up the lever that pulls TV (that would be the case when applying a permanent high vacuum source to it like when idling), or just bypass (remove) the dashpot valve (uh, never try it myself).

Have u checked throttle cable, sticky ? Does high rev go away when lifting ur gas pedal?